Unify under the `bindgen` name.

26 files changed, 11446 insertions, 0 deletions

diff --git a/src/chooser.rs b/src/chooser.rs
new file mode 100644
index 00000000..51392d70
--- /dev/null
+++ b/src/chooser.rs
@@ -0,0 +1,26 @@
+//! A public API for more fine-grained customization of bindgen behavior.
+
+pub use ir::int::IntKind;
+pub use ir::enum_ty::{EnumVariantValue, EnumVariantCustomBehavior};
+use std::fmt;
+
+/// A trait to allow configuring different kinds of types in different
+/// situations.
+pub trait TypeChooser: fmt::Debug {
+    /// The integer kind an integer macro should have, given a name and the
+    /// value of that macro, or `None` if you want the default to be chosen.
+    fn int_macro(&self, _name: &str, _value: i64) -> Option<IntKind> {
+        None
+    }
+
+    /// This function should return whether, given the a given enum variant
+    /// name, and value, returns whether this enum variant will forcibly be a
+    /// constant.
+    fn enum_variant_behavior(&self,
+                             _enum_name: Option<&str>,
+                             _variant_name: &str,
+                             _variant_value: EnumVariantValue)
+                             -> Option<EnumVariantCustomBehavior> {
+        None
+    }
+}
diff --git a/src/clang.rs b/src/clang.rs
new file mode 100644
index 00000000..491aaa07
--- /dev/null
+++ b/src/clang.rs
@@ -0,0 +1,1371 @@
+//! A higher level Clang API built on top of the generated bindings in the
+//! `clang_sys` module.
+
+#![allow(non_upper_case_globals, dead_code)]
+
+
+use cexpr;
+use clang_sys::*;
+use std::{mem, ptr, slice};
+use std::ffi::{CStr, CString};
+use std::fmt;
+use std::hash::Hash;
+use std::hash::Hasher;
+use std::os::raw::{c_char, c_int, c_uint, c_ulong};
+
+/// A cursor into the Clang AST, pointing to an AST node.
+///
+/// We call the AST node pointed to by the cursor the cursor's "referent".
+#[derive(Copy, Clone)]
+pub struct Cursor {
+    x: CXCursor,
+}
+
+impl fmt::Debug for Cursor {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        write!(fmt,
+               "Cursor({} kind: {}, loc: {}, usr: {:?})",
+               self.spelling(),
+               kind_to_str(self.kind()),
+               self.location(),
+               self.usr())
+    }
+}
+
+impl Cursor {
+    /// Get the Unified Symbol Resolution for this cursor's referent, if
+    /// available.
+    ///
+    /// The USR can be used to compare entities across translation units.
+    pub fn usr(&self) -> Option<String> {
+        let s = unsafe { cxstring_into_string(clang_getCursorUSR(self.x)) };
+        if s.is_empty() { None } else { Some(s) }
+    }
+
+    /// Is this cursor's referent a declaration?
+    pub fn is_declaration(&self) -> bool {
+        unsafe { clang_isDeclaration(self.kind()) != 0 }
+    }
+
+    /// Get the null cursor, which has no referent.
+    pub fn null() -> Self {
+        Cursor {
+            x: unsafe { clang_getNullCursor() },
+        }
+    }
+
+    /// Get this cursor's referent's spelling.
+    pub fn spelling(&self) -> String {
+        unsafe { cxstring_into_string(clang_getCursorSpelling(self.x)) }
+    }
+
+    /// Get this cursor's referent's display name.
+    ///
+    /// This is not necessarily a valid identifier. It includes extra
+    /// information, such as parameters for a function, etc.
+    pub fn display_name(&self) -> String {
+        unsafe { cxstring_into_string(clang_getCursorDisplayName(self.x)) }
+    }
+
+    /// Get the mangled name of this cursor's referent.
+    pub fn mangling(&self) -> String {
+        unsafe { cxstring_into_string(clang_Cursor_getMangling(self.x)) }
+    }
+
+    /// Get the `Cursor` for this cursor's referent's lexical parent.
+    ///
+    /// The lexical parent is the parent of the definition. The semantic parent
+    /// is the parent of the declaration. Generally, the lexical parent doesn't
+    /// have any effect on semantics, while the semantic parent does.
+    ///
+    /// In the following snippet, the `Foo` class would be the semantic parent
+    /// of the out-of-line `method` definition, while the lexical parent is the
+    /// translation unit.
+    ///
+    /// ```c++
+    /// class Foo {
+    ///     void method();
+    /// };
+    ///
+    /// void Foo::method() { /* ... */ }
+    /// ```
+    pub fn lexical_parent(&self) -> Cursor {
+        unsafe {
+            Cursor {
+                x: clang_getCursorLexicalParent(self.x),
+            }
+        }
+    }
+
+    /// Get the referent's semantic parent, if one is available.
+    ///
+    /// See documentation for `lexical_parent` for details on semantic vs
+    /// lexical parents.
+    pub fn fallible_semantic_parent(&self) -> Option<Cursor> {
+        let sp = unsafe {
+            Cursor {
+                x: clang_getCursorSemanticParent(self.x),
+            }
+        };
+        if sp == *self || !sp.is_valid() {
+            return None;
+        }
+        Some(sp)
+    }
+
+    /// Get the referent's semantic parent.
+    ///
+    /// See documentation for `lexical_parent` for details on semantic vs
+    /// lexical parents.
+    pub fn semantic_parent(&self) -> Cursor {
+        self.fallible_semantic_parent().unwrap()
+    }
+
+    /// Return the number of template arguments used by this cursor's referent,
+    /// if the referent is either a template specialization or
+    /// declaration. Returns -1 otherwise.
+    ///
+    /// NOTE: This may not return `Some` for some non-fully specialized
+    /// templates, see #193 and #194.
+    pub fn num_template_args(&self) -> Option<u32> {
+        let n: c_int = unsafe { clang_Cursor_getNumTemplateArguments(self.x) };
+
+        if n >= 0 {
+            Some(n as u32)
+        } else {
+            debug_assert_eq!(n, -1);
+            None
+        }
+    }
+
+    /// Get a cursor pointing to this referent's containing translation unit.
+    ///
+    /// Note that we shouldn't create a `TranslationUnit` struct here, because
+    /// bindgen assumes there will only be one of them alive at a time, and
+    /// disposes it on drop. That can change if this would be required, but I
+    /// think we can survive fine without it.
+    pub fn translation_unit(&self) -> Cursor {
+        assert!(self.is_valid());
+        unsafe {
+            let tu = clang_Cursor_getTranslationUnit(self.x);
+            let cursor = Cursor {
+                x: clang_getTranslationUnitCursor(tu),
+            };
+            assert!(cursor.is_valid());
+            cursor
+        }
+    }
+
+    /// Is the referent a top level construct?
+    pub fn is_toplevel(&self) -> bool {
+        let mut semantic_parent = self.fallible_semantic_parent();
+
+        while semantic_parent.is_some() &&
+              (semantic_parent.unwrap().kind() == CXCursor_Namespace ||
+               semantic_parent.unwrap().kind() == CXCursor_NamespaceAlias ||
+               semantic_parent.unwrap().kind() == CXCursor_NamespaceRef) {
+            semantic_parent = semantic_parent.unwrap()
+                .fallible_semantic_parent();
+        }
+
+        let tu = self.translation_unit();
+        // Yes, this can happen with, e.g., macro definitions.
+        semantic_parent == tu.fallible_semantic_parent()
+    }
+
+    /// There are a few kinds of types that we need to treat specially, mainly
+    /// not tracking the type declaration but the location of the cursor, given
+    /// clang doesn't expose a proper declaration for these types.
+    pub fn is_template_like(&self) -> bool {
+        match self.kind() {
+            CXCursor_ClassTemplate |
+            CXCursor_ClassTemplatePartialSpecialization |
+            CXCursor_TypeAliasTemplateDecl => true,
+            _ => false,
+        }
+    }
+
+    /// Get the kind of referent this cursor is pointing to.
+    pub fn kind(&self) -> CXCursorKind {
+        unsafe { clang_getCursorKind(self.x) }
+    }
+
+    /// Is the referent an anonymous record definition?
+    pub fn is_anonymous(&self) -> bool {
+        unsafe { clang_Cursor_isAnonymous(self.x) != 0 }
+    }
+
+    /// Is the referent a template specialization?
+    pub fn is_template(&self) -> bool {
+        self.specialized().is_some()
+    }
+
+    /// Is the referent a fully specialized template specialization without any
+    /// remaining free template arguments?
+    pub fn is_fully_specialized_template(&self) -> bool {
+        self.is_template() && self.num_template_args().unwrap_or(0) > 0
+    }
+
+    /// Is the referent a template specialization that still has remaining free
+    /// template arguments?
+    pub fn is_in_non_fully_specialized_template(&self) -> bool {
+        if self.is_toplevel() {
+            return false;
+        }
+        let parent = self.semantic_parent();
+        (parent.is_template() && !parent.is_fully_specialized_template()) ||
+        parent.is_in_non_fully_specialized_template()
+    }
+
+    /// Is this cursor pointing a valid referent?
+    pub fn is_valid(&self) -> bool {
+        unsafe { clang_isInvalid(self.kind()) == 0 }
+    }
+
+    /// Get the source location for the referent.
+    pub fn location(&self) -> SourceLocation {
+        unsafe {
+            SourceLocation {
+                x: clang_getCursorLocation(self.x),
+            }
+        }
+    }
+
+    /// Get the source location range for the referent.
+    pub fn extent(&self) -> CXSourceRange {
+        unsafe { clang_getCursorExtent(self.x) }
+    }
+
+    /// Get the raw declaration comment for this referent, if one exists.
+    pub fn raw_comment(&self) -> Option<String> {
+        let s = unsafe {
+            cxstring_into_string(clang_Cursor_getRawCommentText(self.x))
+        };
+        if s.is_empty() { None } else { Some(s) }
+    }
+
+    /// Get the referent's parsed comment.
+    pub fn comment(&self) -> Comment {
+        unsafe {
+            Comment {
+                x: clang_Cursor_getParsedComment(self.x),
+            }
+        }
+    }
+
+    /// Get the referent's type.
+    pub fn cur_type(&self) -> Type {
+        unsafe {
+            Type {
+                x: clang_getCursorType(self.x),
+            }
+        }
+    }
+
+    /// Given that this cursor's referent is a reference to another type, or is
+    /// a declaration, get the cursor pointing to the referenced type or type of
+    /// the declared thing.
+    pub fn definition(&self) -> Option<Cursor> {
+        unsafe {
+            let ret = Cursor {
+                x: clang_getCursorDefinition(self.x),
+            };
+
+            if ret.is_valid() { Some(ret) } else { None }
+        }
+    }
+
+    /// Given that this cursor's referent is reference type, get the cursor
+    /// pointing to the referenced type.
+    pub fn referenced(&self) -> Option<Cursor> {
+        unsafe {
+            let ret = Cursor {
+                x: clang_getCursorReferenced(self.x),
+            };
+
+            if ret.is_valid() { Some(ret) } else { None }
+        }
+    }
+
+    /// Get the canonical cursor for this referent.
+    ///
+    /// Many types can be declared multiple times before finally being properly
+    /// defined. This method allows us to get the canonical cursor for the
+    /// referent type.
+    pub fn canonical(&self) -> Cursor {
+        unsafe {
+            Cursor {
+                x: clang_getCanonicalCursor(self.x),
+            }
+        }
+    }
+
+    /// Given that this cursor points to a template specialization, get a cursor
+    /// pointing to the template definition that is being specialized.
+    pub fn specialized(&self) -> Option<Cursor> {
+        unsafe {
+            let ret = Cursor {
+                x: clang_getSpecializedCursorTemplate(self.x),
+            };
+            if ret.is_valid() { Some(ret) } else { None }
+        }
+    }
+
+    /// Assuming that this cursor's referent is a template declaration, get the
+    /// kind of cursor that would be generated for its specializations.
+    pub fn template_kind(&self) -> CXCursorKind {
+        unsafe { clang_getTemplateCursorKind(self.x) }
+    }
+
+    /// Traverse this cursor's referent and its children.
+    ///
+    /// Call the given function on each AST node traversed.
+    pub fn visit<Visitor>(&self, mut visitor: Visitor)
+        where Visitor: FnMut(Cursor) -> CXChildVisitResult,
+    {
+        unsafe {
+            clang_visitChildren(self.x,
+                                visit_children::<Visitor>,
+                                mem::transmute(&mut visitor));
+        }
+    }
+
+    /// Returns whether the given location contains a cursor with the given
+    /// kind in the first level of nesting underneath (doesn't look
+    /// recursively).
+    pub fn contains_cursor(&self, kind: CXCursorKind) -> bool {
+        let mut found = false;
+
+        self.visit(|c| {
+            if c.kind() == kind {
+                found = true;
+                CXChildVisit_Break
+            } else {
+                CXChildVisit_Continue
+            }
+        });
+
+        found
+    }
+
+    /// Is the referent an inlined function?
+    pub fn is_inlined_function(&self) -> bool {
+        clang_Cursor_isFunctionInlined::is_loaded() &&
+        unsafe { clang_Cursor_isFunctionInlined(self.x) != 0 }
+    }
+
+    /// Get the width of this cursor's referent bit field, or `None` if the
+    /// referent is not a bit field.
+    pub fn bit_width(&self) -> Option<u32> {
+        unsafe {
+            let w = clang_getFieldDeclBitWidth(self.x);
+            if w == -1 { None } else { Some(w as u32) }
+        }
+    }
+
+    /// Get the integer representation type used to hold this cursor's referent
+    /// enum type.
+    pub fn enum_type(&self) -> Option<Type> {
+        unsafe {
+            let t = Type {
+                x: clang_getEnumDeclIntegerType(self.x),
+            };
+            if t.is_valid() { Some(t) } else { None }
+        }
+    }
+
+    /// Get the signed constant value for this cursor's enum variant referent.
+    ///
+    /// Returns None if the cursor's referent is not an enum variant.
+    pub fn enum_val_signed(&self) -> Option<i64> {
+        unsafe {
+            if self.kind() == CXCursor_EnumConstantDecl {
+                Some(clang_getEnumConstantDeclValue(self.x) as i64)
+            } else {
+                None
+            }
+        }
+    }
+
+    /// Get the unsigned constant value for this cursor's enum variant referent.
+    ///
+    /// Returns None if the cursor's referent is not an enum variant.
+    pub fn enum_val_unsigned(&self) -> Option<u64> {
+        unsafe {
+            if self.kind() == CXCursor_EnumConstantDecl {
+                Some(clang_getEnumConstantDeclUnsignedValue(self.x) as u64)
+            } else {
+                None
+            }
+        }
+    }
+
+    /// Given that this cursor's referent is a `typedef`, get the `Type` that is
+    /// being aliased.
+    pub fn typedef_type(&self) -> Option<Type> {
+        let inner = Type {
+            x: unsafe { clang_getTypedefDeclUnderlyingType(self.x) },
+        };
+
+        if inner.is_valid() { Some(inner) } else { None }
+    }
+
+    /// Get the linkage kind for this cursor's referent.
+    ///
+    /// This only applies to functions and variables.
+    pub fn linkage(&self) -> CXLinkageKind {
+        unsafe { clang_getCursorLinkage(self.x) }
+    }
+
+    /// Get the visibility of this cursor's referent.
+    pub fn visibility(&self) -> CXVisibilityKind {
+        unsafe { clang_getCursorVisibility(self.x) }
+    }
+
+    /// Given that this cursor's referent is a function, return cursors to its
+    /// parameters.
+    pub fn args(&self) -> Option<Vec<Cursor>> {
+        // XXX: We might want to use and keep num_args
+        // match self.kind() {
+        // CXCursor_FunctionDecl |
+        // CXCursor_CXXMethod => {
+        unsafe {
+            let w = clang_Cursor_getNumArguments(self.x);
+            if w == -1 {
+                None
+            } else {
+                let num = w as u32;
+
+                let mut args = vec![];
+                for i in 0..num {
+                    args.push(Cursor {
+                        x: clang_Cursor_getArgument(self.x, i as c_uint),
+                    });
+                }
+                Some(args)
+            }
+        }
+    }
+
+    /// Given that this cursor's referent is a function/method call or
+    /// declaration, return the number of arguments it takes.
+    ///
+    /// Returns -1 if the cursor's referent is not a function/method call or
+    /// declaration.
+    pub fn num_args(&self) -> Result<u32, ()> {
+        unsafe {
+            let w = clang_Cursor_getNumArguments(self.x);
+            if w == -1 { Err(()) } else { Ok(w as u32) }
+        }
+    }
+
+    /// Get the access specifier for this cursor's referent.
+    pub fn access_specifier(&self) -> CX_CXXAccessSpecifier {
+        unsafe { clang_getCXXAccessSpecifier(self.x) }
+    }
+
+    /// Is this cursor's referent a field declaration that is marked as
+    /// `mutable`?
+    pub fn is_mutable_field(&self) -> bool {
+        unsafe { clang_CXXField_isMutable(self.x) != 0 }
+    }
+
+    /// Is this cursor's referent a member function that is declared `static`?
+    pub fn method_is_static(&self) -> bool {
+        unsafe { clang_CXXMethod_isStatic(self.x) != 0 }
+    }
+
+    /// Is this cursor's referent a member function that is declared `const`?
+    pub fn method_is_const(&self) -> bool {
+        unsafe { clang_CXXMethod_isConst(self.x) != 0 }
+    }
+
+    /// Is this cursor's referent a member function that is declared `const`?
+    pub fn method_is_virtual(&self) -> bool {
+        unsafe { clang_CXXMethod_isVirtual(self.x) != 0 }
+    }
+
+    /// Is this cursor's referent a struct or class with virtual members?
+    pub fn is_virtual_base(&self) -> bool {
+        unsafe { clang_isVirtualBase(self.x) != 0 }
+    }
+
+    /// Try to evaluate this cursor.
+    pub fn evaluate(&self) -> Option<EvalResult> {
+        EvalResult::new(*self)
+    }
+}
+
+extern "C" fn visit_children<Visitor>(cur: CXCursor,
+                                      _parent: CXCursor,
+                                      data: CXClientData)
+                                      -> CXChildVisitResult
+    where Visitor: FnMut(Cursor) -> CXChildVisitResult,
+{
+    let func: &mut Visitor = unsafe { mem::transmute(data) };
+    let child = Cursor {
+        x: cur,
+    };
+
+    (*func)(child)
+}
+
+impl PartialEq for Cursor {
+    fn eq(&self, other: &Cursor) -> bool {
+        unsafe { clang_equalCursors(self.x, other.x) == 1 }
+    }
+}
+
+impl Eq for Cursor {}
+
+impl Hash for Cursor {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        unsafe { clang_hashCursor(self.x) }.hash(state)
+    }
+}
+
+/// The type of a node in clang's AST.
+#[derive(Clone)]
+pub struct Type {
+    x: CXType,
+}
+
+impl PartialEq for Type {
+    fn eq(&self, other: &Self) -> bool {
+        unsafe { clang_equalTypes(self.x, other.x) != 0 }
+    }
+}
+
+impl Eq for Type {}
+
+impl fmt::Debug for Type {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        write!(fmt,
+               "Type({}, kind: {}, decl: {:?}, canon: {:?})",
+               self.spelling(),
+               type_to_str(self.kind()),
+               self.declaration(),
+               self.declaration().canonical())
+    }
+}
+
+/// An error about the layout of a struct, class, or type.
+#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
+pub enum LayoutError {
+    /// Asked for the layout of an invalid type.
+    Invalid,
+    /// Asked for the layout of an incomplete type.
+    Incomplete,
+    /// Asked for the layout of a dependent type.
+    Dependent,
+    /// Asked for the layout of a type that does not have constant size.
+    NotConstantSize,
+    /// Asked for the layout of a field in a type that does not have such a
+    /// field.
+    InvalidFieldName,
+    /// An unknown layout error.
+    Unknown,
+}
+
+impl ::std::convert::From<i32> for LayoutError {
+    fn from(val: i32) -> Self {
+        use self::LayoutError::*;
+        let val = match CXTypeLayoutError::from_raw(val) {
+            Some(val) => val,
+            None => return Unknown,
+        };
+
+        match val {
+            CXTypeLayoutError_Invalid => Invalid,
+            CXTypeLayoutError_Incomplete => Incomplete,
+            CXTypeLayoutError_Dependent => Dependent,
+            CXTypeLayoutError_NotConstantSize => NotConstantSize,
+            CXTypeLayoutError_InvalidFieldName => InvalidFieldName,
+            _ => Unknown,
+        }
+    }
+}
+
+impl Type {
+    /// Get this type's kind.
+    pub fn kind(&self) -> CXTypeKind {
+        self.x.kind
+    }
+
+    /// Get a cursor pointing to this type's declaration.
+    pub fn declaration(&self) -> Cursor {
+        unsafe {
+            Cursor {
+                x: clang_getTypeDeclaration(self.x),
+            }
+        }
+    }
+
+    /// Get a raw display name for this type.
+    pub fn spelling(&self) -> String {
+        unsafe { cxstring_into_string(clang_getTypeSpelling(self.x)) }
+    }
+
+    /// Is this type const qualified?
+    pub fn is_const(&self) -> bool {
+        unsafe { clang_isConstQualifiedType(self.x) != 0 }
+    }
+
+    /// What is the size of this type? Paper over invalid types by returning `0`
+    /// for them.
+    pub fn size(&self) -> usize {
+        unsafe {
+            let val = clang_Type_getSizeOf(self.x);
+            if val < 0 { 0 } else { val as usize }
+        }
+    }
+
+    /// What is the size of this type?
+    pub fn fallible_size(&self) -> Result<usize, LayoutError> {
+        let val = unsafe { clang_Type_getSizeOf(self.x) };
+        if val < 0 {
+            Err(LayoutError::from(val as i32))
+        } else {
+            Ok(val as usize)
+        }
+    }
+
+    /// What is the alignment of this type? Paper over invalid types by
+    /// returning `0`.
+    pub fn align(&self) -> usize {
+        unsafe {
+            let val = clang_Type_getAlignOf(self.x);
+            if val < 0 { 0 } else { val as usize }
+        }
+    }
+
+    /// What is the alignment of this type?
+    pub fn fallible_align(&self) -> Result<usize, LayoutError> {
+        unsafe {
+            let val = clang_Type_getAlignOf(self.x);
+            if val < 0 {
+                Err(LayoutError::from(val as i32))
+            } else {
+                Ok(val as usize)
+            }
+        }
+    }
+
+    /// Get the layout for this type, or an error describing why it does not
+    /// have a valid layout.
+    pub fn fallible_layout(&self) -> Result<::ir::layout::Layout, LayoutError> {
+        use ir::layout::Layout;
+        let size = try!(self.fallible_size());
+        let align = try!(self.fallible_align());
+        Ok(Layout::new(size, align))
+    }
+
+    /// If this type is a class template specialization, return its
+    /// template arguments. Otherwise, return None.
+    pub fn template_args(&self) -> Option<TypeTemplateArgIterator> {
+        let n = unsafe { clang_Type_getNumTemplateArguments(self.x) };
+        if n >= 0 {
+            Some(TypeTemplateArgIterator {
+                x: self.x,
+                length: n as u32,
+                index: 0,
+            })
+        } else {
+            debug_assert_eq!(n, -1);
+            None
+        }
+    }
+
+    /// Given that this type is a pointer type, return the type that it points
+    /// to.
+    pub fn pointee_type(&self) -> Option<Type> {
+        match self.kind() {
+            CXType_Pointer |
+            CXType_RValueReference |
+            CXType_LValueReference |
+            CXType_MemberPointer => {
+                let ret = Type {
+                    x: unsafe { clang_getPointeeType(self.x) },
+                };
+                debug_assert!(ret.is_valid());
+                Some(ret)
+            }
+            _ => None,
+        }
+    }
+
+    /// Given that this type is an array, vector, or complex type, return the
+    /// type of its elements.
+    pub fn elem_type(&self) -> Option<Type> {
+        let current_type = Type {
+            x: unsafe { clang_getElementType(self.x) },
+        };
+        if current_type.is_valid() {
+            Some(current_type)
+        } else {
+            None
+        }
+    }
+
+    /// Given that this type is an array or vector type, return its number of
+    /// elements.
+    pub fn num_elements(&self) -> Option<usize> {
+        let num_elements_returned = unsafe { clang_getNumElements(self.x) };
+        if num_elements_returned != -1 {
+            Some(num_elements_returned as usize)
+        } else {
+            None
+        }
+    }
+
+    /// Get the canonical version of this type. This sees through `typdef`s and
+    /// aliases to get the underlying, canonical type.
+    pub fn canonical_type(&self) -> Type {
+        unsafe {
+            Type {
+                x: clang_getCanonicalType(self.x),
+            }
+        }
+    }
+
+    /// Is this type a variadic function type?
+    pub fn is_variadic(&self) -> bool {
+        unsafe { clang_isFunctionTypeVariadic(self.x) != 0 }
+    }
+
+    /// Given that this type is a function type, get the type of its return
+    /// value.
+    pub fn ret_type(&self) -> Option<Type> {
+        let rt = Type {
+            x: unsafe { clang_getResultType(self.x) },
+        };
+        if rt.is_valid() { Some(rt) } else { None }
+    }
+
+    /// Given that this type is a function type, get its calling convention. If
+    /// this is not a function type, `CXCallingConv_Invalid` is returned.
+    pub fn call_conv(&self) -> CXCallingConv {
+        unsafe { clang_getFunctionTypeCallingConv(self.x) }
+    }
+
+    /// For elaborated types (types which use `class`, `struct`, or `union` to
+    /// disambiguate types from local bindings), get the underlying type.
+    pub fn named(&self) -> Type {
+        unsafe {
+            Type {
+                x: clang_Type_getNamedType(self.x),
+            }
+        }
+    }
+
+    /// Is this a valid type?
+    pub fn is_valid(&self) -> bool {
+        self.kind() != CXType_Invalid
+    }
+
+    /// Is this a valid and exposed type?
+    pub fn is_valid_and_exposed(&self) -> bool {
+        self.is_valid() && self.kind() != CXType_Unexposed
+    }
+
+    /// Is this type a fully specialized template?
+    pub fn is_fully_specialized_template(&self) -> bool {
+        // Yep, the spelling of this containing type-parameter is extremely
+        // nasty... But can happen in <type_traits>. Unfortunately I couldn't
+        // reduce it enough :(
+        !self.spelling().contains("type-parameter") &&
+        self.template_args()
+            .map_or(false, |mut args| {
+                args.len() > 0 &&
+                !args.any(|t| t.spelling().contains("type-parameter"))
+            })
+    }
+}
+
+/// An iterator for a type's template arguments.
+pub struct TypeTemplateArgIterator {
+    x: CXType,
+    length: u32,
+    index: u32,
+}
+
+impl Iterator for TypeTemplateArgIterator {
+    type Item = Type;
+    fn next(&mut self) -> Option<Type> {
+        if self.index < self.length {
+            let idx = self.index as c_uint;
+            self.index += 1;
+            Some(Type {
+                x: unsafe { clang_Type_getTemplateArgumentAsType(self.x, idx) },
+            })
+        } else {
+            None
+        }
+    }
+}
+
+impl ExactSizeIterator for TypeTemplateArgIterator {
+    fn len(&self) -> usize {
+        assert!(self.index <= self.length);
+        (self.length - self.index) as usize
+    }
+}
+
+/// A `SourceLocation` is a file, line, column, and byte offset location for
+/// some source text.
+pub struct SourceLocation {
+    x: CXSourceLocation,
+}
+
+impl SourceLocation {
+    /// Get the (file, line, column, byte offset) tuple for this source
+    /// location.
+    pub fn location(&self) -> (File, usize, usize, usize) {
+        unsafe {
+            let mut file = mem::zeroed();
+            let mut line = 0;
+            let mut col = 0;
+            let mut off = 0;
+            clang_getSpellingLocation(self.x,
+                                      &mut file,
+                                      &mut line,
+                                      &mut col,
+                                      &mut off);
+            (File {
+                x: file,
+            },
+             line as usize,
+             col as usize,
+             off as usize)
+        }
+    }
+}
+
+impl fmt::Display for SourceLocation {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        let (file, line, col, _) = self.location();
+        if let Some(name) = file.name() {
+            write!(f, "{}:{}:{}", name, line, col)
+        } else {
+            "builtin definitions".fmt(f)
+        }
+    }
+}
+
+/// A comment in the source text.
+///
+/// Comments are sort of parsed by Clang, and have a tree structure.
+pub struct Comment {
+    x: CXComment,
+}
+
+impl Comment {
+    /// What kind of comment is this?
+    pub fn kind(&self) -> CXCommentKind {
+        unsafe { clang_Comment_getKind(self.x) }
+    }
+
+    /// Get this comment's children comment
+    pub fn get_children(&self) -> CommentChildrenIterator {
+        CommentChildrenIterator {
+            parent: self.x,
+            length: unsafe { clang_Comment_getNumChildren(self.x) },
+            index: 0,
+        }
+    }
+
+    /// Given that this comment is the start or end of an HTML tag, get its tag
+    /// name.
+    pub fn get_tag_name(&self) -> String {
+        unsafe { cxstring_into_string(clang_HTMLTagComment_getTagName(self.x)) }
+    }
+
+    /// Given that this comment is an HTML start tag, get its attributes.
+    pub fn get_tag_attrs(&self) -> CommentAttributesIterator {
+        CommentAttributesIterator {
+            x: self.x,
+            length: unsafe { clang_HTMLStartTag_getNumAttrs(self.x) },
+            index: 0,
+        }
+    }
+}
+
+/// An iterator for a comment's children
+pub struct CommentChildrenIterator {
+    parent: CXComment,
+    length: c_uint,
+    index: c_uint,
+}
+
+impl Iterator for CommentChildrenIterator {
+    type Item = Comment;
+    fn next(&mut self) -> Option<Comment> {
+        if self.index < self.length {
+            let idx = self.index;
+            self.index += 1;
+            Some(Comment {
+                x: unsafe { clang_Comment_getChild(self.parent, idx) },
+            })
+        } else {
+            None
+        }
+    }
+}
+
+/// An HTML start tag comment attribute
+pub struct CommentAttribute {
+    /// HTML start tag attribute name
+    pub name: String,
+    /// HTML start tag attribute value
+    pub value: String,
+}
+
+/// An iterator for a comment's attributes
+pub struct CommentAttributesIterator {
+    x: CXComment,
+    length: c_uint,
+    index: c_uint,
+}
+
+impl Iterator for CommentAttributesIterator {
+    type Item = CommentAttribute;
+    fn next(&mut self) -> Option<CommentAttribute> {
+        if self.index < self.length {
+            let idx = self.index;
+            self.index += 1;
+            Some(CommentAttribute {
+                name: unsafe {
+                    cxstring_into_string(
+                        clang_HTMLStartTag_getAttrName(self.x, idx))
+                },
+                value: unsafe {
+                    cxstring_into_string(
+                        clang_HTMLStartTag_getAttrValue(self.x, idx))
+                },
+            })
+        } else {
+            None
+        }
+    }
+}
+
+/// A source file.
+pub struct File {
+    x: CXFile,
+}
+
+impl File {
+    /// Get the name of this source file.
+    pub fn name(&self) -> Option<String> {
+        if self.x.is_null() {
+            return None;
+        }
+        Some(unsafe { cxstring_into_string(clang_getFileName(self.x)) })
+    }
+}
+
+fn cxstring_into_string(s: CXString) -> String {
+    if s.data.is_null() {
+        return "".to_owned();
+    }
+    unsafe {
+        let c_str = CStr::from_ptr(clang_getCString(s) as *const _);
+        let ret = c_str.to_string_lossy().into_owned();
+        clang_disposeString(s);
+        ret
+    }
+}
+
+/// An `Index` is an environment for a set of translation units that will
+/// typically end up linked together in one final binary.
+pub struct Index {
+    x: CXIndex,
+}
+
+impl Index {
+    /// Construct a new `Index`.
+    ///
+    /// The `pch` parameter controls whether declarations in pre-compiled
+    /// headers are included when enumerating a translation unit's "locals".
+    ///
+    /// The `diag` parameter controls whether debugging diagnostics are enabled.
+    pub fn new(pch: bool, diag: bool) -> Index {
+        unsafe {
+            Index {
+                x: clang_createIndex(pch as c_int, diag as c_int),
+            }
+        }
+    }
+}
+
+impl fmt::Debug for Index {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        write!(fmt, "Index {{ }}")
+    }
+}
+
+impl Drop for Index {
+    fn drop(&mut self) {
+        unsafe {
+            clang_disposeIndex(self.x);
+        }
+    }
+}
+
+/// A token emitted by clang's lexer.
+#[derive(Debug)]
+pub struct Token {
+    /// The kind of token this is.
+    pub kind: CXTokenKind,
+    /// A display name for this token.
+    pub spelling: String,
+}
+
+/// A translation unit (or "compilation unit").
+pub struct TranslationUnit {
+    x: CXTranslationUnit,
+}
+
+impl fmt::Debug for TranslationUnit {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        write!(fmt, "TranslationUnit {{ }}")
+    }
+}
+
+impl TranslationUnit {
+    /// Parse a source file into a translation unit.
+    pub fn parse(ix: &Index,
+                 file: &str,
+                 cmd_args: &[String],
+                 unsaved: &[UnsavedFile],
+                 opts: CXTranslationUnit_Flags)
+                 -> Option<TranslationUnit> {
+        let fname = CString::new(file).unwrap();
+        let _c_args: Vec<CString> =
+            cmd_args.iter().map(|s| CString::new(s.clone()).unwrap()).collect();
+        let c_args: Vec<*const c_char> =
+            _c_args.iter().map(|s| s.as_ptr()).collect();
+        let mut c_unsaved: Vec<CXUnsavedFile> =
+            unsaved.iter().map(|f| f.x).collect();
+        let tu = unsafe {
+            clang_parseTranslationUnit(ix.x,
+                                       fname.as_ptr(),
+                                       c_args.as_ptr(),
+                                       c_args.len() as c_int,
+                                       c_unsaved.as_mut_ptr(),
+                                       c_unsaved.len() as c_uint,
+                                       opts)
+        };
+        if tu.is_null() {
+            None
+        } else {
+            Some(TranslationUnit {
+                x: tu,
+            })
+        }
+    }
+
+    /// Get the Clang diagnostic information associated with this translation
+    /// unit.
+    pub fn diags(&self) -> Vec<Diagnostic> {
+        unsafe {
+            let num = clang_getNumDiagnostics(self.x) as usize;
+            let mut diags = vec![];
+            for i in 0..num {
+                diags.push(Diagnostic {
+                    x: clang_getDiagnostic(self.x, i as c_uint),
+                });
+            }
+            diags
+        }
+    }
+
+    /// Get a cursor pointing to the root of this translation unit's AST.
+    pub fn cursor(&self) -> Cursor {
+        unsafe {
+            Cursor {
+                x: clang_getTranslationUnitCursor(self.x),
+            }
+        }
+    }
+
+    /// Is this the null translation unit?
+    pub fn is_null(&self) -> bool {
+        self.x.is_null()
+    }
+
+    /// Invoke Clang's lexer on this translation unit and get the stream of
+    /// tokens that come out.
+    pub fn tokens(&self, cursor: &Cursor) -> Option<Vec<Token>> {
+        let range = cursor.extent();
+        let mut tokens = vec![];
+        unsafe {
+            let mut token_ptr = ptr::null_mut();
+            let mut num_tokens: c_uint = 0;
+            clang_tokenize(self.x, range, &mut token_ptr, &mut num_tokens);
+            if token_ptr.is_null() {
+                return None;
+            }
+
+            let token_array = slice::from_raw_parts(token_ptr,
+                                                    num_tokens as usize);
+            for &token in token_array.iter() {
+                let kind = clang_getTokenKind(token);
+                let spelling =
+                    cxstring_into_string(clang_getTokenSpelling(self.x, token));
+
+                tokens.push(Token {
+                    kind: kind,
+                    spelling: spelling,
+                });
+            }
+            clang_disposeTokens(self.x, token_ptr, num_tokens);
+        }
+        Some(tokens)
+    }
+
+    /// Convert a set of tokens from clang into `cexpr` tokens, for further
+    /// processing.
+    pub fn cexpr_tokens(&self,
+                        cursor: &Cursor)
+                        -> Option<Vec<cexpr::token::Token>> {
+        use cexpr::token;
+
+        let mut tokens = match self.tokens(cursor) {
+            Some(tokens) => tokens,
+            None => return None,
+        };
+
+        // FIXME(emilio): LLVM 3.9 at least always include an extra token for no
+        // good reason (except if we're at EOF). So we do this kind of hack,
+        // where we skip known-to-cause problems trailing punctuation and
+        // trailing keywords.
+        //
+        // This is sort of unfortunate, though :(.
+        //
+        // I'll try to get it fixed in LLVM if I have the time to submit a
+        // patch.
+        let mut trim_last_token = false;
+        if let Some(token) = tokens.last() {
+            // The starting of the next macro.
+            trim_last_token |= token.spelling == "#" &&
+                               token.kind == CXToken_Punctuation;
+
+            // A following keyword of any kind, like a following declaration.
+            trim_last_token |= token.kind == CXToken_Keyword;
+        }
+
+        if trim_last_token {
+            tokens.pop().unwrap();
+        }
+
+        Some(tokens.into_iter()
+            .filter_map(|token| {
+                let kind = match token.kind {
+                    CXToken_Punctuation => token::Kind::Punctuation,
+                    CXToken_Literal => token::Kind::Literal,
+                    CXToken_Identifier => token::Kind::Identifier,
+                    CXToken_Keyword => token::Kind::Keyword,
+                    // NB: cexpr is not too happy about comments inside
+                    // expressions, so we strip them down here.
+                    CXToken_Comment => return None,
+                    _ => {
+                        panic!("Found unexpected token kind: {:?}", token.kind)
+                    }
+                };
+
+                Some(token::Token {
+                    kind: kind,
+                    raw: token.spelling.into_bytes().into_boxed_slice(),
+                })
+            })
+            .collect::<Vec<_>>())
+    }
+}
+
+impl Drop for TranslationUnit {
+    fn drop(&mut self) {
+        unsafe {
+            clang_disposeTranslationUnit(self.x);
+        }
+    }
+}
+
+
+/// A diagnostic message generated while parsing a translation unit.
+pub struct Diagnostic {
+    x: CXDiagnostic,
+}
+
+impl Diagnostic {
+    /// Format this diagnostic message as a string, using the given option bit
+    /// flags.
+    pub fn format(&self) -> String {
+        unsafe {
+            let opts = clang_defaultDiagnosticDisplayOptions();
+            cxstring_into_string(clang_formatDiagnostic(self.x, opts))
+        }
+    }
+
+    /// What is the severity of this diagnostic message?
+    pub fn severity(&self) -> CXDiagnosticSeverity {
+        unsafe { clang_getDiagnosticSeverity(self.x) }
+    }
+}
+
+impl Drop for Diagnostic {
+    /// Destroy this diagnostic message.
+    fn drop(&mut self) {
+        unsafe {
+            clang_disposeDiagnostic(self.x);
+        }
+    }
+}
+
+/// A file which has not been saved to disk.
+pub struct UnsavedFile {
+    x: CXUnsavedFile,
+    name: CString,
+    contents: CString,
+}
+
+impl UnsavedFile {
+    /// Construct a new unsaved file with the given `name` and `contents`.
+    pub fn new(name: &str, contents: &str) -> UnsavedFile {
+        let name = CString::new(name).unwrap();
+        let contents = CString::new(contents).unwrap();
+        let x = CXUnsavedFile {
+            Filename: name.as_ptr(),
+            Contents: contents.as_ptr(),
+            Length: contents.as_bytes().len() as c_ulong,
+        };
+        UnsavedFile {
+            x: x,
+            name: name,
+            contents: contents,
+        }
+    }
+}
+
+/// Convert a cursor kind into a static string.
+pub fn kind_to_str(x: CXCursorKind) -> String {
+    unsafe { cxstring_into_string(clang_getCursorKindSpelling(x)) }
+}
+
+/// Convert a type kind to a static string.
+pub fn type_to_str(x: CXTypeKind) -> String {
+    unsafe { cxstring_into_string(clang_getTypeKindSpelling(x)) }
+}
+
+/// Dump the Clang AST to stdout for debugging purposes.
+pub fn ast_dump(c: &Cursor, depth: isize) -> CXChildVisitResult {
+    fn print_indent(depth: isize, s: &str) {
+        for _ in 0..depth {
+            print!("\t");
+        }
+        println!("{}", s);
+    }
+
+    print_indent(depth,
+                 &format!("(kind: {}, spelling: {}, type: {}",
+                          kind_to_str(c.kind()),
+                          c.spelling(),
+                          type_to_str(c.cur_type().kind())));
+
+    // Recurse.
+    c.visit(|s| ast_dump(&s, depth + 1));
+
+    print_indent(depth, ")");
+
+    CXChildVisit_Continue
+}
+
+/// Try to extract the clang version to a string
+pub fn extract_clang_version() -> String {
+    unsafe { cxstring_into_string(clang_getClangVersion()) }
+}
+
+/// A wrapper for the result of evaluating an expression.
+#[derive(Debug)]
+pub struct EvalResult {
+    x: CXEvalResult,
+}
+
+impl EvalResult {
+    /// Evaluate `cursor` and return the result.
+    pub fn new(cursor: Cursor) -> Option<Self> {
+        if !clang_Cursor_Evaluate::is_loaded() {
+            return None;
+        }
+
+        // Clang has an internal assertion we can trigger if we try to evaluate
+        // a cursor containing a variadic template type reference. Triggering
+        // the assertion aborts the process, and we don't want that. Clang
+        // *also* doesn't expose any API for finding variadic vs non-variadic
+        // template type references, let alone whether a type referenced is a
+        // template type, instead they seem to show up as type references to an
+        // unexposed type. Our solution is to just flat out ban all
+        // `CXType_Unexposed` from evaluation.
+        let mut found_cant_eval = false;
+        cursor.visit(|c| {
+            if c.kind() == CXCursor_TypeRef &&
+               c.cur_type().kind() == CXType_Unexposed {
+                found_cant_eval = true;
+                CXChildVisit_Break
+            } else {
+                CXChildVisit_Recurse
+            }
+        });
+        if found_cant_eval {
+            return None;
+        }
+
+        Some(EvalResult {
+            x: unsafe { clang_Cursor_Evaluate(cursor.x) },
+        })
+    }
+
+    fn kind(&self) -> CXEvalResultKind {
+        unsafe { clang_EvalResult_getKind(self.x) }
+    }
+
+    /// Try to get back the result as a double.
+    pub fn as_double(&self) -> Option<f64> {
+        match self.kind() {
+            CXEval_Float => {
+                Some(unsafe { clang_EvalResult_getAsDouble(self.x) } as f64)
+            }
+            _ => None,
+        }
+    }
+
+    /// Try to get back the result as an integer.
+    pub fn as_int(&self) -> Option<i32> {
+        match self.kind() {
+            CXEval_Int => {
+                Some(unsafe { clang_EvalResult_getAsInt(self.x) } as i32)
+            }
+            _ => None,
+        }
+    }
+
+    /// Evaluates the expression as a literal string, that may or may not be
+    /// valid utf-8.
+    pub fn as_literal_string(&self) -> Option<Vec<u8>> {
+        match self.kind() {
+            CXEval_StrLiteral => {
+                let ret = unsafe {
+                    CStr::from_ptr(clang_EvalResult_getAsStr(self.x))
+                };
+                Some(ret.to_bytes().to_vec())
+            }
+            _ => None,
+        }
+    }
+}
+
+impl Drop for EvalResult {
+    fn drop(&mut self) {
+        unsafe { clang_EvalResult_dispose(self.x) };
+    }
+}
diff --git a/src/codegen/helpers.rs b/src/codegen/helpers.rs
new file mode 100644
index 00000000..06dadab0
--- /dev/null
+++ b/src/codegen/helpers.rs
@@ -0,0 +1,190 @@
+//! Helpers for code generation that don't need macro expansion.
+
+use aster;
+use ir::layout::Layout;
+use syntax::ast;
+use syntax::ptr::P;
+
+
+pub mod attributes {
+    use aster;
+    use syntax::ast;
+
+    pub fn repr(which: &str) -> ast::Attribute {
+        aster::AstBuilder::new().attr().list("repr").words(&[which]).build()
+    }
+
+    pub fn repr_list(which_ones: &[&str]) -> ast::Attribute {
+        aster::AstBuilder::new().attr().list("repr").words(which_ones).build()
+    }
+
+    pub fn derives(which_ones: &[&str]) -> ast::Attribute {
+        aster::AstBuilder::new().attr().list("derive").words(which_ones).build()
+    }
+
+    pub fn inline() -> ast::Attribute {
+        aster::AstBuilder::new().attr().word("inline")
+    }
+
+    pub fn doc(comment: &str) -> ast::Attribute {
+        aster::AstBuilder::new().attr().doc(comment)
+    }
+
+    pub fn link_name(name: &str) -> ast::Attribute {
+        aster::AstBuilder::new().attr().name_value("link_name").str(name)
+    }
+}
+
+/// Generates a proper type for a field or type with a given `Layout`, that is,
+/// a type with the correct size and alignment restrictions.
+pub struct BlobTyBuilder {
+    layout: Layout,
+}
+
+impl BlobTyBuilder {
+    pub fn new(layout: Layout) -> Self {
+        BlobTyBuilder {
+            layout: layout,
+        }
+    }
+
+    pub fn build(self) -> P<ast::Ty> {
+        let opaque = self.layout.opaque();
+
+        // FIXME(emilio, #412): We fall back to byte alignment, but there are
+        // some things that legitimately are more than 8-byte aligned.
+        //
+        // Eventually we should be able to `unwrap` here, but...
+        let ty_name = match opaque.known_rust_type_for_array() {
+            Some(ty) => ty,
+            None => {
+                warn!("Found unknown alignment on code generation!");
+                "u8"
+            }
+        };
+
+        let data_len = opaque.array_size().unwrap_or(self.layout.size);
+
+        let inner_ty = aster::AstBuilder::new().ty().path().id(ty_name).build();
+        if data_len == 1 {
+            inner_ty
+        } else {
+            aster::ty::TyBuilder::new().array(data_len).build(inner_ty)
+        }
+    }
+}
+
+pub mod ast_ty {
+    use aster;
+    use ir::context::BindgenContext;
+    use ir::function::FunctionSig;
+    use ir::ty::FloatKind;
+    use syntax::ast;
+    use syntax::ptr::P;
+
+    pub fn raw_type(ctx: &BindgenContext, name: &str) -> P<ast::Ty> {
+        let ident = ctx.rust_ident_raw(&name);
+        match ctx.options().ctypes_prefix {
+            Some(ref prefix) => {
+                let prefix = ctx.rust_ident_raw(prefix);
+                quote_ty!(ctx.ext_cx(), $prefix::$ident)
+            }
+            None => quote_ty!(ctx.ext_cx(), ::std::os::raw::$ident),
+        }
+    }
+
+    pub fn float_kind_rust_type(ctx: &BindgenContext,
+                                fk: FloatKind)
+                                -> P<ast::Ty> {
+        // TODO: we probably should just take the type layout into
+        // account?
+        //
+        // Also, maybe this one shouldn't be the default?
+        //
+        // FIXME: `c_longdouble` doesn't seem to be defined in some
+        // systems, so we use `c_double` directly.
+        match (fk, ctx.options().convert_floats) {
+            (FloatKind::Float, true) => aster::ty::TyBuilder::new().f32(),
+            (FloatKind::Double, true) |
+            (FloatKind::LongDouble, true) => aster::ty::TyBuilder::new().f64(),
+            (FloatKind::Float, false) => raw_type(ctx, "c_float"),
+            (FloatKind::Double, false) |
+            (FloatKind::LongDouble, false) => raw_type(ctx, "c_double"),
+            (FloatKind::Float128, _) => {
+                aster::ty::TyBuilder::new().array(16).u8()
+            }
+        }
+    }
+
+    pub fn int_expr(val: i64) -> P<ast::Expr> {
+        use std::i64;
+        let expr = aster::AstBuilder::new().expr();
+
+        // This is not representable as an i64 if it's negative, so we
+        // special-case it.
+        //
+        // Fix in aster incoming.
+        if val == i64::MIN {
+            expr.neg().uint(1u64 << 63)
+        } else {
+            expr.int(val)
+        }
+    }
+
+    pub fn bool_expr(val: bool) -> P<ast::Expr> {
+        aster::AstBuilder::new().expr().bool(val)
+    }
+
+    pub fn byte_array_expr(bytes: &[u8]) -> P<ast::Expr> {
+        let mut vec = Vec::with_capacity(bytes.len() + 1);
+        for byte in bytes {
+            vec.push(int_expr(*byte as i64));
+        }
+        vec.push(int_expr(0));
+
+        let kind = ast::ExprKind::Vec(vec);
+
+        aster::AstBuilder::new().expr().build_expr_kind(kind)
+    }
+
+    pub fn cstr_expr(mut string: String) -> P<ast::Expr> {
+        string.push('\0');
+        aster::AstBuilder::new()
+            .expr()
+            .build_lit(aster::AstBuilder::new().lit().byte_str(string))
+    }
+
+    pub fn float_expr(f: f64) -> P<ast::Expr> {
+        use aster::symbol::ToSymbol;
+        let mut string = f.to_string();
+
+        // So it gets properly recognised as a floating point constant.
+        if !string.contains('.') {
+            string.push('.');
+        }
+
+        let kind = ast::LitKind::FloatUnsuffixed(string.as_str().to_symbol());
+        aster::AstBuilder::new().expr().lit().build_lit(kind)
+    }
+
+    pub fn arguments_from_signature(signature: &FunctionSig,
+                                    ctx: &BindgenContext)
+                                    -> Vec<P<ast::Expr>> {
+        // TODO: We need to keep in sync the argument names, so we should unify
+        // this with the other loop that decides them.
+        let mut unnamed_arguments = 0;
+        signature.argument_types()
+            .iter()
+            .map(|&(ref name, _ty)| {
+                let arg_name = match *name {
+                    Some(ref name) => ctx.rust_mangle(name).into_owned(),
+                    None => {
+                        unnamed_arguments += 1;
+                        format!("arg{}", unnamed_arguments)
+                    }
+                };
+                aster::expr::ExprBuilder::new().id(arg_name)
+            })
+            .collect::<Vec<_>>()
+    }
+}
diff --git a/src/codegen/mod.rs b/src/codegen/mod.rs
new file mode 100644
index 00000000..7451dd11
--- /dev/null
+++ b/src/codegen/mod.rs
@@ -0,0 +1,2341 @@
+mod helpers;
+
+use aster;
+
+use ir::annotations::FieldAccessorKind;
+use ir::comp::{Base, CompInfo, CompKind, Field, Method, MethodKind};
+use ir::context::{BindgenContext, ItemId};
+use ir::derive::{CanDeriveCopy, CanDeriveDebug};
+use ir::enum_ty::{Enum, EnumVariant, EnumVariantValue};
+use ir::function::{Function, FunctionSig};
+use ir::int::IntKind;
+use ir::item::{Item, ItemAncestors, ItemCanonicalName, ItemCanonicalPath};
+use ir::item_kind::ItemKind;
+use ir::layout::Layout;
+use ir::module::Module;
+use ir::ty::{Type, TypeKind};
+use ir::type_collector::ItemSet;
+use ir::var::Var;
+use self::helpers::{BlobTyBuilder, attributes};
+
+use std::borrow::Cow;
+use std::cell::Cell;
+use std::collections::{HashSet, VecDeque};
+use std::collections::hash_map::{Entry, HashMap};
+use std::fmt::Write;
+use std::iter;
+use std::mem;
+use std::ops;
+use syntax::abi::Abi;
+use syntax::ast;
+use syntax::codemap::{Span, respan};
+use syntax::ptr::P;
+
+fn root_import(ctx: &BindgenContext, module: &Item) -> P<ast::Item> {
+    assert!(ctx.options().enable_cxx_namespaces, "Somebody messed it up");
+    assert!(module.is_module());
+
+    let root = ctx.root_module().canonical_name(ctx);
+    let root_ident = ctx.rust_ident(&root);
+
+    let super_ = aster::AstBuilder::new().id("super");
+    let supers = module.ancestors(ctx)
+        .filter(|id| ctx.resolve_item(*id).is_module())
+        .map(|_| super_.clone())
+        .chain(iter::once(super_));
+
+    let self_ = iter::once(aster::AstBuilder::new().id("self"));
+    let root_ident = iter::once(root_ident);
+
+    let path = self_.chain(supers).chain(root_ident);
+
+    let use_root = aster::AstBuilder::new()
+        .item()
+        .use_()
+        .ids(path)
+        .build()
+        .build();
+
+    quote_item!(ctx.ext_cx(), #[allow(unused_imports)] $use_root).unwrap()
+}
+
+struct CodegenResult<'a> {
+    items: Vec<P<ast::Item>>,
+
+    /// A monotonic counter used to add stable unique id's to stuff that doesn't
+    /// need to be referenced by anything.
+    codegen_id: &'a Cell<usize>,
+
+    /// Whether an union has been generated at least once.
+    saw_union: bool,
+
+    items_seen: HashSet<ItemId>,
+    /// The set of generated function/var names, needed because in C/C++ is
+    /// legal to do something like:
+    ///
+    /// ```c++
+    /// extern "C" {
+    ///   void foo();
+    ///   extern int bar;
+    /// }
+    ///
+    /// extern "C" {
+    ///   void foo();
+    ///   extern int bar;
+    /// }
+    /// ```
+    ///
+    /// Being these two different declarations.
+    functions_seen: HashSet<String>,
+    vars_seen: HashSet<String>,
+
+    /// Used for making bindings to overloaded functions. Maps from a canonical
+    /// function name to the number of overloads we have already codegen'd for
+    /// that name. This lets us give each overload a unique suffix.
+    overload_counters: HashMap<String, u32>,
+}
+
+impl<'a> CodegenResult<'a> {
+    fn new(codegen_id: &'a Cell<usize>) -> Self {
+        CodegenResult {
+            items: vec![],
+            saw_union: false,
+            codegen_id: codegen_id,
+            items_seen: Default::default(),
+            functions_seen: Default::default(),
+            vars_seen: Default::default(),
+            overload_counters: Default::default(),
+        }
+    }
+
+    fn next_id(&mut self) -> usize {
+        self.codegen_id.set(self.codegen_id.get() + 1);
+        self.codegen_id.get()
+    }
+
+    fn saw_union(&mut self) {
+        self.saw_union = true;
+    }
+
+    fn seen(&self, item: ItemId) -> bool {
+        self.items_seen.contains(&item)
+    }
+
+    fn set_seen(&mut self, item: ItemId) {
+        self.items_seen.insert(item);
+    }
+
+    fn seen_function(&self, name: &str) -> bool {
+        self.functions_seen.contains(name)
+    }
+
+    fn saw_function(&mut self, name: &str) {
+        self.functions_seen.insert(name.into());
+    }
+
+    /// Get the overload number for the given function name. Increments the
+    /// counter internally so the next time we ask for the overload for this
+    /// name, we get the incremented value, and so on.
+    fn overload_number(&mut self, name: &str) -> u32 {
+        let mut counter =
+            self.overload_counters.entry(name.into()).or_insert(0);
+        let number = *counter;
+        *counter += 1;
+        number
+    }
+
+    fn seen_var(&self, name: &str) -> bool {
+        self.vars_seen.contains(name)
+    }
+
+    fn saw_var(&mut self, name: &str) {
+        self.vars_seen.insert(name.into());
+    }
+
+    fn inner<F>(&mut self, cb: F) -> Vec<P<ast::Item>>
+        where F: FnOnce(&mut Self),
+    {
+        let mut new = Self::new(self.codegen_id);
+
+        cb(&mut new);
+
+        self.saw_union |= new.saw_union;
+
+        new.items
+    }
+}
+
+impl<'a> ops::Deref for CodegenResult<'a> {
+    type Target = Vec<P<ast::Item>>;
+
+    fn deref(&self) -> &Self::Target {
+        &self.items
+    }
+}
+
+impl<'a> ops::DerefMut for CodegenResult<'a> {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.items
+    }
+}
+
+struct ForeignModBuilder {
+    inner: ast::ForeignMod,
+}
+
+impl ForeignModBuilder {
+    fn new(abi: Abi) -> Self {
+        ForeignModBuilder {
+            inner: ast::ForeignMod {
+                abi: abi,
+                items: vec![],
+            },
+        }
+    }
+
+    fn with_foreign_item(mut self, item: ast::ForeignItem) -> Self {
+        self.inner.items.push(item);
+        self
+    }
+
+    #[allow(dead_code)]
+    fn with_foreign_items<I>(mut self, items: I) -> Self
+        where I: IntoIterator<Item = ast::ForeignItem>,
+    {
+        self.inner.items.extend(items.into_iter());
+        self
+    }
+
+    fn build(self, ctx: &BindgenContext) -> P<ast::Item> {
+        use syntax::codemap::DUMMY_SP;
+        P(ast::Item {
+            ident: ctx.rust_ident(""),
+            id: ast::DUMMY_NODE_ID,
+            node: ast::ItemKind::ForeignMod(self.inner),
+            vis: ast::Visibility::Public,
+            attrs: vec![],
+            span: DUMMY_SP,
+        })
+    }
+}
+
+/// A trait to convert a rust type into a pointer, optionally const, to the same
+/// type.
+///
+/// This is done due to aster's lack of pointer builder, I guess I should PR
+/// there.
+trait ToPtr {
+    fn to_ptr(self, is_const: bool, span: Span) -> P<ast::Ty>;
+}
+
+impl ToPtr for P<ast::Ty> {
+    fn to_ptr(self, is_const: bool, span: Span) -> Self {
+        let ty = ast::TyKind::Ptr(ast::MutTy {
+            ty: self,
+            mutbl: if is_const {
+                ast::Mutability::Immutable
+            } else {
+                ast::Mutability::Mutable
+            },
+        });
+        P(ast::Ty {
+            id: ast::DUMMY_NODE_ID,
+            node: ty,
+            span: span,
+        })
+    }
+}
+
+trait CodeGenerator {
+    /// Extra information from the caller.
+    type Extra;
+
+    fn codegen<'a>(&self,
+                   ctx: &BindgenContext,
+                   result: &mut CodegenResult<'a>,
+                   whitelisted_items: &ItemSet,
+                   extra: &Self::Extra);
+}
+
+impl CodeGenerator for Item {
+    type Extra = ();
+
+    fn codegen<'a>(&self,
+                   ctx: &BindgenContext,
+                   result: &mut CodegenResult<'a>,
+                   whitelisted_items: &ItemSet,
+                   _extra: &()) {
+        if self.is_hidden(ctx) || result.seen(self.id()) {
+            debug!("<Item as CodeGenerator>::codegen: Ignoring hidden or seen: \
+                   self = {:?}", self);
+            return;
+        }
+
+        debug!("<Item as CodeGenerator>::codegen: self = {:?}", self);
+
+        result.set_seen(self.id());
+
+        match *self.kind() {
+            ItemKind::Module(ref module) => {
+                module.codegen(ctx, result, whitelisted_items, self);
+            }
+            ItemKind::Function(ref fun) => {
+                if ctx.options().codegen_config.functions {
+                    fun.codegen(ctx, result, whitelisted_items, self);
+                }
+            }
+            ItemKind::Var(ref var) => {
+                if ctx.options().codegen_config.vars {
+                    var.codegen(ctx, result, whitelisted_items, self);
+                }
+            }
+            ItemKind::Type(ref ty) => {
+                if ctx.options().codegen_config.types {
+                    ty.codegen(ctx, result, whitelisted_items, self);
+                }
+            }
+        }
+    }
+}
+
+impl CodeGenerator for Module {
+    type Extra = Item;
+
+    fn codegen<'a>(&self,
+                   ctx: &BindgenContext,
+                   result: &mut CodegenResult<'a>,
+                   whitelisted_items: &ItemSet,
+                   item: &Item) {
+        debug!("<Module as CodeGenerator>::codegen: item = {:?}", item);
+
+        let codegen_self = |result: &mut CodegenResult,
+                            found_any: &mut bool| {
+            for child in self.children() {
+                if whitelisted_items.contains(child) {
+                    *found_any = true;
+                    ctx.resolve_item(*child)
+                        .codegen(ctx, result, whitelisted_items, &());
+                }
+            }
+
+            if item.id() == ctx.root_module() {
+                let saw_union = result.saw_union;
+                if saw_union && !ctx.options().unstable_rust {
+                    utils::prepend_union_types(ctx, &mut *result);
+                }
+                if ctx.need_bindegen_complex_type() {
+                    utils::prepend_complex_type(ctx, &mut *result);
+                }
+            }
+        };
+
+        if !ctx.options().enable_cxx_namespaces ||
+            (self.is_inline() && !ctx.options().conservative_inline_namespaces) {
+            codegen_self(result, &mut false);
+            return;
+        }
+
+        let mut found_any = false;
+        let inner_items = result.inner(|result| {
+            result.push(root_import(ctx, item));
+            codegen_self(result, &mut found_any);
+        });
+
+        // Don't bother creating an empty module.
+        if !found_any {
+            return;
+        }
+
+        let module = ast::ItemKind::Mod(ast::Mod {
+            inner: ctx.span(),
+            items: inner_items,
+        });
+
+        let name = item.canonical_name(ctx);
+        let item = aster::AstBuilder::new()
+            .item()
+            .pub_()
+            .build_item_kind(name, module);
+
+        result.push(item);
+    }
+}
+
+impl CodeGenerator for Var {
+    type Extra = Item;
+    fn codegen<'a>(&self,
+                   ctx: &BindgenContext,
+                   result: &mut CodegenResult<'a>,
+                   _whitelisted_items: &ItemSet,
+                   item: &Item) {
+        use ir::var::VarType;
+        debug!("<Var as CodeGenerator>::codegen: item = {:?}", item);
+
+        let canonical_name = item.canonical_name(ctx);
+
+        if result.seen_var(&canonical_name) {
+            return;
+        }
+        result.saw_var(&canonical_name);
+
+        let ty = self.ty().to_rust_ty(ctx);
+
+        if let Some(val) = self.val() {
+            let const_item = aster::AstBuilder::new()
+                .item()
+                .pub_()
+                .const_(canonical_name)
+                .expr();
+            let item = match *val {
+                VarType::Bool(val) => {
+                    const_item.build(helpers::ast_ty::bool_expr(val))
+                        .build(ty)
+                }
+                VarType::Int(val) => {
+                    const_item.build(helpers::ast_ty::int_expr(val)).build(ty)
+                }
+                VarType::String(ref bytes) => {
+                    // Account the trailing zero.
+                    //
+                    // TODO: Here we ignore the type we just made up, probably
+                    // we should refactor how the variable type and ty id work.
+                    let len = bytes.len() + 1;
+                    let ty = quote_ty!(ctx.ext_cx(), [u8; $len]);
+
+                    match String::from_utf8(bytes.clone()) {
+                        Ok(string) => {
+                            const_item.build(helpers::ast_ty::cstr_expr(string))
+                                .build(quote_ty!(ctx.ext_cx(), &'static $ty))
+                        }
+                        Err(..) => {
+                            const_item
+                                .build(helpers::ast_ty::byte_array_expr(bytes))
+                                .build(ty)
+                        }
+                    }
+                }
+                VarType::Float(f) => {
+                    const_item.build(helpers::ast_ty::float_expr(f))
+                        .build(ty)
+                }
+                VarType::Char(c) => {
+                    const_item
+                        .build(aster::AstBuilder::new().expr().lit().byte(c))
+                        .build(ty)
+                }
+            };
+
+            result.push(item);
+        } else {
+            let mut attrs = vec![];
+            if let Some(mangled) = self.mangled_name() {
+                attrs.push(attributes::link_name(mangled));
+            } else if canonical_name != self.name() {
+                attrs.push(attributes::link_name(self.name()));
+            }
+
+            let item = ast::ForeignItem {
+                ident: ctx.rust_ident_raw(&canonical_name),
+                attrs: attrs,
+                node: ast::ForeignItemKind::Static(ty, !self.is_const()),
+                id: ast::DUMMY_NODE_ID,
+                span: ctx.span(),
+                vis: ast::Visibility::Public,
+            };
+
+            let item = ForeignModBuilder::new(Abi::C)
+                .with_foreign_item(item)
+                .build(ctx);
+            result.push(item);
+        }
+    }
+}
+
+impl CodeGenerator for Type {
+    type Extra = Item;
+
+    fn codegen<'a>(&self,
+                   ctx: &BindgenContext,
+                   result: &mut CodegenResult<'a>,
+                   whitelisted_items: &ItemSet,
+                   item: &Item) {
+        debug!("<Type as CodeGenerator>::codegen: item = {:?}", item);
+
+        match *self.kind() {
+            TypeKind::Void |
+            TypeKind::NullPtr |
+            TypeKind::Int(..) |
+            TypeKind::Float(..) |
+            TypeKind::Complex(..) |
+            TypeKind::Array(..) |
+            TypeKind::Pointer(..) |
+            TypeKind::BlockPointer |
+            TypeKind::Reference(..) |
+            TypeKind::TemplateRef(..) |
+            TypeKind::Function(..) |
+            TypeKind::ResolvedTypeRef(..) |
+            TypeKind::Named(..) => {
+                // These items don't need code generation, they only need to be
+                // converted to rust types in fields, arguments, and such.
+                return;
+            }
+            TypeKind::Comp(ref ci) => {
+                ci.codegen(ctx, result, whitelisted_items, item)
+            }
+            // NB: The code below will pick the correct
+            // applicable_template_args.
+            TypeKind::TemplateAlias(ref spelling, inner, _) |
+            TypeKind::Alias(ref spelling, inner) => {
+                let inner_item = ctx.resolve_item(inner);
+                let name = item.canonical_name(ctx);
+
+                // Try to catch the common pattern:
+                //
+                // typedef struct foo { ... } foo;
+                //
+                // here.
+                //
+                if inner_item.canonical_name(ctx) == name {
+                    return;
+                }
+
+                // If this is a known named type, disallow generating anything
+                // for it too.
+                if utils::type_from_named(ctx, spelling, inner).is_some() {
+                    return;
+                }
+
+                let mut applicable_template_args =
+                    item.applicable_template_args(ctx);
+                let inner_rust_type = if item.is_opaque(ctx) {
+                    applicable_template_args.clear();
+                    // Pray if there's no layout.
+                    let layout = self.layout(ctx).unwrap_or_else(Layout::zero);
+                    BlobTyBuilder::new(layout).build()
+                } else {
+                    inner_item.to_rust_ty(ctx)
+                };
+
+                let rust_name = ctx.rust_ident(&name);
+                let mut typedef = aster::AstBuilder::new().item().pub_();
+
+                if let Some(comment) = item.comment() {
+                    typedef = typedef.attr().doc(comment);
+                }
+
+                // We prefer using `pub use` over `pub type` because of:
+                // https://github.com/rust-lang/rust/issues/26264
+                let simple_enum_path = match inner_rust_type.node {
+                    ast::TyKind::Path(None, ref p) => {
+                        if applicable_template_args.is_empty() &&
+                            !inner_item.expect_type().canonical_type(ctx).is_builtin_or_named() &&
+                            p.segments.iter().all(|p| p.parameters.is_none()) {
+                            Some(p.clone())
+                        } else {
+                            None
+                        }
+                    },
+                    _ => None,
+                };
+
+                let typedef = if let Some(mut p) = simple_enum_path {
+                    if p.segments.len() == 1 {
+                        p.segments.insert(0, ast::PathSegment {
+                            identifier: ctx.ext_cx().ident_of("self"),
+                            parameters: None,
+                        });
+                    }
+                    typedef.use_().build(p).as_(rust_name)
+                } else {
+                    let mut generics = typedef.type_(rust_name).generics();
+                    for template_arg in applicable_template_args.iter() {
+                        let template_arg = ctx.resolve_type(*template_arg);
+                        if template_arg.is_named() {
+                            let name = template_arg.name().unwrap();
+                            if name.contains("typename ") {
+                                warn!("Item contained `typename`'d template \
+                                       parameter: {:?}", item);
+                                return;
+                            }
+                            generics =
+                                generics.ty_param_id(template_arg.name().unwrap());
+                        }
+                    }
+                    generics.build().build_ty(inner_rust_type)
+                };
+                result.push(typedef)
+            }
+            TypeKind::Enum(ref ei) => {
+                ei.codegen(ctx, result, whitelisted_items, item)
+            }
+            ref u @ TypeKind::UnresolvedTypeRef(..) => {
+                unreachable!("Should have been resolved after parsing {:?}!", u)
+            }
+        }
+    }
+}
+
+struct Vtable<'a> {
+    item_id: ItemId,
+    #[allow(dead_code)]
+    methods: &'a [Method],
+    #[allow(dead_code)]
+    base_classes: &'a [Base],
+}
+
+impl<'a> Vtable<'a> {
+    fn new(item_id: ItemId,
+           methods: &'a [Method],
+           base_classes: &'a [Base])
+           -> Self {
+        Vtable {
+            item_id: item_id,
+            methods: methods,
+            base_classes: base_classes,
+        }
+    }
+}
+
+impl<'a> CodeGenerator for Vtable<'a> {
+    type Extra = Item;
+
+    fn codegen<'b>(&self,
+                   ctx: &BindgenContext,
+                   result: &mut CodegenResult<'b>,
+                   _whitelisted_items: &ItemSet,
+                   item: &Item) {
+        assert_eq!(item.id(), self.item_id);
+        // For now, generate an empty struct, later we should generate function
+        // pointers and whatnot.
+        let vtable = aster::AstBuilder::new()
+            .item()
+            .pub_()
+            .with_attr(attributes::repr("C"))
+            .struct_(self.canonical_name(ctx))
+            .build();
+        result.push(vtable);
+    }
+}
+
+impl<'a> ItemCanonicalName for Vtable<'a> {
+    fn canonical_name(&self, ctx: &BindgenContext) -> String {
+        format!("{}__bindgen_vtable", self.item_id.canonical_name(ctx))
+    }
+}
+
+impl<'a> ItemToRustTy for Vtable<'a> {
+    fn to_rust_ty(&self, ctx: &BindgenContext) -> P<ast::Ty> {
+        aster::ty::TyBuilder::new().id(self.canonical_name(ctx))
+    }
+}
+
+struct Bitfield<'a> {
+    index: usize,
+    fields: Vec<&'a Field>,
+}
+
+impl<'a> Bitfield<'a> {
+    fn new(index: usize, fields: Vec<&'a Field>) -> Self {
+        Bitfield {
+            index: index,
+            fields: fields,
+        }
+    }
+
+    fn codegen_fields(self,
+                      ctx: &BindgenContext,
+                      fields: &mut Vec<ast::StructField>,
+                      methods: &mut Vec<ast::ImplItem>) {
+        use aster::struct_field::StructFieldBuilder;
+        use std::cmp;
+        let mut total_width = self.fields
+            .iter()
+            .fold(0u32, |acc, f| acc + f.bitfield().unwrap());
+
+        if !total_width.is_power_of_two() || total_width < 8 {
+            total_width = cmp::max(8, total_width.next_power_of_two());
+        }
+        debug_assert_eq!(total_width % 8, 0);
+        let total_width_in_bytes = total_width as usize / 8;
+
+        let bitfield_type =
+            BlobTyBuilder::new(Layout::new(total_width_in_bytes,
+                                           total_width_in_bytes))
+                .build();
+        let field_name = format!("_bitfield_{}", self.index);
+        let field_ident = ctx.ext_cx().ident_of(&field_name);
+        let field = StructFieldBuilder::named(&field_name)
+            .pub_()
+            .build_ty(bitfield_type.clone());
+        fields.push(field);
+
+
+        let mut offset = 0;
+        for field in self.fields {
+            let width = field.bitfield().unwrap();
+            let field_name = field.name()
+                .map(ToOwned::to_owned)
+                .unwrap_or_else(|| format!("at_offset_{}", offset));
+
+            let field_item = ctx.resolve_item(field.ty());
+            let field_ty_layout = field_item.kind()
+                .expect_type()
+                .layout(ctx)
+                .expect("Bitfield without layout? Gah!");
+
+            let field_type = field_item.to_rust_ty(ctx);
+            let int_type = BlobTyBuilder::new(field_ty_layout).build();
+
+            let getter_name = ctx.rust_ident(&field_name);
+            let setter_name = ctx.ext_cx()
+                .ident_of(&format!("set_{}", &field_name));
+            let mask = ((1usize << width) - 1) << offset;
+            let prefix = ctx.trait_prefix();
+            // The transmute is unfortunate, but it's needed for enums in
+            // bitfields.
+            let item = quote_item!(ctx.ext_cx(),
+                impl X {
+                    #[inline]
+                    pub fn $getter_name(&self) -> $field_type {
+                        unsafe {
+                            ::$prefix::mem::transmute(
+                                (
+                                    (self.$field_ident &
+                                        ($mask as $bitfield_type))
+                                     >> $offset
+                                ) as $int_type
+                            )
+                        }
+                    }
+
+                    #[inline]
+                    pub fn $setter_name(&mut self, val: $field_type) {
+                        self.$field_ident &= !($mask as $bitfield_type);
+                        self.$field_ident |=
+                            (val as $int_type as $bitfield_type << $offset) &
+                                ($mask as $bitfield_type);
+                    }
+                }
+            )
+                .unwrap();
+
+            let items = match item.unwrap().node {
+                ast::ItemKind::Impl(_, _, _, _, _, items) => items,
+                _ => unreachable!(),
+            };
+
+            methods.extend(items.into_iter());
+            offset += width;
+        }
+    }
+}
+
+impl CodeGenerator for CompInfo {
+    type Extra = Item;
+
+    fn codegen<'a>(&self,
+                   ctx: &BindgenContext,
+                   result: &mut CodegenResult<'a>,
+                   whitelisted_items: &ItemSet,
+                   item: &Item) {
+        use aster::struct_field::StructFieldBuilder;
+
+        debug!("<CompInfo as CodeGenerator>::codegen: item = {:?}", item);
+
+        // Don't output classes with template parameters that aren't types, and
+        // also don't output template specializations, neither total or partial.
+        if self.has_non_type_template_params() {
+            return;
+        }
+
+        if self.is_template_specialization() {
+            let layout = item.kind().expect_type().layout(ctx);
+
+            if let Some(layout) = layout {
+                let fn_name = format!("__bindgen_test_layout_template_{}",
+                                      result.next_id());
+                let fn_name = ctx.rust_ident_raw(&fn_name);
+                let ident = item.to_rust_ty(ctx);
+                let prefix = ctx.trait_prefix();
+                let size_of_expr = quote_expr!(ctx.ext_cx(),
+                                ::$prefix::mem::size_of::<$ident>());
+                let align_of_expr = quote_expr!(ctx.ext_cx(),
+                                ::$prefix::mem::align_of::<$ident>());
+                let size = layout.size;
+                let align = layout.align;
+                let item = quote_item!(ctx.ext_cx(),
+                                       #[test]
+                                       fn $fn_name() {
+                                           assert_eq!($size_of_expr, $size);
+                                           assert_eq!($align_of_expr, $align);
+                                       })
+                    .unwrap();
+                result.push(item);
+            }
+            return;
+        }
+
+        let applicable_template_args = item.applicable_template_args(ctx);
+
+        let mut attributes = vec![];
+        let mut needs_clone_impl = false;
+        if let Some(comment) = item.comment() {
+            attributes.push(attributes::doc(comment));
+        }
+        if self.packed() {
+            attributes.push(attributes::repr_list(&["C", "packed"]));
+        } else {
+            attributes.push(attributes::repr("C"));
+        }
+
+        let is_union = self.kind() == CompKind::Union;
+        let mut derives = vec![];
+        if item.can_derive_debug(ctx, ()) {
+            derives.push("Debug");
+        }
+
+        if item.can_derive_copy(ctx, ()) &&
+           !item.annotations().disallow_copy() {
+            derives.push("Copy");
+            if !applicable_template_args.is_empty() {
+                // FIXME: This requires extra logic if you have a big array in a
+                // templated struct. The reason for this is that the magic:
+                //     fn clone(&self) -> Self { *self }
+                // doesn't work for templates.
+                //
+                // It's not hard to fix though.
+                derives.push("Clone");
+            } else {
+                needs_clone_impl = true;
+            }
+        }
+
+        if !derives.is_empty() {
+            attributes.push(attributes::derives(&derives))
+        }
+
+        let mut template_args_used =
+            vec![false; applicable_template_args.len()];
+        let canonical_name = item.canonical_name(ctx);
+        let builder = if is_union && ctx.options().unstable_rust {
+            aster::AstBuilder::new()
+                .item()
+                .pub_()
+                .with_attrs(attributes)
+                .union_(&canonical_name)
+        } else {
+            aster::AstBuilder::new()
+                .item()
+                .pub_()
+                .with_attrs(attributes)
+                .struct_(&canonical_name)
+        };
+
+        // Generate the vtable from the method list if appropriate.
+        //
+        // TODO: I don't know how this could play with virtual methods that are
+        // not in the list of methods found by us, we'll see. Also, could the
+        // order of the vtable pointers vary?
+        //
+        // FIXME: Once we generate proper vtables, we need to codegen the
+        // vtable, but *not* generate a field for it in the case that
+        // needs_explicit_vtable is false but has_vtable is true.
+        //
+        // Also, we need to generate the vtable in such a way it "inherits" from
+        // the parent too.
+        let mut fields = vec![];
+        if self.needs_explicit_vtable(ctx) {
+            let vtable =
+                Vtable::new(item.id(), self.methods(), self.base_members());
+            vtable.codegen(ctx, result, whitelisted_items, item);
+
+            let vtable_type = vtable.to_rust_ty(ctx).to_ptr(true, ctx.span());
+
+            let vtable_field = StructFieldBuilder::named("vtable_")
+                .pub_()
+                .build_ty(vtable_type);
+
+            fields.push(vtable_field);
+        }
+
+        for (i, base) in self.base_members().iter().enumerate() {
+            // Virtual bases are already taken into account by the vtable
+            // pointer.
+            //
+            // FIXME(emilio): Is this always right?
+            if base.is_virtual() {
+                continue;
+            }
+
+            let base_ty = ctx.resolve_type(base.ty);
+            // NB: We won't include unsized types in our base chain because they
+            // would contribute to our size given the dummy field we insert for
+            // unsized types.
+            if base_ty.is_unsized(ctx) {
+                continue;
+            }
+
+            for (i, ty_id) in applicable_template_args.iter().enumerate() {
+                let template_arg_ty = ctx.resolve_type(*ty_id);
+                if base_ty.signature_contains_named_type(ctx, template_arg_ty) {
+                    template_args_used[i] = true;
+                }
+            }
+
+            let inner = base.ty.to_rust_ty(ctx);
+            let field_name = if i == 0 {
+                "_base".into()
+            } else {
+                format!("_base_{}", i)
+            };
+
+            let field = StructFieldBuilder::named(field_name)
+                .pub_()
+                .build_ty(inner);
+            fields.push(field);
+        }
+        if is_union {
+            result.saw_union();
+        }
+
+        let layout = item.kind().expect_type().layout(ctx);
+
+        let mut current_bitfield_width = None;
+        let mut current_bitfield_layout: Option<Layout> = None;
+        let mut current_bitfield_fields = vec![];
+        let mut bitfield_count = 0;
+        let struct_fields = self.fields();
+        let fields_should_be_private = item.annotations()
+            .private_fields()
+            .unwrap_or(false);
+        let struct_accessor_kind = item.annotations()
+            .accessor_kind()
+            .unwrap_or(FieldAccessorKind::None);
+
+        let mut methods = vec![];
+        let mut anonymous_field_count = 0;
+        for field in struct_fields {
+            debug_assert_eq!(current_bitfield_width.is_some(),
+                             current_bitfield_layout.is_some());
+            debug_assert_eq!(current_bitfield_width.is_some(),
+                             !current_bitfield_fields.is_empty());
+
+            let field_ty = ctx.resolve_type(field.ty());
+
+            // Try to catch a bitfield contination early.
+            if let (Some(ref mut bitfield_width), Some(width)) =
+                   (current_bitfield_width, field.bitfield()) {
+                let layout = current_bitfield_layout.unwrap();
+                debug!("Testing bitfield continuation {} {} {:?}",
+                       *bitfield_width, width, layout);
+                if *bitfield_width + width <= (layout.size * 8) as u32 {
+                    *bitfield_width += width;
+                    current_bitfield_fields.push(field);
+                    continue;
+                }
+            }
+
+            // Flush the current bitfield.
+            if current_bitfield_width.is_some() {
+                debug_assert!(!current_bitfield_fields.is_empty());
+                let bitfield_fields =
+                    mem::replace(&mut current_bitfield_fields, vec![]);
+                bitfield_count += 1;
+                Bitfield::new(bitfield_count, bitfield_fields)
+                    .codegen_fields(ctx, &mut fields, &mut methods);
+                current_bitfield_width = None;
+                current_bitfield_layout = None;
+            }
+            debug_assert!(current_bitfield_fields.is_empty());
+
+            if let Some(width) = field.bitfield() {
+                let layout = field_ty.layout(ctx)
+                    .expect("Bitfield type without layout?");
+                current_bitfield_width = Some(width);
+                current_bitfield_layout = Some(layout);
+                current_bitfield_fields.push(field);
+                continue;
+            }
+
+            for (i, ty_id) in applicable_template_args.iter().enumerate() {
+                let template_arg = ctx.resolve_type(*ty_id);
+                if field_ty.signature_contains_named_type(ctx, template_arg) {
+                    template_args_used[i] = true;
+                }
+            }
+
+            let ty = field.ty().to_rust_ty(ctx);
+
+            // NB: In unstable rust we use proper `union` types.
+            let ty = if is_union && !ctx.options().unstable_rust {
+                if ctx.options().enable_cxx_namespaces {
+                    quote_ty!(ctx.ext_cx(), root::__BindgenUnionField<$ty>)
+                } else {
+                    quote_ty!(ctx.ext_cx(), __BindgenUnionField<$ty>)
+                }
+            } else {
+                ty
+            };
+
+            let mut attrs = vec![];
+            if let Some(comment) = field.comment() {
+                attrs.push(attributes::doc(comment));
+            }
+            let field_name = match field.name() {
+                Some(name) => ctx.rust_mangle(name).into_owned(),
+                None => {
+                    anonymous_field_count += 1;
+                    format!("__bindgen_anon_{}", anonymous_field_count)
+                }
+            };
+
+            let is_private = field.annotations()
+                .private_fields()
+                .unwrap_or(fields_should_be_private);
+
+            let accessor_kind = field.annotations()
+                .accessor_kind()
+                .unwrap_or(struct_accessor_kind);
+
+            let mut field = StructFieldBuilder::named(&field_name);
+
+            if !is_private {
+                field = field.pub_();
+            }
+
+            let field = field.with_attrs(attrs)
+                .build_ty(ty.clone());
+
+            fields.push(field);
+
+            // TODO: Factor the following code out, please!
+            if accessor_kind == FieldAccessorKind::None {
+                continue;
+            }
+
+            let getter_name =
+                ctx.rust_ident_raw(&format!("get_{}", field_name));
+            let mutable_getter_name =
+                ctx.rust_ident_raw(&format!("get_{}_mut", field_name));
+            let field_name = ctx.rust_ident_raw(&field_name);
+
+            let accessor_methods_impl = match accessor_kind {
+                FieldAccessorKind::None => unreachable!(),
+                FieldAccessorKind::Regular => {
+                    quote_item!(ctx.ext_cx(),
+                        impl X {
+                            #[inline]
+                            pub fn $getter_name(&self) -> &$ty {
+                                &self.$field_name
+                            }
+
+                            #[inline]
+                            pub fn $mutable_getter_name(&mut self) -> &mut $ty {
+                                &mut self.$field_name
+                            }
+                        }
+                    )
+                }
+                FieldAccessorKind::Unsafe => {
+                    quote_item!(ctx.ext_cx(),
+                        impl X {
+                            #[inline]
+                            pub unsafe fn $getter_name(&self) -> &$ty {
+                                &self.$field_name
+                            }
+
+                            #[inline]
+                            pub unsafe fn $mutable_getter_name(&mut self)
+                                -> &mut $ty {
+                                &mut self.$field_name
+                            }
+                        }
+                    )
+                }
+                FieldAccessorKind::Immutable => {
+                    quote_item!(ctx.ext_cx(),
+                        impl X {
+                            #[inline]
+                            pub fn $getter_name(&self) -> &$ty {
+                                &self.$field_name
+                            }
+                        }
+                    )
+                }
+            };
+
+            match accessor_methods_impl.unwrap().node {
+                ast::ItemKind::Impl(_, _, _, _, _, ref items) => {
+                    methods.extend(items.clone())
+                }
+                _ => unreachable!(),
+            }
+        }
+
+        // Flush the last bitfield if any.
+        //
+        // FIXME: Reduce duplication with the loop above.
+        // FIXME: May need to pass current_bitfield_layout too.
+        if current_bitfield_width.is_some() {
+            debug_assert!(!current_bitfield_fields.is_empty());
+            let bitfield_fields = mem::replace(&mut current_bitfield_fields,
+                                               vec![]);
+            bitfield_count += 1;
+            Bitfield::new(bitfield_count, bitfield_fields)
+                .codegen_fields(ctx, &mut fields, &mut methods);
+        }
+        debug_assert!(current_bitfield_fields.is_empty());
+
+        if is_union && !ctx.options().unstable_rust {
+            let layout = layout.expect("Unable to get layout information?");
+            let ty = BlobTyBuilder::new(layout).build();
+            let field = StructFieldBuilder::named("bindgen_union_field")
+                .pub_()
+                .build_ty(ty);
+            fields.push(field);
+        }
+
+        // Yeah, sorry about that.
+        if item.is_opaque(ctx) {
+            fields.clear();
+            methods.clear();
+            for i in 0..template_args_used.len() {
+                template_args_used[i] = false;
+            }
+
+            match layout {
+                Some(l) => {
+                    let ty = BlobTyBuilder::new(l).build();
+                    let field =
+                        StructFieldBuilder::named("_bindgen_opaque_blob")
+                            .pub_()
+                            .build_ty(ty);
+                    fields.push(field);
+                }
+                None => {
+                    warn!("Opaque type without layout! Expect dragons!");
+                }
+            }
+        }
+
+        // C requires every struct to be addressable, so what C compilers do is
+        // making the struct 1-byte sized.
+        //
+        // NOTE: This check is conveniently here to avoid the dummy fields we
+        // may add for unused template parameters.
+        if self.is_unsized(ctx) {
+            let ty = BlobTyBuilder::new(Layout::new(1, 1)).build();
+            let field = StructFieldBuilder::named("_address")
+                .pub_()
+                .build_ty(ty);
+            fields.push(field);
+        }
+
+        // Append any extra template arguments that nobody has used so far.
+        for (i, ty) in applicable_template_args.iter().enumerate() {
+            if !template_args_used[i] {
+                let name = ctx.resolve_type(*ty).name().unwrap();
+                let ident = ctx.rust_ident(name);
+                let prefix = ctx.trait_prefix();
+                let phantom = quote_ty!(ctx.ext_cx(),
+                                        ::$prefix::marker::PhantomData<$ident>);
+                let field =
+                    StructFieldBuilder::named(format!("_phantom_{}", i))
+                        .pub_()
+                        .build_ty(phantom);
+                fields.push(field)
+            }
+        }
+
+
+        let mut generics = aster::AstBuilder::new().generics();
+        for template_arg in applicable_template_args.iter() {
+            // Take into account that here only arrive named types, not
+            // template specialisations that would need to be
+            // instantiated.
+            //
+            // TODO: Add template args from the parent, here and in
+            // `to_rust_ty`!!
+            let template_arg = ctx.resolve_type(*template_arg);
+            generics = generics.ty_param_id(template_arg.name().unwrap());
+        }
+
+        let generics = generics.build();
+
+        let rust_struct = builder.with_generics(generics.clone())
+            .with_fields(fields)
+            .build();
+        result.push(rust_struct);
+
+        // Generate the inner types and all that stuff.
+        //
+        // TODO: In the future we might want to be smart, and use nested
+        // modules, and whatnot.
+        for ty in self.inner_types() {
+            let child_item = ctx.resolve_item(*ty);
+            // assert_eq!(child_item.parent_id(), item.id());
+            child_item.codegen(ctx, result, whitelisted_items, &());
+        }
+
+        // NOTE: Some unexposed attributes (like alignment attributes) may
+        // affect layout, so we're bad and pray to the gods for avoid sending
+        // all the tests to shit when parsing things like max_align_t.
+        if self.found_unknown_attr() {
+            warn!("Type {} has an unkown attribute that may affect layout",
+                  canonical_name);
+        }
+
+        if applicable_template_args.is_empty() && !self.found_unknown_attr() {
+            for var in self.inner_vars() {
+                ctx.resolve_item(*var)
+                    .codegen(ctx, result, whitelisted_items, &());
+            }
+
+            if let Some(layout) = layout {
+                let fn_name = format!("bindgen_test_layout_{}", canonical_name);
+                let fn_name = ctx.rust_ident_raw(&fn_name);
+                let ident = ctx.rust_ident_raw(&canonical_name);
+                let prefix = ctx.trait_prefix();
+                let size_of_expr = quote_expr!(ctx.ext_cx(),
+                                ::$prefix::mem::size_of::<$ident>());
+                let align_of_expr = quote_expr!(ctx.ext_cx(),
+                                ::$prefix::mem::align_of::<$ident>());
+                let size = layout.size;
+                let align = layout.align;
+                let item = quote_item!(ctx.ext_cx(),
+                    #[test]
+                    fn $fn_name() {
+                        assert_eq!($size_of_expr, $size);
+                        assert_eq!($align_of_expr, $align);
+                    })
+                    .unwrap();
+                result.push(item);
+            }
+
+            let mut method_names = Default::default();
+            if ctx.options().codegen_config.methods {
+                for method in self.methods() {
+                    assert!(method.kind() != MethodKind::Constructor);
+                    method.codegen_method(ctx,
+                                          &mut methods,
+                                          &mut method_names,
+                                          result,
+                                          whitelisted_items,
+                                          self);
+                }
+            }
+
+            if ctx.options().codegen_config.constructors {
+                for sig in self.constructors() {
+                    Method::new(MethodKind::Constructor,
+                                *sig,
+                                /* const */
+                                false)
+                        .codegen_method(ctx,
+                                        &mut methods,
+                                        &mut method_names,
+                                        result,
+                                        whitelisted_items,
+                                        self);
+                }
+            }
+        }
+
+        // NB: We can't use to_rust_ty here since for opaque types this tries to
+        // use the specialization knowledge to generate a blob field.
+        let ty_for_impl =
+            aster::AstBuilder::new().ty().path().id(&canonical_name).build();
+        if needs_clone_impl {
+            let impl_ = quote_item!(ctx.ext_cx(),
+                impl X {
+                    fn clone(&self) -> Self { *self }
+                }
+            );
+
+            let impl_ = match impl_.unwrap().node {
+                ast::ItemKind::Impl(_, _, _, _, _, ref items) => items.clone(),
+                _ => unreachable!(),
+            };
+
+            let clone_impl = aster::AstBuilder::new()
+                .item()
+                .impl_()
+                .trait_()
+                .id("Clone")
+                .build()
+                .with_generics(generics.clone())
+                .with_items(impl_)
+                .build_ty(ty_for_impl.clone());
+
+            result.push(clone_impl);
+        }
+
+        if !methods.is_empty() {
+            let methods = aster::AstBuilder::new()
+                .item()
+                .impl_()
+                .with_generics(generics)
+                .with_items(methods)
+                .build_ty(ty_for_impl);
+            result.push(methods);
+        }
+    }
+}
+
+trait MethodCodegen {
+    fn codegen_method<'a>(&self,
+                          ctx: &BindgenContext,
+                          methods: &mut Vec<ast::ImplItem>,
+                          method_names: &mut HashMap<String, usize>,
+                          result: &mut CodegenResult<'a>,
+                          whitelisted_items: &ItemSet,
+                          parent: &CompInfo);
+}
+
+impl MethodCodegen for Method {
+    fn codegen_method<'a>(&self,
+                          ctx: &BindgenContext,
+                          methods: &mut Vec<ast::ImplItem>,
+                          method_names: &mut HashMap<String, usize>,
+                          result: &mut CodegenResult<'a>,
+                          whitelisted_items: &ItemSet,
+                          _parent: &CompInfo) {
+        if self.is_virtual() {
+            return; // FIXME
+        }
+        // First of all, output the actual function.
+        let function_item = ctx.resolve_item(self.signature());
+        function_item.codegen(ctx, result, whitelisted_items, &());
+
+        let function = function_item.expect_function();
+        let signature_item = ctx.resolve_item(function.signature());
+        let mut name = match self.kind() {
+            MethodKind::Constructor => "new".into(),
+            _ => function.name().to_owned(),
+        };
+
+        let signature = match *signature_item.expect_type().kind() {
+            TypeKind::Function(ref sig) => sig,
+            _ => panic!("How in the world?"),
+        };
+
+        // Do not generate variadic methods, since rust does not allow
+        // implementing them, and we don't do a good job at it anyway.
+        if signature.is_variadic() {
+            return;
+        }
+
+        let count = {
+            let mut count = method_names.entry(name.clone())
+                .or_insert(0);
+            *count += 1;
+            *count - 1
+        };
+
+        if count != 0 {
+            name.push_str(&count.to_string());
+        }
+
+        let function_name = function_item.canonical_name(ctx);
+        let mut fndecl = utils::rust_fndecl_from_signature(ctx, signature_item)
+            .unwrap();
+        if !self.is_static() && !self.is_constructor() {
+            let mutability = if self.is_const() {
+                ast::Mutability::Immutable
+            } else {
+                ast::Mutability::Mutable
+            };
+
+            assert!(!fndecl.inputs.is_empty());
+
+            // FIXME: use aster here.
+            fndecl.inputs[0] = ast::Arg {
+                ty: P(ast::Ty {
+                    id: ast::DUMMY_NODE_ID,
+                    node: ast::TyKind::Rptr(None, ast::MutTy {
+                        ty: P(ast::Ty {
+                            id: ast::DUMMY_NODE_ID,
+                            node: ast::TyKind::ImplicitSelf,
+                            span: ctx.span()
+                        }),
+                        mutbl: mutability,
+                    }),
+                    span: ctx.span(),
+                }),
+                pat: P(ast::Pat {
+                    id: ast::DUMMY_NODE_ID,
+                    node: ast::PatKind::Ident(
+                        ast::BindingMode::ByValue(ast::Mutability::Immutable),
+                        respan(ctx.span(), ctx.ext_cx().ident_of("self")),
+                        None
+                    ),
+                    span: ctx.span(),
+                }),
+                id: ast::DUMMY_NODE_ID,
+            };
+        }
+
+        // If it's a constructor, we always return `Self`, and we inject the
+        // "this" parameter, so there's no need to ask the user for it.
+        //
+        // Note that constructors in Clang are represented as functions with
+        // return-type = void.
+        if self.is_constructor() {
+            fndecl.inputs.remove(0);
+            fndecl.output =
+                ast::FunctionRetTy::Ty(quote_ty!(ctx.ext_cx(), Self));
+        }
+
+        let sig = ast::MethodSig {
+            unsafety: ast::Unsafety::Unsafe,
+            abi: Abi::Rust,
+            decl: P(fndecl),
+            generics: ast::Generics::default(),
+            constness: respan(ctx.span(), ast::Constness::NotConst),
+        };
+
+        let mut exprs = helpers::ast_ty::arguments_from_signature(&signature,
+                                                                  ctx);
+
+        let mut stmts = vec![];
+
+        // If it's a constructor, we need to insert an extra parameter with a
+        // variable called `__bindgen_tmp` we're going to create.
+        if self.is_constructor() {
+            let tmp_variable_decl =
+                quote_stmt!(ctx.ext_cx(),
+                            let mut __bindgen_tmp = ::std::mem::uninitialized())
+                .unwrap();
+            stmts.push(tmp_variable_decl);
+            exprs[0] = quote_expr!(ctx.ext_cx(), &mut __bindgen_tmp);
+        } else if !self.is_static() {
+            assert!(!exprs.is_empty());
+            exprs[0] = if self.is_const() {
+                quote_expr!(ctx.ext_cx(), &*self)
+            } else {
+                quote_expr!(ctx.ext_cx(), &mut *self)
+            };
+        };
+
+        let call = aster::expr::ExprBuilder::new()
+            .call()
+            .id(function_name)
+            .with_args(exprs)
+            .build();
+
+        stmts.push(ast::Stmt {
+            id: ast::DUMMY_NODE_ID,
+            node: ast::StmtKind::Expr(call),
+            span: ctx.span(),
+        });
+
+        if self.is_constructor() {
+            stmts.push(quote_stmt!(ctx.ext_cx(), __bindgen_tmp).unwrap());
+        }
+
+        let block = ast::Block {
+            stmts: stmts,
+            id: ast::DUMMY_NODE_ID,
+            rules: ast::BlockCheckMode::Default,
+            span: ctx.span(),
+        };
+
+        let mut attrs = vec![];
+        attrs.push(attributes::inline());
+
+        let item = ast::ImplItem {
+            id: ast::DUMMY_NODE_ID,
+            ident: ctx.rust_ident(&name),
+            vis: ast::Visibility::Public,
+            attrs: attrs,
+            node: ast::ImplItemKind::Method(sig, P(block)),
+            defaultness: ast::Defaultness::Final,
+            span: ctx.span(),
+        };
+
+        methods.push(item);
+    }
+}
+
+/// A helper type to construct enums, either bitfield ones or rust-style ones.
+enum EnumBuilder<'a> {
+    Rust(aster::item::ItemEnumBuilder<aster::invoke::Identity>),
+    Bitfield {
+        canonical_name: &'a str,
+        aster: P<ast::Item>,
+    },
+}
+
+impl<'a> EnumBuilder<'a> {
+    /// Create a new enum given an item builder, a canonical name, a name for
+    /// the representation, and whether it should be represented as a rust enum.
+    fn new(aster: aster::item::ItemBuilder<aster::invoke::Identity>,
+           name: &'a str,
+           repr_name: &str,
+           is_rust: bool)
+           -> Self {
+        if is_rust {
+            EnumBuilder::Rust(aster.enum_(name))
+        } else {
+            EnumBuilder::Bitfield {
+                canonical_name: name,
+                aster: aster.tuple_struct(name)
+                    .field()
+                    .pub_()
+                    .ty()
+                    .id(repr_name)
+                    .build(),
+            }
+        }
+    }
+
+    /// Add a variant to this enum.
+    fn with_variant<'b>(self,
+                        ctx: &BindgenContext,
+                        variant: &EnumVariant,
+                        mangling_prefix: Option<&String>,
+                        rust_ty: P<ast::Ty>,
+                        result: &mut CodegenResult<'b>)
+                        -> Self {
+        let variant_name = ctx.rust_mangle(variant.name());
+        let expr = aster::AstBuilder::new().expr();
+        let expr = match variant.val() {
+            EnumVariantValue::Signed(v) => helpers::ast_ty::int_expr(v),
+            EnumVariantValue::Unsigned(v) => expr.uint(v),
+        };
+
+        match self {
+            EnumBuilder::Rust(b) => {
+                EnumBuilder::Rust(b.with_variant_(ast::Variant_ {
+                    name: ctx.rust_ident(&*variant_name),
+                    attrs: vec![],
+                    data: ast::VariantData::Unit(ast::DUMMY_NODE_ID),
+                    disr_expr: Some(expr),
+                }))
+            }
+            EnumBuilder::Bitfield { canonical_name, .. } => {
+                let constant_name = match mangling_prefix {
+                    Some(prefix) => {
+                        Cow::Owned(format!("{}_{}", prefix, variant_name))
+                    }
+                    None => variant_name,
+                };
+
+                let constant = aster::AstBuilder::new()
+                    .item()
+                    .pub_()
+                    .const_(&*constant_name)
+                    .expr()
+                    .call()
+                    .id(canonical_name)
+                    .arg()
+                    .build(expr)
+                    .build()
+                    .build(rust_ty);
+                result.push(constant);
+                self
+            }
+        }
+    }
+
+    fn build<'b>(self,
+                 ctx: &BindgenContext,
+                 rust_ty: P<ast::Ty>,
+                 result: &mut CodegenResult<'b>)
+                 -> P<ast::Item> {
+        match self {
+            EnumBuilder::Rust(b) => b.build(),
+            EnumBuilder::Bitfield { canonical_name, aster } => {
+                let rust_ty_name = ctx.rust_ident_raw(canonical_name);
+                let prefix = ctx.trait_prefix();
+
+                let impl_ = quote_item!(ctx.ext_cx(),
+                    impl ::$prefix::ops::BitOr<$rust_ty> for $rust_ty {
+                        type Output = Self;
+
+                        #[inline]
+                        fn bitor(self, other: Self) -> Self {
+                            $rust_ty_name(self.0 | other.0)
+                        }
+                    }
+                )
+                    .unwrap();
+
+                result.push(impl_);
+                aster
+            }
+        }
+    }
+}
+
+impl CodeGenerator for Enum {
+    type Extra = Item;
+
+    fn codegen<'a>(&self,
+                   ctx: &BindgenContext,
+                   result: &mut CodegenResult<'a>,
+                   _whitelisted_items: &ItemSet,
+                   item: &Item) {
+        debug!("<Enum as CodeGenerator>::codegen: item = {:?}", item);
+
+        let name = item.canonical_name(ctx);
+        let enum_ty = item.expect_type();
+        let layout = enum_ty.layout(ctx);
+
+        let repr = self.repr().map(|repr| ctx.resolve_type(repr));
+        let repr = match repr {
+            Some(repr) => {
+                match *repr.canonical_type(ctx).kind() {
+                    TypeKind::Int(int_kind) => int_kind,
+                    _ => panic!("Unexpected type as enum repr"),
+                }
+            }
+            None => {
+                warn!("Guessing type of enum! Forward declarations of enums \
+                      shouldn't be legal!");
+                IntKind::Int
+            }
+        };
+
+        let signed = repr.is_signed();
+        let size = layout.map(|l| l.size)
+            .or_else(|| repr.known_size())
+            .unwrap_or(0);
+
+        let repr_name = match (signed, size) {
+            (true, 1) => "i8",
+            (false, 1) => "u8",
+            (true, 2) => "i16",
+            (false, 2) => "u16",
+            (true, 4) => "i32",
+            (false, 4) => "u32",
+            (true, 8) => "i64",
+            (false, 8) => "u64",
+            _ => {
+                warn!("invalid enum decl: signed: {}, size: {}", signed, size);
+                "i32"
+            }
+        };
+
+        let mut builder = aster::AstBuilder::new().item().pub_();
+
+        let is_bitfield = {
+            ctx.options().bitfield_enums.matches(&name) ||
+            (enum_ty.name().is_none() &&
+             self.variants()
+                .iter()
+                .any(|v| ctx.options().bitfield_enums.matches(&v.name())))
+        };
+
+        let is_rust_enum = !is_bitfield;
+
+        // FIXME: Rust forbids repr with empty enums. Remove this condition when
+        // this is allowed.
+        if is_rust_enum {
+            if !self.variants().is_empty() {
+                builder = builder.with_attr(attributes::repr(repr_name));
+            }
+        } else {
+            builder = builder.with_attr(attributes::repr("C"));
+        }
+
+        if let Some(comment) = item.comment() {
+            builder = builder.with_attr(attributes::doc(comment));
+        }
+
+        let derives = attributes::derives(&["Debug",
+                                            "Copy",
+                                            "Clone",
+                                            "PartialEq",
+                                            "Eq",
+                                            "Hash"]);
+
+        builder = builder.with_attr(derives);
+
+        fn add_constant<'a>(enum_: &Type,
+                            // Only to avoid recomputing every time.
+                            enum_canonical_name: &str,
+                            // May be the same as "variant" if it's because the
+                            // enum is unnamed and we still haven't seen the
+                            // value.
+                            variant_name: &str,
+                            referenced_name: &str,
+                            enum_rust_ty: P<ast::Ty>,
+                            result: &mut CodegenResult<'a>) {
+            let constant_name = if enum_.name().is_some() {
+                format!("{}_{}", enum_canonical_name, variant_name)
+            } else {
+                variant_name.into()
+            };
+
+            let constant = aster::AstBuilder::new()
+                .item()
+                .pub_()
+                .const_(constant_name)
+                .expr()
+                .path()
+                .ids(&[&*enum_canonical_name, referenced_name])
+                .build()
+                .build(enum_rust_ty);
+            result.push(constant);
+        }
+
+        let mut builder =
+            EnumBuilder::new(builder, &name, repr_name, is_rust_enum);
+
+        // A map where we keep a value -> variant relation.
+        let mut seen_values = HashMap::<_, String>::new();
+        let enum_rust_ty = item.to_rust_ty(ctx);
+        let is_toplevel = item.is_toplevel(ctx);
+
+        // Used to mangle the constants we generate in the unnamed-enum case.
+        let parent_canonical_name = if is_toplevel {
+            None
+        } else {
+            Some(item.parent_id().canonical_name(ctx))
+        };
+
+        let constant_mangling_prefix = if enum_ty.name().is_none() {
+            parent_canonical_name.as_ref().map(|n| &*n)
+        } else {
+            Some(&name)
+        };
+
+        // NB: We defer the creation of constified variants, in case we find
+        // another variant with the same value (which is the common thing to
+        // do).
+        let mut constified_variants = VecDeque::new();
+
+        let mut iter = self.variants().iter().peekable();
+        while let Some(variant) = iter.next().or_else(|| constified_variants.pop_front()) {
+            if variant.hidden() {
+                continue;
+            }
+
+            if variant.force_constification() && iter.peek().is_some() {
+                constified_variants.push_back(variant);
+                continue;
+            }
+
+            match seen_values.entry(variant.val()) {
+                Entry::Occupied(ref entry) => {
+                    if is_rust_enum {
+                        let variant_name = ctx.rust_mangle(variant.name());
+                        let mangled_name = if is_toplevel ||
+                                              enum_ty.name().is_some() {
+                            variant_name
+                        } else {
+                            let parent_name = parent_canonical_name.as_ref()
+                                .unwrap();
+
+                            Cow::Owned(
+                                format!("{}_{}", parent_name, variant_name))
+                        };
+
+                        let existing_variant_name = entry.get();
+                        add_constant(enum_ty,
+                                     &name,
+                                     &*mangled_name,
+                                     existing_variant_name,
+                                     enum_rust_ty.clone(),
+                                     result);
+                    } else {
+                        builder = builder.with_variant(ctx,
+                                          variant,
+                                          constant_mangling_prefix,
+                                          enum_rust_ty.clone(),
+                                          result);
+                    }
+                }
+                Entry::Vacant(entry) => {
+                    builder = builder.with_variant(ctx,
+                                                   variant,
+                                                   constant_mangling_prefix,
+                                                   enum_rust_ty.clone(),
+                                                   result);
+
+                    let variant_name = ctx.rust_mangle(variant.name());
+
+                    // If it's an unnamed enum, or constification is enforced,
+                    // we also generate a constant so it can be properly
+                    // accessed.
+                    if (is_rust_enum && enum_ty.name().is_none()) ||
+                        variant.force_constification() {
+                        let mangled_name = if is_toplevel {
+                            variant_name.clone()
+                        } else {
+                            let parent_name = parent_canonical_name.as_ref()
+                                .unwrap();
+
+                            Cow::Owned(
+                                format!("{}_{}", parent_name, variant_name))
+                        };
+
+                        add_constant(enum_ty,
+                                     &name,
+                                     &mangled_name,
+                                     &variant_name,
+                                     enum_rust_ty.clone(),
+                                     result);
+                    }
+
+                    entry.insert(variant_name.into_owned());
+                }
+            }
+        }
+
+        let enum_ = builder.build(ctx, enum_rust_ty, result);
+        result.push(enum_);
+    }
+}
+
+trait ToRustTy {
+    type Extra;
+
+    fn to_rust_ty(&self,
+                  ctx: &BindgenContext,
+                  extra: &Self::Extra)
+                  -> P<ast::Ty>;
+}
+
+trait ItemToRustTy {
+    fn to_rust_ty(&self, ctx: &BindgenContext) -> P<ast::Ty>;
+}
+
+// Convenience implementation.
+impl ItemToRustTy for ItemId {
+    fn to_rust_ty(&self, ctx: &BindgenContext) -> P<ast::Ty> {
+        ctx.resolve_item(*self).to_rust_ty(ctx)
+    }
+}
+
+impl ItemToRustTy for Item {
+    fn to_rust_ty(&self, ctx: &BindgenContext) -> P<ast::Ty> {
+        self.kind().expect_type().to_rust_ty(ctx, self)
+    }
+}
+
+impl ToRustTy for Type {
+    type Extra = Item;
+
+    fn to_rust_ty(&self, ctx: &BindgenContext, item: &Item) -> P<ast::Ty> {
+        use self::helpers::ast_ty::*;
+
+        match *self.kind() {
+            TypeKind::Void => raw_type(ctx, "c_void"),
+            // TODO: we should do something smart with nullptr, or maybe *const
+            // c_void is enough?
+            TypeKind::NullPtr => {
+                raw_type(ctx, "c_void").to_ptr(true, ctx.span())
+            }
+            TypeKind::Int(ik) => {
+                match ik {
+                    IntKind::Bool => aster::ty::TyBuilder::new().bool(),
+                    IntKind::Char => raw_type(ctx, "c_char"),
+                    IntKind::UChar => raw_type(ctx, "c_uchar"),
+                    IntKind::Short => raw_type(ctx, "c_short"),
+                    IntKind::UShort => raw_type(ctx, "c_ushort"),
+                    IntKind::Int => raw_type(ctx, "c_int"),
+                    IntKind::UInt => raw_type(ctx, "c_uint"),
+                    IntKind::Long => raw_type(ctx, "c_long"),
+                    IntKind::ULong => raw_type(ctx, "c_ulong"),
+                    IntKind::LongLong => raw_type(ctx, "c_longlong"),
+                    IntKind::ULongLong => raw_type(ctx, "c_ulonglong"),
+
+                    IntKind::I8 => aster::ty::TyBuilder::new().i8(),
+                    IntKind::U8 => aster::ty::TyBuilder::new().u8(),
+                    IntKind::I16 => aster::ty::TyBuilder::new().i16(),
+                    IntKind::U16 => aster::ty::TyBuilder::new().u16(),
+                    IntKind::I32 => aster::ty::TyBuilder::new().i32(),
+                    IntKind::U32 => aster::ty::TyBuilder::new().u32(),
+                    IntKind::I64 => aster::ty::TyBuilder::new().i64(),
+                    IntKind::U64 => aster::ty::TyBuilder::new().u64(),
+                    IntKind::Custom { name, .. } => {
+                        let ident = ctx.rust_ident_raw(name);
+                        quote_ty!(ctx.ext_cx(), $ident)
+                    }
+                    // FIXME: This doesn't generate the proper alignment, but we
+                    // can't do better right now. We should be able to use
+                    // i128/u128 when they're available.
+                    IntKind::U128 | IntKind::I128 => {
+                        aster::ty::TyBuilder::new().array(2).u64()
+                    }
+                }
+            }
+            TypeKind::Float(fk) => float_kind_rust_type(ctx, fk),
+            TypeKind::Complex(fk) => {
+                let float_path = float_kind_rust_type(ctx, fk);
+
+                ctx.generated_bindegen_complex();
+                if ctx.options().enable_cxx_namespaces {
+                    quote_ty!(ctx.ext_cx(), root::__BindgenComplex<$float_path>)
+                } else {
+                    quote_ty!(ctx.ext_cx(), __BindgenComplex<$float_path>)
+                }
+            }
+            TypeKind::Function(ref fs) => {
+                let ty = fs.to_rust_ty(ctx, item);
+                let prefix = ctx.trait_prefix();
+                quote_ty!(ctx.ext_cx(), ::$prefix::option::Option<$ty>)
+            }
+            TypeKind::Array(item, len) => {
+                let inner = item.to_rust_ty(ctx);
+                aster::ty::TyBuilder::new().array(len).build(inner)
+            }
+            TypeKind::Enum(..) => {
+                let path = item.namespace_aware_canonical_path(ctx);
+                aster::AstBuilder::new().ty().path().ids(path).build()
+            }
+            TypeKind::TemplateRef(inner, ref template_args) => {
+                // PS: Sorry for the duplication here.
+                let mut inner_ty = inner.to_rust_ty(ctx).unwrap();
+
+                if let ast::TyKind::Path(_, ref mut path) = inner_ty.node {
+                    let template_args = template_args.iter()
+                        .map(|arg| arg.to_rust_ty(ctx))
+                        .collect::<Vec<_>>();
+
+                    path.segments.last_mut().unwrap().parameters = if template_args.is_empty() {
+                        None
+                    } else {
+                        Some(P(ast::PathParameters::AngleBracketed(
+                            ast::AngleBracketedParameterData {
+                                lifetimes: vec![],
+                                types: P::from_vec(template_args),
+                                bindings: P::from_vec(vec![]),
+                            }
+                        )))
+                    }
+                }
+
+                P(inner_ty)
+            }
+            TypeKind::ResolvedTypeRef(inner) => inner.to_rust_ty(ctx),
+            TypeKind::TemplateAlias(ref spelling, inner, _) |
+            TypeKind::Alias(ref spelling, inner) => {
+                let applicable_named_args =
+                    item.applicable_template_args(ctx)
+                        .into_iter()
+                        .filter(|arg| ctx.resolve_type(*arg).is_named())
+                        .collect::<Vec<_>>();
+
+                if item.is_opaque(ctx) && !applicable_named_args.is_empty() {
+                    // Pray if there's no available layout.
+                    let layout = self.layout(ctx).unwrap_or_else(Layout::zero);
+                    BlobTyBuilder::new(layout).build()
+                } else if let Some(ty) = utils::type_from_named(ctx,
+                                                                spelling,
+                                                                inner) {
+                    ty
+                } else {
+                    utils::build_templated_path(item,
+                                                ctx,
+                                                applicable_named_args)
+                }
+            }
+            TypeKind::Comp(ref info) => {
+                let template_args = item.applicable_template_args(ctx);
+                if info.has_non_type_template_params() ||
+                    (item.is_opaque(ctx) && !template_args.is_empty()) {
+                    return match self.layout(ctx) {
+                        Some(layout) => BlobTyBuilder::new(layout).build(),
+                        None => {
+                            warn!("Couldn't compute layout for a type with non \
+                                  type template params or opaque, expect \
+                                  dragons!");
+                            aster::AstBuilder::new().ty().unit()
+                        }
+                    };
+                }
+
+                utils::build_templated_path(item, ctx, template_args)
+            }
+            TypeKind::BlockPointer => {
+                let void = raw_type(ctx, "c_void");
+                void.to_ptr(/* is_const = */
+                            false,
+                            ctx.span())
+            }
+            TypeKind::Pointer(inner) |
+            TypeKind::Reference(inner) => {
+                let inner = ctx.resolve_item(inner);
+                let inner_ty = inner.expect_type();
+                let ty = inner.to_rust_ty(ctx);
+
+                // Avoid the first function pointer level, since it's already
+                // represented in Rust.
+                if inner_ty.canonical_type(ctx).is_function() {
+                    ty
+                } else {
+                    let is_const = self.is_const() ||
+                                   inner.expect_type().is_const();
+                    ty.to_ptr(is_const, ctx.span())
+                }
+            }
+            TypeKind::Named(..) => {
+                let name = item.canonical_name(ctx);
+                let ident = ctx.rust_ident(&name);
+                quote_ty!(ctx.ext_cx(), $ident)
+            }
+            ref u @ TypeKind::UnresolvedTypeRef(..) => {
+                unreachable!("Should have been resolved after parsing {:?}!", u)
+            }
+        }
+    }
+}
+
+impl ToRustTy for FunctionSig {
+    type Extra = Item;
+
+    fn to_rust_ty(&self, ctx: &BindgenContext, _item: &Item) -> P<ast::Ty> {
+        // TODO: we might want to consider ignoring the reference return value.
+        let return_item = ctx.resolve_item(self.return_type());
+        let ret =
+            if let TypeKind::Void = *return_item.kind().expect_type().kind() {
+                ast::FunctionRetTy::Default(ctx.span())
+            } else {
+                ast::FunctionRetTy::Ty(return_item.to_rust_ty(ctx))
+            };
+
+        let mut unnamed_arguments = 0;
+        let arguments = self.argument_types().iter().map(|&(ref name, ty)| {
+            let arg_item = ctx.resolve_item(ty);
+            let arg_ty = arg_item.kind().expect_type();
+
+            // From the C90 standard[1]:
+            //
+            //     A declaration of a parameter as "array of type" shall be
+            //     adjusted to "qualified pointer to type", where the type
+            //     qualifiers (if any) are those specified within the [ and ] of
+            //     the array type derivation.
+            //
+            // [1]: http://c0x.coding-guidelines.com/6.7.5.3.html
+            let arg_ty = if let TypeKind::Array(t, _) = *arg_ty.canonical_type(ctx).kind() {
+                t.to_rust_ty(ctx).to_ptr(arg_ty.is_const(), ctx.span())
+            } else {
+                arg_item.to_rust_ty(ctx)
+            };
+
+            let arg_name = match *name {
+                Some(ref name) => ctx.rust_mangle(name).into_owned(),
+                None => {
+                    unnamed_arguments += 1;
+                    format!("arg{}", unnamed_arguments)
+                }
+            };
+
+            assert!(!arg_name.is_empty());
+
+            ast::Arg {
+                ty: arg_ty,
+                pat: aster::AstBuilder::new().pat().id(arg_name),
+                id: ast::DUMMY_NODE_ID,
+            }
+        }).collect::<Vec<_>>();
+
+        let decl = P(ast::FnDecl {
+            inputs: arguments,
+            output: ret,
+            variadic: self.is_variadic(),
+        });
+
+        let fnty = ast::TyKind::BareFn(P(ast::BareFnTy {
+            unsafety: ast::Unsafety::Unsafe,
+            abi: self.abi(),
+            lifetimes: vec![],
+            decl: decl,
+        }));
+
+        P(ast::Ty {
+            id: ast::DUMMY_NODE_ID,
+            node: fnty,
+            span: ctx.span(),
+        })
+    }
+}
+
+impl CodeGenerator for Function {
+    type Extra = Item;
+
+    fn codegen<'a>(&self,
+                   ctx: &BindgenContext,
+                   result: &mut CodegenResult<'a>,
+                   _whitelisted_items: &ItemSet,
+                   item: &Item) {
+        debug!("<Function as CodeGenerator>::codegen: item = {:?}", item);
+
+        let name = self.name();
+        let mut canonical_name = item.canonical_name(ctx);
+        let mangled_name = self.mangled_name();
+
+        {
+            let seen_symbol_name = mangled_name.unwrap_or(&canonical_name);
+
+            // TODO: Maybe warn here if there's a type/argument mismatch, or
+            // something?
+            if result.seen_function(seen_symbol_name) {
+                return;
+            }
+            result.saw_function(seen_symbol_name);
+        }
+
+        let signature_item = ctx.resolve_item(self.signature());
+        let signature = signature_item.kind().expect_type().canonical_type(ctx);
+        let signature = match *signature.kind() {
+            TypeKind::Function(ref sig) => sig,
+            _ => panic!("Signature kind is not a Function: {:?}", signature),
+        };
+
+        let fndecl = utils::rust_fndecl_from_signature(ctx, signature_item);
+
+        let mut attributes = vec![];
+
+        if let Some(comment) = item.comment() {
+            attributes.push(attributes::doc(comment));
+        }
+
+        if let Some(mangled) = mangled_name {
+            attributes.push(attributes::link_name(mangled));
+        } else if name != canonical_name {
+            attributes.push(attributes::link_name(name));
+        }
+
+        let foreign_item_kind =
+            ast::ForeignItemKind::Fn(fndecl, ast::Generics::default());
+
+        // Handle overloaded functions by giving each overload its own unique
+        // suffix.
+        let times_seen = result.overload_number(&canonical_name);
+        if times_seen > 0 {
+            write!(&mut canonical_name, "{}", times_seen).unwrap();
+        }
+
+        let foreign_item = ast::ForeignItem {
+            ident: ctx.rust_ident_raw(&canonical_name),
+            attrs: attributes,
+            node: foreign_item_kind,
+            id: ast::DUMMY_NODE_ID,
+            span: ctx.span(),
+            vis: ast::Visibility::Public,
+        };
+
+        let item = ForeignModBuilder::new(signature.abi())
+            .with_foreign_item(foreign_item)
+            .build(ctx);
+
+        result.push(item);
+    }
+}
+
+pub fn codegen(context: &mut BindgenContext) -> Vec<P<ast::Item>> {
+    context.gen(|context| {
+        let counter = Cell::new(0);
+        let mut result = CodegenResult::new(&counter);
+
+        debug!("codegen: {:?}", context.options());
+
+        let whitelisted_items: ItemSet = context.whitelisted_items().collect();
+
+        if context.options().emit_ir {
+            for &id in whitelisted_items.iter() {
+                let item = context.resolve_item(id);
+                println!("ir: {:?} = {:#?}", id, item);
+            }
+        }
+
+        context.resolve_item(context.root_module())
+            .codegen(context, &mut result, &whitelisted_items, &());
+
+        result.items
+    })
+}
+
+mod utils {
+    use aster;
+    use ir::context::{BindgenContext, ItemId};
+    use ir::item::{Item, ItemCanonicalPath};
+    use ir::ty::TypeKind;
+    use std::mem;
+    use super::ItemToRustTy;
+    use syntax::ast;
+    use syntax::ptr::P;
+
+    pub fn prepend_union_types(ctx: &BindgenContext,
+                               result: &mut Vec<P<ast::Item>>) {
+        let prefix = ctx.trait_prefix();
+
+        // TODO(emilio): The fmt::Debug impl could be way nicer with
+        // std::intrinsics::type_name, but...
+        let union_field_decl = quote_item!(ctx.ext_cx(),
+            #[repr(C)]
+            pub struct __BindgenUnionField<T>(
+                ::$prefix::marker::PhantomData<T>);
+        )
+            .unwrap();
+
+        let union_field_impl = quote_item!(&ctx.ext_cx(),
+            impl<T> __BindgenUnionField<T> {
+                #[inline]
+                pub fn new() -> Self {
+                    __BindgenUnionField(::$prefix::marker::PhantomData)
+                }
+
+                #[inline]
+                pub unsafe fn as_ref(&self) -> &T {
+                    ::$prefix::mem::transmute(self)
+                }
+
+                #[inline]
+                pub unsafe fn as_mut(&mut self) -> &mut T {
+                    ::$prefix::mem::transmute(self)
+                }
+            }
+        )
+            .unwrap();
+
+        let union_field_default_impl = quote_item!(&ctx.ext_cx(),
+            impl<T> ::$prefix::default::Default for __BindgenUnionField<T> {
+                #[inline]
+                fn default() -> Self {
+                    Self::new()
+                }
+            }
+        )
+            .unwrap();
+
+        let union_field_clone_impl = quote_item!(&ctx.ext_cx(),
+            impl<T> ::$prefix::clone::Clone for __BindgenUnionField<T> {
+                #[inline]
+                fn clone(&self) -> Self {
+                    Self::new()
+                }
+            }
+        )
+            .unwrap();
+
+        let union_field_copy_impl = quote_item!(&ctx.ext_cx(),
+            impl<T> ::$prefix::marker::Copy for __BindgenUnionField<T> {}
+        )
+            .unwrap();
+
+        let union_field_debug_impl = quote_item!(ctx.ext_cx(),
+            impl<T> ::std::fmt::Debug for __BindgenUnionField<T> {
+                fn fmt(&self, fmt: &mut ::std::fmt::Formatter)
+                       -> ::std::fmt::Result {
+                    fmt.write_str("__BindgenUnionField")
+                }
+            }
+        )
+            .unwrap();
+
+        let items = vec![
+            union_field_decl, union_field_impl,
+            union_field_default_impl,
+            union_field_clone_impl,
+            union_field_copy_impl,
+            union_field_debug_impl,
+        ];
+
+        let old_items = mem::replace(result, items);
+        result.extend(old_items.into_iter());
+    }
+
+    pub fn prepend_complex_type(ctx: &BindgenContext,
+                                result: &mut Vec<P<ast::Item>>) {
+        let complex_type = quote_item!(ctx.ext_cx(),
+            #[derive(PartialEq, Copy, Clone, Hash, Debug, Default)]
+            #[repr(C)]
+            pub struct __BindgenComplex<T> {
+                pub re: T,
+                pub im: T
+            }
+        )
+            .unwrap();
+
+        let items = vec![complex_type];
+        let old_items = mem::replace(result, items);
+        result.extend(old_items.into_iter());
+    }
+
+    pub fn build_templated_path(item: &Item,
+                                ctx: &BindgenContext,
+                                template_args: Vec<ItemId>)
+                                -> P<ast::Ty> {
+        let path = item.namespace_aware_canonical_path(ctx);
+        let builder = aster::AstBuilder::new().ty().path();
+
+        let template_args = template_args
+            .iter()
+            .map(|arg| arg.to_rust_ty(ctx))
+            .collect::<Vec<_>>();
+
+        // XXX: I suck at aster.
+        if path.len() == 1 {
+            return builder.segment(&path[0])
+                .with_tys(template_args)
+                .build()
+                .build();
+        }
+
+        let mut builder = builder.id(&path[0]);
+        for (i, segment) in path.iter().skip(1).enumerate() {
+            // Take into account the skip(1)
+            builder = if i == path.len() - 2 {
+                // XXX Extra clone courtesy of the borrow checker.
+                builder.segment(&segment)
+                    .with_tys(template_args.clone())
+                    .build()
+            } else {
+                builder.segment(&segment).build()
+            }
+        }
+
+        builder.build()
+    }
+
+    fn primitive_ty(ctx: &BindgenContext, name: &str) -> P<ast::Ty> {
+        let ident = ctx.rust_ident_raw(&name);
+        quote_ty!(ctx.ext_cx(), $ident)
+    }
+
+    pub fn type_from_named(ctx: &BindgenContext,
+                           name: &str,
+                           _inner: ItemId)
+                           -> Option<P<ast::Ty>> {
+        // FIXME: We could use the inner item to check this is really a
+        // primitive type but, who the heck overrides these anyway?
+        Some(match name {
+            "int8_t" => primitive_ty(ctx, "i8"),
+            "uint8_t" => primitive_ty(ctx, "u8"),
+            "int16_t" => primitive_ty(ctx, "i16"),
+            "uint16_t" => primitive_ty(ctx, "u16"),
+            "int32_t" => primitive_ty(ctx, "i32"),
+            "uint32_t" => primitive_ty(ctx, "u32"),
+            "int64_t" => primitive_ty(ctx, "i64"),
+            "uint64_t" => primitive_ty(ctx, "u64"),
+
+            "uintptr_t" | "size_t" => primitive_ty(ctx, "usize"),
+
+            "intptr_t" | "ptrdiff_t" | "ssize_t" => primitive_ty(ctx, "isize"),
+            _ => return None,
+        })
+    }
+
+    pub fn rust_fndecl_from_signature(ctx: &BindgenContext,
+                                      sig: &Item)
+                                      -> P<ast::FnDecl> {
+        use codegen::ToRustTy;
+
+        let signature = sig.kind().expect_type().canonical_type(ctx);
+        let signature = match *signature.kind() {
+            TypeKind::Function(ref sig) => sig,
+            _ => panic!("How?"),
+        };
+
+        let decl_ty = signature.to_rust_ty(ctx, sig);
+        match decl_ty.unwrap().node {
+            ast::TyKind::BareFn(bare_fn) => bare_fn.unwrap().decl,
+            _ => panic!("How did this happen exactly?"),
+        }
+    }
+}
diff --git a/src/ir/annotations.rs b/src/ir/annotations.rs
new file mode 100644
index 00000000..98be0540
--- /dev/null
+++ b/src/ir/annotations.rs
@@ -0,0 +1,188 @@
+//! Types and functions related to bindgen annotation comments.
+//!
+//! Users can add annotations in doc comments to types that they would like to
+//! replace other types with, mark as opaque, etc. This module deals with all of
+//! that stuff.
+
+use clang;
+
+/// What kind of accessor should we provide for a field?
+#[derive(Copy, PartialEq, Clone, Debug)]
+pub enum FieldAccessorKind {
+    /// No accessor.
+    None,
+    /// Plain accessor.
+    Regular,
+    /// Unsafe accessor.
+    Unsafe,
+    /// Immutable accessor.
+    Immutable,
+}
+
+/// Annotations for a given item, or a field.
+///
+/// You can see the kind of comments that are accepted in the Doxygen
+/// documentation:
+///
+/// http://www.stack.nl/~dimitri/doxygen/manual/docblocks.html
+#[derive(Clone, PartialEq, Debug)]
+pub struct Annotations {
+    /// Whether this item is marked as opaque. Only applies to types.
+    opaque: bool,
+    /// Whether this item should be hidden from the output. Only applies to
+    /// types, or enum variants.
+    hide: bool,
+    /// Whether this type should be replaced by another. The name is a
+    /// namespace-aware path.
+    use_instead_of: Option<Vec<String>>,
+    /// Manually disable deriving copy/clone on this type. Only applies to
+    /// struct or union types.
+    disallow_copy: bool,
+    /// Whether fields should be marked as private or not. You can set this on
+    /// structs (it will apply to all the fields), or individual fields.
+    private_fields: Option<bool>,
+    /// The kind of accessor this field will have. Also can be applied to
+    /// structs so all the fields inside share it by default.
+    accessor_kind: Option<FieldAccessorKind>,
+    /// Whether this enum variant should be constified.
+    ///
+    /// This is controlled by the `constant` attribute, this way:
+    ///
+    /// ```cpp
+    /// enum Foo {
+    ///     Bar = 0, /**< <div rustbindgen constant></div> */
+    ///     Baz = 0,
+    /// };
+    /// ```
+    ///
+    /// In that case, bindgen will generate a constant for `Bar` instead of
+    /// `Baz`.
+    constify_enum_variant: bool,
+}
+
+fn parse_accessor(s: &str) -> FieldAccessorKind {
+    match s {
+        "false" => FieldAccessorKind::None,
+        "unsafe" => FieldAccessorKind::Unsafe,
+        "immutable" => FieldAccessorKind::Immutable,
+        _ => FieldAccessorKind::Regular,
+    }
+}
+
+impl Default for Annotations {
+    fn default() -> Self {
+        Annotations {
+            opaque: false,
+            hide: false,
+            use_instead_of: None,
+            disallow_copy: false,
+            private_fields: None,
+            accessor_kind: None,
+            constify_enum_variant: false,
+        }
+    }
+}
+
+impl Annotations {
+    /// Construct new annotations for the given cursor and its bindgen comments
+    /// (if any).
+    pub fn new(cursor: &clang::Cursor) -> Option<Annotations> {
+        let mut anno = Annotations::default();
+        let mut matched_one = false;
+        anno.parse(&cursor.comment(), &mut matched_one);
+
+        if matched_one { Some(anno) } else { None }
+    }
+
+    /// Should this type be hidden?
+    pub fn hide(&self) -> bool {
+        self.hide
+    }
+
+    /// Should this type be opaque?
+    pub fn opaque(&self) -> bool {
+        self.opaque
+    }
+
+    /// For a given type, indicates the type it should replace.
+    ///
+    /// For example, in the following code:
+    ///
+    /// ```cpp
+    ///
+    /// /** <div rustbindgen replaces="Bar"></div> */
+    /// struct Foo { int x; };
+    ///
+    /// struct Bar { char foo; };
+    /// ```
+    ///
+    /// the generated code would look something like:
+    ///
+    /// ```
+    /// /** <div rustbindgen replaces="Bar"></div> */
+    /// struct Bar {
+    ///     x: ::std::os::raw::c_int,
+    /// };
+    /// ```
+    ///
+    /// That is, code for `Foo` is used to generate `Bar`.
+    pub fn use_instead_of(&self) -> Option<&[String]> {
+        self.use_instead_of.as_ref().map(|s| &**s)
+    }
+
+    /// Should we avoid implementing the `Copy` trait?
+    pub fn disallow_copy(&self) -> bool {
+        self.disallow_copy
+    }
+
+    /// Should the fields be private?
+    pub fn private_fields(&self) -> Option<bool> {
+        self.private_fields
+    }
+
+    /// What kind of accessors should we provide for this type's fields?
+    pub fn accessor_kind(&self) -> Option<FieldAccessorKind> {
+        self.accessor_kind
+    }
+
+    fn parse(&mut self, comment: &clang::Comment, matched: &mut bool) {
+        use clang_sys::CXComment_HTMLStartTag;
+        if comment.kind() == CXComment_HTMLStartTag &&
+           comment.get_tag_name() == "div" &&
+           comment.get_tag_attrs()
+            .next()
+            .map_or(false, |attr| attr.name == "rustbindgen") {
+            *matched = true;
+            for attr in comment.get_tag_attrs() {
+                match attr.name.as_str() {
+                    "opaque" => self.opaque = true,
+                    "hide" => self.hide = true,
+                    "nocopy" => self.disallow_copy = true,
+                    "replaces" => {
+                        self.use_instead_of = Some(attr.value
+                            .split("::")
+                            .map(Into::into)
+                            .collect())
+                    }
+                    "private" => {
+                        self.private_fields = Some(attr.value != "false")
+                    }
+                    "accessor" => {
+                        self.accessor_kind = Some(parse_accessor(&attr.value))
+                    }
+                    "constant" => self.constify_enum_variant = true,
+                    _ => {}
+                }
+            }
+        }
+
+        for child in comment.get_children() {
+            self.parse(&child, matched);
+        }
+    }
+
+    /// Returns whether we've parsed a "constant" attribute.
+    pub fn constify_enum_variant(&self) -> bool {
+        self.constify_enum_variant
+    }
+}
diff --git a/src/ir/comp.rs b/src/ir/comp.rs
new file mode 100644
index 00000000..968bf879
--- /dev/null
+++ b/src/ir/comp.rs
@@ -0,0 +1,962 @@
+//! Compound types (unions and structs) in our intermediate representation.
+
+use clang;
+use parse::{ClangItemParser, ParseError};
+use std::cell::Cell;
+use super::annotations::Annotations;
+use super::context::{BindgenContext, ItemId};
+use super::derive::{CanDeriveCopy, CanDeriveDebug};
+use super::item::Item;
+use super::layout::Layout;
+use super::ty::Type;
+use super::type_collector::{ItemSet, TypeCollector};
+
+/// The kind of compound type.
+#[derive(Debug, Copy, Clone, PartialEq)]
+pub enum CompKind {
+    /// A struct.
+    Struct,
+    /// A union.
+    Union,
+}
+
+/// The kind of C++ method.
+#[derive(Debug, Copy, Clone, PartialEq)]
+pub enum MethodKind {
+    /// A constructor. We represent it as method for convenience, to avoid code
+    /// duplication.
+    Constructor,
+    /// A static method.
+    Static,
+    /// A normal method.
+    Normal,
+    /// A virtual method.
+    Virtual,
+}
+
+/// A struct representing a C++ method, either static, normal, or virtual.
+#[derive(Debug)]
+pub struct Method {
+    kind: MethodKind,
+    /// The signature of the method. Take into account this is not a `Type`
+    /// item, but a `Function` one.
+    ///
+    /// This is tricky and probably this field should be renamed.
+    signature: ItemId,
+    is_const: bool,
+}
+
+impl Method {
+    /// Construct a new `Method`.
+    pub fn new(kind: MethodKind, signature: ItemId, is_const: bool) -> Self {
+        Method {
+            kind: kind,
+            signature: signature,
+            is_const: is_const,
+        }
+    }
+
+    /// What kind of method is this?
+    pub fn kind(&self) -> MethodKind {
+        self.kind
+    }
+
+    /// Is this a constructor?
+    pub fn is_constructor(&self) -> bool {
+        self.kind == MethodKind::Constructor
+    }
+
+    /// Is this a virtual method?
+    pub fn is_virtual(&self) -> bool {
+        self.kind == MethodKind::Virtual
+    }
+
+    /// Is this a static method?
+    pub fn is_static(&self) -> bool {
+        self.kind == MethodKind::Static
+    }
+
+    /// Get the `ItemId` for the `Function` signature for this method.
+    pub fn signature(&self) -> ItemId {
+        self.signature
+    }
+
+    /// Is this a const qualified method?
+    pub fn is_const(&self) -> bool {
+        self.is_const
+    }
+}
+
+/// A struct representing a C++ field.
+#[derive(Clone, Debug)]
+pub struct Field {
+    /// The name of the field, empty if it's an unnamed bitfield width.
+    name: Option<String>,
+    /// The inner type.
+    ty: ItemId,
+    /// The doc comment on the field if any.
+    comment: Option<String>,
+    /// Annotations for this field, or the default.
+    annotations: Annotations,
+    /// If this field is a bitfield, and how many bits does it contain if it is.
+    bitfield: Option<u32>,
+    /// If the C++ field is marked as `mutable`
+    mutable: bool,
+}
+
+impl Field {
+    /// Construct a new `Field`.
+    pub fn new(name: Option<String>,
+               ty: ItemId,
+               comment: Option<String>,
+               annotations: Option<Annotations>,
+               bitfield: Option<u32>,
+               mutable: bool)
+               -> Field {
+        Field {
+            name: name,
+            ty: ty,
+            comment: comment,
+            annotations: annotations.unwrap_or_default(),
+            bitfield: bitfield,
+            mutable: mutable,
+        }
+    }
+
+    /// Get the name of this field.
+    pub fn name(&self) -> Option<&str> {
+        self.name.as_ref().map(|n| &**n)
+    }
+
+    /// Get the type of this field.
+    pub fn ty(&self) -> ItemId {
+        self.ty
+    }
+
+    /// Get the comment for this field.
+    pub fn comment(&self) -> Option<&str> {
+        self.comment.as_ref().map(|c| &**c)
+    }
+
+    /// If this is a bitfield, how many bits does it need?
+    pub fn bitfield(&self) -> Option<u32> {
+        self.bitfield
+    }
+
+    /// Is this field marked as `mutable`?
+    pub fn is_mutable(&self) -> bool {
+        self.mutable
+    }
+
+    /// Get the annotations for this field.
+    pub fn annotations(&self) -> &Annotations {
+        &self.annotations
+    }
+}
+
+impl CanDeriveDebug for Field {
+    type Extra = ();
+
+    fn can_derive_debug(&self, ctx: &BindgenContext, _: ()) -> bool {
+        self.ty.can_derive_debug(ctx, ())
+    }
+}
+
+impl<'a> CanDeriveCopy<'a> for Field {
+    type Extra = ();
+
+    fn can_derive_copy(&self, ctx: &BindgenContext, _: ()) -> bool {
+        self.ty.can_derive_copy(ctx, ())
+    }
+
+    fn can_derive_copy_in_array(&self, ctx: &BindgenContext, _: ()) -> bool {
+        self.ty.can_derive_copy_in_array(ctx, ())
+    }
+}
+
+
+/// The kind of inheritance a base class is using.
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub enum BaseKind {
+    /// Normal inheritance, like:
+    ///
+    /// ```cpp
+    /// class A : public B {};
+    /// ```
+    Normal,
+    /// Virtual inheritance, like:
+    ///
+    /// ```cpp
+    /// class A: public virtual B {};
+    /// ```
+    Virtual,
+}
+
+/// A base class.
+#[derive(Clone, Debug)]
+pub struct Base {
+    /// The type of this base class.
+    pub ty: ItemId,
+    /// The kind of inheritance we're doing.
+    pub kind: BaseKind,
+}
+
+impl Base {
+    /// Whether this base class is inheriting virtually.
+    pub fn is_virtual(&self) -> bool {
+        self.kind == BaseKind::Virtual
+    }
+}
+
+/// A compound type.
+///
+/// Either a struct or union, a compound type is built up from the combination
+/// of fields which also are associated with their own (potentially compound)
+/// type.
+#[derive(Debug)]
+pub struct CompInfo {
+    /// Whether this is a struct or a union.
+    kind: CompKind,
+
+    /// The members of this struct or union.
+    fields: Vec<Field>,
+
+    /// The template parameters of this class. These are non-concrete, and
+    /// should always be a Type(TypeKind::Named(name)), but still they need to
+    /// be registered with an unique type id in the context.
+    template_args: Vec<ItemId>,
+
+    /// The method declarations inside this class, if in C++ mode.
+    methods: Vec<Method>,
+
+    /// The different constructors this struct or class contains.
+    constructors: Vec<ItemId>,
+
+    /// Vector of classes this one inherits from.
+    base_members: Vec<Base>,
+
+    /// The parent reference template if any.
+    ref_template: Option<ItemId>,
+
+    /// The inner types that were declared inside this class, in something like:
+    ///
+    /// class Foo {
+    ///     typedef int FooTy;
+    ///     struct Bar {
+    ///         int baz;
+    ///     };
+    /// }
+    ///
+    /// static Foo::Bar const = {3};
+    inner_types: Vec<ItemId>,
+
+    /// Set of static constants declared inside this class.
+    inner_vars: Vec<ItemId>,
+
+    /// Whether this type should generate an vtable (TODO: Should be able to
+    /// look at the virtual methods and ditch this field).
+    has_vtable: bool,
+
+    /// Whether this type has destructor.
+    has_destructor: bool,
+
+    /// Whether this type has a base type with more than one member.
+    ///
+    /// TODO: We should be able to compute this.
+    has_nonempty_base: bool,
+
+    /// If this type has a template parameter which is not a type (e.g.: a
+    /// size_t)
+    has_non_type_template_params: bool,
+
+    /// Whether this struct layout is packed.
+    packed: bool,
+
+    /// Whether this struct is anonymous.
+    is_anonymous: bool,
+
+    /// Used to know if we've found an opaque attribute that could cause us to
+    /// generate a type with invalid layout. This is explicitly used to avoid us
+    /// generating bad alignments when parsing types like max_align_t.
+    ///
+    /// It's not clear what the behavior should be here, if generating the item
+    /// and pray, or behave as an opaque type.
+    found_unknown_attr: bool,
+
+    /// Used to detect if we've run in a can_derive_debug cycle while cycling
+    /// around the template arguments.
+    detect_derive_debug_cycle: Cell<bool>,
+
+    /// Used to detect if we've run in a has_destructor cycle while cycling
+    /// around the template arguments.
+    detect_has_destructor_cycle: Cell<bool>,
+}
+
+impl CompInfo {
+    /// Construct a new compound type.
+    pub fn new(kind: CompKind) -> Self {
+        CompInfo {
+            kind: kind,
+            fields: vec![],
+            template_args: vec![],
+            methods: vec![],
+            constructors: vec![],
+            base_members: vec![],
+            ref_template: None,
+            inner_types: vec![],
+            inner_vars: vec![],
+            has_vtable: false,
+            has_destructor: false,
+            has_nonempty_base: false,
+            has_non_type_template_params: false,
+            packed: false,
+            is_anonymous: false,
+            found_unknown_attr: false,
+            detect_derive_debug_cycle: Cell::new(false),
+            detect_has_destructor_cycle: Cell::new(false),
+        }
+    }
+
+    /// Is this compound type unsized?
+    pub fn is_unsized(&self, ctx: &BindgenContext) -> bool {
+        !self.has_vtable(ctx) && self.fields.is_empty() &&
+        self.base_members.iter().all(|base| {
+            ctx.resolve_type(base.ty).canonical_type(ctx).is_unsized(ctx)
+        }) &&
+        self.ref_template
+            .map_or(true, |template| ctx.resolve_type(template).is_unsized(ctx))
+    }
+
+    /// Does this compound type have a destructor?
+    pub fn has_destructor(&self, ctx: &BindgenContext) -> bool {
+        if self.detect_has_destructor_cycle.get() {
+            warn!("Cycle detected looking for destructors");
+            // Assume no destructor, since we don't have an explicit one.
+            return false;
+        }
+
+        self.detect_has_destructor_cycle.set(true);
+
+        let has_destructor = self.has_destructor ||
+                             match self.kind {
+            CompKind::Union => false,
+            CompKind::Struct => {
+                // NB: We can't rely on a type with type parameters
+                // not having destructor.
+                //
+                // This is unfortunate, but...
+                self.ref_template.as_ref().map_or(false, |t| {
+                    ctx.resolve_type(*t).has_destructor(ctx)
+                }) ||
+                self.template_args.iter().any(|t| {
+                    ctx.resolve_type(*t).has_destructor(ctx)
+                }) ||
+                self.base_members.iter().any(|base| {
+                    ctx.resolve_type(base.ty).has_destructor(ctx)
+                }) ||
+                self.fields.iter().any(|field| {
+                    ctx.resolve_type(field.ty)
+                        .has_destructor(ctx)
+                })
+            }
+        };
+
+        self.detect_has_destructor_cycle.set(false);
+
+        has_destructor
+    }
+
+    /// Is this type a template specialization?
+    pub fn is_template_specialization(&self) -> bool {
+        self.ref_template.is_some()
+    }
+
+    /// Get the template declaration this specialization is specializing.
+    pub fn specialized_template(&self) -> Option<ItemId> {
+        self.ref_template
+    }
+
+    /// Compute the layout of this type.
+    ///
+    /// This is called as a fallback under some circumstances where LLVM doesn't
+    /// give us the correct layout.
+    ///
+    /// If we're a union without known layout, we try to compute it from our
+    /// members. This is not ideal, but clang fails to report the size for these
+    /// kind of unions, see test/headers/template_union.hpp
+    pub fn layout(&self, ctx: &BindgenContext) -> Option<Layout> {
+        use std::cmp;
+
+        // We can't do better than clang here, sorry.
+        if self.kind == CompKind::Struct {
+            return None;
+        }
+
+        let mut max_size = 0;
+        let mut max_align = 0;
+        for field in &self.fields {
+            let field_layout = ctx.resolve_type(field.ty)
+                .layout(ctx);
+
+            if let Some(layout) = field_layout {
+                max_size = cmp::max(max_size, layout.size);
+                max_align = cmp::max(max_align, layout.align);
+            }
+        }
+
+        Some(Layout::new(max_size, max_align))
+    }
+
+    /// Get this type's set of fields.
+    pub fn fields(&self) -> &[Field] {
+        &self.fields
+    }
+
+    /// Get this type's set of free template arguments. Empty if this is not a
+    /// template.
+    pub fn template_args(&self) -> &[ItemId] {
+        &self.template_args
+    }
+
+    /// Does this type have any template parameters that aren't types
+    /// (e.g. int)?
+    pub fn has_non_type_template_params(&self) -> bool {
+        self.has_non_type_template_params
+    }
+
+    /// Does this type have a virtual table?
+    pub fn has_vtable(&self, ctx: &BindgenContext) -> bool {
+        self.has_vtable ||
+        self.base_members().iter().any(|base| {
+            ctx.resolve_type(base.ty)
+                .has_vtable(ctx)
+        }) ||
+        self.ref_template.map_or(false, |template| {
+            ctx.resolve_type(template).has_vtable(ctx)
+        })
+    }
+
+    /// Get this type's set of methods.
+    pub fn methods(&self) -> &[Method] {
+        &self.methods
+    }
+
+    /// Get this type's set of constructors.
+    pub fn constructors(&self) -> &[ItemId] {
+        &self.constructors
+    }
+
+    /// What kind of compound type is this?
+    pub fn kind(&self) -> CompKind {
+        self.kind
+    }
+
+    /// The set of types that this one inherits from.
+    pub fn base_members(&self) -> &[Base] {
+        &self.base_members
+    }
+
+    /// Construct a new compound type from a Clang type.
+    pub fn from_ty(potential_id: ItemId,
+                   ty: &clang::Type,
+                   location: Option<clang::Cursor>,
+                   ctx: &mut BindgenContext)
+                   -> Result<Self, ParseError> {
+        use clang_sys::*;
+        // Sigh... For class templates we want the location, for
+        // specialisations, we want the declaration...  So just try both.
+        //
+        // TODO: Yeah, this code reads really bad.
+        let mut cursor = ty.declaration();
+        let mut kind = Self::kind_from_cursor(&cursor);
+        if kind.is_err() {
+            if let Some(location) = location {
+                kind = Self::kind_from_cursor(&location);
+                cursor = location;
+            }
+        }
+
+        let kind = try!(kind);
+
+        debug!("CompInfo::from_ty({:?}, {:?})", kind, cursor);
+
+        let mut ci = CompInfo::new(kind);
+        ci.is_anonymous = cursor.is_anonymous();
+        ci.template_args = match ty.template_args() {
+            // In forward declarations and not specializations,
+            // etc, they are in
+            // the ast, we'll meet them in
+            // CXCursor_TemplateTypeParameter
+            None => vec![],
+            Some(arg_types) => {
+                let num_arg_types = arg_types.len();
+                let mut specialization = true;
+
+                let args = arg_types.filter(|t| t.kind() != CXType_Invalid)
+                    .filter_map(|t| {
+                        if t.spelling().starts_with("type-parameter") {
+                            specialization = false;
+                            None
+                        } else {
+                            Some(Item::from_ty_or_ref(t, None, None, ctx))
+                        }
+                    })
+                    .collect::<Vec<_>>();
+
+                if specialization && args.len() != num_arg_types {
+                    ci.has_non_type_template_params = true;
+                    warn!("warning: Template parameter is not a type");
+                }
+
+                if specialization { args } else { vec![] }
+            }
+        };
+
+        ci.ref_template = cursor.specialized()
+            .and_then(|c| Item::parse(c, None, ctx).ok());
+
+        let mut maybe_anonymous_struct_field = None;
+        cursor.visit(|cur| {
+            if cur.kind() != CXCursor_FieldDecl {
+                if let Some((ty, _)) = maybe_anonymous_struct_field {
+                    let field = Field::new(None, ty, None, None, None, false);
+                    ci.fields.push(field);
+                }
+                maybe_anonymous_struct_field = None;
+            }
+
+            match cur.kind() {
+                CXCursor_FieldDecl => {
+                    match maybe_anonymous_struct_field.take() {
+                        Some((ty, clang_ty)) => {
+                            let mut used = false;
+                            cur.visit(|child| {
+                                if child.cur_type() == clang_ty {
+                                    used = true;
+                                }
+                                CXChildVisit_Continue
+                            });
+                            if !used {
+                                let field = Field::new(None,
+                                                       ty,
+                                                       None,
+                                                       None,
+                                                       None,
+                                                       false);
+                                ci.fields.push(field);
+                            }
+                        }
+                        None => {}
+                    }
+
+                    let bit_width = cur.bit_width();
+                    let field_type = Item::from_ty_or_ref(cur.cur_type(),
+                                                          Some(cur),
+                                                          Some(potential_id),
+                                                          ctx);
+
+                    let comment = cur.raw_comment();
+                    let annotations = Annotations::new(&cur);
+                    let name = cur.spelling();
+                    let is_mutable = cursor.is_mutable_field();
+
+                    // Name can be empty if there are bitfields, for example,
+                    // see tests/headers/struct_with_bitfields.h
+                    assert!(!name.is_empty() || bit_width.is_some(),
+                            "Empty field name?");
+
+                    let name = if name.is_empty() { None } else { Some(name) };
+
+                    let field = Field::new(name,
+                                           field_type,
+                                           comment,
+                                           annotations,
+                                           bit_width,
+                                           is_mutable);
+                    ci.fields.push(field);
+
+                    // No we look for things like attributes and stuff.
+                    cur.visit(|cur| {
+                        if cur.kind() == CXCursor_UnexposedAttr {
+                            ci.found_unknown_attr = true;
+                        }
+                        CXChildVisit_Continue
+                    });
+
+                }
+                CXCursor_UnexposedAttr => {
+                    ci.found_unknown_attr = true;
+                }
+                CXCursor_EnumDecl |
+                CXCursor_TypeAliasDecl |
+                CXCursor_TypedefDecl |
+                CXCursor_StructDecl |
+                CXCursor_UnionDecl |
+                CXCursor_ClassTemplate |
+                CXCursor_ClassDecl => {
+                    let inner = Item::parse(cur, Some(potential_id), ctx)
+                        .expect("Inner ClassDecl");
+                    if !ci.inner_types.contains(&inner) {
+                        ci.inner_types.push(inner);
+                    }
+                    // A declaration of an union or a struct without name could
+                    // also be an unnamed field, unfortunately.
+                    if cur.spelling().is_empty() &&
+                       cur.kind() != CXCursor_EnumDecl {
+                        let ty = cur.cur_type();
+                        maybe_anonymous_struct_field = Some((inner, ty));
+                    }
+                }
+                CXCursor_PackedAttr => {
+                    ci.packed = true;
+                }
+                CXCursor_TemplateTypeParameter => {
+                    // Yes! You can arrive here with an empty template parameter
+                    // name! Awesome, isn't it?
+                    //
+                    // see tests/headers/empty_template_param_name.hpp
+                    if cur.spelling().is_empty() {
+                        return CXChildVisit_Continue;
+                    }
+
+                    let param =
+                        Item::named_type(cur.spelling(), potential_id, ctx);
+                    ci.template_args.push(param);
+                }
+                CXCursor_CXXBaseSpecifier => {
+                    let is_virtual_base = cur.is_virtual_base();
+                    ci.has_vtable |= is_virtual_base;
+
+                    let kind = if is_virtual_base {
+                        BaseKind::Virtual
+                    } else {
+                        BaseKind::Normal
+                    };
+
+                    let type_id = Item::from_ty_or_ref(cur.cur_type(),
+                                                       Some(cur),
+                                                       None,
+                                                       ctx);
+                    ci.base_members.push(Base {
+                        ty: type_id,
+                        kind: kind,
+                    });
+                }
+                CXCursor_Constructor |
+                CXCursor_Destructor |
+                CXCursor_CXXMethod => {
+                    let is_virtual = cur.method_is_virtual();
+                    let is_static = cur.method_is_static();
+                    debug_assert!(!(is_static && is_virtual), "How?");
+
+                    ci.has_destructor |= cur.kind() == CXCursor_Destructor;
+                    ci.has_vtable |= is_virtual;
+
+                    // This used to not be here, but then I tried generating
+                    // stylo bindings with this (without path filters), and
+                    // cried a lot with a method in gfx/Point.h
+                    // (ToUnknownPoint), that somehow was causing the same type
+                    // to be inserted in the map two times.
+                    //
+                    // I couldn't make a reduced test case, but anyway...
+                    // Methods of template functions not only use to be inlined,
+                    // but also instantiated, and we wouldn't be able to call
+                    // them, so just bail out.
+                    if !ci.template_args.is_empty() {
+                        return CXChildVisit_Continue;
+                    }
+
+                    // NB: This gets us an owned `Function`, not a
+                    // `FunctionSig`.
+                    let signature = match Item::parse(cur, Some(potential_id), ctx) {
+                        Ok(item) if ctx.resolve_item(item).kind().is_function() => item,
+                        _ => return CXChildVisit_Continue,
+                    };
+
+                    match cur.kind() {
+                        CXCursor_Constructor => {
+                            ci.constructors.push(signature);
+                        }
+                        // TODO(emilio): Bind the destructor?
+                        CXCursor_Destructor => {}
+                        CXCursor_CXXMethod => {
+                            let is_const = cur.method_is_const();
+                            let method_kind = if is_static {
+                                MethodKind::Static
+                            } else if is_virtual {
+                                MethodKind::Virtual
+                            } else {
+                                MethodKind::Normal
+                            };
+
+                            let method =
+                                Method::new(method_kind, signature, is_const);
+
+                            ci.methods.push(method);
+                        }
+                        _ => unreachable!("How can we see this here?"),
+                    }
+                }
+                CXCursor_NonTypeTemplateParameter => {
+                    ci.has_non_type_template_params = true;
+                }
+                CXCursor_VarDecl => {
+                    let linkage = cur.linkage();
+                    if linkage != CXLinkage_External &&
+                       linkage != CXLinkage_UniqueExternal {
+                        return CXChildVisit_Continue;
+                    }
+
+                    let visibility = cur.visibility();
+                    if visibility != CXVisibility_Default {
+                        return CXChildVisit_Continue;
+                    }
+
+                    if let Ok(item) = Item::parse(cur,
+                                                  Some(potential_id),
+                                                  ctx) {
+                        ci.inner_vars.push(item);
+                    }
+                }
+                // Intentionally not handled
+                CXCursor_CXXAccessSpecifier |
+                CXCursor_CXXFinalAttr |
+                CXCursor_FunctionTemplate |
+                CXCursor_ConversionFunction => {}
+                _ => {
+                    warn!("unhandled comp member `{}` (kind {:?}) in `{}` ({})",
+                          cur.spelling(),
+                          cur.kind(),
+                          cursor.spelling(),
+                          cur.location());
+                }
+            }
+            CXChildVisit_Continue
+        });
+
+        if let Some((ty, _)) = maybe_anonymous_struct_field {
+            let field = Field::new(None, ty, None, None, None, false);
+            ci.fields.push(field);
+        }
+
+        Ok(ci)
+    }
+
+    fn kind_from_cursor(cursor: &clang::Cursor)
+                        -> Result<CompKind, ParseError> {
+        use clang_sys::*;
+        Ok(match cursor.kind() {
+            CXCursor_UnionDecl => CompKind::Union,
+            CXCursor_ClassDecl |
+            CXCursor_StructDecl => CompKind::Struct,
+            CXCursor_CXXBaseSpecifier |
+            CXCursor_ClassTemplatePartialSpecialization |
+            CXCursor_ClassTemplate => {
+                match cursor.template_kind() {
+                    CXCursor_UnionDecl => CompKind::Union,
+                    _ => CompKind::Struct,
+                }
+            }
+            _ => {
+                warn!("Unknown kind for comp type: {:?}", cursor);
+                return Err(ParseError::Continue);
+            }
+        })
+    }
+
+    /// Do any of the types that participate in this type's "signature" use the
+    /// named type `ty`?
+    ///
+    /// See also documentation for `ir::Item::signature_contains_named_type`.
+    pub fn signature_contains_named_type(&self,
+                                         ctx: &BindgenContext,
+                                         ty: &Type)
+                                         -> bool {
+        // We don't generate these, so rather don't make the codegen step to
+        // think we got it covered.
+        if self.has_non_type_template_params() {
+            return false;
+        }
+        self.template_args.iter().any(|arg| {
+            ctx.resolve_type(*arg)
+                .signature_contains_named_type(ctx, ty)
+        })
+    }
+
+    /// Get the set of types that were declared within this compound type
+    /// (e.g. nested class definitions).
+    pub fn inner_types(&self) -> &[ItemId] {
+        &self.inner_types
+    }
+
+    /// Get the set of static variables declared within this compound type.
+    pub fn inner_vars(&self) -> &[ItemId] {
+        &self.inner_vars
+    }
+
+    /// Have we found a field with an opaque type that could potentially mess up
+    /// the layout of this compound type?
+    pub fn found_unknown_attr(&self) -> bool {
+        self.found_unknown_attr
+    }
+
+    /// Is this compound type packed?
+    pub fn packed(&self) -> bool {
+        self.packed
+    }
+
+    /// Returns whether this type needs an explicit vtable because it has
+    /// virtual methods and none of its base classes has already a vtable.
+    pub fn needs_explicit_vtable(&self, ctx: &BindgenContext) -> bool {
+        self.has_vtable(ctx) &&
+        !self.base_members.iter().any(|base| {
+            // NB: Ideally, we could rely in all these types being `comp`, and
+            // life would be beautiful.
+            //
+            // Unfortunately, given the way we implement --match-pat, and also
+            // that you can inherit from templated types, we need to handle
+            // other cases here too.
+            ctx.resolve_type(base.ty)
+                .canonical_type(ctx)
+                .as_comp()
+                .map_or(false, |ci| ci.has_vtable(ctx))
+        })
+    }
+}
+
+impl CanDeriveDebug for CompInfo {
+    type Extra = Option<Layout>;
+
+    fn can_derive_debug(&self,
+                        ctx: &BindgenContext,
+                        layout: Option<Layout>)
+                        -> bool {
+        if self.has_non_type_template_params() {
+            return layout.map_or(false, |l| l.opaque().can_derive_debug(ctx, ()));
+        }
+
+        // We can reach here recursively via template parameters of a member,
+        // for example.
+        if self.detect_derive_debug_cycle.get() {
+            warn!("Derive debug cycle detected!");
+            return true;
+        }
+
+        if self.kind == CompKind::Union {
+            if ctx.options().unstable_rust {
+                return false;
+            }
+
+            return layout.unwrap_or_else(Layout::zero)
+                .opaque()
+                .can_derive_debug(ctx, ());
+        }
+
+        self.detect_derive_debug_cycle.set(true);
+
+        let can_derive_debug = {
+            self.base_members
+                .iter()
+                .all(|base| base.ty.can_derive_debug(ctx, ())) &&
+            self.template_args
+                .iter()
+                .all(|id| id.can_derive_debug(ctx, ())) &&
+            self.fields
+                .iter()
+                .all(|f| f.can_derive_debug(ctx, ())) &&
+            self.ref_template.map_or(true, |id| id.can_derive_debug(ctx, ()))
+        };
+
+        self.detect_derive_debug_cycle.set(false);
+
+        can_derive_debug
+    }
+}
+
+impl<'a> CanDeriveCopy<'a> for CompInfo {
+    type Extra = (&'a Item, Option<Layout>);
+
+    fn can_derive_copy(&self,
+                       ctx: &BindgenContext,
+                       (item, layout): (&Item, Option<Layout>))
+                       -> bool {
+        if self.has_non_type_template_params() {
+            return layout.map_or(false, |l| l.opaque().can_derive_copy(ctx, ()));
+        }
+
+        // NOTE: Take into account that while unions in C and C++ are copied by
+        // default, the may have an explicit destructor in C++, so we can't
+        // defer this check just for the union case.
+        if self.has_destructor(ctx) {
+            return false;
+        }
+
+        if self.kind == CompKind::Union {
+            if !ctx.options().unstable_rust {
+                // NOTE: If there's no template parameters we can derive copy
+                // unconditionally, since arrays are magical for rustc, and
+                // __BindgenUnionField always implements copy.
+                return true;
+            }
+
+            // https://github.com/rust-lang/rust/issues/36640
+            if !self.template_args.is_empty() || self.ref_template.is_some() ||
+               !item.applicable_template_args(ctx).is_empty() {
+                return false;
+            }
+        }
+
+        // With template args, use a safe subset of the types,
+        // since copyability depends on the types itself.
+        self.ref_template
+            .as_ref()
+            .map_or(true, |t| t.can_derive_copy(ctx, ())) &&
+        self.base_members
+            .iter()
+            .all(|base| base.ty.can_derive_copy(ctx, ())) &&
+        self.fields.iter().all(|field| field.can_derive_copy(ctx, ()))
+    }
+
+    fn can_derive_copy_in_array(&self,
+                                ctx: &BindgenContext,
+                                extra: (&Item, Option<Layout>))
+                                -> bool {
+        self.can_derive_copy(ctx, extra)
+    }
+}
+
+impl TypeCollector for CompInfo {
+    type Extra = Item;
+
+    fn collect_types(&self,
+                     context: &BindgenContext,
+                     types: &mut ItemSet,
+                     item: &Item) {
+        if let Some(template) = self.specialized_template() {
+            types.insert(template);
+        }
+
+        let applicable_template_args = item.applicable_template_args(context);
+        for arg in applicable_template_args {
+            types.insert(arg);
+        }
+
+        for base in self.base_members() {
+            types.insert(base.ty);
+        }
+
+        for field in self.fields() {
+            types.insert(field.ty());
+        }
+
+        for &ty in self.inner_types() {
+            types.insert(ty);
+        }
+
+        for &var in self.inner_vars() {
+            types.insert(var);
+        }
+
+        // FIXME(emilio): Methods, VTable?
+    }
+}
diff --git a/src/ir/context.rs b/src/ir/context.rs
new file mode 100644
index 00000000..b0143bd5
--- /dev/null
+++ b/src/ir/context.rs
@@ -0,0 +1,1267 @@
+//! Common context that is passed around during parsing and codegen.
+
+use BindgenOptions;
+use cexpr;
+use chooser::TypeChooser;
+use clang::{self, Cursor};
+use parse::ClangItemParser;
+use std::borrow::Cow;
+use std::cell::Cell;
+use std::collections::{HashMap, VecDeque, hash_map};
+use std::collections::btree_map::{self, BTreeMap};
+use std::fmt;
+use super::derive::{CanDeriveCopy, CanDeriveDebug};
+use super::int::IntKind;
+use super::item::{Item, ItemCanonicalPath};
+use super::item_kind::ItemKind;
+use super::module::{Module, ModuleKind};
+use super::ty::{FloatKind, Type, TypeKind};
+use super::type_collector::{ItemSet, TypeCollector};
+use syntax::ast::Ident;
+use syntax::codemap::{DUMMY_SP, Span};
+use syntax::ext::base::ExtCtxt;
+
+/// A single identifier for an item.
+///
+/// TODO: Build stronger abstractions on top of this, like TypeId(ItemId)?
+#[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub struct ItemId(usize);
+
+impl ItemId {
+    /// Get a numeric representation of this id.
+    pub fn as_usize(&self) -> usize {
+        self.0
+    }
+}
+
+impl CanDeriveDebug for ItemId {
+    type Extra = ();
+
+    fn can_derive_debug(&self, ctx: &BindgenContext, _: ()) -> bool {
+        ctx.resolve_item(*self).can_derive_debug(ctx, ())
+    }
+}
+
+impl<'a> CanDeriveCopy<'a> for ItemId {
+    type Extra = ();
+
+    fn can_derive_copy(&self, ctx: &BindgenContext, _: ()) -> bool {
+        ctx.resolve_item(*self).can_derive_copy(ctx, ())
+    }
+
+    fn can_derive_copy_in_array(&self, ctx: &BindgenContext, _: ()) -> bool {
+        ctx.resolve_item(*self).can_derive_copy_in_array(ctx, ())
+    }
+}
+
+/// A key used to index a resolved type, so we only process it once.
+///
+/// This is almost always a USR string (an unique identifier generated by
+/// clang), but it can also be the canonical declaration if the type is unnamed,
+/// in which case clang may generate the same USR for multiple nested unnamed
+/// types.
+#[derive(Eq, PartialEq, Hash, Debug)]
+enum TypeKey {
+    USR(String),
+    Declaration(Cursor),
+}
+
+// This is just convenience to avoid creating a manual debug impl for the
+// context.
+struct GenContext<'ctx>(ExtCtxt<'ctx>);
+
+impl<'ctx> fmt::Debug for GenContext<'ctx> {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        write!(fmt, "GenContext {{ ... }}")
+    }
+}
+
+/// A context used during parsing and generation of structs.
+#[derive(Debug)]
+pub struct BindgenContext<'ctx> {
+    /// The map of all the items parsed so far.
+    ///
+    /// It's a BTreeMap because we want the keys to be sorted to have consistent
+    /// output.
+    items: BTreeMap<ItemId, Item>,
+
+    /// The next item id to use during this bindings regeneration.
+    next_item_id: ItemId,
+
+    /// Clang USR to type map. This is needed to be able to associate types with
+    /// item ids during parsing.
+    types: HashMap<TypeKey, ItemId>,
+
+    /// A cursor to module map. Similar reason than above.
+    modules: HashMap<Cursor, ItemId>,
+
+    /// The root module, this is guaranteed to be an item of kind Module.
+    root_module: ItemId,
+
+    /// Current module being traversed.
+    current_module: ItemId,
+
+    /// A stack with the current type declarations and types we're parsing. This
+    /// is needed to avoid infinite recursion when parsing a type like:
+    ///
+    /// struct c { struct c* next; };
+    ///
+    /// This means effectively, that a type has a potential ID before knowing if
+    /// it's a correct type. But that's not important in practice.
+    ///
+    /// We could also use the `types` HashMap, but my intention with it is that
+    /// only valid types and declarations end up there, and this could
+    /// potentially break that assumption.
+    ///
+    /// FIXME: Should not be public, though... meh.
+    pub currently_parsed_types: Vec<(Cursor, ItemId)>,
+
+    /// A HashSet with all the already parsed macro names. This is done to avoid
+    /// hard errors while parsing duplicated macros, as well to allow macro
+    /// expression parsing.
+    parsed_macros: HashMap<Vec<u8>, cexpr::expr::EvalResult>,
+
+    /// The active replacements collected from replaces="xxx" annotations.
+    replacements: HashMap<Vec<String>, ItemId>,
+
+    collected_typerefs: bool,
+
+    /// Dummy structures for code generation.
+    gen_ctx: Option<&'ctx GenContext<'ctx>>,
+    span: Span,
+
+    /// The clang index for parsing.
+    index: clang::Index,
+
+    /// The translation unit for parsing.
+    translation_unit: clang::TranslationUnit,
+
+    /// The options given by the user via cli or other medium.
+    options: BindgenOptions,
+
+    /// Whether a bindgen complex was generated
+    generated_bindegen_complex: Cell<bool>,
+}
+
+impl<'ctx> BindgenContext<'ctx> {
+    /// Construct the context for the given `options`.
+    pub fn new(options: BindgenOptions) -> Self {
+        use clang_sys;
+
+        let index = clang::Index::new(false, true);
+
+        let parse_options =
+            clang_sys::CXTranslationUnit_DetailedPreprocessingRecord;
+        let translation_unit =
+            clang::TranslationUnit::parse(&index,
+                                          "",
+                                          &options.clang_args,
+                                          &[],
+                                          parse_options)
+                .expect("TranslationUnit::parse");
+
+        let root_module = Self::build_root_module(ItemId(0));
+        let mut me = BindgenContext {
+            items: Default::default(),
+            types: Default::default(),
+            modules: Default::default(),
+            next_item_id: ItemId(1),
+            root_module: root_module.id(),
+            current_module: root_module.id(),
+            currently_parsed_types: vec![],
+            parsed_macros: Default::default(),
+            replacements: Default::default(),
+            collected_typerefs: false,
+            gen_ctx: None,
+            span: DUMMY_SP,
+            index: index,
+            translation_unit: translation_unit,
+            options: options,
+            generated_bindegen_complex: Cell::new(false),
+        };
+
+        me.add_item(root_module, None, None);
+
+        me
+    }
+
+    /// Get the user-provided type chooser by reference, if any.
+    pub fn type_chooser(&self) -> Option<&TypeChooser> {
+        self.options().type_chooser.as_ref().map(|t| &**t)
+    }
+
+    /// Define a new item.
+    ///
+    /// This inserts it into the internal items set, and its type into the
+    /// internal types set.
+    pub fn add_item(&mut self,
+                    item: Item,
+                    declaration: Option<Cursor>,
+                    location: Option<Cursor>) {
+        debug!("BindgenContext::add_item({:?}, declaration: {:?}, loc: {:?}",
+               item,
+               declaration,
+               location);
+        debug_assert!(declaration.is_some() || !item.kind().is_type() ||
+                      item.kind().expect_type().is_builtin_or_named(),
+                      "Adding a type without declaration?");
+
+        let id = item.id();
+        let is_type = item.kind().is_type();
+        let is_unnamed = is_type && item.expect_type().name().is_none();
+
+        // Be sure to track all the generated children under namespace, even
+        // those generated after resolving typerefs, etc.
+        if item.id() != item.parent_id() {
+            if let Some(mut parent) = self.items.get_mut(&item.parent_id()) {
+                if let Some(mut module) = parent.as_module_mut() {
+                    module.children_mut().push(item.id());
+                }
+            }
+        }
+
+        let old_item = self.items.insert(id, item);
+        assert!(old_item.is_none(), "Inserted type twice?");
+
+        // Unnamed items can have an USR, but they can't be referenced from
+        // other sites explicitly and the USR can match if the unnamed items are
+        // nested, so don't bother tracking them.
+        if is_type && declaration.is_some() {
+            let mut declaration = declaration.unwrap();
+            if !declaration.is_valid() {
+                if let Some(location) = location {
+                    if location.is_template_like() {
+                        declaration = location;
+                    }
+                }
+            }
+            declaration = declaration.canonical();
+            if !declaration.is_valid() {
+                // This could happen, for example, with types like `int*` or
+                // similar.
+                //
+                // Fortunately, we don't care about those types being
+                // duplicated, so we can just ignore them.
+                debug!("Invalid declaration {:?} found for type {:?}",
+                       declaration,
+                       self.items.get(&id).unwrap().kind().expect_type());
+                return;
+            }
+
+            let key = if is_unnamed {
+                TypeKey::Declaration(declaration)
+            } else if let Some(usr) = declaration.usr() {
+                TypeKey::USR(usr)
+            } else {
+                warn!("Valid declaration with no USR: {:?}, {:?}",
+                       declaration,
+                       location);
+                TypeKey::Declaration(declaration)
+            };
+
+            let old = self.types.insert(key, id);
+            debug_assert_eq!(old, None);
+        }
+    }
+
+    // TODO: Move all this syntax crap to other part of the code.
+
+    /// Given that we are in the codegen phase, get the syntex context.
+    pub fn ext_cx(&self) -> &ExtCtxt<'ctx> {
+        &self.gen_ctx.expect("Not in gen phase").0
+    }
+
+    /// Given that we are in the codegen phase, get the current syntex span.
+    pub fn span(&self) -> Span {
+        self.span
+    }
+
+    /// Mangles a name so it doesn't conflict with any keyword.
+    pub fn rust_mangle<'a>(&self, name: &'a str) -> Cow<'a, str> {
+        use syntax::parse::token;
+        let ident = self.rust_ident_raw(name);
+        let token = token::Ident(ident);
+        if token.is_any_keyword() || name.contains("@") ||
+           name.contains("?") || name.contains("$") ||
+           "bool" == name {
+            let mut s = name.to_owned();
+            s = s.replace("@", "_");
+            s = s.replace("?", "_");
+            s = s.replace("$", "_");
+            s.push_str("_");
+            return Cow::Owned(s);
+        }
+        Cow::Borrowed(name)
+    }
+
+    /// Returns a mangled name as a rust identifier.
+    pub fn rust_ident(&self, name: &str) -> Ident {
+        self.rust_ident_raw(&self.rust_mangle(name))
+    }
+
+    /// Returns a mangled name as a rust identifier.
+    pub fn rust_ident_raw(&self, name: &str) -> Ident {
+        self.ext_cx().ident_of(name)
+    }
+
+    /// Iterate over all items that have been defined.
+    pub fn items<'a>(&'a self) -> btree_map::Iter<'a, ItemId, Item> {
+        self.items.iter()
+    }
+
+    /// Have we collected all unresolved type references yet?
+    pub fn collected_typerefs(&self) -> bool {
+        self.collected_typerefs
+    }
+
+    /// Gather all the unresolved type references.
+    fn collect_typerefs
+        (&mut self)
+         -> Vec<(ItemId, clang::Type, Option<clang::Cursor>, Option<ItemId>)> {
+        debug_assert!(!self.collected_typerefs);
+        self.collected_typerefs = true;
+        let mut typerefs = vec![];
+        for (id, ref mut item) in &mut self.items {
+            let kind = item.kind();
+            let ty = match kind.as_type() {
+                Some(ty) => ty,
+                None => continue,
+            };
+
+            match *ty.kind() {
+                TypeKind::UnresolvedTypeRef(ref ty, loc, parent_id) => {
+                    typerefs.push((*id, ty.clone(), loc, parent_id));
+                }
+                _ => {}
+            };
+        }
+        typerefs
+    }
+
+    /// Collect all of our unresolved type references and resolve them.
+    fn resolve_typerefs(&mut self) {
+        let typerefs = self.collect_typerefs();
+
+        for (id, ty, loc, parent_id) in typerefs {
+            let _resolved = {
+                let resolved = Item::from_ty(&ty, loc, parent_id, self)
+                    .expect("What happened?");
+                let mut item = self.items.get_mut(&id).unwrap();
+
+                *item.kind_mut().as_type_mut().unwrap().kind_mut() =
+                    TypeKind::ResolvedTypeRef(resolved);
+                resolved
+            };
+
+            // Something in the STL is trolling me. I don't need this assertion
+            // right now, but worth investigating properly once this lands.
+            //
+            // debug_assert!(self.items.get(&resolved).is_some(), "How?");
+        }
+    }
+
+    /// Iterate over all items and replace any item that has been named in a
+    /// `replaces="SomeType"` annotation with the replacement type.
+    fn process_replacements(&mut self) {
+        if self.replacements.is_empty() {
+            debug!("No replacements to process");
+            return;
+        }
+
+        // FIXME: This is linear, but the replaces="xxx" annotation was already
+        // there, and for better or worse it's useful, sigh...
+        //
+        // We leverage the ResolvedTypeRef thing, though, which is cool :P.
+
+        let mut replacements = vec![];
+
+        for (id, item) in self.items.iter() {
+            if item.annotations().use_instead_of().is_some() {
+                continue;
+            }
+
+            // Calls to `canonical_name` are expensive, so eagerly filter out
+            // items that cannot be replaced.
+            let ty = match item.kind().as_type() {
+                Some(ty) => ty,
+                None => continue,
+            };
+
+            match *ty.kind() {
+                TypeKind::Comp(ref ci) if !ci.is_template_specialization() => {}
+                TypeKind::TemplateAlias(..) |
+                TypeKind::Alias(..) => {}
+                _ => continue,
+            }
+
+            let path = item.canonical_path(self);
+            let replacement = self.replacements.get(&path[1..]);
+
+            if let Some(replacement) = replacement {
+                if replacement != id {
+                    // We set this just after parsing the annotation. It's
+                    // very unlikely, but this can happen.
+                    if self.items.get(replacement).is_some() {
+                        replacements.push((*id, *replacement));
+                    }
+                }
+            }
+        }
+
+        for (id, replacement) in replacements {
+            debug!("Replacing {:?} with {:?}", id, replacement);
+
+            let new_parent = {
+                let mut item = self.items.get_mut(&id).unwrap();
+                *item.kind_mut().as_type_mut().unwrap().kind_mut() =
+                    TypeKind::ResolvedTypeRef(replacement);
+                item.parent_id()
+            };
+
+
+            // Reparent the item.
+            let old_parent = self.resolve_item(replacement).parent_id();
+
+            if new_parent == old_parent {
+                continue;
+            }
+
+            if let Some(mut module) = self.items
+                .get_mut(&old_parent)
+                .unwrap()
+                .as_module_mut() {
+                // Deparent the replacement.
+                let position = module.children()
+                    .iter()
+                    .position(|id| *id == replacement)
+                    .unwrap();
+                module.children_mut().remove(position);
+            }
+
+            if let Some(mut module) = self.items
+                .get_mut(&new_parent)
+                .unwrap()
+                .as_module_mut() {
+                module.children_mut().push(replacement);
+            }
+
+            self.items
+                .get_mut(&replacement)
+                .unwrap()
+                .set_parent_for_replacement(new_parent);
+            self.items
+                .get_mut(&id)
+                .unwrap()
+                .set_parent_for_replacement(old_parent);
+        }
+    }
+
+    /// Enter the code generation phase, invoke the given callback `cb`, and
+    /// leave the code generation phase.
+    pub fn gen<F, Out>(&mut self, cb: F) -> Out
+        where F: FnOnce(&Self) -> Out,
+    {
+        use aster::symbol::ToSymbol;
+        use syntax::ext::expand::ExpansionConfig;
+        use syntax::codemap::{ExpnInfo, MacroBang, NameAndSpan};
+        use syntax::ext::base;
+        use syntax::parse;
+        use std::mem;
+
+        let cfg = ExpansionConfig::default("xxx".to_owned());
+        let sess = parse::ParseSess::new();
+        let mut loader = base::DummyResolver;
+        let mut ctx = GenContext(base::ExtCtxt::new(&sess, cfg, &mut loader));
+
+        ctx.0.bt_push(ExpnInfo {
+            call_site: self.span,
+            callee: NameAndSpan {
+                format: MacroBang("".to_symbol()),
+                allow_internal_unstable: false,
+                span: None,
+            },
+        });
+
+        // FIXME: This is evil, we should move code generation to use a wrapper
+        // of BindgenContext instead, I guess. Even though we know it's fine
+        // because we remove it before the end of this function.
+        self.gen_ctx = Some(unsafe { mem::transmute(&ctx) });
+
+        self.assert_no_dangling_references();
+
+        if !self.collected_typerefs() {
+            self.resolve_typerefs();
+            self.process_replacements();
+        }
+
+        let ret = cb(self);
+        self.gen_ctx = None;
+        ret
+    }
+
+    /// This function trying to find any dangling references inside of `items`
+    fn assert_no_dangling_references(&self) {
+        if cfg!(feature = "assert_no_dangling_items") {
+            for _ in self.assert_no_dangling_item_traversal() {
+                // The iterator's next method does the asserting for us.
+            }
+        }
+    }
+
+    fn assert_no_dangling_item_traversal<'me>
+        (&'me self)
+         -> AssertNoDanglingItemIter<'me, 'ctx> {
+        assert!(self.in_codegen_phase());
+        assert!(self.current_module == self.root_module);
+
+        let mut roots = self.items().map(|(&id, _)| id);
+
+        let mut seen = BTreeMap::<ItemId, ItemId>::new();
+        let next_child = roots.next().map(|id| id).unwrap();
+        seen.insert(next_child, next_child);
+
+        let to_iterate = seen.iter().map(|(&id, _)| id).rev().collect();
+
+        AssertNoDanglingItemIter {
+            ctx: self,
+            seen: seen,
+            to_iterate: to_iterate,
+        }
+    }
+
+    // This deserves a comment. Builtin types don't get a valid declaration, so
+    // we can't add it to the cursor->type map.
+    //
+    // That being said, they're not generated anyway, and are few, so the
+    // duplication and special-casing is fine.
+    //
+    // If at some point we care about the memory here, probably a map TypeKind
+    // -> builtin type ItemId would be the best to improve that.
+    fn add_builtin_item(&mut self, item: Item) {
+        debug!("add_builtin_item: item = {:?}", item);
+        debug_assert!(item.kind().is_type());
+        let id = item.id();
+        let old_item = self.items.insert(id, item);
+        assert!(old_item.is_none(), "Inserted type twice?");
+    }
+
+    fn build_root_module(id: ItemId) -> Item {
+        let module = Module::new(Some("root".into()), ModuleKind::Normal);
+        Item::new(id, None, None, id, ItemKind::Module(module))
+    }
+
+    /// Get the root module.
+    pub fn root_module(&self) -> ItemId {
+        self.root_module
+    }
+
+    /// Resolve the given `ItemId` as a type.
+    ///
+    /// Panics if there is no item for the given `ItemId` or if the resolved
+    /// item is not a `Type`.
+    pub fn resolve_type(&self, type_id: ItemId) -> &Type {
+        self.items.get(&type_id).unwrap().kind().expect_type()
+    }
+
+    /// Resolve the given `ItemId` as a type, or `None` if there is no item with
+    /// the given id.
+    ///
+    /// Panics if the id resolves to an item that is not a type.
+    pub fn safe_resolve_type(&self, type_id: ItemId) -> Option<&Type> {
+        self.items.get(&type_id).map(|t| t.kind().expect_type())
+    }
+
+    /// Resolve the given `ItemId` into an `Item`, or `None` if no such item
+    /// exists.
+    pub fn resolve_item_fallible(&self, item_id: ItemId) -> Option<&Item> {
+        self.items.get(&item_id)
+    }
+
+    /// Resolve the given `ItemId` into an `Item`.
+    ///
+    /// Panics if the given id does not resolve to any item.
+    pub fn resolve_item(&self, item_id: ItemId) -> &Item {
+        match self.items.get(&item_id) {
+            Some(item) => item,
+            None => panic!("Not an item: {:?}", item_id),
+        }
+    }
+
+    /// Get the current module.
+    pub fn current_module(&self) -> ItemId {
+        self.current_module
+    }
+
+    /// This is one of the hackiest methods in all the parsing code. This method
+    /// is used to allow having templates with another argument names instead of
+    /// the canonical ones.
+    ///
+    /// This is surprisingly difficult to do with libclang, due to the fact that
+    /// partial template specializations don't provide explicit template
+    /// argument information.
+    ///
+    /// The only way to do this as far as I know, is inspecting manually the
+    /// AST, looking for TypeRefs inside. This, unfortunately, doesn't work for
+    /// more complex cases, see the comment on the assertion below.
+    ///
+    /// To see an example of what this handles:
+    ///
+    /// ```c++
+    ///     template<typename T>
+    ///     class Incomplete {
+    ///       T p;
+    ///     };
+    ///
+    ///     template<typename U>
+    ///     class Foo {
+    ///       Incomplete<U> bar;
+    ///     };
+    /// ```
+    fn build_template_wrapper(&mut self,
+                              with_id: ItemId,
+                              wrapping: ItemId,
+                              parent_id: ItemId,
+                              ty: &clang::Type,
+                              location: clang::Cursor,
+                              declaration: clang::Cursor)
+                              -> ItemId {
+        use clang_sys::*;
+        let mut args = vec![];
+        location.visit(|c| {
+            if c.kind() == CXCursor_TypeRef {
+                // The `with_id` id will potentially end up unused if we give up
+                // on this type (for example, its a tricky partial template
+                // specialization), so if we pass `with_id` as the parent, it is
+                // potentially a dangling reference. Instead, use the canonical
+                // template declaration as the parent. It is already parsed and
+                // has a known-resolvable `ItemId`.
+                let new_ty = Item::from_ty_or_ref(c.cur_type(),
+                                                  Some(c),
+                                                  Some(wrapping),
+                                                  self);
+                args.push(new_ty);
+            }
+            CXChildVisit_Continue
+        });
+
+        let item = {
+            let wrapping_type = self.resolve_type(wrapping);
+            if let TypeKind::Comp(ref ci) = *wrapping_type.kind() {
+                let old_args = ci.template_args();
+
+                // The following assertion actually fails with partial template
+                // specialization. But as far as I know there's no way at all to
+                // grab the specialized types from neither the AST or libclang,
+                // which sucks. The same happens for specialized type alias
+                // template declarations, where we have that ugly hack up there.
+                //
+                // This flaw was already on the old parser, but I now think it
+                // has no clear solution (apart from patching libclang to
+                // somehow expose them, of course).
+                //
+                // For an easy example in which there's no way at all of getting
+                // the `int` type, except manually parsing the spelling:
+                //
+                //     template<typename T, typename U>
+                //     class Incomplete {
+                //       T d;
+                //       U p;
+                //     };
+                //
+                //     template<typename U>
+                //     class Foo {
+                //       Incomplete<U, int> bar;
+                //     };
+                //
+                // debug_assert_eq!(old_args.len(), args.len());
+                //
+                // That being said, this is not so common, so just error! and
+                // hope for the best, returning the previous type, who knows.
+                if old_args.len() != args.len() {
+                    error!("Found partial template specialization, \
+                            expect dragons!");
+                    return wrapping;
+                }
+            } else {
+                assert_eq!(declaration.kind(),
+                           ::clang_sys::CXCursor_TypeAliasTemplateDecl,
+                           "Expected wrappable type");
+            }
+
+            let type_kind = TypeKind::TemplateRef(wrapping, args);
+            let name = ty.spelling();
+            let name = if name.is_empty() { None } else { Some(name) };
+            let ty = Type::new(name,
+                               ty.fallible_layout().ok(),
+                               type_kind,
+                               ty.is_const());
+            Item::new(with_id, None, None, parent_id, ItemKind::Type(ty))
+        };
+
+        // Bypass all the validations in add_item explicitly.
+        debug!("build_template_wrapper: inserting item: {:?}", item);
+        debug_assert!(with_id == item.id());
+        self.items.insert(with_id, item);
+        with_id
+    }
+
+    /// Looks up for an already resolved type, either because it's builtin, or
+    /// because we already have it in the map.
+    pub fn builtin_or_resolved_ty(&mut self,
+                                  with_id: ItemId,
+                                  parent_id: Option<ItemId>,
+                                  ty: &clang::Type,
+                                  location: Option<clang::Cursor>)
+                                  -> Option<ItemId> {
+        use clang_sys::{CXCursor_TypeAliasTemplateDecl, CXCursor_TypeRef};
+        debug!("builtin_or_resolved_ty: {:?}, {:?}, {:?}",
+               ty,
+               location,
+               parent_id);
+        let mut declaration = ty.declaration();
+        if !declaration.is_valid() {
+            if let Some(location) = location {
+                if location.is_template_like() {
+                    declaration = location;
+                }
+            }
+        }
+        let canonical_declaration = declaration.canonical();
+        if canonical_declaration.is_valid() {
+            let id = self.types
+                .get(&TypeKey::Declaration(canonical_declaration))
+                .map(|id| *id)
+                .or_else(|| {
+                    canonical_declaration.usr()
+                        .and_then(|usr| self.types.get(&TypeKey::USR(usr)))
+                        .map(|id| *id)
+                });
+            if let Some(id) = id {
+                debug!("Already resolved ty {:?}, {:?}, {:?} {:?}",
+                       id,
+                       declaration,
+                       ty,
+                       location);
+
+                // If the declaration existed, we *might* be done, but it's not
+                // the case for class templates, where the template arguments
+                // may vary.
+                //
+                // In this case, we create a TemplateRef with the new template
+                // arguments, pointing to the canonical template.
+                //
+                // Note that we only do it if parent_id is some, and we have a
+                // location for building the new arguments, the template
+                // argument names don't matter in the global context.
+                if declaration.is_template_like() &&
+                   *ty != canonical_declaration.cur_type() &&
+                   location.is_some() &&
+                   parent_id.is_some() {
+                    // For specialized type aliases, there's no way to get the
+                    // template parameters as of this writing (for a struct
+                    // specialization we wouldn't be in this branch anyway).
+                    //
+                    // Explicitly return `None` if there aren't any
+                    // unspecialized parameters (contains any `TypeRef`) so we
+                    // resolve the canonical type if there is one and it's
+                    // exposed.
+                    //
+                    // This is _tricky_, I know :(
+                    if declaration.kind() == CXCursor_TypeAliasTemplateDecl &&
+                       !location.unwrap().contains_cursor(CXCursor_TypeRef) &&
+                       ty.canonical_type().is_valid_and_exposed() {
+                        return None;
+                    }
+
+                    return Some(self.build_template_wrapper(with_id,
+                                                id,
+                                                parent_id.unwrap(),
+                                                ty,
+                                                location.unwrap(),
+                                                declaration));
+                }
+
+                return Some(self.build_ty_wrapper(with_id, id, parent_id, ty));
+            }
+        }
+
+        debug!("Not resolved, maybe builtin?");
+
+        // Else, build it.
+        self.build_builtin_ty(ty, declaration)
+    }
+
+    // This is unfortunately a lot of bloat, but is needed to properly track
+    // constness et. al.
+    //
+    // We should probably make the constness tracking separate, so it doesn't
+    // bloat that much, but hey, we already bloat the heck out of builtin types.
+    fn build_ty_wrapper(&mut self,
+                        with_id: ItemId,
+                        wrapped_id: ItemId,
+                        parent_id: Option<ItemId>,
+                        ty: &clang::Type)
+                        -> ItemId {
+        let spelling = ty.spelling();
+        let is_const = ty.is_const();
+        let layout = ty.fallible_layout().ok();
+        let type_kind = TypeKind::ResolvedTypeRef(wrapped_id);
+        let ty = Type::new(Some(spelling), layout, type_kind, is_const);
+        let item = Item::new(with_id,
+                             None,
+                             None,
+                             parent_id.unwrap_or(self.current_module),
+                             ItemKind::Type(ty));
+        self.add_builtin_item(item);
+        with_id
+    }
+
+    /// Returns the next item id to be used for an item.
+    pub fn next_item_id(&mut self) -> ItemId {
+        let ret = self.next_item_id;
+        self.next_item_id = ItemId(self.next_item_id.0 + 1);
+        ret
+    }
+
+    fn build_builtin_ty(&mut self,
+                        ty: &clang::Type,
+                        _declaration: Cursor)
+                        -> Option<ItemId> {
+        use clang_sys::*;
+        let type_kind = match ty.kind() {
+            CXType_NullPtr => TypeKind::NullPtr,
+            CXType_Void => TypeKind::Void,
+            CXType_Bool => TypeKind::Int(IntKind::Bool),
+            CXType_Int => TypeKind::Int(IntKind::Int),
+            CXType_UInt => TypeKind::Int(IntKind::UInt),
+            CXType_SChar | CXType_Char_S => TypeKind::Int(IntKind::Char),
+            CXType_UChar | CXType_Char_U => TypeKind::Int(IntKind::UChar),
+            CXType_Short => TypeKind::Int(IntKind::Short),
+            CXType_UShort => TypeKind::Int(IntKind::UShort),
+            CXType_WChar | CXType_Char16 => TypeKind::Int(IntKind::U16),
+            CXType_Char32 => TypeKind::Int(IntKind::U32),
+            CXType_Long => TypeKind::Int(IntKind::Long),
+            CXType_ULong => TypeKind::Int(IntKind::ULong),
+            CXType_LongLong => TypeKind::Int(IntKind::LongLong),
+            CXType_ULongLong => TypeKind::Int(IntKind::ULongLong),
+            CXType_Int128 => TypeKind::Int(IntKind::I128),
+            CXType_UInt128 => TypeKind::Int(IntKind::U128),
+            CXType_Float => TypeKind::Float(FloatKind::Float),
+            CXType_Double => TypeKind::Float(FloatKind::Double),
+            CXType_LongDouble => TypeKind::Float(FloatKind::LongDouble),
+            CXType_Float128 => TypeKind::Float(FloatKind::Float128),
+            CXType_Complex => {
+                let float_type = ty.elem_type()
+                    .expect("Not able to resolve complex type?");
+                let float_kind = match float_type.kind() {
+                    CXType_Float => FloatKind::Float,
+                    CXType_Double => FloatKind::Double,
+                    CXType_LongDouble => FloatKind::LongDouble,
+                    _ => panic!("Non floating-type complex?"),
+                };
+                TypeKind::Complex(float_kind)
+            }
+            _ => return None,
+        };
+
+        let spelling = ty.spelling();
+        let is_const = ty.is_const();
+        let layout = ty.fallible_layout().ok();
+        let ty = Type::new(Some(spelling), layout, type_kind, is_const);
+        let id = self.next_item_id();
+        let item =
+            Item::new(id, None, None, self.root_module, ItemKind::Type(ty));
+        self.add_builtin_item(item);
+        Some(id)
+    }
+
+    /// Get the current Clang translation unit that is being processed.
+    pub fn translation_unit(&self) -> &clang::TranslationUnit {
+        &self.translation_unit
+    }
+
+    /// Have we parsed the macro named `macro_name` already?
+    pub fn parsed_macro(&self, macro_name: &[u8]) -> bool {
+        self.parsed_macros.contains_key(macro_name)
+    }
+
+    /// Get the currently parsed macros.
+    pub fn parsed_macros(&self) -> &HashMap<Vec<u8>, cexpr::expr::EvalResult> {
+        debug_assert!(!self.in_codegen_phase());
+        &self.parsed_macros
+    }
+
+    /// Mark the macro named `macro_name` as parsed.
+    pub fn note_parsed_macro(&mut self,
+                             id: Vec<u8>,
+                             value: cexpr::expr::EvalResult) {
+        self.parsed_macros.insert(id, value);
+    }
+
+    /// Are we in the codegen phase?
+    pub fn in_codegen_phase(&self) -> bool {
+        self.gen_ctx.is_some()
+    }
+
+    /// Mark the type with the given `name` as replaced by the type with id
+    /// `potential_ty`.
+    ///
+    /// Replacement types are declared using the `replaces="xxx"` annotation,
+    /// and implies that the original type is hidden.
+    pub fn replace(&mut self, name: &[String], potential_ty: ItemId) {
+        match self.replacements.entry(name.into()) {
+            hash_map::Entry::Vacant(entry) => {
+                debug!("Defining replacement for {:?} as {:?}",
+                       name,
+                       potential_ty);
+                entry.insert(potential_ty);
+            }
+            hash_map::Entry::Occupied(occupied) => {
+                warn!("Replacement for {:?} already defined as {:?}; \
+                       ignoring duplicate replacement definition as {:?}",
+                      name,
+                      occupied.get(),
+                      potential_ty);
+            }
+        }
+    }
+
+    /// Is the item with the given `name` hidden? Or is the item with the given
+    /// `name` and `id` replaced by another type, and effectively hidden?
+    pub fn hidden_by_name(&self, path: &[String], id: ItemId) -> bool {
+        debug_assert!(self.in_codegen_phase(),
+                      "You're not supposed to call this yet");
+        self.options.hidden_types.matches(&path[1..].join("::")) ||
+        self.is_replaced_type(path, id)
+    }
+
+    /// Has the item with the given `name` and `id` been replaced by another
+    /// type?
+    pub fn is_replaced_type(&self, path: &[String], id: ItemId) -> bool {
+        match self.replacements.get(path) {
+            Some(replaced_by) if *replaced_by != id => true,
+            _ => false,
+        }
+    }
+
+    /// Is the type with the given `name` marked as opaque?
+    pub fn opaque_by_name(&self, path: &[String]) -> bool {
+        debug_assert!(self.in_codegen_phase(),
+                      "You're not supposed to call this yet");
+        self.options.opaque_types.matches(&path[1..].join("::"))
+    }
+
+    /// Get the options used to configure this bindgen context.
+    pub fn options(&self) -> &BindgenOptions {
+        &self.options
+    }
+
+    /// Tokenizes a namespace cursor in order to get the name and kind of the
+    /// namespace,
+    fn tokenize_namespace(&self,
+                          cursor: &clang::Cursor)
+                          -> (Option<String>, ModuleKind) {
+        assert_eq!(cursor.kind(), ::clang_sys::CXCursor_Namespace,
+                   "Be a nice person");
+        let tokens = match self.translation_unit.tokens(&cursor) {
+            Some(tokens) => tokens,
+            None => return (None, ModuleKind::Normal),
+        };
+
+        let mut iter = tokens.iter();
+        let mut kind = ModuleKind::Normal;
+        let mut found_namespace_keyword = false;
+        let mut module_name = None;
+        while let Some(token) = iter.next() {
+            match &*token.spelling {
+                "inline" => {
+                    assert!(!found_namespace_keyword);
+                    assert!(kind != ModuleKind::Inline);
+                    kind = ModuleKind::Inline;
+                }
+                "namespace" => {
+                    found_namespace_keyword = true;
+                }
+                "{" => {
+                    assert!(found_namespace_keyword);
+                    break;
+                }
+                name if found_namespace_keyword => {
+                    module_name = Some(name.to_owned());
+                    break;
+                }
+                _ => {
+                    panic!("Unknown token while processing namespace: {:?}",
+                           token);
+                }
+            }
+        };
+
+        (module_name, kind)
+    }
+
+    /// Given a CXCursor_Namespace cursor, return the item id of the
+    /// corresponding module, or create one on the fly.
+    pub fn module(&mut self, cursor: clang::Cursor) -> ItemId {
+        use clang_sys::*;
+        assert_eq!(cursor.kind(), CXCursor_Namespace, "Be a nice person");
+        let cursor = cursor.canonical();
+        if let Some(id) = self.modules.get(&cursor) {
+            return *id;
+        }
+
+        let (module_name, kind) = self.tokenize_namespace(&cursor);
+
+        let module_id = self.next_item_id();
+        let module = Module::new(module_name, kind);
+        let module = Item::new(module_id,
+                               None,
+                               None,
+                               self.current_module,
+                               ItemKind::Module(module));
+
+        self.modules.insert(cursor, module.id());
+
+        self.add_item(module, None, None);
+
+        module_id
+    }
+
+    /// Start traversing the module with the given `module_id`, invoke the
+    /// callback `cb`, and then return to traversing the original module.
+    pub fn with_module<F>(&mut self, module_id: ItemId, cb: F)
+        where F: FnOnce(&mut Self),
+    {
+        debug_assert!(self.resolve_item(module_id).kind().is_module(), "Wat");
+
+        let previous_id = self.current_module;
+        self.current_module = module_id;
+
+        cb(self);
+
+        self.current_module = previous_id;
+    }
+
+    /// Iterate over all (explicitly or transitively) whitelisted items.
+    ///
+    /// If no items are explicitly whitelisted, then all items are considered
+    /// whitelisted.
+    pub fn whitelisted_items<'me>(&'me self)
+                                  -> WhitelistedItemsIter<'me, 'ctx> {
+        assert!(self.in_codegen_phase());
+        assert!(self.current_module == self.root_module);
+
+        let roots = self.items()
+            .filter(|&(_, item)| {
+                // If nothing is explicitly whitelisted, then everything is fair
+                // game.
+                if self.options().whitelisted_types.is_empty() &&
+                   self.options().whitelisted_functions.is_empty() &&
+                   self.options().whitelisted_vars.is_empty() {
+                    return true;
+                }
+
+                // If this is a type that explicitly replaces another, we assume
+                // you know what you're doing.
+                if item.annotations().use_instead_of().is_some() {
+                    return true;
+                }
+
+                let name = item.canonical_path(self)[1..].join("::");
+                debug!("whitelisted_items: testing {:?}", name);
+                match *item.kind() {
+                    ItemKind::Module(..) => true,
+                    ItemKind::Function(_) => {
+                        self.options().whitelisted_functions.matches(&name)
+                    }
+                    ItemKind::Var(_) => {
+                        self.options().whitelisted_vars.matches(&name)
+                    }
+                    ItemKind::Type(ref ty) => {
+                        if self.options().whitelisted_types.matches(&name) {
+                            return true;
+                        }
+
+                        let parent = self.resolve_item(item.parent_id());
+                        if parent.is_module() {
+                            let mut prefix_path = parent.canonical_path(self);
+
+                            // Unnamed top-level enums are special and we
+                            // whitelist them via the `whitelisted_vars` filter,
+                            // since they're effectively top-level constants,
+                            // and there's no way for them to be referenced
+                            // consistently.
+                            if let TypeKind::Enum(ref enum_) = *ty.kind() {
+                                if ty.name().is_none() &&
+                                   enum_.variants().iter().any(|variant| {
+                                    prefix_path.push(variant.name().into());
+                                    let name = prefix_path[1..].join("::");
+                                    prefix_path.pop().unwrap();
+                                    self.options()
+                                        .whitelisted_vars
+                                        .matches(&name)
+                                }) {
+                                    return true;
+                                }
+                            }
+                        }
+
+                        false
+                    }
+                }
+            })
+            .map(|(&id, _)| id);
+
+        let seen: ItemSet = roots.collect();
+
+        // The .rev() preserves the expected ordering traversal, resulting in
+        // more stable-ish bindgen-generated names for anonymous types (like
+        // unions).
+        let to_iterate = seen.iter().cloned().rev().collect();
+
+        WhitelistedItemsIter {
+            ctx: self,
+            seen: seen,
+            to_iterate: to_iterate,
+        }
+    }
+
+    /// Convenient method for getting the prefix to use for most traits in
+    /// codegen depending on the `use_core` option.
+    pub fn trait_prefix(&self) -> Ident {
+        if self.options().use_core {
+            self.rust_ident_raw("core")
+        } else {
+            self.rust_ident_raw("std")
+        }
+    }
+
+    /// Call if a binden complex is generated
+    pub fn generated_bindegen_complex(&self) {
+        self.generated_bindegen_complex.set(true)
+    }
+
+    /// Whether we need to generate the binden complex type
+    pub fn need_bindegen_complex_type(&self) -> bool {
+        self.generated_bindegen_complex.get()
+    }
+}
+
+/// An iterator over whitelisted items.
+///
+/// See `BindgenContext::whitelisted_items` for more information.
+pub struct WhitelistedItemsIter<'ctx, 'gen>
+    where 'gen: 'ctx,
+{
+    ctx: &'ctx BindgenContext<'gen>,
+
+    // The set of whitelisted items we have seen. If you think of traversing
+    // whitelisted items like GC tracing, this is the mark bits, and contains
+    // both black and gray items.
+    seen: ItemSet,
+
+    // The set of whitelisted items that we have seen but have yet to iterate
+    // over and collect transitive references from. To return to the GC analogy,
+    // this is the mark stack, containing the set of gray items which we have
+    // not finished tracing yet.
+    to_iterate: Vec<ItemId>,
+}
+
+impl<'ctx, 'gen> Iterator for WhitelistedItemsIter<'ctx, 'gen>
+    where 'gen: 'ctx,
+{
+    type Item = ItemId;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        let id = match self.to_iterate.pop() {
+            None => return None,
+            Some(id) => id,
+        };
+
+        debug_assert!(self.seen.contains(&id));
+        debug_assert!(self.ctx.items.contains_key(&id));
+
+        let mut sub_types = ItemSet::new();
+        id.collect_types(self.ctx, &mut sub_types, &());
+
+        for id in sub_types {
+            if self.seen.insert(id) {
+                self.to_iterate.push(id);
+            }
+        }
+
+        Some(id)
+    }
+}
+
+/// An iterator to find any dangling items.
+///
+/// See `BindgenContext::assert_no_dangling_item_traversal` for more
+/// information.
+pub struct AssertNoDanglingItemIter<'ctx, 'gen>
+    where 'gen: 'ctx,
+{
+    ctx: &'ctx BindgenContext<'gen>,
+    seen: BTreeMap<ItemId, ItemId>,
+    to_iterate: VecDeque<ItemId>,
+}
+
+impl<'ctx, 'gen> Iterator for AssertNoDanglingItemIter<'ctx, 'gen>
+    where 'gen: 'ctx,
+{
+    type Item = ItemId;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        let id = match self.to_iterate.pop_front() {
+            None => {
+                // We've traversed everything reachable from the previous
+                // root(s), see if we have any more roots.
+                match self.ctx
+                    .items()
+                    .filter(|&(id, _)| !self.seen.contains_key(id))
+                    .next()
+                    .map(|(id, _)| *id) {
+                    None => return None,
+                    Some(id) => {
+                        // This is a new root.
+                        self.seen.insert(id, id);
+                        id
+                    }
+                }
+            }
+            Some(id) => id,
+        };
+
+        let mut sub_types = ItemSet::new();
+        id.collect_types(self.ctx, &mut sub_types, &());
+
+        if self.ctx.resolve_item_fallible(id).is_none() {
+            let mut path = vec![];
+            let mut current = id;
+            loop {
+                let predecessor = *self.seen
+                    .get(&current)
+                    .expect("We know we found this item id, so it must have a \
+                            predecessor");
+                if predecessor == current {
+                    break;
+                }
+                path.push(predecessor);
+                current = predecessor;
+            }
+            path.reverse();
+            panic!("Found reference to dangling id = {:?}\nvia path = {:?}",
+                   id,
+                   path);
+        }
+
+        for sub_id in sub_types {
+            if self.seen.insert(sub_id, id).is_none() {
+                // We've never visited this sub item before.
+                self.to_iterate.push_back(sub_id);
+            }
+        }
+
+        Some(id)
+    }
+}
diff --git a/src/ir/derive.rs b/src/ir/derive.rs
new file mode 100644
index 00000000..d13a8117
--- /dev/null
+++ b/src/ir/derive.rs
@@ -0,0 +1,67 @@
+//! Traits for determining whether we can derive traits for a thing or not.
+
+use super::context::BindgenContext;
+
+/// A trait that encapsulates the logic for whether or not we can derive `Debug`
+/// for a given thing.
+///
+/// This should ideally be a no-op that just returns `true`, but instead needs
+/// to be a recursive method that checks whether all the proper members can
+/// derive debug or not, because of the limit rust has on 32 items as max in the
+/// array.
+pub trait CanDeriveDebug {
+    /// Implementations can define this type to get access to any extra
+    /// information required to determine whether they can derive `Debug`. If
+    /// extra information is unneeded, then this should simply be the unit type.
+    type Extra;
+
+    /// Return `true` if `Debug` can be derived for this thing, `false`
+    /// otherwise.
+    fn can_derive_debug(&self,
+                        ctx: &BindgenContext,
+                        extra: Self::Extra)
+                        -> bool;
+}
+
+/// A trait that encapsulates the logic for whether or not we can derive `Copy`
+/// for a given thing.
+pub trait CanDeriveCopy<'a> {
+    /// Implementations can define this type to get access to any extra
+    /// information required to determine whether they can derive `Copy`. If
+    /// extra information is unneeded, then this should simply be the unit type.
+    type Extra;
+
+    /// Return `true` if `Copy` can be derived for this thing, `false`
+    /// otherwise.
+    fn can_derive_copy(&'a self,
+                       ctx: &'a BindgenContext,
+                       extra: Self::Extra)
+                       -> bool;
+
+    /// For some reason, deriving copies of an array of a type that is not known
+    /// to be `Copy` is a compile error. e.g.:
+    ///
+    /// ```rust
+    /// #[derive(Copy, Clone)]
+    /// struct A<T> {
+    ///     member: T,
+    /// }
+    /// ```
+    ///
+    /// is fine, while:
+    ///
+    /// ```rust,ignore
+    /// #[derive(Copy, Clone)]
+    /// struct A<T> {
+    ///     member: [T; 1],
+    /// }
+    /// ```
+    ///
+    /// is an error.
+    ///
+    /// That's the whole point of the existence of `can_derive_copy_in_array`.
+    fn can_derive_copy_in_array(&'a self,
+                                ctx: &'a BindgenContext,
+                                extra: Self::Extra)
+                                -> bool;
+}
diff --git a/src/ir/enum_ty.rs b/src/ir/enum_ty.rs
new file mode 100644
index 00000000..ca4e77db
--- /dev/null
+++ b/src/ir/enum_ty.rs
@@ -0,0 +1,183 @@
+//! Intermediate representation for C/C++ enumerations.
+
+use clang;
+use ir::annotations::Annotations;
+use parse::{ClangItemParser, ParseError};
+use super::context::{BindgenContext, ItemId};
+use super::item::Item;
+use super::ty::TypeKind;
+
+/// An enum representing custom handling that can be given to a variant.
+#[derive(Copy, Clone, Debug, PartialEq, Eq)]
+pub enum EnumVariantCustomBehavior {
+    /// This variant will be constified, that is, forced to generate a constant.
+    Constify,
+    /// This variant will be hidden entirely from the resulting enum.
+    Hide,
+}
+
+/// A C/C++ enumeration.
+#[derive(Debug)]
+pub struct Enum {
+    /// The representation used for this enum; it should be an `IntKind` type or
+    /// an alias to one.
+    ///
+    /// It's `None` if the enum is a forward declaration and isn't defined
+    /// anywhere else, see `tests/headers/func_ptr_in_struct.h`.
+    repr: Option<ItemId>,
+
+    /// The different variants, with explicit values.
+    variants: Vec<EnumVariant>,
+}
+
+impl Enum {
+    /// Construct a new `Enum` with the given representation and variants.
+    pub fn new(repr: Option<ItemId>, variants: Vec<EnumVariant>) -> Self {
+        Enum {
+            repr: repr,
+            variants: variants,
+        }
+    }
+
+    /// Get this enumeration's representation.
+    pub fn repr(&self) -> Option<ItemId> {
+        self.repr
+    }
+
+    /// Get this enumeration's variants.
+    pub fn variants(&self) -> &[EnumVariant] {
+        &self.variants
+    }
+
+    /// Construct an enumeration from the given Clang type.
+    pub fn from_ty(ty: &clang::Type,
+                   ctx: &mut BindgenContext)
+                   -> Result<Self, ParseError> {
+        use clang_sys::*;
+        if ty.kind() != CXType_Enum {
+            return Err(ParseError::Continue);
+        }
+
+        let declaration = ty.declaration().canonical();
+        let repr = declaration.enum_type()
+            .and_then(|et| Item::from_ty(&et, None, None, ctx).ok());
+        let mut variants = vec![];
+
+        // Assume signedness since the default type by the C standard is an int.
+        let is_signed =
+            repr.and_then(|r| ctx.resolve_type(r).safe_canonical_type(ctx))
+                .map_or(true, |ty| {
+                    match *ty.kind() {
+                        TypeKind::Int(ref int_kind) => int_kind.is_signed(),
+                        ref other => {
+                            panic!("Since when enums can be non-integers? {:?}",
+                               other)
+                        }
+                    }
+                });
+
+        let type_name = ty.spelling();
+        let type_name = if type_name.is_empty() { None } else { Some(type_name) };
+        let type_name = type_name.as_ref().map(String::as_str);
+
+        declaration.visit(|cursor| {
+            if cursor.kind() == CXCursor_EnumConstantDecl {
+                let value = if is_signed {
+                    cursor.enum_val_signed().map(EnumVariantValue::Signed)
+                } else {
+                    cursor.enum_val_unsigned().map(EnumVariantValue::Unsigned)
+                };
+                if let Some(val) = value {
+                    let name = cursor.spelling();
+                    let custom_behavior = ctx.type_chooser()
+                        .and_then(|t| {
+                            t.enum_variant_behavior(type_name, &name, val)
+                        })
+                        .or_else(|| {
+                            Annotations::new(&cursor).and_then(|anno| {
+                                if anno.hide() {
+                                    Some(EnumVariantCustomBehavior::Hide)
+                                } else if anno.constify_enum_variant() {
+                                    Some(EnumVariantCustomBehavior::Constify)
+                                } else {
+                                    None
+                                }
+                            })
+                        });
+
+                    let comment = cursor.raw_comment();
+                    variants.push(
+                        EnumVariant::new(name, comment, val, custom_behavior));
+                }
+            }
+            CXChildVisit_Continue
+        });
+        Ok(Enum::new(repr, variants))
+    }
+}
+
+/// A single enum variant, to be contained only in an enum.
+#[derive(Debug)]
+pub struct EnumVariant {
+    /// The name of the variant.
+    name: String,
+
+    /// An optional doc comment.
+    comment: Option<String>,
+
+    /// The integer value of the variant.
+    val: EnumVariantValue,
+
+    /// The custom behavior this variant may have, if any.
+    custom_behavior: Option<EnumVariantCustomBehavior>,
+}
+
+/// A constant value assigned to an enumeration variant.
+#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub enum EnumVariantValue {
+    /// A signed constant.
+    Signed(i64),
+
+    /// An unsigned constant.
+    Unsigned(u64),
+}
+
+impl EnumVariant {
+    /// Construct a new enumeration variant from the given parts.
+    pub fn new(name: String,
+               comment: Option<String>,
+               val: EnumVariantValue,
+               custom_behavior: Option<EnumVariantCustomBehavior>)
+               -> Self {
+        EnumVariant {
+            name: name,
+            comment: comment,
+            val: val,
+            custom_behavior: custom_behavior,
+        }
+    }
+
+    /// Get this variant's name.
+    pub fn name(&self) -> &str {
+        &self.name
+    }
+
+    /// Get this variant's value.
+    pub fn val(&self) -> EnumVariantValue {
+        self.val
+    }
+
+    /// Returns whether this variant should be enforced to be a constant by code
+    /// generation.
+    pub fn force_constification(&self) -> bool {
+        self.custom_behavior
+            .map_or(false, |b| b == EnumVariantCustomBehavior::Constify)
+    }
+
+    /// Returns whether the current variant should be hidden completely from the
+    /// resulting rust enum.
+    pub fn hidden(&self) -> bool {
+        self.custom_behavior
+            .map_or(false, |b| b == EnumVariantCustomBehavior::Hide)
+    }
+}
diff --git a/src/ir/function.rs b/src/ir/function.rs
new file mode 100644
index 00000000..50c442db
--- /dev/null
+++ b/src/ir/function.rs
@@ -0,0 +1,318 @@
+//! Intermediate representation for C/C++ functions and methods.
+
+use clang;
+use clang_sys::CXCallingConv;
+use parse::{ClangItemParser, ClangSubItemParser, ParseError, ParseResult};
+use super::context::{BindgenContext, ItemId};
+use super::item::Item;
+use super::ty::TypeKind;
+use super::type_collector::{ItemSet, TypeCollector};
+use syntax::abi;
+
+/// A function declaration, with a signature, arguments, and argument names.
+///
+/// The argument names vector must be the same length as the ones in the
+/// signature.
+#[derive(Debug)]
+pub struct Function {
+    /// The name of this function.
+    name: String,
+
+    /// The mangled name, that is, the symbol.
+    mangled_name: Option<String>,
+
+    /// The id pointing to the current function signature.
+    signature: ItemId,
+
+    /// The doc comment on the function, if any.
+    comment: Option<String>,
+}
+
+impl Function {
+    /// Construct a new function.
+    pub fn new(name: String,
+               mangled_name: Option<String>,
+               sig: ItemId,
+               comment: Option<String>)
+               -> Self {
+        Function {
+            name: name,
+            mangled_name: mangled_name,
+            signature: sig,
+            comment: comment,
+        }
+    }
+
+    /// Get this function's name.
+    pub fn name(&self) -> &str {
+        &self.name
+    }
+
+    /// Get this function's name.
+    pub fn mangled_name(&self) -> Option<&str> {
+        self.mangled_name.as_ref().map(|n| &**n)
+    }
+
+    /// Get this function's signature.
+    pub fn signature(&self) -> ItemId {
+        self.signature
+    }
+}
+
+/// A function signature.
+#[derive(Debug)]
+pub struct FunctionSig {
+    /// The return type of the function.
+    return_type: ItemId,
+
+    /// The type of the arguments, optionally with the name of the argument when
+    /// declared.
+    argument_types: Vec<(Option<String>, ItemId)>,
+
+    /// Whether this function is variadic.
+    is_variadic: bool,
+
+    /// The ABI of this function.
+    abi: abi::Abi,
+}
+
+fn get_abi(cc: CXCallingConv) -> abi::Abi {
+    use clang_sys::*;
+    match cc {
+        CXCallingConv_Default => abi::Abi::C,
+        CXCallingConv_C => abi::Abi::C,
+        CXCallingConv_X86StdCall => abi::Abi::Stdcall,
+        CXCallingConv_X86FastCall => abi::Abi::Fastcall,
+        CXCallingConv_AAPCS => abi::Abi::Aapcs,
+        CXCallingConv_X86_64Win64 => abi::Abi::Win64,
+        other => panic!("unsupported calling convention: {:?}", other),
+    }
+}
+
+/// Get the mangled name for the cursor's referent.
+pub fn cursor_mangling(cursor: &clang::Cursor) -> Option<String> {
+    // We early return here because libclang may crash in some case
+    // if we pass in a variable inside a partial specialized template.
+    // See servo/rust-bindgen#67.
+    if cursor.is_in_non_fully_specialized_template() {
+        return None;
+    }
+
+    let mut mangling = cursor.mangling();
+    if mangling.is_empty() {
+        return None;
+    }
+
+    // Try to undo backend linkage munging (prepended _, generally)
+    if cfg!(target_os = "macos") {
+        mangling.remove(0);
+    }
+
+    Some(mangling)
+}
+
+impl FunctionSig {
+    /// Construct a new function signature.
+    pub fn new(return_type: ItemId,
+               arguments: Vec<(Option<String>, ItemId)>,
+               is_variadic: bool,
+               abi: abi::Abi)
+               -> Self {
+        FunctionSig {
+            return_type: return_type,
+            argument_types: arguments,
+            is_variadic: is_variadic,
+            abi: abi,
+        }
+    }
+
+    /// Construct a new function signature from the given Clang type.
+    pub fn from_ty(ty: &clang::Type,
+                   cursor: &clang::Cursor,
+                   ctx: &mut BindgenContext)
+                   -> Result<Self, ParseError> {
+        use clang_sys::*;
+        debug!("FunctionSig::from_ty {:?} {:?}", ty, cursor);
+
+        // Skip function templates
+        if cursor.kind() == CXCursor_FunctionTemplate {
+            return Err(ParseError::Continue);
+        }
+
+        // Don't parse operatorxx functions in C++
+        let spelling = cursor.spelling();
+        if spelling.starts_with("operator") {
+            return Err(ParseError::Continue);
+        }
+
+        let cursor = if cursor.is_valid() {
+            *cursor
+        } else {
+            ty.declaration()
+        };
+
+        let mut args: Vec<_> = match cursor.kind() {
+            CXCursor_FunctionDecl |
+            CXCursor_Constructor |
+            CXCursor_CXXMethod => {
+                // For CXCursor_FunctionDecl, cursor.args() is the reliable way
+                // to get parameter names and types.
+                cursor.args()
+                    .unwrap()
+                    .iter()
+                    .map(|arg| {
+                        let arg_ty = arg.cur_type();
+                        let name = arg.spelling();
+                        let name =
+                            if name.is_empty() { None } else { Some(name) };
+                        let ty = Item::from_ty(&arg_ty, Some(*arg), None, ctx)
+                            .expect("Argument?");
+                        (name, ty)
+                    })
+                    .collect()
+            }
+            _ => {
+                // For non-CXCursor_FunctionDecl, visiting the cursor's children
+                // is the only reliable way to get parameter names.
+                let mut args = vec![];
+                cursor.visit(|c| {
+                    if c.kind() == CXCursor_ParmDecl {
+                        let ty =
+                            Item::from_ty(&c.cur_type(), Some(c), None, ctx)
+                                .expect("ParmDecl?");
+                        let name = c.spelling();
+                        let name =
+                            if name.is_empty() { None } else { Some(name) };
+                        args.push((name, ty));
+                    }
+                    CXChildVisit_Continue
+                });
+                args
+            }
+        };
+
+        let is_method = cursor.kind() == CXCursor_CXXMethod;
+        let is_constructor = cursor.kind() == CXCursor_Constructor;
+        if (is_constructor || is_method) &&
+           cursor.lexical_parent() != cursor.semantic_parent() {
+            // Only parse constructors once.
+            return Err(ParseError::Continue);
+        }
+
+        if is_method || is_constructor {
+            let is_const = is_method && cursor.method_is_const();
+            let is_virtual = is_method && cursor.method_is_virtual();
+            let is_static = is_method && cursor.method_is_static();
+            if !is_static && !is_virtual {
+                let class = Item::parse(cursor.semantic_parent(), None, ctx)
+                    .expect("Expected to parse the class");
+                let ptr =
+                    Item::builtin_type(TypeKind::Pointer(class), is_const, ctx);
+                args.insert(0, (Some("this".into()), ptr));
+            } else if is_virtual {
+                let void = Item::builtin_type(TypeKind::Void, false, ctx);
+                let ptr =
+                    Item::builtin_type(TypeKind::Pointer(void), false, ctx);
+                args.insert(0, (Some("this".into()), ptr));
+            }
+        }
+
+        let ty_ret_type = try!(ty.ret_type().ok_or(ParseError::Continue));
+        let ret = try!(Item::from_ty(&ty_ret_type, None, None, ctx));
+        let abi = get_abi(ty.call_conv());
+
+        Ok(Self::new(ret, args, ty.is_variadic(), abi))
+    }
+
+    /// Get this function signature's return type.
+    pub fn return_type(&self) -> ItemId {
+        self.return_type
+    }
+
+    /// Get this function signature's argument (name, type) pairs.
+    pub fn argument_types(&self) -> &[(Option<String>, ItemId)] {
+        &self.argument_types
+    }
+
+    /// Get this function signature's ABI.
+    pub fn abi(&self) -> abi::Abi {
+        self.abi
+    }
+
+    /// Is this function signature variadic?
+    pub fn is_variadic(&self) -> bool {
+        // Clang reports some functions as variadic when they *might* be
+        // variadic. We do the argument check because rust doesn't codegen well
+        // variadic functions without an initial argument.
+        self.is_variadic && !self.argument_types.is_empty()
+    }
+}
+
+impl ClangSubItemParser for Function {
+    fn parse(cursor: clang::Cursor,
+             context: &mut BindgenContext)
+             -> Result<ParseResult<Self>, ParseError> {
+        use clang_sys::*;
+        match cursor.kind() {
+            // FIXME(emilio): Generate destructors properly.
+            CXCursor_FunctionDecl |
+            CXCursor_Constructor |
+            CXCursor_CXXMethod => {}
+            _ => return Err(ParseError::Continue),
+        };
+
+        debug!("Function::parse({:?}, {:?})", cursor, cursor.cur_type());
+
+        let visibility = cursor.visibility();
+        if visibility != CXVisibility_Default {
+            return Err(ParseError::Continue);
+        }
+
+        if cursor.access_specifier() == CX_CXXPrivate {
+            return Err(ParseError::Continue);
+        }
+
+        if cursor.is_inlined_function() {
+            return Err(ParseError::Continue);
+        }
+
+        let linkage = cursor.linkage();
+        if linkage != CXLinkage_External && linkage != CXLinkage_UniqueExternal {
+            return Err(ParseError::Continue);
+        }
+
+        // Grab the signature using Item::from_ty.
+        let sig = try!(Item::from_ty(&cursor.cur_type(),
+                                     Some(cursor),
+                                     None,
+                                     context));
+
+        let name = cursor.spelling();
+        assert!(!name.is_empty(), "Empty function name?");
+
+        let mut mangled_name = cursor_mangling(&cursor);
+        if mangled_name.as_ref() == Some(&name) {
+            mangled_name = None;
+        }
+
+        let comment = cursor.raw_comment();
+
+        let function = Self::new(name, mangled_name, sig, comment);
+        Ok(ParseResult::New(function, Some(cursor)))
+    }
+}
+
+impl TypeCollector for FunctionSig {
+    type Extra = Item;
+
+    fn collect_types(&self,
+                     _context: &BindgenContext,
+                     types: &mut ItemSet,
+                     _item: &Item) {
+        types.insert(self.return_type());
+
+        for &(_, ty) in self.argument_types() {
+            types.insert(ty);
+        }
+    }
+}
diff --git a/src/ir/int.rs b/src/ir/int.rs
new file mode 100644
index 00000000..89068e0f
--- /dev/null
+++ b/src/ir/int.rs
@@ -0,0 +1,113 @@
+//! Intermediate representation for integral types.
+
+/// Which integral type are we dealing with?
+#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord)]
+pub enum IntKind {
+    /// A `bool`.
+    Bool,
+
+    /// A `char`.
+    Char,
+
+    /// An `unsigned char`.
+    UChar,
+
+    /// A `short`.
+    Short,
+
+    /// An `unsigned short`.
+    UShort,
+
+    /// An `int`.
+    Int,
+
+    /// An `unsigned int`.
+    UInt,
+
+    /// A `long`.
+    Long,
+
+    /// An `unsigned long`.
+    ULong,
+
+    /// A `long long`.
+    LongLong,
+
+    /// An `unsigned long long`.
+    ULongLong,
+
+    /// A 8-bit signed integer.
+    I8,
+
+    /// A 8-bit unsigned integer.
+    U8,
+
+    /// A 16-bit signed integer.
+    I16,
+
+    /// Either a `char16_t` or a `wchar_t`.
+    U16,
+
+    /// A 32-bit signed integer.
+    I32,
+
+    /// A 32-bit unsigned integer.
+    U32,
+
+    /// A 64-bit signed integer.
+    I64,
+
+    /// A 64-bit unsigned integer.
+    U64,
+
+    /// An `int128_t`
+    I128,
+
+    /// A `uint128_t`.
+    U128,
+
+    /// A custom integer type, used to allow custom macro types depending on
+    /// range.
+    Custom {
+        /// The name of the type, which would be used without modification.
+        name: &'static str,
+        /// Whether the type is signed or not.
+        is_signed: bool,
+    },
+}
+
+impl IntKind {
+    /// Is this integral type signed?
+    pub fn is_signed(&self) -> bool {
+        use self::IntKind::*;
+        match *self {
+            Bool | UChar | UShort | UInt | ULong | ULongLong | U8 | U16 |
+            U32 | U64 | U128 => false,
+
+            Char | Short | Int | Long | LongLong | I8 | I16 | I32 | I64 |
+            I128 => true,
+
+            Custom { is_signed, .. } => is_signed,
+        }
+    }
+
+    /// If this type has a known size, return it (in bytes). This is to
+    /// alleviate libclang sometimes not giving us a layout (like in the case
+    /// when an enum is defined inside a class with template parameters).
+    pub fn known_size(&self) -> Option<usize> {
+        use self::IntKind::*;
+        Some(match *self {
+            Bool | UChar | Char | U8 | I8 => 1,
+            U16 | I16 => 2,
+            U32 | I32 => 4,
+            U64 | I64 => 8,
+            I128 | U128 => 16,
+            _ => return None,
+        })
+    }
+
+    /// Whether this type's signedness matches the value.
+    pub fn signedness_matches(&self, val: i64) -> bool {
+        val >= 0 || self.is_signed()
+    }
+}
diff --git a/src/ir/item.rs b/src/ir/item.rs
new file mode 100644
index 00000000..df8fd222
--- /dev/null
+++ b/src/ir/item.rs
@@ -0,0 +1,1370 @@
+//! Bindgen's core intermediate representation type.
+
+use clang;
+use clang_sys;
+use parse::{ClangItemParser, ClangSubItemParser, ParseError, ParseResult};
+use std::cell::{Cell, RefCell};
+use std::fmt::Write;
+use std::iter;
+use super::annotations::Annotations;
+use super::context::{BindgenContext, ItemId};
+use super::derive::{CanDeriveCopy, CanDeriveDebug};
+use super::function::Function;
+use super::item_kind::ItemKind;
+use super::module::Module;
+use super::ty::{Type, TypeKind};
+use super::type_collector::{ItemSet, TypeCollector};
+
+/// A trait to get the canonical name from an item.
+///
+/// This is the trait that will eventually isolate all the logic related to name
+/// mangling and that kind of stuff.
+///
+/// This assumes no nested paths, at some point I'll have to make it a more
+/// complex thing.
+///
+/// This name is required to be safe for Rust, that is, is not expected to
+/// return any rust keyword from here.
+pub trait ItemCanonicalName {
+    /// Get the canonical name for this item.
+    fn canonical_name(&self, ctx: &BindgenContext) -> String;
+}
+
+/// The same, but specifies the path that needs to be followed to reach an item.
+///
+/// To contrast with canonical_name, here's an example:
+///
+/// ```c++
+/// namespace foo {
+///     const BAR = 3;
+/// }
+/// ```
+///
+/// For bar, the canonical path is `vec!["foo", "BAR"]`, while the canonical
+/// name is just `"BAR"`.
+pub trait ItemCanonicalPath {
+    /// Get the namespace-aware canonical path for this item. This means that if
+    /// namespaces are disabled, you'll get a single item, and otherwise you get
+    /// the whole path.
+    fn namespace_aware_canonical_path(&self,
+                                      ctx: &BindgenContext)
+                                      -> Vec<String>;
+
+    /// Get the canonical path for this item.
+    fn canonical_path(&self, ctx: &BindgenContext) -> Vec<String>;
+}
+
+/// A trait for iterating over an item and its parents and up its ancestor chain
+/// up to (but not including) the implicit root module.
+pub trait ItemAncestors {
+    /// Get an iterable over this item's ancestors.
+    fn ancestors<'a, 'b>(&self,
+                         ctx: &'a BindgenContext<'b>)
+                         -> ItemAncestorsIter<'a, 'b>;
+}
+
+cfg_if! {
+    if #[cfg(debug_assertions)] {
+        type DebugOnlyItemSet = ItemSet;
+    } else {
+        struct DebugOnlyItemSet;
+
+        impl DebugOnlyItemSet {
+            fn new() -> Self {
+                DebugOnlyItemSet
+            }
+
+            fn contains(&self,_id: &ItemId) -> bool {
+                false
+            }
+
+            fn insert(&mut self, _id: ItemId) {}
+        }
+    }
+}
+
+/// An iterator over an item and its ancestors.
+pub struct ItemAncestorsIter<'a, 'b>
+    where 'b: 'a,
+{
+    item: ItemId,
+    ctx: &'a BindgenContext<'b>,
+    seen: DebugOnlyItemSet,
+}
+
+impl<'a, 'b> ItemAncestorsIter<'a, 'b>
+    where 'b: 'a,
+{
+    fn new(ctx: &'a BindgenContext<'b>, item: ItemId) -> Self {
+        ItemAncestorsIter {
+            item: item,
+            ctx: ctx,
+            seen: DebugOnlyItemSet::new(),
+        }
+    }
+}
+
+impl<'a, 'b> Iterator for ItemAncestorsIter<'a, 'b>
+    where 'b: 'a,
+{
+    type Item = ItemId;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        let item = self.ctx.resolve_item(self.item);
+
+        if item.parent_id() == self.item {
+            None
+        } else {
+            self.item = item.parent_id();
+
+            debug_assert!(!self.seen.contains(&item.id()));
+            self.seen.insert(item.id());
+
+            Some(item.id())
+        }
+    }
+}
+
+// Pure convenience
+impl ItemCanonicalName for ItemId {
+    fn canonical_name(&self, ctx: &BindgenContext) -> String {
+        debug_assert!(ctx.in_codegen_phase(),
+                      "You're not supposed to call this yet");
+        ctx.resolve_item(*self).canonical_name(ctx)
+    }
+}
+
+impl ItemCanonicalPath for ItemId {
+    fn namespace_aware_canonical_path(&self,
+                                      ctx: &BindgenContext)
+                                      -> Vec<String> {
+        debug_assert!(ctx.in_codegen_phase(),
+                      "You're not supposed to call this yet");
+        ctx.resolve_item(*self).namespace_aware_canonical_path(ctx)
+    }
+
+    fn canonical_path(&self, ctx: &BindgenContext) -> Vec<String> {
+        debug_assert!(ctx.in_codegen_phase(),
+                      "You're not supposed to call this yet");
+        ctx.resolve_item(*self).canonical_path(ctx)
+    }
+}
+
+impl ItemAncestors for ItemId {
+    fn ancestors<'a, 'b>(&self,
+                         ctx: &'a BindgenContext<'b>)
+                         -> ItemAncestorsIter<'a, 'b> {
+        ItemAncestorsIter::new(ctx, *self)
+    }
+}
+
+impl ItemAncestors for Item {
+    fn ancestors<'a, 'b>(&self,
+                         ctx: &'a BindgenContext<'b>)
+                         -> ItemAncestorsIter<'a, 'b> {
+        self.id().ancestors(ctx)
+    }
+}
+
+impl TypeCollector for ItemId {
+    type Extra = ();
+
+    fn collect_types(&self,
+                     ctx: &BindgenContext,
+                     types: &mut ItemSet,
+                     extra: &()) {
+        ctx.resolve_item(*self).collect_types(ctx, types, extra);
+    }
+}
+
+impl TypeCollector for Item {
+    type Extra = ();
+
+    fn collect_types(&self,
+                     ctx: &BindgenContext,
+                     types: &mut ItemSet,
+                     _extra: &()) {
+        if self.is_hidden(ctx) || types.contains(&self.id()) {
+            return;
+        }
+
+        match *self.kind() {
+            ItemKind::Type(ref ty) => {
+                // There are some types, like resolved type references, where we
+                // don't want to stop collecting types even though they may be
+                // opaque.
+                if ty.should_be_traced_unconditionally() || !self.is_opaque(ctx) {
+                    ty.collect_types(ctx, types, self);
+                }
+            }
+            ItemKind::Function(ref fun) => {
+                // Just the same way, it has not real meaning for a function to
+                // be opaque, so we trace across it.
+                types.insert(fun.signature());
+            }
+            ItemKind::Var(ref var) => {
+                types.insert(var.ty());
+            }
+            _ => {} // FIXME.
+        }
+    }
+}
+
+impl CanDeriveDebug for Item {
+    type Extra = ();
+
+    fn can_derive_debug(&self, ctx: &BindgenContext, _: ()) -> bool {
+        match self.kind {
+            ItemKind::Type(ref ty) => {
+                if self.is_opaque(ctx) {
+                    ty.layout(ctx)
+                        .map_or(true, |l| l.opaque().can_derive_debug(ctx, ()))
+                } else {
+                    ty.can_derive_debug(ctx, ())
+                }
+            }
+            _ => false,
+        }
+    }
+}
+
+impl<'a> CanDeriveCopy<'a> for Item {
+    type Extra = ();
+
+    fn can_derive_copy(&self, ctx: &BindgenContext, _: ()) -> bool {
+        match self.kind {
+            ItemKind::Type(ref ty) => {
+                if self.is_opaque(ctx) {
+                    ty.layout(ctx)
+                        .map_or(true, |l| l.opaque().can_derive_copy(ctx, ()))
+                } else {
+                    ty.can_derive_copy(ctx, self)
+                }
+            }
+            _ => false,
+        }
+    }
+
+    fn can_derive_copy_in_array(&self, ctx: &BindgenContext, _: ()) -> bool {
+        match self.kind {
+            ItemKind::Type(ref ty) => {
+                if self.is_opaque(ctx) {
+                    ty.layout(ctx)
+                        .map_or(true, |l| l.opaque().can_derive_copy_in_array(ctx, ()))
+                } else {
+                    ty.can_derive_copy_in_array(ctx, self)
+                }
+            }
+            _ => false,
+        }
+    }
+}
+
+/// An item is the base of the bindgen representation, it can be either a
+/// module, a type, a function, or a variable (see `ItemKind` for more
+/// information).
+///
+/// Items refer to each other by `ItemId`. Every item has its parent's
+/// id. Depending on the kind of item this is, it may also refer to other items,
+/// such as a compound type item referring to other types. Collectively, these
+/// references form a graph.
+///
+/// The entry-point to this graph is the "root module": a meta-item used to hold
+/// all top-level items.
+///
+/// An item may have a comment, and annotations (see the `annotations` module).
+///
+/// Note that even though we parse all the types of annotations in comments, not
+/// all of them apply to every item. Those rules are described in the
+/// `annotations` module.
+#[derive(Debug)]
+pub struct Item {
+    /// This item's id.
+    id: ItemId,
+
+    /// The item's local id, unique only amongst its siblings.  Only used for
+    /// anonymous items.
+    ///
+    /// Lazily initialized in local_id().
+    ///
+    /// Note that only structs, unions, and enums get a local type id. In any
+    /// case this is an implementation detail.
+    local_id: Cell<Option<usize>>,
+
+    /// The next local id to use for a child..
+    next_child_local_id: Cell<usize>,
+
+    /// A cached copy of the canonical name, as returned by `canonical_name`.
+    ///
+    /// This is a fairly used operation during codegen so this makes bindgen
+    /// considerably faster in those cases.
+    canonical_name_cache: RefCell<Option<String>>,
+
+    /// A doc comment over the item, if any.
+    comment: Option<String>,
+    /// Annotations extracted from the doc comment, or the default ones
+    /// otherwise.
+    annotations: Annotations,
+    /// An item's parent id. This will most likely be a class where this item
+    /// was declared, or a module, etc.
+    ///
+    /// All the items have a parent, except the root module, in which case the
+    /// parent id is its own id.
+    parent_id: ItemId,
+    /// The item kind.
+    kind: ItemKind,
+}
+
+impl Item {
+    /// Construct a new `Item`.
+    pub fn new(id: ItemId,
+               comment: Option<String>,
+               annotations: Option<Annotations>,
+               parent_id: ItemId,
+               kind: ItemKind)
+               -> Self {
+        debug_assert!(id != parent_id || kind.is_module());
+        Item {
+            id: id,
+            local_id: Cell::new(None),
+            next_child_local_id: Cell::new(1),
+            canonical_name_cache: RefCell::new(None),
+            parent_id: parent_id,
+            comment: comment,
+            annotations: annotations.unwrap_or_default(),
+            kind: kind,
+        }
+    }
+
+    /// Get this `Item`'s identifier.
+    pub fn id(&self) -> ItemId {
+        self.id
+    }
+
+    /// Get this `Item`'s parent's identifier.
+    ///
+    /// For the root module, the parent's ID is its own ID.
+    pub fn parent_id(&self) -> ItemId {
+        self.parent_id
+    }
+
+    /// Set this item's parent id.
+    ///
+    /// This is only used so replacements get generated in the proper module.
+    pub fn set_parent_for_replacement(&mut self, id: ItemId) {
+        self.parent_id = id;
+    }
+
+    /// Get this `Item`'s comment, if it has any.
+    pub fn comment(&self) -> Option<&str> {
+        self.comment.as_ref().map(|c| &**c)
+    }
+
+    /// What kind of item is this?
+    pub fn kind(&self) -> &ItemKind {
+        &self.kind
+    }
+
+    /// Get a mutable reference to this item's kind.
+    pub fn kind_mut(&mut self) -> &mut ItemKind {
+        &mut self.kind
+    }
+
+    /// Get an identifier that differentiates this item from its siblings.
+    ///
+    /// This should stay relatively stable in the face of code motion outside or
+    /// below this item's lexical scope, meaning that this can be useful for
+    /// generating relatively stable identifiers within a scope.
+    pub fn local_id(&self, ctx: &BindgenContext) -> usize {
+        if self.local_id.get().is_none() {
+            let parent = ctx.resolve_item(self.parent_id);
+            let local_id = parent.next_child_local_id.get();
+            parent.next_child_local_id.set(local_id + 1);
+            self.local_id.set(Some(local_id));
+        }
+        self.local_id.get().unwrap()
+    }
+
+    /// Returns whether this item is a top-level item, from the point of view of
+    /// bindgen.
+    ///
+    /// This point of view changes depending on whether namespaces are enabled
+    /// or not. That way, in the following example:
+    ///
+    /// ```c++
+    /// namespace foo {
+    ///     static int var;
+    /// }
+    /// ```
+    ///
+    /// `var` would be a toplevel item if namespaces are disabled, but won't if
+    /// they aren't.
+    ///
+    /// This function is used to determine when the codegen phase should call
+    /// `codegen` on an item, since any item that is not top-level will be
+    /// generated by its parent.
+    pub fn is_toplevel(&self, ctx: &BindgenContext) -> bool {
+        // FIXME: Workaround for some types falling behind when parsing weird
+        // stl classes, for example.
+        if ctx.options().enable_cxx_namespaces && self.kind().is_module() &&
+           self.id() != ctx.root_module() {
+            return false;
+        }
+
+        let mut parent = self.parent_id;
+        loop {
+            let parent_item = match ctx.resolve_item_fallible(parent) {
+                Some(item) => item,
+                None => return false,
+            };
+
+            if parent_item.id() == ctx.root_module() {
+                return true;
+            } else if ctx.options().enable_cxx_namespaces ||
+                      !parent_item.kind().is_module() {
+                return false;
+            }
+
+            parent = parent_item.parent_id();
+        }
+    }
+
+    /// Get a reference to this item's underlying `Type`. Panic if this is some
+    /// other kind of item.
+    pub fn expect_type(&self) -> &Type {
+        self.kind().expect_type()
+    }
+
+    /// Get a reference to this item's underlying `Type`, or `None` if this is
+    /// some other kind of item.
+    pub fn as_type(&self) -> Option<&Type> {
+        self.kind().as_type()
+    }
+
+    /// Get a reference to this item's underlying `Function`. Panic if this is
+    /// some other kind of item.
+    pub fn expect_function(&self) -> &Function {
+        self.kind().expect_function()
+    }
+
+    /// Checks whether an item contains in its "type signature" some named type.
+    ///
+    /// This function is used to avoid unused template parameter errors in Rust
+    /// when generating typedef declarations, and also to know whether we need
+    /// to generate a `PhantomData` member for a template parameter.
+    ///
+    /// For example, in code like the following:
+    ///
+    /// ```c++
+    /// template<typename T, typename U>
+    /// struct Foo {
+    ///     T bar;
+    ///
+    ///     struct Baz {
+    ///         U bas;
+    ///     };
+    /// };
+    /// ```
+    ///
+    /// Both `Foo` and `Baz` contain both `T` and `U` template parameters in
+    /// their signature:
+    ///
+    ///  * `Foo<T, U>`
+    ///  * `Bar<T, U>`
+    ///
+    /// But the Rust structure for `Foo` would look like:
+    ///
+    /// ```rust
+    /// struct Foo<T, U> {
+    ///     bar: T,
+    ///     _phantom0: ::std::marker::PhantomData<U>,
+    /// }
+    /// ```
+    ///
+    /// because none of its member fields contained the `U` type in the
+    /// signature. Similarly, `Bar` would contain a `PhantomData<T>` type, for
+    /// the same reason.
+    ///
+    /// Note that this is somewhat similar to `applicable_template_args`, but
+    /// this also takes into account other kind of types, like arrays,
+    /// (`[T; 40]`), pointers: `*mut T`, etc...
+    ///
+    /// Normally we could do this check just in the `Type` kind, but we also
+    /// need to check the `applicable_template_args` more generally, since we
+    /// could need a type transitively from our parent, see the test added in
+    /// commit 2a3f93074dd2898669dbbce6e97e5cc4405d7cb1.
+    ///
+    /// It's kind of unfortunate (in the sense that it's a sort of complex
+    /// process), but I think it should get all the cases.
+    fn signature_contains_named_type(&self,
+                                     ctx: &BindgenContext,
+                                     ty: &Type)
+                                     -> bool {
+        debug_assert!(ty.is_named());
+        self.expect_type().signature_contains_named_type(ctx, ty) ||
+        self.applicable_template_args(ctx).iter().any(|template| {
+            ctx.resolve_type(*template).signature_contains_named_type(ctx, ty)
+        })
+    }
+
+    /// Returns the template arguments that apply to a struct. This is a concept
+    /// needed because of type declarations inside templates, for example:
+    ///
+    /// ```c++
+    /// template<typename T>
+    /// class Foo {
+    ///     typedef T element_type;
+    ///     typedef int Bar;
+    ///
+    ///     template<typename U>
+    ///     class Baz {
+    ///     };
+    /// };
+    /// ```
+    ///
+    /// In this case, the applicable template arguments for the different types
+    /// would be:
+    ///
+    ///  * `Foo`: [`T`]
+    ///  * `Foo::element_type`: [`T`]
+    ///  * `Foo::Bar`: [`T`]
+    ///  * `Foo::Baz`: [`T`, `U`]
+    ///
+    /// You might notice that we can't generate something like:
+    ///
+    /// ```rust,ignore
+    /// type Foo_Bar<T> = ::std::os::raw::c_int;
+    /// ```
+    ///
+    /// since that would be invalid Rust. Still, conceptually, `Bar` *could* use
+    /// the template parameter type `T`, and that's exactly what this method
+    /// represents. The unused template parameters get stripped in the
+    /// `signature_contains_named_type` check.
+    pub fn applicable_template_args(&self,
+                                    ctx: &BindgenContext)
+                                    -> Vec<ItemId> {
+        let ty = match *self.kind() {
+            ItemKind::Type(ref ty) => ty,
+            _ => return vec![],
+        };
+
+        fn parent_contains(ctx: &BindgenContext,
+                           parent_template_args: &[ItemId],
+                           item: ItemId)
+                           -> bool {
+            let item_ty = ctx.resolve_type(item);
+            parent_template_args.iter().any(|parent_item| {
+                let parent_ty = ctx.resolve_type(*parent_item);
+                match (parent_ty.kind(), item_ty.kind()) {
+                    (&TypeKind::Named(ref n), &TypeKind::Named(ref i)) => {
+                        n == i
+                    }
+                    _ => false,
+                }
+            })
+        }
+
+        match *ty.kind() {
+            TypeKind::Named(..) => vec![self.id()],
+            TypeKind::Array(inner, _) |
+            TypeKind::Pointer(inner) |
+            TypeKind::Reference(inner) |
+            TypeKind::ResolvedTypeRef(inner) => {
+                ctx.resolve_item(inner).applicable_template_args(ctx)
+            }
+            TypeKind::Alias(_, inner) => {
+                let parent_args = ctx.resolve_item(self.parent_id())
+                    .applicable_template_args(ctx);
+                let inner = ctx.resolve_item(inner);
+
+                // Avoid unused type parameters, sigh.
+                parent_args.iter()
+                    .cloned()
+                    .filter(|arg| {
+                        let arg = ctx.resolve_type(*arg);
+                        arg.is_named() &&
+                        inner.signature_contains_named_type(ctx, arg)
+                    })
+                    .collect()
+            }
+            // XXX Is this completely correct? Partial template specialization
+            // is hard anyways, sigh...
+            TypeKind::TemplateAlias(_, _, ref args) |
+            TypeKind::TemplateRef(_, ref args) => args.clone(),
+            // In a template specialization we've got all we want.
+            TypeKind::Comp(ref ci) if ci.is_template_specialization() => {
+                ci.template_args().iter().cloned().collect()
+            }
+            TypeKind::Comp(ref ci) => {
+                let mut parent_template_args =
+                    ctx.resolve_item(self.parent_id())
+                        .applicable_template_args(ctx);
+
+                for ty in ci.template_args() {
+                    if !parent_contains(ctx, &parent_template_args, *ty) {
+                        parent_template_args.push(*ty);
+                    }
+                }
+
+                parent_template_args
+            }
+            _ => vec![],
+        }
+    }
+
+    /// Is this item a module?
+    pub fn is_module(&self) -> bool {
+        match self.kind {
+            ItemKind::Module(..) => true,
+            _ => false,
+        }
+    }
+
+    /// Get this item's annotations.
+    pub fn annotations(&self) -> &Annotations {
+        &self.annotations
+    }
+
+    /// Whether this item should be hidden.
+    ///
+    /// This may be due to either annotations or to other kind of configuration.
+    pub fn is_hidden(&self, ctx: &BindgenContext) -> bool {
+        debug_assert!(ctx.in_codegen_phase(),
+                      "You're not supposed to call this yet");
+        self.annotations.hide() ||
+        ctx.hidden_by_name(&self.canonical_path(ctx), self.id)
+    }
+
+    /// Is this item opaque?
+    pub fn is_opaque(&self, ctx: &BindgenContext) -> bool {
+        debug_assert!(ctx.in_codegen_phase(),
+                      "You're not supposed to call this yet");
+        self.annotations.opaque() ||
+        ctx.opaque_by_name(&self.canonical_path(ctx))
+    }
+
+    /// Is this a reference to another type?
+    pub fn is_type_ref(&self) -> bool {
+        self.as_type().map_or(false, |ty| ty.is_type_ref())
+    }
+
+    /// Is this item a var type?
+    pub fn is_var(&self) -> bool {
+        match *self.kind() {
+            ItemKind::Var(..) => true,
+            _ => false,
+        }
+    }
+
+    /// Take out item NameOptions
+    pub fn name<'item, 'ctx>(&'item self,
+                             ctx: &'item BindgenContext<'ctx>)
+                             -> NameOptions<'item, 'ctx> {
+        NameOptions::new(self, ctx)
+    }
+
+    /// Get the target item id for name generation.
+    fn name_target(&self, ctx: &BindgenContext) -> ItemId {
+        let mut targets_seen = DebugOnlyItemSet::new();
+        let mut item = self;
+
+        loop {
+            debug_assert!(!targets_seen.contains(&item.id()));
+            targets_seen.insert(item.id());
+
+            if self.annotations().use_instead_of().is_some() {
+                return self.id();
+            }
+
+            match *item.kind() {
+                ItemKind::Type(ref ty) => {
+                    match *ty.kind() {
+                        // If we're a template specialization, our name is our
+                        // parent's name.
+                        TypeKind::Comp(ref ci)
+                            if ci.is_template_specialization() => {
+                            let specialized =
+                                ci.specialized_template().unwrap();
+                            item = ctx.resolve_item(specialized);
+                        }
+                        // Same as above.
+                        TypeKind::ResolvedTypeRef(inner) |
+                        TypeKind::TemplateRef(inner, _) => {
+                            item = ctx.resolve_item(inner);
+                        }
+                        _ => return item.id(),
+                    }
+                }
+                _ => return item.id(),
+            }
+        }
+    }
+
+    /// Get this function item's name, or `None` if this item is not a function.
+    fn func_name(&self) -> Option<&str> {
+        match *self.kind() {
+            ItemKind::Function(ref func) => Some(func.name()),
+            _ => None,
+        }
+    }
+
+    /// Get the overload index for this method. If this is not a method, return
+    /// `None`.
+    fn overload_index(&self, ctx: &BindgenContext) -> Option<usize> {
+        self.func_name().and_then(|func_name| {
+            let parent = ctx.resolve_item(self.parent_id());
+            if let ItemKind::Type(ref ty) = *parent.kind() {
+                if let TypeKind::Comp(ref ci) = *ty.kind() {
+                    // All the constructors have the same name, so no need to
+                    // resolve and check.
+                    return ci.constructors()
+                        .iter()
+                        .position(|c| *c == self.id())
+                        .or_else(|| {
+                            ci.methods()
+                                .iter()
+                                .filter(|m| {
+                                    let item = ctx.resolve_item(m.signature());
+                                    let func = item.expect_function();
+                                    func.name() == func_name
+                                })
+                                .position(|m| m.signature() == self.id())
+                        });
+                }
+            }
+
+            None
+        })
+    }
+
+    /// Get this item's base name (aka non-namespaced name).
+    fn base_name(&self, ctx: &BindgenContext) -> String {
+        if let Some(path) = self.annotations().use_instead_of() {
+            return path.last().unwrap().clone();
+        }
+
+        match *self.kind() {
+            ItemKind::Var(ref var) => var.name().to_owned(),
+            ItemKind::Module(ref module) => {
+                module.name()
+                    .map(ToOwned::to_owned)
+                    .unwrap_or_else(|| {
+                        format!("_bindgen_mod_{}", self.exposed_id(ctx))
+                    })
+            }
+            ItemKind::Type(ref ty) => {
+                let name = match *ty.kind() {
+                    TypeKind::ResolvedTypeRef(..) => {
+                        panic!("should have resolved this in name_target()")
+                    }
+                    _ => ty.name(),
+                };
+                name.map(ToOwned::to_owned)
+                    .unwrap_or_else(|| {
+                        format!("_bindgen_ty_{}", self.exposed_id(ctx))
+                    })
+            }
+            ItemKind::Function(ref fun) => {
+                let mut name = fun.name().to_owned();
+
+                if let Some(idx) = self.overload_index(ctx) {
+                    if idx > 0 {
+                        write!(&mut name, "{}", idx).unwrap();
+                    }
+                }
+
+                name
+            }
+        }
+    }
+
+    /// Get the canonical name without taking into account the replaces
+    /// annotation.
+    ///
+    /// This is the base logic used to implement hiding and replacing via
+    /// annotations, and also to implement proper name mangling.
+    ///
+    /// The idea is that each generated type in the same "level" (read: module
+    /// or namespace) has a unique canonical name.
+    ///
+    /// This name should be derived from the immutable state contained in the
+    /// type and the parent chain, since it should be consistent.
+    pub fn real_canonical_name(&self,
+                               ctx: &BindgenContext,
+                               opt: &NameOptions)
+                               -> String {
+        let target = ctx.resolve_item(self.name_target(ctx));
+
+        // Short-circuit if the target has an override, and just use that.
+        if let Some(path) = target.annotations.use_instead_of() {
+            if ctx.options().enable_cxx_namespaces {
+                return path.last().unwrap().clone();
+            }
+            return path.join("_").to_owned();
+        }
+
+        let base_name = target.base_name(ctx);
+
+        // Named template type arguments are never namespaced, and never
+        // mangled.
+        if target.as_type().map_or(false, |ty| ty.is_named()) {
+            return base_name;
+        }
+
+        // Concatenate this item's ancestors' names together.
+        let mut names: Vec<_> = target.parent_id()
+            .ancestors(ctx)
+            .filter(|id| *id != ctx.root_module())
+            .take_while(|id| {
+                // Stop iterating ancestors once we reach a namespace.
+                !opt.within_namespaces || !ctx.resolve_item(*id).is_module()
+            })
+            .map(|id| {
+                let item = ctx.resolve_item(id);
+                let target = ctx.resolve_item(item.name_target(ctx));
+                target.base_name(ctx)
+            })
+            .filter(|name| !name.is_empty())
+            .collect();
+
+        names.reverse();
+
+        if !base_name.is_empty() {
+            names.push(base_name);
+        }
+
+        let name = names.join("_");
+
+        ctx.rust_mangle(&name).into_owned()
+    }
+
+    fn exposed_id(&self, ctx: &BindgenContext) -> String {
+        // Only use local ids for enums, classes, structs and union types.  All
+        // other items use their global id.
+        let ty_kind = self.kind().as_type().map(|t| t.kind());
+        if let Some(ty_kind) = ty_kind {
+            match *ty_kind {
+                TypeKind::Comp(..) |
+                TypeKind::Enum(..) => return self.local_id(ctx).to_string(),
+                _ => {}
+            }
+        }
+
+        // Note that this `id_` prefix prevents (really unlikely) collisions
+        // between the global id and the local id of an item with the same
+        // parent.
+        format!("id_{}", self.id().as_usize())
+    }
+
+    /// Get a reference to this item's `Module`, or `None` if this is not a
+    /// `Module` item.
+    pub fn as_module(&self) -> Option<&Module> {
+        match self.kind {
+            ItemKind::Module(ref module) => Some(module),
+            _ => None,
+        }
+    }
+
+    /// Get a mutable reference to this item's `Module`, or `None` if this is
+    /// not a `Module` item.
+    pub fn as_module_mut(&mut self) -> Option<&mut Module> {
+        match self.kind {
+            ItemKind::Module(ref mut module) => Some(module),
+            _ => None,
+        }
+    }
+}
+
+// An utility function to handle recursing inside nested types.
+fn visit_child(cur: clang::Cursor,
+               id: ItemId,
+               ty: &clang::Type,
+               parent_id: Option<ItemId>,
+               ctx: &mut BindgenContext,
+               result: &mut Result<ItemId, ParseError>)
+               -> clang_sys::CXChildVisitResult {
+    use clang_sys::*;
+    if result.is_ok() {
+        return CXChildVisit_Break;
+    }
+
+    *result = Item::from_ty_with_id(id, ty, Some(cur), parent_id, ctx);
+
+    match *result {
+        Ok(..) => CXChildVisit_Break,
+        Err(ParseError::Recurse) => {
+            cur.visit(|c| visit_child(c, id, ty, parent_id, ctx, result));
+            CXChildVisit_Continue
+        }
+        Err(ParseError::Continue) => CXChildVisit_Continue,
+    }
+}
+
+impl ClangItemParser for Item {
+    fn builtin_type(kind: TypeKind,
+                    is_const: bool,
+                    ctx: &mut BindgenContext)
+                    -> ItemId {
+        // Feel free to add more here, I'm just lazy.
+        match kind {
+            TypeKind::Void |
+            TypeKind::Int(..) |
+            TypeKind::Pointer(..) |
+            TypeKind::Float(..) => {}
+            _ => panic!("Unsupported builtin type"),
+        }
+
+        let ty = Type::new(None, None, kind, is_const);
+        let id = ctx.next_item_id();
+        let module = ctx.root_module();
+        ctx.add_item(Item::new(id, None, None, module, ItemKind::Type(ty)),
+                     None,
+                     None);
+        id
+    }
+
+
+    fn parse(cursor: clang::Cursor,
+             parent_id: Option<ItemId>,
+             ctx: &mut BindgenContext)
+             -> Result<ItemId, ParseError> {
+        use ir::function::Function;
+        use ir::module::Module;
+        use ir::var::Var;
+        use clang_sys::*;
+
+        if !cursor.is_valid() {
+            return Err(ParseError::Continue);
+        }
+
+        let comment = cursor.raw_comment();
+        let annotations = Annotations::new(&cursor);
+
+        let current_module = ctx.current_module();
+        let relevant_parent_id = parent_id.unwrap_or(current_module);
+
+        macro_rules! try_parse {
+            ($what:ident) => {
+                match $what::parse(cursor, ctx) {
+                    Ok(ParseResult::New(item, declaration)) => {
+                        let id = ctx.next_item_id();
+
+                        ctx.add_item(Item::new(id, comment, annotations,
+                                               relevant_parent_id,
+                                               ItemKind::$what(item)),
+                                         declaration,
+                                         Some(cursor));
+                        return Ok(id);
+                    }
+                    Ok(ParseResult::AlreadyResolved(id)) => {
+                        return Ok(id);
+                    }
+                    Err(ParseError::Recurse) => return Err(ParseError::Recurse),
+                    Err(ParseError::Continue) => {},
+                }
+            }
+        }
+
+        try_parse!(Module);
+
+        // NOTE: Is extremely important to parse functions and vars **before**
+        // types.  Otherwise we can parse a function declaration as a type
+        // (which is legal), and lose functions to generate.
+        //
+        // In general, I'm not totally confident this split between
+        // ItemKind::Function and TypeKind::FunctionSig is totally worth it, but
+        // I guess we can try.
+        try_parse!(Function);
+        try_parse!(Var);
+
+        // Types are sort of special, so to avoid parsing template classes
+        // twice, handle them separately.
+        {
+            let applicable_cursor = cursor.definition().unwrap_or(cursor);
+            match Self::from_ty(&applicable_cursor.cur_type(),
+                                Some(applicable_cursor),
+                                parent_id,
+                                ctx) {
+                Ok(ty) => return Ok(ty),
+                Err(ParseError::Recurse) => return Err(ParseError::Recurse),
+                Err(ParseError::Continue) => {}
+            }
+        }
+
+        // Guess how does clang treat extern "C" blocks?
+        if cursor.kind() == CXCursor_UnexposedDecl {
+            Err(ParseError::Recurse)
+        } else {
+            // We whitelist cursors here known to be unhandled, to prevent being
+            // too noisy about this.
+            match cursor.kind() {
+                CXCursor_MacroDefinition |
+                CXCursor_MacroExpansion |
+                CXCursor_UsingDeclaration |
+                CXCursor_UsingDirective |
+                CXCursor_StaticAssert |
+                CXCursor_InclusionDirective => {
+                    debug!("Unhandled cursor kind {:?}: {:?}",
+                           cursor.kind(),
+                           cursor);
+                }
+                _ => {
+                    // ignore toplevel operator overloads
+                    let spelling = cursor.spelling();
+                    if !spelling.starts_with("operator") {
+                        error!("Unhandled cursor kind {:?}: {:?}",
+                               cursor.kind(),
+                               cursor);
+                    }
+                }
+            }
+
+            Err(ParseError::Continue)
+        }
+    }
+
+    fn from_ty_or_ref(ty: clang::Type,
+                      location: Option<clang::Cursor>,
+                      parent_id: Option<ItemId>,
+                      ctx: &mut BindgenContext)
+                      -> ItemId {
+        let id = ctx.next_item_id();
+        Self::from_ty_or_ref_with_id(id, ty, location, parent_id, ctx)
+    }
+
+    /// Parse a C++ type. If we find a reference to a type that has not been
+    /// defined yet, use `UnresolvedTypeRef` as a placeholder.
+    ///
+    /// This logic is needed to avoid parsing items with the incorrect parent
+    /// and it's sort of complex to explain, so I'll just point to
+    /// `tests/headers/typeref.hpp` to see the kind of constructs that forced
+    /// this.
+    ///
+    /// Typerefs are resolved once parsing is completely done, see
+    /// `BindgenContext::resolve_typerefs`.
+    fn from_ty_or_ref_with_id(potential_id: ItemId,
+                              ty: clang::Type,
+                              location: Option<clang::Cursor>,
+                              parent_id: Option<ItemId>,
+                              ctx: &mut BindgenContext)
+                              -> ItemId {
+        debug!("from_ty_or_ref_with_id: {:?} {:?}, {:?}, {:?}",
+               potential_id,
+               ty,
+               location,
+               parent_id);
+
+        if ctx.collected_typerefs() {
+            debug!("refs already collected, resolving directly");
+            return Self::from_ty_with_id(potential_id,
+                                         &ty,
+                                         location,
+                                         parent_id,
+                                         ctx)
+                .expect("Unable to resolve type");
+        }
+
+        if let Some(ty) =
+            ctx.builtin_or_resolved_ty(potential_id, parent_id, &ty, location) {
+            debug!("{:?} already resolved: {:?}", ty, location);
+            return ty;
+        }
+
+        debug!("New unresolved type reference: {:?}, {:?}", ty, location);
+
+        let is_const = ty.is_const();
+        let kind = TypeKind::UnresolvedTypeRef(ty, location, parent_id);
+        let current_module = ctx.current_module();
+        ctx.add_item(Item::new(potential_id,
+                               None,
+                               None,
+                               parent_id.unwrap_or(current_module),
+                               ItemKind::Type(Type::new(None,
+                                                        None,
+                                                        kind,
+                                                        is_const))),
+                     Some(clang::Cursor::null()),
+                     None);
+        potential_id
+    }
+
+
+    fn from_ty(ty: &clang::Type,
+               location: Option<clang::Cursor>,
+               parent_id: Option<ItemId>,
+               ctx: &mut BindgenContext)
+               -> Result<ItemId, ParseError> {
+        let id = ctx.next_item_id();
+        Self::from_ty_with_id(id, ty, location, parent_id, ctx)
+    }
+
+    /// This is one of the trickiest methods you'll find (probably along with
+    /// some of the ones that handle templates in `BindgenContext`).
+    ///
+    /// This method parses a type, given the potential id of that type (if
+    /// parsing it was correct), an optional location we're scanning, which is
+    /// critical some times to obtain information, an optional parent item id,
+    /// that will, if it's `None`, become the current module id, and the
+    /// context.
+    fn from_ty_with_id(id: ItemId,
+                       ty: &clang::Type,
+                       location: Option<clang::Cursor>,
+                       parent_id: Option<ItemId>,
+                       ctx: &mut BindgenContext)
+                       -> Result<ItemId, ParseError> {
+        use clang_sys::*;
+
+        let decl = {
+            let decl = ty.declaration();
+            decl.definition().unwrap_or(decl)
+        };
+
+        let comment = decl.raw_comment()
+            .or_else(|| location.as_ref().and_then(|l| l.raw_comment()));
+        let annotations = Annotations::new(&decl)
+            .or_else(|| location.as_ref().and_then(|l| Annotations::new(l)));
+
+        if let Some(ref annotations) = annotations {
+            if let Some(ref replaced) = annotations.use_instead_of() {
+                ctx.replace(replaced, id);
+            }
+        }
+
+        if let Some(ty) =
+               ctx.builtin_or_resolved_ty(id, parent_id, ty, location) {
+            return Ok(ty);
+        }
+
+        // First, check we're not recursing.
+        let mut valid_decl = decl.kind() != CXCursor_NoDeclFound;
+        let declaration_to_look_for = if valid_decl {
+            decl.canonical()
+        } else if location.is_some() &&
+                                                location.unwrap().kind() ==
+                                                CXCursor_ClassTemplate {
+            valid_decl = true;
+            location.unwrap()
+        } else {
+            decl
+        };
+
+        if valid_decl {
+            if let Some(&(_, item_id)) = ctx.currently_parsed_types
+                .iter()
+                .find(|&&(d, _)| d == declaration_to_look_for) {
+                debug!("Avoiding recursion parsing type: {:?}", ty);
+                return Ok(item_id);
+            }
+        }
+
+        let current_module = ctx.current_module();
+        if valid_decl {
+            ctx.currently_parsed_types.push((declaration_to_look_for, id));
+        }
+
+        let result = Type::from_clang_ty(id, ty, location, parent_id, ctx);
+        let relevant_parent_id = parent_id.unwrap_or(current_module);
+        let ret = match result {
+            Ok(ParseResult::AlreadyResolved(ty)) => Ok(ty),
+            Ok(ParseResult::New(item, declaration)) => {
+                ctx.add_item(Item::new(id,
+                                       comment,
+                                       annotations,
+                                       relevant_parent_id,
+                                       ItemKind::Type(item)),
+                             declaration,
+                             location);
+                Ok(id)
+            }
+            Err(ParseError::Continue) => Err(ParseError::Continue),
+            Err(ParseError::Recurse) => {
+                debug!("Item::from_ty recursing in the ast");
+                let mut result = Err(ParseError::Recurse);
+                if let Some(ref location) = location {
+                    // Need to pop here, otherwise we'll get stuck.
+                    //
+                    // TODO: Find a nicer interface, really. Also, the
+                    // declaration_to_look_for suspiciously shares a lot of
+                    // logic with ir::context, so we should refactor that.
+                    if valid_decl {
+                        let (popped_decl, _) =
+                            ctx.currently_parsed_types.pop().unwrap();
+                        assert_eq!(popped_decl, declaration_to_look_for);
+                    }
+
+                    location.visit(|cur| {
+                        visit_child(cur, id, ty, parent_id, ctx, &mut result)
+                    });
+
+                    if valid_decl {
+                        ctx.currently_parsed_types
+                            .push((declaration_to_look_for, id));
+                    }
+                }
+                // If we have recursed into the AST all we know, and we still
+                // haven't found what we've got, let's just make a named type.
+                //
+                // This is what happens with some template members, for example.
+                //
+                // FIXME: Maybe we should restrict this to things with parent?
+                // It's harmless, but if we restrict that, then
+                // tests/headers/nsStyleAutoArray.hpp crashes.
+                if let Err(ParseError::Recurse) = result {
+                    warn!("Unknown type, assuming named template type: \
+                          id = {:?}; spelling = {}",
+                          id,
+                          ty.spelling());
+                    Ok(Self::named_type_with_id(id,
+                                                ty.spelling(),
+                                                relevant_parent_id,
+                                                ctx))
+                } else {
+                    result
+                }
+            }
+        };
+
+        if valid_decl {
+            let (popped_decl, _) = ctx.currently_parsed_types.pop().unwrap();
+            assert_eq!(popped_decl, declaration_to_look_for);
+        }
+
+        ret
+    }
+
+    /// A named type is a template parameter, e.g., the "T" in Foo<T>. They're
+    /// always local so it's the only exception when there's no declaration for
+    /// a type.
+    ///
+    /// It must have an id, and must not be the current module id. Ideally we
+    /// could assert the parent id is a Comp(..) type, but that info isn't
+    /// available yet.
+    fn named_type_with_id<S>(id: ItemId,
+                             name: S,
+                             parent_id: ItemId,
+                             ctx: &mut BindgenContext)
+                             -> ItemId
+        where S: Into<String>,
+    {
+        // see tests/headers/const_tparam.hpp
+        // and tests/headers/variadic_tname.hpp
+        let name = name.into().replace("const ", "").replace(".", "");
+
+        ctx.add_item(Item::new(id,
+                               None,
+                               None,
+                               parent_id,
+                               ItemKind::Type(Type::named(name))),
+                     None,
+                     None);
+
+        id
+    }
+
+    fn named_type<S>(name: S,
+                     parent_id: ItemId,
+                     ctx: &mut BindgenContext)
+                     -> ItemId
+        where S: Into<String>,
+    {
+        let id = ctx.next_item_id();
+        Self::named_type_with_id(id, name, parent_id, ctx)
+    }
+}
+
+impl ItemCanonicalName for Item {
+    fn canonical_name(&self, ctx: &BindgenContext) -> String {
+        debug_assert!(ctx.in_codegen_phase(),
+                      "You're not supposed to call this yet");
+        if self.canonical_name_cache.borrow().is_none() {
+            let in_namespace = ctx.options().enable_cxx_namespaces ||
+                               ctx.options().disable_name_namespacing;
+
+            *self.canonical_name_cache.borrow_mut() = if in_namespace {
+                Some(self.name(ctx).within_namespaces().get())
+            } else {
+                Some(self.name(ctx).get())
+            };
+        }
+        return self.canonical_name_cache.borrow().as_ref().unwrap().clone();
+    }
+}
+
+impl ItemCanonicalPath for Item {
+    fn namespace_aware_canonical_path(&self,
+                                      ctx: &BindgenContext)
+                                      -> Vec<String> {
+        let path = self.canonical_path(ctx);
+        if ctx.options().enable_cxx_namespaces {
+            return path;
+        }
+        if ctx.options().disable_name_namespacing {
+            return vec![path.last().unwrap().clone()];
+        }
+        return vec![path[1..].join("_")];
+    }
+
+    fn canonical_path(&self, ctx: &BindgenContext) -> Vec<String> {
+        if let Some(path) = self.annotations().use_instead_of() {
+            let mut ret =
+                vec![ctx.resolve_item(ctx.root_module()).name(ctx).get()];
+            ret.extend_from_slice(path);
+            return ret;
+        }
+
+        let target = ctx.resolve_item(self.name_target(ctx));
+        let mut path: Vec<_> = target.ancestors(ctx)
+            .chain(iter::once(ctx.root_module()))
+            .map(|id| ctx.resolve_item(id))
+            .filter(|item| {
+                item.id() == target.id() ||
+                item.as_module().map_or(false, |module| {
+                    !module.is_inline() ||
+                        ctx.options().conservative_inline_namespaces
+                })
+            })
+            .map(|item| {
+                ctx.resolve_item(item.name_target(ctx))
+                    .name(ctx)
+                    .within_namespaces()
+                    .get()
+            })
+            .collect();
+        path.reverse();
+        path
+    }
+}
+
+/// Builder struct for naming variations, which hold inside different
+/// flags for naming options.
+#[derive(Debug)]
+pub struct NameOptions<'item, 'ctx>
+    where 'ctx: 'item,
+{
+    item: &'item Item,
+    ctx: &'item BindgenContext<'ctx>,
+    within_namespaces: bool,
+}
+
+impl<'item, 'ctx> NameOptions<'item, 'ctx> {
+    /// Construct a new `NameOptions`
+    pub fn new(item: &'item Item, ctx: &'item BindgenContext<'ctx>) -> Self {
+        NameOptions {
+            item: item,
+            ctx: ctx,
+            within_namespaces: false,
+        }
+    }
+
+    /// Construct the name without the item's containing C++ namespaces mangled
+    /// into it. In other words, the item's name within the item's namespace.
+    pub fn within_namespaces(&mut self) -> &mut Self {
+        self.within_namespaces = true;
+        self
+    }
+
+    /// Construct a name `String`
+    pub fn get(&self) -> String {
+        self.item.real_canonical_name(self.ctx, self)
+    }
+}
diff --git a/src/ir/item_kind.rs b/src/ir/item_kind.rs
new file mode 100644
index 00000000..d9e4690c
--- /dev/null
+++ b/src/ir/item_kind.rs
@@ -0,0 +1,114 @@
+//! Different variants of an `Item` in our intermediate representation.
+
+use super::function::Function;
+use super::module::Module;
+use super::ty::Type;
+use super::var::Var;
+
+/// A item we parse and translate.
+#[derive(Debug)]
+pub enum ItemKind {
+    /// A module, created implicitly once (the root module), or via C++
+    /// namespaces.
+    Module(Module),
+
+    /// A type declared in any of the multiple ways it can be declared.
+    Type(Type),
+
+    /// A function or method declaration.
+    Function(Function),
+
+    /// A variable declaration, most likely a static.
+    Var(Var),
+}
+
+impl ItemKind {
+    /// Get a reference to this `ItemKind`'s underying `Module`, or `None` if it
+    /// is some other kind.
+    pub fn as_module(&self) -> Option<&Module> {
+        match *self {
+            ItemKind::Module(ref module) => Some(module),
+            _ => None,
+        }
+    }
+
+    /// Is this a module?
+    pub fn is_module(&self) -> bool {
+        self.as_module().is_some()
+    }
+
+    /// Get a reference to this `ItemKind`'s underying `Module`, or panic if it
+    /// is some other kind.
+    pub fn expect_module(&self) -> &Module {
+        self.as_module().expect("Not a module")
+    }
+
+    /// Get a reference to this `ItemKind`'s underying `Function`, or `None` if
+    /// it is some other kind.
+    pub fn as_function(&self) -> Option<&Function> {
+        match *self {
+            ItemKind::Function(ref func) => Some(func),
+            _ => None,
+        }
+    }
+
+    /// Is this a function?
+    pub fn is_function(&self) -> bool {
+        self.as_function().is_some()
+    }
+
+    /// Get a reference to this `ItemKind`'s underying `Function`, or panic if
+    /// it is some other kind.
+    pub fn expect_function(&self) -> &Function {
+        self.as_function().expect("Not a function")
+    }
+
+    /// Get a reference to this `ItemKind`'s underying `Type`, or `None` if
+    /// it is some other kind.
+    pub fn as_type(&self) -> Option<&Type> {
+        match *self {
+            ItemKind::Type(ref ty) => Some(ty),
+            _ => None,
+        }
+    }
+
+    /// Get a mutable reference to this `ItemKind`'s underying `Type`, or `None`
+    /// if it is some other kind.
+    pub fn as_type_mut(&mut self) -> Option<&mut Type> {
+        match *self {
+            ItemKind::Type(ref mut ty) => Some(ty),
+            _ => None,
+        }
+    }
+
+    /// Is this a type?
+    pub fn is_type(&self) -> bool {
+        self.as_type().is_some()
+    }
+
+    /// Get a reference to this `ItemKind`'s underying `Type`, or panic if it is
+    /// some other kind.
+    pub fn expect_type(&self) -> &Type {
+        self.as_type().expect("Not a type")
+    }
+
+    /// Get a reference to this `ItemKind`'s underying `Var`, or `None` if it is
+    /// some other kind.
+    pub fn as_var(&self) -> Option<&Var> {
+        match *self {
+            ItemKind::Var(ref v) => Some(v),
+            _ => None,
+        }
+    }
+
+    /// Is this a variable?
+    pub fn is_var(&self) -> bool {
+        self.as_var().is_some()
+    }
+
+    /// Get a reference to this `ItemKind`'s underying `Var`, or panic if it is
+    /// some other kind.
+    pub fn expect_var(&self) -> &Var {
+        self.as_var().expect("Not a var")
+    }
+}
diff --git a/src/ir/layout.rs b/src/ir/layout.rs
new file mode 100644
index 00000000..033fff62
--- /dev/null
+++ b/src/ir/layout.rs
@@ -0,0 +1,91 @@
+//! Intermediate representation for the physical layout of some type.
+
+use std::cmp;
+use super::context::BindgenContext;
+use super::derive::{CanDeriveCopy, CanDeriveDebug};
+use super::ty::RUST_DERIVE_IN_ARRAY_LIMIT;
+
+/// A type that represents the struct layout of a type.
+#[derive(Debug, Clone, Copy)]
+pub struct Layout {
+    /// The size (in bytes) of this layout.
+    pub size: usize,
+    /// The alignment (in bytes) of this layout.
+    pub align: usize,
+    /// Whether this layout's members are packed or not.
+    pub packed: bool,
+}
+
+impl Layout {
+    /// Construct a new `Layout` with the given `size` and `align`. It is not
+    /// packed.
+    pub fn new(size: usize, align: usize) -> Self {
+        Layout {
+            size: size,
+            align: align,
+            packed: false,
+        }
+    }
+
+    /// Is this a zero-sized layout?
+    pub fn is_zero(&self) -> bool {
+        self.size == 0 && self.align == 0
+    }
+
+    /// Construct a zero-sized layout.
+    pub fn zero() -> Self {
+        Self::new(0, 0)
+    }
+
+    /// Get this layout as an opaque type.
+    pub fn opaque(&self) -> Opaque {
+        Opaque(*self)
+    }
+}
+
+/// When we are treating a type as opaque, it is just a blob with a `Layout`.
+pub struct Opaque(pub Layout);
+
+impl Opaque {
+    /// Return the known rust type we should use to create a correctly-aligned
+    /// field with this layout.
+    pub fn known_rust_type_for_array(&self) -> Option<&'static str> {
+        Some(match self.0.align {
+            8 => "u64",
+            4 => "u32",
+            2 => "u16",
+            1 => "u8",
+            _ => return None,
+        })
+    }
+
+    /// Return the array size that an opaque type for this layout should have if
+    /// we know the correct type for it, or `None` otherwise.
+    pub fn array_size(&self) -> Option<usize> {
+        if self.known_rust_type_for_array().is_some() {
+            Some(self.0.size / cmp::max(self.0.align, 1))
+        } else {
+            None
+        }
+    }
+}
+
+impl CanDeriveDebug for Opaque {
+    type Extra = ();
+
+    fn can_derive_debug(&self, _: &BindgenContext, _: ()) -> bool {
+        self.array_size().map_or(false, |size| size <= RUST_DERIVE_IN_ARRAY_LIMIT)
+    }
+}
+
+impl<'a> CanDeriveCopy<'a> for Opaque {
+    type Extra = ();
+
+    fn can_derive_copy(&self, _: &BindgenContext, _: ()) -> bool {
+        self.array_size().map_or(false, |size| size <= RUST_DERIVE_IN_ARRAY_LIMIT)
+    }
+
+    fn can_derive_copy_in_array(&self, ctx: &BindgenContext, _: ()) -> bool {
+        self.can_derive_copy(ctx, ())
+    }
+}
diff --git a/src/ir/mod.rs b/src/ir/mod.rs
new file mode 100644
index 00000000..73793b16
--- /dev/null
+++ b/src/ir/mod.rs
@@ -0,0 +1,19 @@
+//! The ir module defines bindgen's intermediate representation.
+//!
+//! Parsing C/C++ generates the IR, while code generation outputs Rust code from
+//! the IR.
+
+pub mod annotations;
+pub mod comp;
+pub mod context;
+pub mod derive;
+pub mod enum_ty;
+pub mod function;
+pub mod int;
+pub mod item;
+pub mod item_kind;
+pub mod layout;
+pub mod module;
+pub mod ty;
+pub mod type_collector;
+pub mod var;
diff --git a/src/ir/module.rs b/src/ir/module.rs
new file mode 100644
index 00000000..002fe36e
--- /dev/null
+++ b/src/ir/module.rs
@@ -0,0 +1,78 @@
+//! Intermediate representation for modules (AKA C++ namespaces).
+
+use clang;
+use parse::{ClangSubItemParser, ParseError, ParseResult};
+use parse_one;
+use super::context::{BindgenContext, ItemId};
+
+/// Whether this module is inline or not.
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+pub enum ModuleKind {
+    /// This module is not inline.
+    Normal,
+    /// This module is inline, as in `inline namespace foo {}`.
+    Inline,
+}
+
+/// A module, as in, a C++ namespace.
+#[derive(Clone, Debug)]
+pub struct Module {
+    /// The name of the module, or none if it's anonymous.
+    name: Option<String>,
+    /// The kind of module this is.
+    kind: ModuleKind,
+    /// The children of this module, just here for convenience.
+    children_ids: Vec<ItemId>,
+}
+
+impl Module {
+    /// Construct a new `Module`.
+    pub fn new(name: Option<String>, kind: ModuleKind) -> Self {
+        Module {
+            name: name,
+            kind: kind,
+            children_ids: vec![],
+        }
+    }
+
+    /// Get this module's name.
+    pub fn name(&self) -> Option<&str> {
+        self.name.as_ref().map(|n| &**n)
+    }
+
+    /// Get a mutable reference to this module's children.
+    pub fn children_mut(&mut self) -> &mut Vec<ItemId> {
+        &mut self.children_ids
+    }
+
+    /// Get this module's children.
+    pub fn children(&self) -> &[ItemId] {
+        &self.children_ids
+    }
+
+    /// Whether this namespace is inline.
+    pub fn is_inline(&self) -> bool {
+        self.kind == ModuleKind::Inline
+    }
+}
+
+impl ClangSubItemParser for Module {
+    fn parse(cursor: clang::Cursor,
+             ctx: &mut BindgenContext)
+             -> Result<ParseResult<Self>, ParseError> {
+        use clang_sys::*;
+        match cursor.kind() {
+            CXCursor_Namespace => {
+                let module_id = ctx.module(cursor);
+                ctx.with_module(module_id, |ctx| {
+                    cursor.visit(|cursor| {
+                        parse_one(ctx, cursor, Some(module_id))
+                    })
+                });
+
+                Ok(ParseResult::AlreadyResolved(module_id))
+            }
+            _ => Err(ParseError::Continue),
+        }
+    }
+}
diff --git a/src/ir/ty.rs b/src/ir/ty.rs
new file mode 100644
index 00000000..c1ed5b64
--- /dev/null
+++ b/src/ir/ty.rs
@@ -0,0 +1,926 @@
+//! Everything related to types in our intermediate representation.
+
+use clang::{self, Cursor};
+use parse::{ClangItemParser, ParseError, ParseResult};
+use super::comp::CompInfo;
+use super::context::{BindgenContext, ItemId};
+use super::derive::{CanDeriveCopy, CanDeriveDebug};
+use super::enum_ty::Enum;
+use super::function::FunctionSig;
+use super::int::IntKind;
+use super::item::Item;
+use super::layout::Layout;
+use super::type_collector::{ItemSet, TypeCollector};
+
+/// The base representation of a type in bindgen.
+///
+/// A type has an optional name, which if present cannot be empty, a `layout`
+/// (size, alignment and packedness) if known, a `Kind`, which determines which
+/// kind of type it is, and whether the type is const.
+#[derive(Debug)]
+pub struct Type {
+    /// The name of the type, or None if it was an unnamed struct or union.
+    name: Option<String>,
+    /// The layout of the type, if known.
+    layout: Option<Layout>,
+    /// The inner kind of the type
+    kind: TypeKind,
+    /// Whether this type is const-qualified.
+    is_const: bool,
+}
+
+/// The maximum number of items in an array for which Rust implements common
+/// traits, and so if we have a type containing an array with more than this
+/// many items, we won't be able to derive common traits on that type.
+///
+/// We need type-level integers yesterday :'(
+pub const RUST_DERIVE_IN_ARRAY_LIMIT: usize = 32;
+
+impl Type {
+    /// Get the underlying `CompInfo` for this type, or `None` if this is some
+    /// other kind of type.
+    pub fn as_comp(&self) -> Option<&CompInfo> {
+        match self.kind {
+            TypeKind::Comp(ref ci) => Some(ci),
+            _ => None,
+        }
+    }
+
+    /// Construct a new `Type`.
+    pub fn new(name: Option<String>,
+               layout: Option<Layout>,
+               kind: TypeKind,
+               is_const: bool)
+               -> Self {
+        Type {
+            name: name,
+            layout: layout,
+            kind: kind,
+            is_const: is_const,
+        }
+    }
+
+    /// Which kind of type is this?
+    pub fn kind(&self) -> &TypeKind {
+        &self.kind
+    }
+
+    /// Overrides the kind of the item. This is mostly a template alias
+    /// implementation detail, and debug assertions guard it like so.
+    pub fn set_kind(&mut self, kind: TypeKind) {
+        if cfg!(debug_assertions) {
+            match (&self.kind, &kind) {
+                (&TypeKind::Alias(ref alias_name, alias_inner),
+                 &TypeKind::TemplateAlias(ref name, inner, _)) => {
+                    assert_eq!(alias_name, name);
+                    assert_eq!(alias_inner, inner);
+                }
+                _ => panic!("Unexpected kind in `set_kind`!"),
+            };
+        }
+        self.kind = kind;
+    }
+
+    /// Get a mutable reference to this type's kind.
+    pub fn kind_mut(&mut self) -> &mut TypeKind {
+        &mut self.kind
+    }
+
+    /// Get this type's name.
+    pub fn name(&self) -> Option<&str> {
+        self.name.as_ref().map(|name| &**name)
+    }
+
+    /// Is this a compound type?
+    pub fn is_comp(&self) -> bool {
+        match self.kind {
+            TypeKind::Comp(..) => true,
+            _ => false,
+        }
+    }
+
+    /// Is this a named type?
+    pub fn is_named(&self) -> bool {
+        match self.kind {
+            TypeKind::Named(..) => true,
+            _ => false,
+        }
+    }
+
+    /// Is this a template alias type?
+    pub fn is_template_alias(&self) -> bool {
+        match self.kind {
+            TypeKind::TemplateAlias(..) => true,
+            _ => false,
+        }
+    }
+
+    /// Is this a function type?
+    pub fn is_function(&self) -> bool {
+        match self.kind {
+            TypeKind::Function(..) => true,
+            _ => false,
+        }
+    }
+
+    /// Is this an enum type?
+    pub fn is_enum(&self) -> bool {
+        match self.kind {
+            TypeKind::Enum(..) => true,
+            _ => false,
+        }
+    }
+
+    /// Is this either a builtin or named type?
+    pub fn is_builtin_or_named(&self) -> bool {
+        match self.kind {
+            TypeKind::Void |
+            TypeKind::NullPtr |
+            TypeKind::Function(..) |
+            TypeKind::Array(..) |
+            TypeKind::Reference(..) |
+            TypeKind::Pointer(..) |
+            TypeKind::BlockPointer |
+            TypeKind::Int(..) |
+            TypeKind::Float(..) |
+            TypeKind::Named(..) => true,
+            _ => false,
+        }
+    }
+
+    /// Creates a new named type, with name `name`.
+    pub fn named(name: String) -> Self {
+        assert!(!name.is_empty());
+        // TODO: stop duplicating the name, it's stupid.
+        let kind = TypeKind::Named(name.clone());
+        Self::new(Some(name), None, kind, false)
+    }
+
+    /// Is this a floating point type?
+    pub fn is_float(&self) -> bool {
+        match self.kind {
+            TypeKind::Float(..) => true,
+            _ => false,
+        }
+    }
+
+    /// Is this a boolean type?
+    pub fn is_bool(&self) -> bool {
+        match self.kind {
+            TypeKind::Int(IntKind::Bool) => true,
+            _ => false,
+        }
+    }
+
+    /// Is this an integer type?
+    pub fn is_integer(&self) -> bool {
+        match self.kind {
+            TypeKind::Int(..) => true,
+            _ => false,
+        }
+    }
+
+    /// Is this a `const` qualified type?
+    pub fn is_const(&self) -> bool {
+        self.is_const
+    }
+
+    /// Is this a reference to another type?
+    pub fn is_type_ref(&self) -> bool {
+        match self.kind {
+            TypeKind::ResolvedTypeRef(_) |
+            TypeKind::UnresolvedTypeRef(_, _, _) => true,
+            _ => false,
+        }
+    }
+
+    /// What is the layout of this type?
+    pub fn layout(&self, ctx: &BindgenContext) -> Option<Layout> {
+        use std::mem;
+
+        self.layout.or_else(|| {
+            match self.kind {
+                TypeKind::Comp(ref ci) => ci.layout(ctx),
+                // FIXME(emilio): This is a hack for anonymous union templates.
+                // Use the actual pointer size!
+                TypeKind::Pointer(..) |
+                TypeKind::BlockPointer => {
+                    Some(Layout::new(mem::size_of::<*mut ()>(),
+                                     mem::align_of::<*mut ()>()))
+                }
+                TypeKind::ResolvedTypeRef(inner) => {
+                    ctx.resolve_type(inner).layout(ctx)
+                }
+                _ => None,
+            }
+        })
+    }
+
+    /// Whether this type has a vtable.
+    pub fn has_vtable(&self, ctx: &BindgenContext) -> bool {
+        // FIXME: Can we do something about template parameters? Huh...
+        match self.kind {
+            TypeKind::TemplateRef(t, _) |
+            TypeKind::TemplateAlias(_, t, _) |
+            TypeKind::Alias(_, t) |
+            TypeKind::ResolvedTypeRef(t) => ctx.resolve_type(t).has_vtable(ctx),
+            TypeKind::Comp(ref info) => info.has_vtable(ctx),
+            _ => false,
+        }
+
+    }
+
+    /// Returns whether this type has a destructor.
+    pub fn has_destructor(&self, ctx: &BindgenContext) -> bool {
+        match self.kind {
+            TypeKind::TemplateRef(t, _) |
+            TypeKind::TemplateAlias(_, t, _) |
+            TypeKind::Alias(_, t) |
+            TypeKind::ResolvedTypeRef(t) => {
+                ctx.resolve_type(t).has_destructor(ctx)
+            }
+            TypeKind::Comp(ref info) => info.has_destructor(ctx),
+            _ => false,
+        }
+    }
+
+    /// See the comment in `Item::signature_contains_named_type`.
+    pub fn signature_contains_named_type(&self,
+                                         ctx: &BindgenContext,
+                                         ty: &Type)
+                                         -> bool {
+        let name = match *ty.kind() {
+            TypeKind::Named(ref name) => name,
+            ref other @ _ => unreachable!("Not a named type: {:?}", other),
+        };
+
+        match self.kind {
+            TypeKind::Named(ref this_name) => this_name == name,
+            TypeKind::ResolvedTypeRef(t) |
+            TypeKind::Array(t, _) |
+            TypeKind::Pointer(t) |
+            TypeKind::Alias(_, t) => {
+                ctx.resolve_type(t)
+                    .signature_contains_named_type(ctx, ty)
+            }
+            TypeKind::Function(ref sig) => {
+                sig.argument_types().iter().any(|&(_, arg)| {
+                    ctx.resolve_type(arg)
+                        .signature_contains_named_type(ctx, ty)
+                }) ||
+                ctx.resolve_type(sig.return_type())
+                    .signature_contains_named_type(ctx, ty)
+            }
+            TypeKind::TemplateAlias(_, _, ref template_args) |
+            TypeKind::TemplateRef(_, ref template_args) => {
+                template_args.iter().any(|arg| {
+                    ctx.resolve_type(*arg)
+                        .signature_contains_named_type(ctx, ty)
+                })
+            }
+            TypeKind::Comp(ref ci) => ci.signature_contains_named_type(ctx, ty),
+            _ => false,
+        }
+    }
+
+    /// See safe_canonical_type.
+    pub fn canonical_type<'tr>(&'tr self,
+                               ctx: &'tr BindgenContext)
+                               -> &'tr Type {
+        self.safe_canonical_type(ctx)
+            .expect("Should have been resolved after parsing!")
+    }
+
+    /// Returns the canonical type of this type, that is, the "inner type".
+    ///
+    /// For example, for a `typedef`, the canonical type would be the
+    /// `typedef`ed type, for a template specialization, would be the template
+    /// its specializing, and so on. Return None if the type is unresolved.
+    pub fn safe_canonical_type<'tr>(&'tr self,
+                                    ctx: &'tr BindgenContext)
+                                    -> Option<&'tr Type> {
+        match self.kind {
+            TypeKind::Named(..) |
+            TypeKind::Array(..) |
+            TypeKind::Comp(..) |
+            TypeKind::Int(..) |
+            TypeKind::Float(..) |
+            TypeKind::Complex(..) |
+            TypeKind::Function(..) |
+            TypeKind::Enum(..) |
+            TypeKind::Reference(..) |
+            TypeKind::Void |
+            TypeKind::NullPtr |
+            TypeKind::BlockPointer |
+            TypeKind::Pointer(..) => Some(self),
+
+            TypeKind::ResolvedTypeRef(inner) |
+            TypeKind::Alias(_, inner) |
+            TypeKind::TemplateAlias(_, inner, _) |
+            TypeKind::TemplateRef(inner, _) => {
+                ctx.resolve_type(inner).safe_canonical_type(ctx)
+            }
+
+            TypeKind::UnresolvedTypeRef(..) => None,
+        }
+    }
+
+    /// There are some types we don't want to stop at when finding an opaque
+    /// item, so we can arrive to the proper item that needs to be generated.
+    pub fn should_be_traced_unconditionally(&self) -> bool {
+        match self.kind {
+            TypeKind::Function(..) |
+            TypeKind::Pointer(..) |
+            TypeKind::Array(..) |
+            TypeKind::Reference(..) |
+            TypeKind::TemplateRef(..) |
+            TypeKind::ResolvedTypeRef(..) => true,
+            _ => false,
+        }
+    }
+}
+
+impl CanDeriveDebug for Type {
+    type Extra = ();
+
+    fn can_derive_debug(&self, ctx: &BindgenContext, _: ()) -> bool {
+        match self.kind {
+            TypeKind::Array(t, len) => {
+                len <= RUST_DERIVE_IN_ARRAY_LIMIT && t.can_derive_debug(ctx, ())
+            }
+            TypeKind::ResolvedTypeRef(t) |
+            TypeKind::TemplateAlias(_, t, _) |
+            TypeKind::Alias(_, t) => t.can_derive_debug(ctx, ()),
+            TypeKind::Comp(ref info) => {
+                info.can_derive_debug(ctx, self.layout(ctx))
+            }
+            _ => true,
+        }
+    }
+}
+
+impl<'a> CanDeriveCopy<'a> for Type {
+    type Extra = &'a Item;
+
+    fn can_derive_copy(&self, ctx: &BindgenContext, item: &Item) -> bool {
+        match self.kind {
+            TypeKind::Array(t, len) => {
+                len <= RUST_DERIVE_IN_ARRAY_LIMIT &&
+                t.can_derive_copy_in_array(ctx, ())
+            }
+            TypeKind::ResolvedTypeRef(t) |
+            TypeKind::TemplateAlias(_, t, _) |
+            TypeKind::TemplateRef(t, _) |
+            TypeKind::Alias(_, t) => t.can_derive_copy(ctx, ()),
+            TypeKind::Comp(ref info) => {
+                info.can_derive_copy(ctx, (item, self.layout(ctx)))
+            }
+            _ => true,
+        }
+    }
+
+    fn can_derive_copy_in_array(&self,
+                                ctx: &BindgenContext,
+                                item: &Item)
+                                -> bool {
+        match self.kind {
+            TypeKind::ResolvedTypeRef(t) |
+            TypeKind::TemplateAlias(_, t, _) |
+            TypeKind::Alias(_, t) |
+            TypeKind::Array(t, _) => t.can_derive_copy_in_array(ctx, ()),
+            TypeKind::Named(..) => false,
+            _ => self.can_derive_copy(ctx, item),
+        }
+    }
+}
+
+/// The kind of float this type represents.
+#[derive(Debug, Copy, Clone, PartialEq)]
+pub enum FloatKind {
+    /// A `float`.
+    Float,
+    /// A `double`.
+    Double,
+    /// A `long double`.
+    LongDouble,
+    /// A `__float128`.
+    Float128,
+}
+
+/// The different kinds of types that we can parse.
+#[derive(Debug)]
+pub enum TypeKind {
+    /// The void type.
+    Void,
+
+    /// The `nullptr_t` type.
+    NullPtr,
+
+    /// A compound type, that is, a class, struct, or union.
+    Comp(CompInfo),
+
+    /// An integer type, of a given kind. `bool` and `char` are also considered
+    /// integers.
+    Int(IntKind),
+
+    /// A floating point type.
+    Float(FloatKind),
+
+    /// A complex floating point type.
+    Complex(FloatKind),
+
+    /// A type alias, with a name, that points to another type.
+    Alias(String, ItemId),
+
+    /// A templated alias, pointing to an inner type, just as `Alias`, but with
+    /// template parameters.
+    TemplateAlias(String, ItemId, Vec<ItemId>),
+
+    /// An array of a type and a lenght.
+    Array(ItemId, usize),
+
+    /// A function type, with a given signature.
+    Function(FunctionSig),
+
+    /// An `enum` type.
+    Enum(Enum),
+
+    /// A pointer to a type. The bool field represents whether it's const or
+    /// not.
+    Pointer(ItemId),
+
+    /// A pointer to an Apple block.
+    BlockPointer,
+
+    /// A reference to a type, as in: int& foo().
+    Reference(ItemId),
+
+    /// A reference to a template, with different template parameter names. To
+    /// see why this is needed, check out the creation of this variant in
+    /// `Type::from_clang_ty`.
+    TemplateRef(ItemId, Vec<ItemId>),
+
+    /// A reference to a yet-to-resolve type. This stores the clang cursor
+    /// itself, and postpones its resolution.
+    ///
+    /// These are gone in a phase after parsing where these are mapped to
+    /// already known types, and are converted to ResolvedTypeRef.
+    ///
+    /// see tests/headers/typeref.hpp to see somewhere where this is a problem.
+    UnresolvedTypeRef(clang::Type,
+                      Option<clang::Cursor>,
+                      /* parent_id */
+                      Option<ItemId>),
+
+    /// An indirection to another type.
+    ///
+    /// These are generated after we resolve a forward declaration, or when we
+    /// replace one type with another.
+    ResolvedTypeRef(ItemId),
+
+    /// A named type, that is, a template parameter.
+    Named(String),
+}
+
+impl Type {
+    /// Whether this type is unsized, that is, has no members. This is used to
+    /// derive whether we should generate a dummy `_address` field for structs,
+    /// to comply to the C and C++ layouts, that specify that every type needs
+    /// to be addressable.
+    pub fn is_unsized(&self, ctx: &BindgenContext) -> bool {
+        debug_assert!(ctx.in_codegen_phase(), "Not yet");
+
+        match self.kind {
+            TypeKind::Void => true,
+            TypeKind::Comp(ref ci) => ci.is_unsized(ctx),
+            TypeKind::Array(inner, size) => {
+                size == 0 || ctx.resolve_type(inner).is_unsized(ctx)
+            }
+            TypeKind::ResolvedTypeRef(inner) |
+            TypeKind::Alias(_, inner) |
+            TypeKind::TemplateAlias(_, inner, _) |
+            TypeKind::TemplateRef(inner, _) => {
+                ctx.resolve_type(inner).is_unsized(ctx)
+            }
+            TypeKind::Named(..) |
+            TypeKind::Int(..) |
+            TypeKind::Float(..) |
+            TypeKind::Complex(..) |
+            TypeKind::Function(..) |
+            TypeKind::Enum(..) |
+            TypeKind::Reference(..) |
+            TypeKind::NullPtr |
+            TypeKind::BlockPointer |
+            TypeKind::Pointer(..) => false,
+
+            TypeKind::UnresolvedTypeRef(..) => {
+                unreachable!("Should have been resolved after parsing!");
+            }
+        }
+    }
+
+    /// This is another of the nasty methods. This one is the one that takes
+    /// care of the core logic of converting a clang type to a `Type`.
+    ///
+    /// It's sort of nasty and full of special-casing, but hopefully the
+    /// comments in every special case justify why they're there.
+    pub fn from_clang_ty(potential_id: ItemId,
+                         ty: &clang::Type,
+                         location: Option<Cursor>,
+                         parent_id: Option<ItemId>,
+                         ctx: &mut BindgenContext)
+                         -> Result<ParseResult<Self>, ParseError> {
+        use clang_sys::*;
+        {
+            let already_resolved =
+                ctx.builtin_or_resolved_ty(potential_id,
+                                           parent_id,
+                                           ty,
+                                           location);
+            if let Some(ty) = already_resolved {
+                debug!("{:?} already resolved: {:?}", ty, location);
+                return Ok(ParseResult::AlreadyResolved(ty));
+            }
+        }
+
+        let layout = ty.fallible_layout().ok();
+        let cursor = ty.declaration();
+        let mut name = cursor.spelling();
+
+        debug!("from_clang_ty: {:?}, ty: {:?}, loc: {:?}",
+               potential_id,
+               ty,
+               location);
+        debug!("currently_parsed_types: {:?}", ctx.currently_parsed_types);
+
+        let canonical_ty = ty.canonical_type();
+        let kind = match ty.kind() {
+            CXType_Unexposed if *ty != canonical_ty &&
+                                canonical_ty.kind() != CXType_Invalid => {
+                debug!("Looking for canonical type: {:?}", canonical_ty);
+                return Self::from_clang_ty(potential_id,
+                                           &canonical_ty,
+                                           location,
+                                           parent_id,
+                                           ctx);
+            }
+            CXType_Unexposed | CXType_Invalid => {
+                // For some reason Clang doesn't give us any hint in some
+                // situations where we should generate a function pointer (see
+                // tests/headers/func_ptr_in_struct.h), so we do a guess here
+                // trying to see if it has a valid return type.
+                if ty.ret_type().is_some() {
+                    let signature = try!(FunctionSig::from_ty(ty,
+                                                  &location.unwrap_or(cursor),
+                                                  ctx));
+                    TypeKind::Function(signature)
+                    // Same here, with template specialisations we can safely
+                    // assume this is a Comp(..)
+                } else if ty.is_fully_specialized_template() {
+                    debug!("Template specialization: {:?}", ty);
+                    let complex =
+                        CompInfo::from_ty(potential_id, ty, location, ctx)
+                            .expect("C'mon");
+                    TypeKind::Comp(complex)
+                } else if let Some(location) = location {
+                    match location.kind() {
+                        CXCursor_ClassTemplatePartialSpecialization |
+                        CXCursor_CXXBaseSpecifier |
+                        CXCursor_ClassTemplate => {
+                            if location.kind() == CXCursor_CXXBaseSpecifier {
+                                // In the case we're parsing a base specifier
+                                // inside an unexposed or invalid type, it means
+                                // that we're parsing one of two things:
+                                //
+                                //  * A template parameter.
+                                //  * A complex class that isn't exposed.
+                                //
+                                // This means, unfortunately, that there's no
+                                // good way to differentiate between them.
+                                //
+                                // Probably we could try to look at the
+                                // declaration and complicate more this logic,
+                                // but we'll keep it simple... if it's a valid
+                                // C++ identifier, we'll consider it as a
+                                // template parameter.
+                                //
+                                // This is because:
+                                //
+                                //  * We expect every other base that is a
+                                //    proper identifier (that is, a simple
+                                //    struct/union declaration), to be exposed,
+                                //    so this path can't be reached in that
+                                //    case.
+                                //
+                                //  * Quite conveniently, complex base
+                                //    specifiers preserve their full names (that
+                                //    is: Foo<T> instead of Foo). We can take
+                                //    advantage of this.
+                                //
+                                // If we find some edge case where this doesn't
+                                // work (which I guess is unlikely, see the
+                                // different test cases[1][2][3][4]), we'd need
+                                // to find more creative ways of differentiating
+                                // these two cases.
+                                //
+                                // [1]: inherit_named.hpp
+                                // [2]: forward-inherit-struct-with-fields.hpp
+                                // [3]: forward-inherit-struct.hpp
+                                // [4]: inherit-namespaced.hpp
+                                if location.spelling()
+                                    .chars()
+                                    .all(|c| c.is_alphanumeric() || c == '_') {
+                                    return Err(ParseError::Recurse);
+                                }
+                            } else {
+                                name = location.spelling();
+                            }
+                            let complex = CompInfo::from_ty(potential_id,
+                                                            ty,
+                                                            Some(location),
+                                                            ctx)
+                                .expect("C'mon");
+                            TypeKind::Comp(complex)
+                        }
+                        CXCursor_TypeAliasTemplateDecl => {
+                            debug!("TypeAliasTemplateDecl");
+
+                            // We need to manually unwind this one.
+                            let mut inner = Err(ParseError::Continue);
+                            let mut args = vec![];
+
+                            location.visit(|cur| {
+                                match cur.kind() {
+                                    CXCursor_TypeAliasDecl => {
+                                        let current = cur.cur_type();
+
+                                        debug_assert!(current.kind() ==
+                                                      CXType_Typedef);
+
+                                        name = current.spelling();
+
+                                        let inner_ty = cur.typedef_type()
+                                            .expect("Not valid Type?");
+                                        inner =
+                                            Item::from_ty(&inner_ty,
+                                                          Some(cur),
+                                                          Some(potential_id),
+                                                          ctx);
+                                    }
+                                    CXCursor_TemplateTypeParameter => {
+                                        // See the comment in src/ir/comp.rs
+                                        // about the same situation.
+                                        if cur.spelling().is_empty() {
+                                            return CXChildVisit_Continue;
+                                        }
+
+                                        let param =
+                                            Item::named_type(cur.spelling(),
+                                                             potential_id,
+                                                             ctx);
+                                        args.push(param);
+                                    }
+                                    _ => {}
+                                }
+                                CXChildVisit_Continue
+                            });
+
+                            let inner_type = match inner {
+                                Ok(inner) => inner,
+                                Err(..) => {
+                                    error!("Failed to parse template alias \
+                                           {:?}",
+                                           location);
+                                    return Err(ParseError::Continue);
+                                }
+                            };
+
+                            TypeKind::TemplateAlias(name.clone(),
+                                                    inner_type,
+                                                    args)
+                        }
+                        CXCursor_TemplateRef => {
+                            let referenced = location.referenced().unwrap();
+                            let referenced_ty = referenced.cur_type();
+
+                            debug!("TemplateRef: location = {:?}; referenced = \
+                                    {:?}; referenced_ty = {:?}",
+                                   location,
+                                   referenced,
+                                   referenced_ty);
+
+                            return Self::from_clang_ty(potential_id,
+                                                       &referenced_ty,
+                                                       Some(referenced),
+                                                       parent_id,
+                                                       ctx);
+                        }
+                        CXCursor_TypeRef => {
+                            let referenced = location.referenced().unwrap();
+                            let referenced_ty = referenced.cur_type();
+                            let declaration = referenced_ty.declaration();
+
+                            debug!("TypeRef: location = {:?}; referenced = \
+                                    {:?}; referenced_ty = {:?}",
+                                   location,
+                                   referenced,
+                                   referenced_ty);
+
+                            let item =
+                                Item::from_ty_or_ref_with_id(potential_id,
+                                                             referenced_ty,
+                                                             Some(declaration),
+                                                             parent_id,
+                                                             ctx);
+                            return Ok(ParseResult::AlreadyResolved(item));
+                        }
+                        CXCursor_NamespaceRef => {
+                            return Err(ParseError::Continue);
+                        }
+                        _ => {
+                            if ty.kind() == CXType_Unexposed {
+                                warn!("Unexposed type {:?}, recursing inside, \
+                                      loc: {:?}",
+                                      ty,
+                                      location);
+                                return Err(ParseError::Recurse);
+                            }
+
+                            // If the type name is empty we're probably
+                            // over-recursing to find a template parameter name
+                            // or something like that, so just don't be too
+                            // noisy with it since it causes confusion, see for
+                            // example the discussion in:
+                            //
+                            // https://github.com/jamesmunns/teensy3-rs/issues/9
+                            if !ty.spelling().is_empty() {
+                                warn!("invalid type {:?}", ty);
+                            } else {
+                                warn!("invalid type {:?}", ty);
+                            }
+                            return Err(ParseError::Continue);
+                        }
+                    }
+                } else {
+                    // TODO: Don't duplicate this!
+                    if ty.kind() == CXType_Unexposed {
+                        warn!("Unexposed type {:?}, recursing inside", ty);
+                        return Err(ParseError::Recurse);
+                    }
+
+                    if !ty.spelling().is_empty() {
+                        warn!("invalid type {:?}", ty);
+                    } else {
+                        warn!("invalid type {:?}", ty);
+                    }
+                    return Err(ParseError::Continue);
+                }
+            }
+            CXType_Auto => {
+                if canonical_ty == *ty {
+                    debug!("Couldn't find deduced type: {:?}", ty);
+                    return Err(ParseError::Continue);
+                }
+
+                return Self::from_clang_ty(potential_id,
+                                           &canonical_ty,
+                                           location,
+                                           parent_id,
+                                           ctx);
+            }
+            // NOTE: We don't resolve pointers eagerly because the pointee type
+            // might not have been parsed, and if it contains templates or
+            // something else we might get confused, see the comment inside
+            // TypeRef.
+            //
+            // We might need to, though, if the context is already in the
+            // process of resolving them.
+            CXType_MemberPointer |
+            CXType_Pointer => {
+                let inner = Item::from_ty_or_ref(ty.pointee_type().unwrap(),
+                                                 location,
+                                                 parent_id,
+                                                 ctx);
+                TypeKind::Pointer(inner)
+            }
+            CXType_BlockPointer => TypeKind::BlockPointer,
+            // XXX: RValueReference is most likely wrong, but I don't think we
+            // can even add bindings for that, so huh.
+            CXType_RValueReference |
+            CXType_LValueReference => {
+                let inner = Item::from_ty_or_ref(ty.pointee_type().unwrap(),
+                                                 location,
+                                                 parent_id,
+                                                 ctx);
+                TypeKind::Reference(inner)
+            }
+            // XXX DependentSizedArray is wrong
+            CXType_VariableArray |
+            CXType_DependentSizedArray |
+            CXType_IncompleteArray => {
+                let inner = Item::from_ty(ty.elem_type().as_ref().unwrap(),
+                                          location,
+                                          parent_id,
+                                          ctx)
+                    .expect("Not able to resolve array element?");
+                TypeKind::Pointer(inner)
+            }
+            CXType_FunctionNoProto |
+            CXType_FunctionProto => {
+                let signature = try!(FunctionSig::from_ty(ty,
+                                              &location.unwrap_or(cursor),
+                                              ctx));
+                TypeKind::Function(signature)
+            }
+            CXType_Typedef => {
+                let inner = cursor.typedef_type().expect("Not valid Type?");
+                let inner =
+                    Item::from_ty_or_ref(inner, location, parent_id, ctx);
+                TypeKind::Alias(ty.spelling(), inner)
+            }
+            CXType_Enum => {
+                let enum_ = Enum::from_ty(ty, ctx).expect("Not an enum?");
+                TypeKind::Enum(enum_)
+            }
+            CXType_Record => {
+                let complex =
+                    CompInfo::from_ty(potential_id, ty, location, ctx)
+                        .expect("Not a complex type?");
+                TypeKind::Comp(complex)
+            }
+            // FIXME: We stub vectors as arrays since in 99% of the cases the
+            // layout is going to be correct, and there's no way we can generate
+            // vector types properly in Rust for now.
+            //
+            // That being said, that should be fixed eventually.
+            CXType_Vector |
+            CXType_ConstantArray => {
+                let inner = Item::from_ty(ty.elem_type().as_ref().unwrap(),
+                                          location,
+                                          parent_id,
+                                          ctx)
+                    .expect("Not able to resolve array element?");
+                TypeKind::Array(inner, ty.num_elements().unwrap())
+            }
+            CXType_Elaborated => {
+                return Self::from_clang_ty(potential_id,
+                                           &ty.named(),
+                                           location,
+                                           parent_id,
+                                           ctx);
+            }
+            _ => {
+                error!("unsupported type: kind = {:?}; ty = {:?}; at {:?}",
+                       ty.kind(),
+                       ty,
+                       location);
+                return Err(ParseError::Continue);
+            }
+        };
+
+        let name = if name.is_empty() { None } else { Some(name) };
+        let is_const = ty.is_const();
+
+        let ty = Type::new(name, layout, kind, is_const);
+        // TODO: maybe declaration.canonical()?
+        Ok(ParseResult::New(ty, Some(cursor.canonical())))
+    }
+}
+
+impl TypeCollector for Type {
+    type Extra = Item;
+
+    fn collect_types(&self,
+                     context: &BindgenContext,
+                     types: &mut ItemSet,
+                     item: &Item) {
+        match *self.kind() {
+            TypeKind::Pointer(inner) |
+            TypeKind::Reference(inner) |
+            TypeKind::Array(inner, _) |
+            TypeKind::Alias(_, inner) |
+            TypeKind::ResolvedTypeRef(inner) => {
+                types.insert(inner);
+            }
+
+            TypeKind::TemplateAlias(_, inner, ref template_args) |
+            TypeKind::TemplateRef(inner, ref template_args) => {
+                types.insert(inner);
+                for &item in template_args {
+                    types.insert(item);
+                }
+            }
+            TypeKind::Comp(ref ci) => ci.collect_types(context, types, item),
+            TypeKind::Function(ref sig) => {
+                sig.collect_types(context, types, item)
+            }
+            TypeKind::Named(_) => {}
+            // FIXME: Pending types!
+            ref other @ _ => {
+                debug!("<Type as TypeCollector>::collect_types: Ignoring: \
+                       {:?}",
+                       other);
+            }
+        }
+    }
+}
diff --git a/src/ir/type_collector.rs b/src/ir/type_collector.rs
new file mode 100644
index 00000000..0f10152d
--- /dev/null
+++ b/src/ir/type_collector.rs
@@ -0,0 +1,22 @@
+//! Collecting type items.
+
+use std::collections::BTreeSet;
+use super::context::{BindgenContext, ItemId};
+
+/// A set of items.
+pub type ItemSet = BTreeSet<ItemId>;
+
+/// Collect all the type items referenced by this item.
+pub trait TypeCollector {
+    /// If a particular type needs extra information beyond what it has in
+    /// `self` and `context` to find its referenced type items, its
+    /// implementation can define this associated type, forcing callers to pass
+    /// the needed information through.
+    type Extra;
+
+    /// Add each type item referenced by `self` into the `types` set.
+    fn collect_types(&self,
+                     context: &BindgenContext,
+                     types: &mut ItemSet,
+                     extra: &Self::Extra);
+}
diff --git a/src/ir/var.rs b/src/ir/var.rs
new file mode 100644
index 00000000..329393fa
--- /dev/null
+++ b/src/ir/var.rs
@@ -0,0 +1,317 @@
+//! Intermediate representation of variables.
+
+use cexpr;
+use clang;
+use parse::{ClangItemParser, ClangSubItemParser, ParseError, ParseResult};
+use std::num::Wrapping;
+use super::context::{BindgenContext, ItemId};
+use super::function::cursor_mangling;
+use super::int::IntKind;
+use super::item::Item;
+use super::ty::{FloatKind, TypeKind};
+
+/// The type for a constant variable.
+#[derive(Debug)]
+pub enum VarType {
+    /// A boolean.
+    Bool(bool),
+    /// An integer.
+    Int(i64),
+    /// A floating point number.
+    Float(f64),
+    /// A character.
+    Char(u8),
+    /// A string, not necessarily well-formed utf-8.
+    String(Vec<u8>),
+}
+
+/// A `Var` is our intermediate representation of a variable.
+#[derive(Debug)]
+pub struct Var {
+    /// The name of the variable.
+    name: String,
+    /// The mangled name of the variable.
+    mangled_name: Option<String>,
+    /// The type of the variable.
+    ty: ItemId,
+    /// The value of the variable, that needs to be suitable for `ty`.
+    val: Option<VarType>,
+    /// Whether this variable is const.
+    is_const: bool,
+}
+
+impl Var {
+    /// Construct a new `Var`.
+    pub fn new(name: String,
+               mangled: Option<String>,
+               ty: ItemId,
+               val: Option<VarType>,
+               is_const: bool)
+               -> Var {
+        assert!(!name.is_empty());
+        Var {
+            name: name,
+            mangled_name: mangled,
+            ty: ty,
+            val: val,
+            is_const: is_const,
+        }
+    }
+
+    /// Is this variable `const` qualified?
+    pub fn is_const(&self) -> bool {
+        self.is_const
+    }
+
+    /// The value of this constant variable, if any.
+    pub fn val(&self) -> Option<&VarType> {
+        self.val.as_ref()
+    }
+
+    /// Get this variable's type.
+    pub fn ty(&self) -> ItemId {
+        self.ty
+    }
+
+    /// Get this variable's name.
+    pub fn name(&self) -> &str {
+        &self.name
+    }
+
+    /// Get this variable's mangled name.
+    pub fn mangled_name(&self) -> Option<&str> {
+        self.mangled_name.as_ref().map(|n| &**n)
+    }
+}
+
+impl ClangSubItemParser for Var {
+    fn parse(cursor: clang::Cursor,
+             ctx: &mut BindgenContext)
+             -> Result<ParseResult<Self>, ParseError> {
+        use clang_sys::*;
+        use cexpr::expr::EvalResult;
+        use cexpr::literal::CChar;
+        match cursor.kind() {
+            CXCursor_MacroDefinition => {
+                let value = parse_macro(ctx, &cursor, ctx.translation_unit());
+
+                let (id, value) = match value {
+                    Some(v) => v,
+                    None => return Err(ParseError::Continue),
+                };
+
+                assert!(!id.is_empty(), "Empty macro name?");
+
+                let previously_defined = ctx.parsed_macro(&id);
+
+                // NB: It's important to "note" the macro even if the result is
+                // not an integer, otherwise we might loose other kind of
+                // derived macros.
+                ctx.note_parsed_macro(id.clone(), value.clone());
+
+                if previously_defined {
+                    let name = String::from_utf8(id).unwrap();
+                    warn!("Duplicated macro definition: {}", name);
+                    return Err(ParseError::Continue);
+                }
+
+                // NOTE: Unwrapping, here and above, is safe, because the
+                // identifier of a token comes straight from clang, and we
+                // enforce utf8 there, so we should have already panicked at
+                // this point.
+                let name = String::from_utf8(id).unwrap();
+                let (type_kind, val) = match value {
+                    EvalResult::Invalid => return Err(ParseError::Continue),
+                    EvalResult::Float(f) => {
+                        (TypeKind::Float(FloatKind::Float), VarType::Float(f))
+                    }
+                    EvalResult::Char(c) => {
+                        let c = match c {
+                            CChar::Char(c) => {
+                                assert_eq!(c.len_utf8(), 1);
+                                c as u8
+                            }
+                            CChar::Raw(c) => {
+                                assert!(c <= ::std::u8::MAX as u64);
+                                c as u8
+                            }
+                        };
+
+                        (TypeKind::Int(IntKind::U8), VarType::Char(c))
+                    }
+                    EvalResult::Str(val) => {
+                        let char_ty =
+                            Item::builtin_type(TypeKind::Int(IntKind::U8),
+                                               true,
+                                               ctx);
+                        (TypeKind::Pointer(char_ty), VarType::String(val))
+                    }
+                    EvalResult::Int(Wrapping(value)) => {
+                        let kind = ctx.type_chooser()
+                            .and_then(|c| c.int_macro(&name, value))
+                            .unwrap_or_else(|| {
+                                if value < 0 {
+                                    if value < i32::min_value() as i64 {
+                                        IntKind::LongLong
+                                    } else {
+                                        IntKind::Int
+                                    }
+                                } else if value > u32::max_value() as i64 {
+                                    IntKind::ULongLong
+                                } else {
+                                    IntKind::UInt
+                                }
+                            });
+
+                        (TypeKind::Int(kind), VarType::Int(value))
+                    }
+                };
+
+                let ty = Item::builtin_type(type_kind, true, ctx);
+
+                Ok(ParseResult::New(Var::new(name, None, ty, Some(val), true),
+                                    Some(cursor)))
+            }
+            CXCursor_VarDecl => {
+                let name = cursor.spelling();
+                if name.is_empty() {
+                    warn!("Empty constant name?");
+                    return Err(ParseError::Continue);
+                }
+
+                let ty = cursor.cur_type();
+
+                // XXX this is redundant, remove!
+                let is_const = ty.is_const();
+
+                let ty = match Item::from_ty(&ty, Some(cursor), None, ctx) {
+                    Ok(ty) => ty,
+                    Err(e) => {
+                        assert_eq!(ty.kind(), CXType_Auto,
+                                   "Couldn't resolve constant type, and it \
+                                   wasn't an nondeductible auto type!");
+                        return Err(e);
+                    }
+                };
+
+                // Note: Ty might not be totally resolved yet, see
+                // tests/headers/inner_const.hpp
+                //
+                // That's fine because in that case we know it's not a literal.
+                let canonical_ty = ctx.safe_resolve_type(ty)
+                    .and_then(|t| t.safe_canonical_type(ctx));
+
+                let is_integer = canonical_ty.map_or(false, |t| t.is_integer());
+                let is_float = canonical_ty.map_or(false, |t| t.is_float());
+
+                // TODO: We could handle `char` more gracefully.
+                // TODO: Strings, though the lookup is a bit more hard (we need
+                // to look at the canonical type of the pointee too, and check
+                // is char, u8, or i8 I guess).
+                let value = if is_integer {
+                    let kind = match *canonical_ty.unwrap().kind() {
+                        TypeKind::Int(kind) => kind,
+                        _ => unreachable!(),
+                    };
+
+                    let mut val = cursor.evaluate()
+                        .and_then(|v| v.as_int())
+                        .map(|val| val as i64);
+                    if val.is_none() || !kind.signedness_matches(val.unwrap()) {
+                        let tu = ctx.translation_unit();
+                        val = get_integer_literal_from_cursor(&cursor, tu);
+                    }
+
+                    val.map(|val| {
+                        if kind == IntKind::Bool {
+                            VarType::Bool(val != 0)
+                        } else {
+                            VarType::Int(val)
+                        }
+                    })
+                } else if is_float {
+                    cursor.evaluate()
+                        .and_then(|v| v.as_double())
+                        .map(VarType::Float)
+                } else {
+                    cursor.evaluate()
+                        .and_then(|v| v.as_literal_string())
+                        .map(VarType::String)
+                };
+
+                let mangling = cursor_mangling(&cursor);
+                let var = Var::new(name, mangling, ty, value, is_const);
+
+                Ok(ParseResult::New(var, Some(cursor)))
+            }
+            _ => {
+                /* TODO */
+                Err(ParseError::Continue)
+            }
+        }
+    }
+}
+
+/// Try and parse a macro using all the macros parsed until now.
+fn parse_macro(ctx: &BindgenContext,
+               cursor: &clang::Cursor,
+               unit: &clang::TranslationUnit)
+               -> Option<(Vec<u8>, cexpr::expr::EvalResult)> {
+    use cexpr::{expr, nom};
+
+    let cexpr_tokens = match unit.cexpr_tokens(cursor) {
+        None => return None,
+        Some(tokens) => tokens,
+    };
+
+    let parser = expr::IdentifierParser::new(ctx.parsed_macros());
+    let result = parser.macro_definition(&cexpr_tokens);
+
+    match result {
+        nom::IResult::Done(_, (id, val)) => Some((id.into(), val)),
+        _ => None,
+    }
+}
+
+fn parse_int_literal_tokens(cursor: &clang::Cursor,
+                            unit: &clang::TranslationUnit)
+                            -> Option<i64> {
+    use cexpr::{expr, nom};
+    use cexpr::expr::EvalResult;
+
+    let cexpr_tokens = match unit.cexpr_tokens(cursor) {
+        None => return None,
+        Some(tokens) => tokens,
+    };
+
+    // TODO(emilio): We can try to parse other kinds of literals.
+    match expr::expr(&cexpr_tokens) {
+        nom::IResult::Done(_, EvalResult::Int(Wrapping(val))) => Some(val),
+        _ => None,
+    }
+}
+
+fn get_integer_literal_from_cursor(cursor: &clang::Cursor,
+                                   unit: &clang::TranslationUnit)
+                                   -> Option<i64> {
+    use clang_sys::*;
+    let mut value = None;
+    cursor.visit(|c| {
+        match c.kind() {
+            CXCursor_IntegerLiteral |
+            CXCursor_UnaryOperator => {
+                value = parse_int_literal_tokens(&c, unit);
+            }
+            CXCursor_UnexposedExpr => {
+                value = get_integer_literal_from_cursor(&c, unit);
+            }
+            _ => (),
+        }
+        if value.is_some() {
+            CXChildVisit_Break
+        } else {
+            CXChildVisit_Continue
+        }
+    });
+    value
+}
diff --git a/src/lib.rs b/src/lib.rs
new file mode 100644
index 00000000..60b750de
--- /dev/null
+++ b/src/lib.rs
@@ -0,0 +1,808 @@
+//! Generate Rust bindings for C and C++ libraries.
+//!
+//! Provide a C/C++ header file, receive Rust FFI code to call into C/C++
+//! functions and use types defined in the header.
+//!
+//! See the [Builder](./struct.Builder.html) struct for usage.
+
+#![deny(missing_docs)]
+#![deny(warnings)]
+#![deny(unused_extern_crates)]
+
+// We internally use the deprecated BindgenOptions all over the place. Once we
+// remove its `pub` declaration, we can un-deprecate it and remove this pragma.
+#![allow(deprecated)]
+
+// To avoid rather annoying warnings when matching with CXCursor_xxx as a
+// constant.
+#![allow(non_upper_case_globals)]
+
+#[macro_use]
+#[allow(unused_extern_crates)]
+extern crate cfg_if;
+extern crate cexpr;
+extern crate syntex_syntax as syntax;
+extern crate aster;
+extern crate quasi;
+extern crate clang_sys;
+extern crate regex;
+#[macro_use]
+extern crate lazy_static;
+
+#[cfg(feature = "logging")]
+#[macro_use]
+extern crate log;
+
+#[cfg(not(feature = "logging"))]
+#[macro_use]
+mod log_stubs;
+
+// A macro to declare an internal module for which we *must* provide
+// documentation for. If we are building with the "docs_" feature, then the
+// module is declared public, and our `#![deny(missing_docs)]` pragma applies to
+// it. This feature is used in CI, so we won't let anything slip by
+// undocumented. Normal builds, however, will leave the module private, so that
+// we don't expose internals to library consumers.
+macro_rules! doc_mod {
+    ($m:ident, $doc_mod_name:ident) => {
+        cfg_if! {
+            if #[cfg(feature = "docs_")] {
+                pub mod $doc_mod_name {
+                    //! Autogenerated documentation module.
+                    pub use super::$m::*;
+                }
+            } else {
+            }
+        }
+    };
+}
+
+mod clang;
+mod ir;
+mod parse;
+mod regex_set;
+mod uses;
+
+pub mod chooser;
+
+#[cfg(rustfmt)]
+mod codegen;
+
+doc_mod!(clang, clang_docs);
+doc_mod!(ir, ir_docs);
+doc_mod!(parse, parse_docs);
+doc_mod!(regex_set, regex_set_docs);
+doc_mod!(uses, uses_docs);
+
+mod codegen {
+    include!(concat!(env!("OUT_DIR"), "/codegen.rs"));
+}
+
+use ir::context::{BindgenContext, ItemId};
+use ir::item::Item;
+use parse::{ClangItemParser, ParseError};
+use regex_set::RegexSet;
+
+use std::fs::OpenOptions;
+use std::io::{self, Write};
+use std::path::Path;
+use std::sync::{Arc, Mutex};
+
+use syntax::ast;
+use syntax::codemap::{DUMMY_SP, Span};
+use syntax::print::pp::eof;
+use syntax::print::pprust;
+use syntax::ptr::P;
+
+/// A type used to indicate which kind of items do we have to generate.
+///
+/// TODO(emilio): Use `bitflags!`
+#[derive(Debug, Clone)]
+pub struct CodegenConfig {
+    /// Whether to generate functions.
+    pub functions: bool,
+    /// Whether to generate types.
+    pub types: bool,
+    /// Whether to generate constants.
+    pub vars: bool,
+    /// Whether to generate methods.
+    pub methods: bool,
+    /// Whether to generate constructors.
+    pub constructors: bool,
+}
+
+impl CodegenConfig {
+    /// Generate all kinds of items.
+    pub fn all() -> Self {
+        CodegenConfig {
+            functions: true,
+            types: true,
+            vars: true,
+            methods: true,
+            constructors: true,
+        }
+    }
+
+    /// Generate nothing.
+    pub fn nothing() -> Self {
+        CodegenConfig {
+            functions: false,
+            types: false,
+            vars: false,
+            methods: false,
+            constructors: false,
+        }
+    }
+}
+
+impl Default for CodegenConfig {
+    fn default() -> Self {
+        CodegenConfig::all()
+    }
+}
+
+/// Configure and generate Rust bindings for a C/C++ header.
+///
+/// This is the main entry point to the library.
+///
+/// ```ignore
+/// use bindgen::builder;
+///
+/// // Configure and generate bindings.
+/// let bindings = try!(builder().header("path/to/input/header")
+///                              .whitelisted_type("SomeCoolClass")
+///                              .whitelisted_function("do_some_cool_thing")
+///                              .generate());
+///
+/// // Write the generated bindings to an output file.
+/// try!(bindings.write_to_file("path/to/output.rs"));
+/// ```
+#[derive(Debug,Default)]
+pub struct Builder {
+    options: BindgenOptions,
+}
+
+/// Construct a new [`Builder`](./struct.Builder.html).
+pub fn builder() -> Builder {
+    Default::default()
+}
+
+impl Builder {
+    /// Set the input C/C++ header.
+    pub fn header<T: Into<String>>(mut self, header: T) -> Builder {
+        let header = header.into();
+        self.options.input_header = Some(header);
+        self
+    }
+
+    /// Generate a C/C++ file that includes the header and has dummy uses of
+    /// every type defined in the header.
+    pub fn dummy_uses<T: Into<String>>(mut self, dummy_uses: T) -> Builder {
+        self.options.dummy_uses = Some(dummy_uses.into());
+        self
+    }
+
+    /// Hide the given type from the generated bindings.
+    pub fn hide_type<T: AsRef<str>>(mut self, arg: T) -> Builder {
+        self.options.hidden_types.insert(arg);
+        self
+    }
+
+    /// Treat the given type as opaque in the generated bindings.
+    pub fn opaque_type<T: AsRef<str>>(mut self, arg: T) -> Builder {
+        self.options.opaque_types.insert(arg);
+        self
+    }
+
+    /// Whitelist the given type so that it (and all types that it transitively
+    /// refers to) appears in the generated bindings.
+    pub fn whitelisted_type<T: AsRef<str>>(mut self, arg: T) -> Builder {
+        self.options.whitelisted_types.insert(arg);
+        self
+    }
+
+    /// Whitelist the given function so that it (and all types that it
+    /// transitively refers to) appears in the generated bindings.
+    pub fn whitelisted_function<T: AsRef<str>>(mut self, arg: T) -> Builder {
+        self.options.whitelisted_functions.insert(arg);
+        self
+    }
+
+    /// Whitelist the given variable so that it (and all types that it
+    /// transitively refers to) appears in the generated bindings.
+    pub fn whitelisted_var<T: AsRef<str>>(mut self, arg: T) -> Builder {
+        self.options.whitelisted_vars.insert(arg);
+        self
+    }
+
+    /// Mark the given enum (or set of enums, if using a pattern) as being
+    /// bitfield-like.
+    ///
+    /// This makes bindgen generate a type that isn't a rust `enum`.
+    pub fn bitfield_enum<T: AsRef<str>>(mut self, arg: T) -> Builder {
+        self.options.bitfield_enums.insert(arg);
+        self
+    }
+
+    /// Add a string to prepend to the generated bindings. The string is passed
+    /// through without any modification.
+    pub fn raw_line<T: Into<String>>(mut self, arg: T) -> Builder {
+        self.options.raw_lines.push(arg.into());
+        self
+    }
+
+    /// Add an argument to be passed straight through to clang.
+    pub fn clang_arg<T: Into<String>>(mut self, arg: T) -> Builder {
+        self.options.clang_args.push(arg.into());
+        self
+    }
+
+    /// Make the generated bindings link the given shared library.
+    pub fn link<T: Into<String>>(mut self, library: T) -> Builder {
+        self.options.links.push((library.into(), LinkType::Default));
+        self
+    }
+
+    /// Make the generated bindings link the given static library.
+    pub fn link_static<T: Into<String>>(mut self, library: T) -> Builder {
+        self.options.links.push((library.into(), LinkType::Static));
+        self
+    }
+
+    /// Make the generated bindings link the given framework.
+    pub fn link_framework<T: Into<String>>(mut self, library: T) -> Builder {
+        self.options.links.push((library.into(), LinkType::Framework));
+        self
+    }
+
+    /// Emit bindings for builtin definitions (for example `__builtin_va_list`)
+    /// in the generated Rust.
+    pub fn emit_builtins(mut self) -> Builder {
+        self.options.builtins = true;
+        self
+    }
+
+    /// Avoid converting floats to f32/f64 by default.
+    pub fn no_convert_floats(mut self) -> Self {
+        self.options.convert_floats = false;
+        self
+    }
+
+    /// Emit Clang AST.
+    pub fn emit_clang_ast(mut self) -> Builder {
+        self.options.emit_ast = true;
+        self
+    }
+
+    /// Emit IR.
+    pub fn emit_ir(mut self) -> Builder {
+        self.options.emit_ir = true;
+        self
+    }
+
+    /// Enable C++ namespaces.
+    pub fn enable_cxx_namespaces(mut self) -> Builder {
+        self.options.enable_cxx_namespaces = true;
+        self
+    }
+
+    /// Disable auto-namespacing of names if namespaces are disabled.
+    ///
+    /// By default, if namespaces are disabled, bindgen tries to mangle the
+    /// names to from `foo::bar::Baz` to look like `foo_bar_Baz`, instead of
+    /// just `Baz`.
+    ///
+    /// This option disables that behavior.
+    ///
+    /// Note that this intentionally doesn't change the names using for
+    /// whitelisting and blacklisting, that should still be mangled with the
+    /// namespaces.
+    ///
+    /// Note, also, that using this option may cause duplicated names to be
+    /// generated.
+    pub fn disable_name_namespacing(mut self) -> Builder {
+        self.options.disable_name_namespacing = true;
+        self
+    }
+
+    /// Treat inline namespaces conservatively.
+    ///
+    /// This is tricky, because in C++ is technically legal to override an item
+    /// defined in an inline namespace:
+    ///
+    /// ```cpp
+    /// inline namespace foo {
+    ///     using Bar = int;
+    /// }
+    /// using Bar = long;
+    /// ```
+    ///
+    /// Even though referencing `Bar` is a compiler error.
+    ///
+    /// We want to support this (arguably esoteric) use case, but we don't want
+    /// to make the rest of bindgen users pay an usability penalty for that.
+    ///
+    /// To support this, we need to keep all the inline namespaces around, but
+    /// then bindgen usage is a bit more difficult, because you cannot
+    /// reference, e.g., `std::string` (you'd need to use the proper inline
+    /// namespace).
+    ///
+    /// We could complicate a lot of the logic to detect name collisions, and if
+    /// not detected generate a `pub use inline_ns::*` or something like that.
+    ///
+    /// That's probably something we can do if we see this option is needed in a
+    /// lot of cases, to improve it's usability, but my guess is that this is
+    /// not going to be too useful.
+    pub fn conservative_inline_namespaces(mut self) -> Builder {
+        self.options.conservative_inline_namespaces = true;
+        self
+    }
+
+    /// Ignore functions.
+    pub fn ignore_functions(mut self) -> Builder {
+        self.options.codegen_config.functions = false;
+        self
+    }
+
+    /// Ignore methods.
+    pub fn ignore_methods(mut self) -> Builder {
+        self.options.codegen_config.methods = false;
+        self
+    }
+
+    /// Avoid generating any unstable Rust in the generated bindings.
+    pub fn no_unstable_rust(mut self) -> Builder {
+        self.options.unstable_rust = false;
+        self
+    }
+
+    /// Use core instead of libstd in the generated bindings.
+    pub fn use_core(mut self) -> Builder {
+        self.options.use_core = true;
+        self
+    }
+
+    /// Use the given prefix for the raw types instead of `::std::os::raw`.
+    pub fn ctypes_prefix<T: Into<String>>(mut self, prefix: T) -> Builder {
+        self.options.ctypes_prefix = Some(prefix.into());
+        self
+    }
+
+    /// Allows configuring types in different situations, see the `TypeChooser`
+    /// documentation.
+    pub fn type_chooser(mut self, cb: Box<chooser::TypeChooser>) -> Self {
+        self.options.type_chooser = Some(cb);
+        self
+    }
+
+    /// Choose what to generate using a CodegenConfig.
+    pub fn with_codegen_config(mut self, config: CodegenConfig) -> Self {
+        self.options.codegen_config = config;
+        self
+    }
+
+    /// Generate the Rust bindings using the options built up thus far.
+    pub fn generate<'ctx>(self) -> Result<Bindings<'ctx>, ()> {
+        Bindings::generate(self.options, None)
+    }
+}
+
+/// Configuration options for generated bindings.
+///
+/// Deprecated: use a `Builder` instead.
+#[derive(Debug)]
+#[deprecated]
+pub struct BindgenOptions {
+    /// The set of types that have been blacklisted and should not appear
+    /// anywhere in the generated code.
+    pub hidden_types: RegexSet,
+
+    /// The set of types that should be treated as opaque structures in the
+    /// generated code.
+    pub opaque_types: RegexSet,
+
+    /// The set of types that we should have bindings for in the generated
+    /// code.
+    ///
+    /// This includes all types transitively reachable from any type in this
+    /// set. One might think of whitelisted types/vars/functions as GC roots,
+    /// and the generated Rust code as including everything that gets marked.
+    pub whitelisted_types: RegexSet,
+
+    /// Whitelisted functions. See docs for `whitelisted_types` for more.
+    pub whitelisted_functions: RegexSet,
+
+    /// Whitelisted variables. See docs for `whitelisted_types` for more.
+    pub whitelisted_vars: RegexSet,
+
+    /// The enum patterns to mark an enum as bitfield.
+    pub bitfield_enums: RegexSet,
+
+    /// Whether we should generate builtins or not.
+    pub builtins: bool,
+
+    /// The set of libraries we should link in the generated Rust code.
+    pub links: Vec<(String, LinkType)>,
+
+    /// True if we should dump the Clang AST for debugging purposes.
+    pub emit_ast: bool,
+
+    /// True if we should dump our internal IR for debugging purposes.
+    pub emit_ir: bool,
+
+    /// True if we should emulate C++ namespaces with Rust modules in the
+    /// generated bindings.
+    pub enable_cxx_namespaces: bool,
+
+    /// True if we should avoid mangling names with namespaces.
+    pub disable_name_namespacing: bool,
+
+    /// True if we shold derive Debug trait implementations for C/C++ structures
+    /// and types.
+    pub derive_debug: bool,
+
+    /// True if we can use unstable Rust code in the bindings, false if we
+    /// cannot.
+    pub unstable_rust: bool,
+
+    /// True if we should avoid using libstd to use libcore instead.
+    pub use_core: bool,
+
+    /// An optional prefix for the "raw" types, like `c_int`, `c_void`...
+    pub ctypes_prefix: Option<String>,
+
+    /// True if we should generate constant names that are **directly** under
+    /// namespaces.
+    pub namespaced_constants: bool,
+
+    /// True if we should use MSVC name mangling rules.
+    pub msvc_mangling: bool,
+
+    /// Whether we should convert float types to f32/f64 types.
+    pub convert_floats: bool,
+
+    /// The set of raw lines to prepend to the generated Rust code.
+    pub raw_lines: Vec<String>,
+
+    /// The set of arguments to pass straight through to Clang.
+    pub clang_args: Vec<String>,
+
+    /// The input header file.
+    pub input_header: Option<String>,
+
+    /// Generate a dummy C/C++ file that includes the header and has dummy uses
+    /// of all types defined therein. See the `uses` module for more.
+    pub dummy_uses: Option<String>,
+
+    /// A user-provided type chooser to allow customizing different kinds of
+    /// situations.
+    pub type_chooser: Option<Box<chooser::TypeChooser>>,
+
+    /// Which kind of items should we generate? By default, we'll generate all
+    /// of them.
+    pub codegen_config: CodegenConfig,
+
+    /// Whether to treat inline namespaces conservatively.
+    ///
+    /// See the builder method description for more details.
+    pub conservative_inline_namespaces: bool,
+}
+
+impl BindgenOptions {
+    fn build(&mut self) {
+        self.whitelisted_vars.build();
+        self.whitelisted_types.build();
+        self.whitelisted_functions.build();
+        self.hidden_types.build();
+        self.opaque_types.build();
+        self.bitfield_enums.build();
+    }
+}
+
+impl Default for BindgenOptions {
+    fn default() -> BindgenOptions {
+        BindgenOptions {
+            hidden_types: Default::default(),
+            opaque_types: Default::default(),
+            whitelisted_types: Default::default(),
+            whitelisted_functions: Default::default(),
+            whitelisted_vars: Default::default(),
+            bitfield_enums: Default::default(),
+            builtins: false,
+            links: vec![],
+            emit_ast: false,
+            emit_ir: false,
+            derive_debug: true,
+            enable_cxx_namespaces: false,
+            disable_name_namespacing: false,
+            unstable_rust: true,
+            use_core: false,
+            ctypes_prefix: None,
+            namespaced_constants: true,
+            msvc_mangling: false,
+            convert_floats: true,
+            raw_lines: vec![],
+            clang_args: vec![],
+            input_header: None,
+            dummy_uses: None,
+            type_chooser: None,
+            codegen_config: CodegenConfig::all(),
+            conservative_inline_namespaces: false,
+        }
+    }
+}
+
+/// The linking type to use with a given library.
+///
+/// TODO: #104: This is ignored at the moment, but shouldn't be.
+#[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord)]
+pub enum LinkType {
+    /// Use shared library linking. This is the default.
+    Default,
+    /// Use static linking.
+    Static,
+    /// The library is an OSX framework.
+    Framework,
+}
+
+fn ensure_libclang_is_loaded() {
+    if clang_sys::is_loaded() {
+        return;
+    }
+
+    // XXX (issue #350): Ensure that our dynamically loaded `libclang`
+    // doesn't get dropped prematurely, nor is loaded multiple times
+    // across different threads.
+
+    lazy_static! {
+        static ref LIBCLANG: Mutex<Option<Arc<clang_sys::SharedLibrary>>> = {
+            Mutex::new(None)
+        };
+    }
+
+    let mut libclang = LIBCLANG.lock().unwrap();
+    if !clang_sys::is_loaded() {
+        if libclang.is_none() {
+            // TODO(emilio): Return meaningful error (breaking).
+            clang_sys::load().expect("Unable to find libclang");
+            *libclang = Some(clang_sys::get_library()
+                .expect("We just loaded libclang and it had \
+                                     better still be here!"));
+        } else {
+            clang_sys::set_library(libclang.clone());
+        }
+    }
+}
+
+/// Generated Rust bindings.
+#[derive(Debug)]
+pub struct Bindings<'ctx> {
+    context: BindgenContext<'ctx>,
+    module: ast::Mod,
+}
+
+impl<'ctx> Bindings<'ctx> {
+    /// Generate bindings for the given options.
+    ///
+    /// Deprecated - use a `Builder` instead
+    #[deprecated]
+    pub fn generate(mut options: BindgenOptions,
+                    span: Option<Span>)
+                    -> Result<Bindings<'ctx>, ()> {
+        let span = span.unwrap_or(DUMMY_SP);
+        ensure_libclang_is_loaded();
+
+        options.build();
+
+        // TODO: Make this path fixup configurable?
+        if let Some(clang) = clang_sys::support::Clang::find(None) {
+            // If --target is specified, assume caller knows what they're doing
+            // and don't mess with include paths for them
+            let has_target_arg = options.clang_args
+                .iter()
+                .rposition(|arg| arg.starts_with("--target"))
+                .is_some();
+            if !has_target_arg {
+                // TODO: distinguish C and C++ paths? C++'s should be enough, I
+                // guess.
+                for path in clang.cpp_search_paths.into_iter() {
+                    if let Ok(path) = path.into_os_string().into_string() {
+                        options.clang_args.push("-isystem".to_owned());
+                        options.clang_args.push(path);
+                    }
+                }
+            }
+        }
+
+        if let Some(h) = options.input_header.as_ref() {
+            options.clang_args.push(h.clone())
+        }
+
+        let mut context = BindgenContext::new(options);
+        try!(parse(&mut context));
+
+        let module = ast::Mod {
+            inner: span,
+            items: codegen::codegen(&mut context),
+        };
+
+        Ok(Bindings {
+            context: context,
+            module: module,
+        })
+    }
+
+    /// Convert these bindings into a Rust AST.
+    pub fn into_ast(self) -> Vec<P<ast::Item>> {
+        self.module.items
+    }
+
+    /// Convert these bindings into source text (with raw lines prepended).
+    pub fn to_string(&self) -> String {
+        let mut mod_str = vec![];
+        {
+            let ref_writer = Box::new(mod_str.by_ref()) as Box<Write>;
+            self.write(ref_writer).expect("Could not write bindings to string");
+        }
+        String::from_utf8(mod_str).unwrap()
+    }
+
+    /// Write these bindings as source text to a file.
+    pub fn write_to_file<P: AsRef<Path>>(&self, path: P) -> io::Result<()> {
+        let file = try!(OpenOptions::new()
+            .write(true)
+            .truncate(true)
+            .create(true)
+            .open(path));
+        self.write(Box::new(file))
+    }
+
+    /// Write these bindings as source text to the given `Write`able.
+    pub fn write<'a>(&self, mut writer: Box<Write + 'a>) -> io::Result<()> {
+        try!(writer.write("/* automatically generated by rust-bindgen */\n\n"
+            .as_bytes()));
+
+        for line in self.context.options().raw_lines.iter() {
+            try!(writer.write(line.as_bytes()));
+            try!(writer.write("\n".as_bytes()));
+        }
+        if !self.context.options().raw_lines.is_empty() {
+            try!(writer.write("\n".as_bytes()));
+        }
+
+        let mut ps = pprust::rust_printer(writer);
+        try!(ps.print_mod(&self.module, &[]));
+        try!(ps.print_remaining_comments());
+        try!(eof(&mut ps.s));
+        ps.s.out.flush()
+    }
+
+    /// Generate and write dummy uses of all the types we parsed, if we've been
+    /// requested to do so in the options.
+    ///
+    /// See the `uses` module for more information.
+    pub fn write_dummy_uses(&mut self) -> io::Result<()> {
+        let file =
+            if let Some(ref dummy_path) = self.context.options().dummy_uses {
+                Some(try!(OpenOptions::new()
+                .write(true)
+                .truncate(true)
+                .create(true)
+                .open(dummy_path)))
+            } else {
+                None
+            };
+
+        if let Some(file) = file {
+            try!(uses::generate_dummy_uses(&mut self.context, file));
+        }
+
+        Ok(())
+    }
+}
+
+/// Determines whether the given cursor is in any of the files matched by the
+/// options.
+fn filter_builtins(ctx: &BindgenContext, cursor: &clang::Cursor) -> bool {
+    let (file, _, _, _) = cursor.location().location();
+
+    match file.name() {
+        None => ctx.options().builtins,
+        Some(..) => true,
+    }
+}
+
+/// Parse one `Item` from the Clang cursor.
+pub fn parse_one(ctx: &mut BindgenContext,
+                 cursor: clang::Cursor,
+                 parent: Option<ItemId>)
+                 -> clang_sys::CXChildVisitResult {
+    if !filter_builtins(ctx, &cursor) {
+        return CXChildVisit_Continue;
+    }
+
+    use clang_sys::CXChildVisit_Continue;
+    match Item::parse(cursor, parent, ctx) {
+        Ok(..) => {}
+        Err(ParseError::Continue) => {}
+        Err(ParseError::Recurse) => {
+            cursor.visit(|child| parse_one(ctx, child, parent));
+        }
+    }
+    CXChildVisit_Continue
+}
+
+/// Parse the Clang AST into our `Item` internal representation.
+fn parse(context: &mut BindgenContext) -> Result<(), ()> {
+    use clang_sys::*;
+
+    let mut any_error = false;
+    for d in context.translation_unit().diags().iter() {
+        let msg = d.format();
+        let is_err = d.severity() >= CXDiagnostic_Error;
+        println!("{}, err: {}", msg, is_err);
+        any_error |= is_err;
+    }
+
+    if any_error {
+        return Err(());
+    }
+
+    let cursor = context.translation_unit().cursor();
+    if context.options().emit_ast {
+        cursor.visit(|cur| clang::ast_dump(&cur, 0));
+    }
+
+    let root = context.root_module();
+    context.with_module(root, |context| {
+        cursor.visit(|cursor| parse_one(context, cursor, None))
+    });
+
+    assert!(context.current_module() == context.root_module(),
+            "How did this happen?");
+    Ok(())
+}
+
+/// Extracted Clang version data
+#[derive(Debug)]
+pub struct ClangVersion {
+    /// Major and minor semvar, if parsing was successful
+    pub parsed: Option<(u32, u32)>,
+    /// full version string
+    pub full: String,
+}
+
+/// Get the major and the minor semvar numbers of Clang's version
+pub fn clang_version() -> ClangVersion {
+    if !clang_sys::is_loaded() {
+        // TODO(emilio): Return meaningful error (breaking).
+        clang_sys::load().expect("Unable to find libclang");
+    }
+
+    let raw_v: String = clang::extract_clang_version();
+    let split_v: Option<Vec<&str>> = raw_v.split_whitespace()
+        .nth(2)
+        .map(|v| v.split('.').collect());
+    match split_v {
+        Some(v) => {
+            if v.len() >= 2 {
+                let maybe_major = v[0].parse::<u32>();
+                let maybe_minor = v[1].parse::<u32>();
+                match (maybe_major, maybe_minor) {
+                    (Ok(major), Ok(minor)) => {
+                        return ClangVersion {
+                            parsed: Some((major, minor)),
+                            full: raw_v.clone(),
+                        }
+                    }
+                    _ => {}
+                }
+            }
+        }
+        None => {}
+    };
+    ClangVersion {
+        parsed: None,
+        full: raw_v.clone(),
+    }
+}
diff --git a/src/log_stubs.rs b/src/log_stubs.rs
new file mode 100644
index 00000000..4262e120
--- /dev/null
+++ b/src/log_stubs.rs
@@ -0,0 +1,30 @@
+macro_rules! log {
+    (target: $target:expr, $lvl:expr, $($arg)+) => {
+        let _ = $target;
+        let _ = log!($lvl, $($arg)+);
+    };
+    ($lvl:expr, $($arg:tt)+) => {
+        let _ = $lvl;
+        let _ = format_args!($($arg)+);
+    };
+}
+macro_rules! error {
+    (target: $target:expr, $($arg:tt)*) => { log!($target, $($arg)*); };
+    ($($arg:tt)*) => { log!("", $($arg)*); };
+}
+macro_rules! warn {
+    (target: $target:expr, $($arg:tt)*) => { log!($target, $($arg)*); };
+    ($($arg:tt)*) => { log!("", $($arg)*); };
+}
+macro_rules! info {
+    (target: $target:expr, $($arg:tt)*) => { log!($target, $($arg)*); };
+    ($($arg:tt)*) => { log!("", $($arg)*); };
+}
+macro_rules! debug {
+    (target: $target:expr, $($arg:tt)*) => { log!($target, $($arg)*); };
+    ($($arg:tt)*) => { log!("", $($arg)*); };
+}
+macro_rules! trace {
+    (target: $target:expr, $($arg:tt)*) => { log!($target, $($arg)*); };
+    ($($arg:tt)*) => { log!("", $($arg)*); };
+}
diff --git a/src/main.rs b/src/main.rs
new file mode 100644
index 00000000..a7bd9618
--- /dev/null
+++ b/src/main.rs
@@ -0,0 +1,59 @@
+extern crate bindgen;
+extern crate env_logger;
+#[macro_use]
+extern crate log;
+extern crate clang_sys;
+extern crate clap;
+extern crate rustc_serialize;
+
+use bindgen::clang_version;
+use std::env;
+
+mod options;
+use options::builder_from_flags;
+
+pub fn main() {
+    log::set_logger(|max_log_level| {
+            use env_logger::Logger;
+            let env_logger = Logger::new();
+            max_log_level.set(env_logger.filter());
+            Box::new(env_logger)
+        })
+        .expect("Failed to set logger.");
+
+    let bind_args: Vec<_> = env::args().collect();
+
+    let version = clang_version();
+    let expected_version = if cfg!(feature = "llvm_stable") {
+        (3, 8)
+    } else {
+        (3, 9)
+    };
+
+    info!("Clang Version: {}", version.full);
+
+    match version.parsed {
+        None => warn!("Couldn't parse libclang version"),
+        Some(version) if version != expected_version => {
+            warn!("Using clang {:?}, expected {:?}",
+                   version,
+                   expected_version);
+        }
+        _ => {}
+    }
+
+    match builder_from_flags(bind_args.into_iter()) {
+        Ok((builder, output)) => {
+            let mut bindings = builder.generate()
+                .expect("Unable to generate bindings");
+            bindings.write(output)
+                .expect("Unable to write output");
+            bindings.write_dummy_uses()
+                .expect("Unable to write dummy uses to file.");
+        }
+        Err(error) => {
+            println!("{}", error);
+            std::process::exit(1);
+        }
+    };
+}
diff --git a/src/options.rs b/src/options.rs
new file mode 100644
index 00000000..3456bfea
--- /dev/null
+++ b/src/options.rs
@@ -0,0 +1,311 @@
+use clap::{App, Arg};
+use bindgen::{Builder, CodegenConfig, builder};
+use std::fs::File;
+use std::io::{self, Error, ErrorKind};
+
+/// Construct a new [`Builder`](./struct.Builder.html) from command line flags.
+pub fn builder_from_flags<I>(args: I)
+                             -> Result<(Builder, Box<io::Write>), io::Error>
+    where I: Iterator<Item = String>,
+{
+    let matches = App::new("bindgen")
+        .version(env!("CARGO_PKG_VERSION"))
+        .about("Generates Rust bindings from C/C++ headers.")
+        .usage("bindgen [FLAGS] [OPTIONS] <header> -- <clang-args>...")
+        .args(&[
+            Arg::with_name("header")
+                .help("C or C++ header file")
+                .required(true),
+            Arg::with_name("bitfield-enum")
+                .long("bitfield-enum")
+                .help("Mark any enum whose name matches <regex> as a set of \
+                       bitfield flags instead of an enumeration.")
+                .value_name("regex")
+                .takes_value(true)
+                .multiple(true)
+                .number_of_values(1),
+            Arg::with_name("blacklist-type")
+                .long("blacklist-type")
+                .help("Mark a type as hidden.")
+                .value_name("type")
+                .takes_value(true)
+                .multiple(true)
+                .number_of_values(1),
+            Arg::with_name("builtins")
+                .long("builtins")
+                .help("Output bindings for builtin definitions, e.g. \
+                       __builtin_va_list."),
+            Arg::with_name("ctypes-prefix")
+                .long("ctypes-prefix")
+                .help("Use the given prefix before raw types instead of \
+                      ::std::os::raw.")
+                .value_name("prefix")
+                .takes_value(true),
+            // All positional arguments after the end of options marker, `--`
+            Arg::with_name("clang-args")
+                .multiple(true),
+            Arg::with_name("dummy-uses")
+                .long("dummy-uses")
+                .help("For testing purposes, generate a C/C++ file containing \
+                       dummy uses of all types defined in the input header.")
+                .takes_value(true),
+            Arg::with_name("emit-clang-ast")
+                .long("emit-clang-ast")
+                .help("Output the Clang AST for debugging purposes."),
+            Arg::with_name("emit-ir")
+                .long("emit-ir")
+                .help("Output our internal IR for debugging purposes."),
+            Arg::with_name("enable-cxx-namespaces")
+                .long("enable-cxx-namespaces")
+                .help("Enable support for C++ namespaces."),
+            Arg::with_name("disable-name-namespacing")
+                .long("disable-name-namespacing")
+                .help("Disable name namespacing if namespaces are disabled."),
+            Arg::with_name("framework")
+                .long("framework-link")
+                .help("Link to framework.")
+                .takes_value(true)
+                .multiple(true)
+                .number_of_values(1),
+            Arg::with_name("ignore-functions")
+                .long("ignore-functions")
+                .help("Do not generate bindings for functions or methods. This \
+                       is useful when you only care about struct layouts."),
+            Arg::with_name("generate")
+                .long("generate")
+                .help("Generate a given kind of items, split by commas. \
+                       Valid values are \"functions\",\"types\", \"vars\" and \
+                       \"methods\".")
+                .takes_value(true),
+            Arg::with_name("ignore-methods")
+                .long("ignore-methods")
+                .help("Do not generate bindings for methods."),
+            Arg::with_name("dynamic")
+                .short("l")
+                .long("link")
+                .help("Link to dynamic library.")
+                .takes_value(true)
+                .multiple(true)
+                .number_of_values(1),
+            Arg::with_name("no-convert-floats")
+                .long("no-convert-floats")
+                .help("Don't automatically convert floats to f32/f64."),
+            Arg::with_name("no-unstable-rust")
+                .long("no-unstable-rust")
+                .help("Do not generate unstable Rust code.")
+                .multiple(true), // FIXME: Pass legacy test suite
+            Arg::with_name("opaque-type")
+                .long("opaque-type")
+                .help("Mark a type as opaque.")
+                .value_name("type")
+                .takes_value(true)
+                .multiple(true)
+                .number_of_values(1),
+            Arg::with_name("output")
+                .short("o")
+                .long("output")
+                .help("Write Rust bindings to <output>.")
+                .takes_value(true),
+            Arg::with_name("raw-line")
+                .long("raw-line")
+                .help("Add a raw line of Rust code at the beginning of output.")
+                .takes_value(true)
+                .multiple(true)
+                .number_of_values(1),
+            Arg::with_name("static")
+                .long("static-link")
+                .help("Link to static library.")
+                .takes_value(true)
+                .multiple(true)
+                .number_of_values(1),
+            Arg::with_name("use-core")
+                .long("use-core")
+                .help("Use types from Rust core instead of std."),
+            Arg::with_name("conservative-inline-namespaces")
+                .long("conservative-inline-namespaces")
+                .help("Conservatively generate inline namespaces to avoid name \
+                       conflicts."),
+            Arg::with_name("use-msvc-mangling")
+                .long("use-msvc-mangling")
+                .help("MSVC C++ ABI mangling. DEPRECATED: Has no effect."),
+            Arg::with_name("whitelist-function")
+                .long("whitelist-function")
+                .help("Whitelist all the free-standing functions matching \
+                       <regex>. Other non-whitelisted functions will not be \
+                       generated.")
+                .value_name("regex")
+                .takes_value(true)
+                .multiple(true)
+                .number_of_values(1),
+            Arg::with_name("whitelist-type")
+                .long("whitelist-type")
+                .help("Whitelist the type. Other non-whitelisted types will \
+                       not be generated.")
+                .value_name("type")
+                .takes_value(true)
+                .multiple(true)
+                .number_of_values(1),
+            Arg::with_name("whitelist-var")
+                .long("whitelist-var")
+                .help("Whitelist all the free-standing variables matching \
+                       <regex>. Other non-whitelisted variables will not be \
+                       generated.")
+                .value_name("regex")
+                .takes_value(true)
+                .multiple(true)
+                .number_of_values(1),
+        ]) // .args()
+        .get_matches_from(args);
+
+    let mut builder = builder();
+
+    if let Some(header) = matches.value_of("header") {
+        builder = builder.header(header);
+    } else {
+        return Err(Error::new(ErrorKind::Other, "Header not found"));
+    }
+
+    if let Some(bitfields) = matches.values_of("bitfield-enum") {
+        for regex in bitfields {
+            builder = builder.bitfield_enum(regex);
+        }
+    }
+
+    if let Some(hidden_types) = matches.values_of("blacklist-type") {
+        for ty in hidden_types {
+            builder = builder.hide_type(ty);
+        }
+    }
+
+    if matches.is_present("builtins") {
+        builder = builder.emit_builtins();
+    }
+
+    if let Some(prefix) = matches.value_of("ctypes-prefix") {
+        builder = builder.ctypes_prefix(prefix);
+    }
+
+    if let Some(dummy) = matches.value_of("dummy-uses") {
+        builder = builder.dummy_uses(dummy);
+    }
+
+    if let Some(links) = matches.values_of("dynamic") {
+        for library in links {
+            builder = builder.link(library);
+        }
+    }
+
+    if let Some(what_to_generate) = matches.value_of("generate") {
+        let mut config = CodegenConfig::nothing();
+        for what in what_to_generate.split(",") {
+            match what {
+                "functions" => config.functions = true,
+                "types" => config.types = true,
+                "vars" => config.vars = true,
+                "methods" => config.methods = true,
+                _ => {
+                    return Err(Error::new(ErrorKind::Other,
+                                          "Unknown generate item"));
+                }
+            }
+        }
+        builder = builder.with_codegen_config(config);
+    }
+
+    if matches.is_present("emit-clang-ast") {
+        builder = builder.emit_clang_ast();
+    }
+
+    if matches.is_present("emit-ir") {
+        builder = builder.emit_ir();
+    }
+
+    if matches.is_present("enable-cxx-namespaces") {
+        builder = builder.enable_cxx_namespaces();
+    }
+
+    if matches.is_present("disable-name-namespacing") {
+        builder = builder.disable_name_namespacing();
+    }
+
+    if let Some(links) = matches.values_of("framework") {
+        for framework in links {
+            builder = builder.link_framework(framework);
+        }
+    }
+
+    if matches.is_present("ignore-functions") {
+        builder = builder.ignore_functions();
+    }
+
+    if matches.is_present("ignore-methods") {
+        builder = builder.ignore_methods();
+    }
+
+    if matches.is_present("no-unstable-rust") {
+        builder = builder.no_unstable_rust();
+    }
+
+    if matches.is_present("no-convert-floats") {
+        builder = builder.no_convert_floats();
+    }
+
+    if let Some(opaque_types) = matches.values_of("opaque-type") {
+        for ty in opaque_types {
+            builder = builder.opaque_type(ty);
+        }
+    }
+
+    if let Some(lines) = matches.values_of("raw-line") {
+        for line in lines {
+            builder = builder.raw_line(line);
+        }
+    }
+
+    if let Some(links) = matches.values_of("static") {
+        for library in links {
+            builder = builder.link_static(library);
+        }
+    }
+
+    if matches.is_present("use-core") {
+        builder = builder.use_core();
+    }
+
+    if matches.is_present("conservative-inline-namespaces") {
+        builder = builder.conservative_inline_namespaces();
+    }
+
+    if let Some(whitelist) = matches.values_of("whitelist-function") {
+        for regex in whitelist {
+            builder = builder.whitelisted_function(regex);
+        }
+    }
+
+    if let Some(whitelist) = matches.values_of("whitelist-type") {
+        for regex in whitelist {
+            builder = builder.whitelisted_type(regex);
+        }
+    }
+
+    if let Some(whitelist) = matches.values_of("whitelist-var") {
+        for regex in whitelist {
+            builder = builder.whitelisted_var(regex);
+        }
+    }
+
+    if let Some(args) = matches.values_of("clang-args") {
+        for arg in args {
+            builder = builder.clang_arg(arg);
+        }
+    }
+
+    let output = if let Some(path) = matches.value_of("output") {
+        let file = try!(File::create(path));
+        Box::new(io::BufWriter::new(file)) as Box<io::Write>
+    } else {
+        Box::new(io::BufWriter::new(io::stdout())) as Box<io::Write>
+    };
+
+    Ok((builder, output))
+}
diff --git a/src/parse.rs b/src/parse.rs
new file mode 100644
index 00000000..0e4164f0
--- /dev/null
+++ b/src/parse.rs
@@ -0,0 +1,104 @@
+//! Common traits and types related to parsing our IR from Clang cursors.
+
+use clang;
+use ir::context::{BindgenContext, ItemId};
+use ir::ty::TypeKind;
+
+/// Not so much an error in the traditional sense, but a control flow message
+/// when walking over Clang's AST with a cursor.
+#[derive(Debug)]
+pub enum ParseError {
+    /// Recurse down the current AST node's children.
+    Recurse,
+    /// Continue on to the next sibling AST node, or back up to the parent's
+    /// siblings if we've exhausted all of this node's siblings (and so on).
+    Continue,
+}
+
+/// The result of parsing a Clang AST node.
+#[derive(Debug)]
+pub enum ParseResult<T> {
+    /// We've already resolved this item before, here is the extant `ItemId` for
+    /// it.
+    AlreadyResolved(ItemId),
+
+    /// This is a newly parsed item. If the cursor is `Some`, it points to the
+    /// AST node where the new `T` was declared.
+    New(T, Option<clang::Cursor>),
+}
+
+/// An intermediate representation "sub-item" (i.e. one of the types contained
+/// inside an `ItemKind` variant) that can be parsed from a Clang cursor.
+pub trait ClangSubItemParser: Sized {
+    /// Attempt to parse this type from the given cursor.
+    ///
+    /// The fact that is a reference guarantees it's held by the context, and
+    /// allow returning already existing types.
+    fn parse(cursor: clang::Cursor,
+             context: &mut BindgenContext)
+             -> Result<ParseResult<Self>, ParseError>;
+}
+
+/// An intermediate representation item that can be parsed from a Clang cursor.
+pub trait ClangItemParser: Sized {
+    /// Parse this item from the given Clang cursor.
+    fn parse(cursor: clang::Cursor,
+             parent: Option<ItemId>,
+             context: &mut BindgenContext)
+             -> Result<ItemId, ParseError>;
+
+    /// Parse this item from the given Clang type.
+    fn from_ty(ty: &clang::Type,
+               location: Option<clang::Cursor>,
+               parent: Option<ItemId>,
+               ctx: &mut BindgenContext)
+               -> Result<ItemId, ParseError>;
+
+    /// Identical to `from_ty`, but use the given `id` as the `ItemId` for the
+    /// newly parsed item.
+    fn from_ty_with_id(id: ItemId,
+                       ty: &clang::Type,
+                       location: Option<clang::Cursor>,
+                       parent: Option<ItemId>,
+                       ctx: &mut BindgenContext)
+                       -> Result<ItemId, ParseError>;
+
+    /// Parse this item from the given Clang type, or if we haven't resolved all
+    /// the other items this one depends on, an unresolved reference.
+    fn from_ty_or_ref(ty: clang::Type,
+                      location: Option<clang::Cursor>,
+                      parent_id: Option<ItemId>,
+                      context: &mut BindgenContext)
+                      -> ItemId;
+
+    /// Identical to `from_ty_or_ref`, but use the given `potential_id` as the
+    /// `ItemId` for the newly parsed item.
+    fn from_ty_or_ref_with_id(potential_id: ItemId,
+                              ty: clang::Type,
+                              location: Option<clang::Cursor>,
+                              parent_id: Option<ItemId>,
+                              context: &mut BindgenContext)
+                              -> ItemId;
+
+    /// Create a named template type.
+    fn named_type<S>(name: S,
+                     parent: ItemId,
+                     context: &mut BindgenContext)
+                     -> ItemId
+        where S: Into<String>;
+
+    /// Identical to `named_type`, but use `id` as the resulting item's
+    /// `ItemId`.
+    fn named_type_with_id<S>(id: ItemId,
+                             name: S,
+                             parent: ItemId,
+                             context: &mut BindgenContext)
+                             -> ItemId
+        where S: Into<String>;
+
+    /// Create a builtin type.
+    fn builtin_type(kind: TypeKind,
+                    is_const: bool,
+                    context: &mut BindgenContext)
+                    -> ItemId;
+}
diff --git a/src/regex_set.rs b/src/regex_set.rs
new file mode 100644
index 00000000..dbdb6565
--- /dev/null
+++ b/src/regex_set.rs
@@ -0,0 +1,69 @@
+//! A type that represents the union of a set of regular expressions.
+
+use regex::RegexSet as RxSet;
+
+// Yeah, I'm aware this is sorta crappy, should be cheaper to compile a regex
+// ORing all the patterns, I guess...
+
+/// A dynamic set of regular expressions.
+#[derive(Debug)]
+pub struct RegexSet {
+    items: Vec<String>,
+    set: Option<RxSet>,
+}
+
+impl RegexSet {
+    /// Is this set empty?
+    pub fn is_empty(&self) -> bool {
+        self.items.is_empty()
+    }
+
+    /// Extend this set with every regex in the iterator.
+    pub fn extend<I, S>(&mut self, iter: I)
+        where I: IntoIterator<Item = S>,
+              S: AsRef<str>
+    {
+        for s in iter.into_iter() {
+            self.insert(s)
+        }
+    }
+
+    /// Insert a new regex into this set.
+    pub fn insert<S>(&mut self, string: S)
+        where S: AsRef<str>
+    {
+        self.items.push(format!("^{}$", string.as_ref()));
+        self.set = None;
+    }
+
+    /// Construct a RegexSet from the set of entries we've accumulated.
+    ///
+    /// Must be called before calling `matches()`, or it will always return
+    /// false.
+    pub fn build(&mut self) {
+        self.set = match RxSet::new(&self.items) {
+            Ok(x) => Some(x),
+            Err(e) => {
+                error!("Invalid regex in {:?}: {:?}", self.items, e);
+                None
+            },
+        }
+    }
+
+    /// Does the given `string` match any of the regexes in this set?
+    pub fn matches<S>(&self, string: S) -> bool
+        where S: AsRef<str>
+    {
+        let s = string.as_ref();
+        self.set.as_ref().map(|set| set.is_match(s)).unwrap_or(false)
+    }
+}
+
+impl Default for RegexSet {
+    fn default() -> Self {
+        RegexSet {
+            items: vec![],
+            set: None,
+        }
+    }
+}
diff --git a/src/uses.rs b/src/uses.rs
new file mode 100644
index 00000000..47f72da6
--- /dev/null
+++ b/src/uses.rs
@@ -0,0 +1,102 @@
+//! Take in our IR and output a C/C++ file with dummy uses of each IR type.
+//!
+//! Say that we had this C++ header, `header.hpp`:
+//!
+//! ```c++
+//! class Point {
+//!     int x;
+//!     int y;
+//! }
+//!
+//! enum Bar {
+//!     THIS,
+//!     THAT,
+//!     OTHER
+//! }
+//! ```
+//!
+//! If we generated dummy uses for this header, we would get a `.cpp` file like
+//! this:
+//!
+//! ```c++
+//! #include "header.hpp"
+//!
+//! void dummy(Point*) {}
+//! void dummy(Bar*) {}
+//! ```
+//!
+//! This is useful because we can compile this `.cpp` file into an object file,
+//! and then compare its debugging information to the debugging information
+//! generated for our Rust bindings. These two sets of debugging information had
+//! better agree on the C/C++ types' physical layout, or else our bindings are
+//! incorrect!
+//!
+//! "But you still haven't explained why we have to generate the dummy uses" you
+//! complain. Well if the types are never used, then they are elided when the
+//! C/C++ compiler generates debugging information.
+
+use ir::context::BindgenContext;
+use ir::item::{Item, ItemAncestors, ItemCanonicalName};
+use std::io;
+
+// Like `canonical_path`, except we always take namespaces into account, ignore
+// the generated names of anonymous items, and return a `String`.
+//
+// TODO: Would it be easier to try and demangle the USR?
+fn namespaced_name(ctx: &BindgenContext, item: &Item) -> String {
+    let mut names: Vec<_> = item.ancestors(ctx)
+        .map(|id| ctx.resolve_item(id).canonical_name(ctx))
+        .filter(|name| !name.starts_with("_bindgen_"))
+        .collect();
+    names.reverse();
+    names.join("::")
+}
+
+/// Generate the dummy uses for all the items in the given context, and write
+/// the dummy uses to `dest`.
+pub fn generate_dummy_uses<W>(ctx: &mut BindgenContext,
+                              mut dest: W)
+                              -> io::Result<()>
+    where W: io::Write,
+{
+    ctx.gen(|ctx| {
+        let input_header = ctx.options()
+            .input_header
+            .as_ref()
+            .expect("Should not generate dummy uses without an input header");
+
+        try!(writeln!(dest, "/* automatically generated by rust-bindgen */"));
+        try!(writeln!(dest, ""));
+        try!(writeln!(dest, "#include \"{}\"", input_header));
+        try!(writeln!(dest, ""));
+
+        let type_items = ctx.whitelisted_items()
+            .map(|id| ctx.resolve_item(id))
+            .filter(|item| {
+                // We only want type items.
+                if let Some(ty) = item.kind().as_type() {
+                    // However, we don't want anonymous types, as we can't
+                    // generate dummy uses for them.
+                    ty.name().is_some() &&
+                        // Nor do we want builtin types or named template type
+                        // arguments. Again, we can't generate dummy uses for
+                        // these.
+                        !ty.is_builtin_or_named() &&
+                        // And finally, we won't be creating any dummy
+                        // specializations, so ignore template declarations and
+                        // partial specializations.
+                        item.applicable_template_args(ctx).is_empty()
+                } else {
+                    false
+                }
+            })
+            .map(|item| namespaced_name(ctx, item))
+            .enumerate();
+
+        for (idx, name) in type_items {
+            try!(writeln!(dest, "void dummy{}({}*) {{ }}", idx, name));
+        }
+
+        Ok(())
+    })
+}