Use the generated root module via a relative path

We previously generated uses of the root module with absolute paths:

    use root;

However this only works if the generated bindings are the root of the
crate. If they were in some submodule then that path would not be
valid. They are now generated relative to the current module, like this:

    use self::super::super::root;

Fixes #96

10 files changed, 50 insertions, 28 deletions

diff --git a/libbindgen/src/codegen/mod.rs b/libbindgen/src/codegen/mod.rs
index ad9ac2de..7fa76d56 100644
--- a/libbindgen/src/codegen/mod.rs
+++ b/libbindgen/src/codegen/mod.rs
@@ -9,7 +9,7 @@ use ir::context::{BindgenContext, ItemId};
 use ir::enum_ty::{Enum, EnumVariant, EnumVariantValue};
 use ir::function::{Function, FunctionSig};
 use ir::int::IntKind;
-use ir::item::{Item, ItemCanonicalName, ItemCanonicalPath};
+use ir::item::{Item, ItemAncestors, ItemCanonicalName, ItemCanonicalPath};
 use ir::item_kind::ItemKind;
 use ir::layout::Layout;
 use ir::module::Module;
@@ -22,6 +22,7 @@ use std::borrow::Cow;
 use std::collections::HashSet;
 use std::collections::hash_map::{Entry, HashMap};
 use std::fmt::Write;
+use std::iter;
 use std::mem;
 use std::ops;
 use syntax::abi::Abi;
@@ -29,12 +30,33 @@ use syntax::ast;
 use syntax::codemap::{Span, respan};
 use syntax::ptr::P;
 
-fn root_import(ctx: &BindgenContext) -> P<ast::Item> {
+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);
-    quote_item!(ctx.ext_cx(), #[allow(unused_imports)] use $root_ident;)
-        .unwrap()
+
+    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 {
@@ -286,7 +308,7 @@ impl CodeGenerator for Module {
 
         let mut found_any = false;
         let inner_items = result.inner(|result| {
-            result.push(root_import(ctx));
+            result.push(root_import(ctx, item));
             codegen_self(result, &mut found_any);
         });
 
diff --git a/libbindgen/tests/expectations/tests/duplicated-namespaces-definitions.rs b/libbindgen/tests/expectations/tests/duplicated-namespaces-definitions.rs
index 314a24a3..da06a2a9 100644
--- a/libbindgen/tests/expectations/tests/duplicated-namespaces-definitions.rs
+++ b/libbindgen/tests/expectations/tests/duplicated-namespaces-definitions.rs
@@ -6,10 +6,10 @@
 
 pub mod root {
     #[allow(unused_imports)]
-    use root;
+    use self::super::root;
     pub mod foo {
         #[allow(unused_imports)]
-        use root;
+        use self::super::super::root;
         #[repr(C)]
         #[derive(Debug, Copy)]
         pub struct Bar {
@@ -27,7 +27,7 @@ pub mod root {
     }
     pub mod bar {
         #[allow(unused_imports)]
-        use root;
+        use self::super::super::root;
         #[repr(C)]
         #[derive(Debug, Copy)]
         pub struct Foo {
diff --git a/libbindgen/tests/expectations/tests/duplicated-namespaces.rs b/libbindgen/tests/expectations/tests/duplicated-namespaces.rs
index 7a283160..42976657 100644
--- a/libbindgen/tests/expectations/tests/duplicated-namespaces.rs
+++ b/libbindgen/tests/expectations/tests/duplicated-namespaces.rs
@@ -6,5 +6,5 @@
 
 pub mod root {
     #[allow(unused_imports)]
-    use root;
+    use self::super::root;
 }
diff --git a/libbindgen/tests/expectations/tests/duplicated_constants_in_ns.rs b/libbindgen/tests/expectations/tests/duplicated_constants_in_ns.rs
index 3acc53e8..3721740c 100644
--- a/libbindgen/tests/expectations/tests/duplicated_constants_in_ns.rs
+++ b/libbindgen/tests/expectations/tests/duplicated_constants_in_ns.rs
@@ -6,15 +6,15 @@
 
 pub mod root {
     #[allow(unused_imports)]
-    use root;
+    use self::super::root;
     pub mod foo {
         #[allow(unused_imports)]
-        use root;
+        use self::super::super::root;
         pub const FOO: ::std::os::raw::c_int = 4;
     }
     pub mod bar {
         #[allow(unused_imports)]
-        use root;
+        use self::super::super::root;
         pub const FOO: ::std::os::raw::c_int = 5;
     }
 }
diff --git a/libbindgen/tests/expectations/tests/module-whitelisted.rs b/libbindgen/tests/expectations/tests/module-whitelisted.rs
index 7e63c8c8..6f88c54b 100644
--- a/libbindgen/tests/expectations/tests/module-whitelisted.rs
+++ b/libbindgen/tests/expectations/tests/module-whitelisted.rs
@@ -6,7 +6,7 @@
 
 pub mod root {
     #[allow(unused_imports)]
-    use root;
+    use self::super::root;
     #[repr(C)]
     #[derive(Debug, Copy)]
     pub struct Test {
diff --git a/libbindgen/tests/expectations/tests/namespace.rs b/libbindgen/tests/expectations/tests/namespace.rs
index 34c2da1e..3d6e5974 100644
--- a/libbindgen/tests/expectations/tests/namespace.rs
+++ b/libbindgen/tests/expectations/tests/namespace.rs
@@ -6,14 +6,14 @@
 
 pub mod root {
     #[allow(unused_imports)]
-    use root;
+    use self::super::root;
     extern "C" {
         #[link_name = "_Z9top_levelv"]
         pub fn top_level();
     }
     pub mod whatever {
         #[allow(unused_imports)]
-        use root;
+        use self::super::super::root;
         pub type whatever_int_t = ::std::os::raw::c_int;
         extern "C" {
             #[link_name = "_ZN8whatever11in_whateverEv"]
@@ -22,7 +22,7 @@ pub mod root {
     }
     pub mod _bindgen_mod_id_13 {
         #[allow(unused_imports)]
-        use root;
+        use self::super::super::root;
         extern "C" {
             #[link_name = "_ZN12_GLOBAL__N_13fooEv"]
             pub fn foo();
@@ -51,7 +51,7 @@ pub mod root {
     }
     pub mod w {
         #[allow(unused_imports)]
-        use root;
+        use self::super::super::root;
         pub type whatever_int_t = ::std::os::raw::c_uint;
         #[repr(C)]
         #[derive(Debug)]
diff --git a/libbindgen/tests/expectations/tests/nested_within_namespace.rs b/libbindgen/tests/expectations/tests/nested_within_namespace.rs
index 949b5adb..0c9c31ef 100644
--- a/libbindgen/tests/expectations/tests/nested_within_namespace.rs
+++ b/libbindgen/tests/expectations/tests/nested_within_namespace.rs
@@ -6,10 +6,10 @@
 
 pub mod root {
     #[allow(unused_imports)]
-    use root;
+    use self::super::root;
     pub mod foo {
         #[allow(unused_imports)]
-        use root;
+        use self::super::super::root;
         #[repr(C)]
         #[derive(Debug, Copy)]
         pub struct Bar {
diff --git a/libbindgen/tests/expectations/tests/template_alias_namespace.rs b/libbindgen/tests/expectations/tests/template_alias_namespace.rs
index 36806d44..cf4a079c 100644
--- a/libbindgen/tests/expectations/tests/template_alias_namespace.rs
+++ b/libbindgen/tests/expectations/tests/template_alias_namespace.rs
@@ -6,13 +6,13 @@
 
 pub mod root {
     #[allow(unused_imports)]
-    use root;
+    use self::super::root;
     pub mod JS {
         #[allow(unused_imports)]
-        use root;
+        use self::super::super::root;
         pub mod detail {
             #[allow(unused_imports)]
-            use root;
+            use self::super::super::super::root;
             pub type Wrapped<T> = T;
         }
         #[repr(C)]
diff --git a/libbindgen/tests/expectations/tests/whitelist-namespaces-basic.rs b/libbindgen/tests/expectations/tests/whitelist-namespaces-basic.rs
index 8806cbf4..cbb12f6b 100644
--- a/libbindgen/tests/expectations/tests/whitelist-namespaces-basic.rs
+++ b/libbindgen/tests/expectations/tests/whitelist-namespaces-basic.rs
@@ -6,13 +6,13 @@
 
 pub mod root {
     #[allow(unused_imports)]
-    use root;
+    use self::super::root;
     pub mod outer {
         #[allow(unused_imports)]
-        use root;
+        use self::super::super::root;
         pub mod inner {
             #[allow(unused_imports)]
-            use root;
+            use self::super::super::super::root;
             #[repr(C)]
             #[derive(Debug, Copy)]
             pub struct Helper {
diff --git a/libbindgen/tests/expectations/tests/whitelist-namespaces.rs b/libbindgen/tests/expectations/tests/whitelist-namespaces.rs
index 42cccdee..bc257af6 100644
--- a/libbindgen/tests/expectations/tests/whitelist-namespaces.rs
+++ b/libbindgen/tests/expectations/tests/whitelist-namespaces.rs
@@ -6,13 +6,13 @@
 
 pub mod root {
     #[allow(unused_imports)]
-    use root;
+    use self::super::root;
     pub mod outer {
         #[allow(unused_imports)]
-        use root;
+        use self::super::super::root;
         pub mod inner {
             #[allow(unused_imports)]
-            use root;
+            use self::super::super::super::root;
             #[repr(C)]
             #[derive(Debug, Copy)]
             pub struct Helper {