hack: Use a local clone of refcell to not depend on borrow_state

This is the same that we do in components/style in servo.

5 files changed, 470 insertions, 6 deletions

diff --git a/src/gen.rs b/src/gen.rs
index d6b43ff9..4273e636 100644
--- a/src/gen.rs
+++ b/src/gen.rs
@@ -1,5 +1,5 @@
 use std;
-use std::cell::RefCell;
+use hacks::refcell::RefCell;
 use std::vec::Vec;
 use std::rc::Rc;
 use std::collections::HashMap;
diff --git a/src/hacks/refcell.rs b/src/hacks/refcell.rs
new file mode 100644
index 00000000..408e95d4
--- /dev/null
+++ b/src/hacks/refcell.rs
@@ -0,0 +1,464 @@
+// Copyright 2012-2014 The Rust Project Developers.
+// See http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+//! A fork of std::cell::RefCell that makes `as_unsafe_cell` usable on stable Rust.
+//!
+//! FIXME(https://github.com/rust-lang/rust/issues/27708): Remove this
+//! (revert commit f7f81e0ed0b62402db291e28a9bb16f7194ebf78 / PR #11835)
+//! when `std::cell::RefCell::as_unsafe_cell` is in Rust’s stable channel.
+
+#![allow(unsafe_code, dead_code)]
+
+use std::cell::{UnsafeCell, Cell};
+use std::cmp::Ordering;
+use std::ops::{Deref, DerefMut};
+
+/// A fork of std::cell::RefCell that makes `as_unsafe_cell` usable on stable Rust.
+///
+/// FIXME(https://github.com/rust-lang/rust/issues/27708): Remove this
+/// (revert commit f7f81e0ed0b62402db291e28a9bb16f7194ebf78 / PR #11835)
+/// when `std::cell::RefCell::as_unsafe_cell` is in Rust’s stable channel.
+#[derive(Debug)]
+pub struct RefCell<T: ?Sized> {
+    borrow: Cell<BorrowFlag>,
+    value: UnsafeCell<T>,
+}
+type BorrowFlag = usize;
+
+/// An enumeration of values returned from the `state` method on a `RefCell<T>`.
+#[derive(Copy, Clone, PartialEq, Eq, Debug)]
+pub enum BorrowState {
+    /// The cell is currently being read, there is at least one active `borrow`.
+    Reading,
+    /// The cell is currently being written to, there is an active `borrow_mut`.
+    Writing,
+    /// There are no outstanding borrows on this cell.
+    Unused,
+}
+
+// Values [1, MAX-1] represent the number of `Ref` active
+// (will not outgrow its range since `usize` is the size of the address space)
+const UNUSED: BorrowFlag = 0;
+const WRITING: BorrowFlag = !0;
+
+impl<T> RefCell<T> {
+    /// Creates a new `RefCell` containing `value`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::cell::RefCell;
+    ///
+    /// let c = RefCell::new(5);
+    /// ```
+    #[inline]
+    pub fn new(value: T) -> RefCell<T> {
+        RefCell {
+            value: UnsafeCell::new(value),
+            borrow: Cell::new(UNUSED),
+        }
+    }
+
+    /// Consumes the `RefCell`, returning the wrapped value.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::cell::RefCell;
+    ///
+    /// let c = RefCell::new(5);
+    ///
+    /// let five = c.into_inner();
+    /// ```
+    #[inline]
+    pub fn into_inner(self) -> T {
+        // Since this function takes `self` (the `RefCell`) by value, the
+        // compiler statically verifies that it is not currently borrowed.
+        // Therefore the following assertion is just a `debug_assert!`.
+        debug_assert!(self.borrow.get() == UNUSED);
+        unsafe { self.value.into_inner() }
+    }
+}
+
+impl<T: ?Sized> RefCell<T> {
+    /// Query the current state of this `RefCell`
+    ///
+    /// The returned value can be dispatched on to determine if a call to
+    /// `borrow` or `borrow_mut` would succeed.
+    #[inline]
+    pub fn borrow_state(&self) -> BorrowState {
+        match self.borrow.get() {
+            WRITING => BorrowState::Writing,
+            UNUSED => BorrowState::Unused,
+            _ => BorrowState::Reading,
+        }
+    }
+
+    /// Immutably borrows the wrapped value.
+    ///
+    /// The borrow lasts until the returned `Ref` exits scope. Multiple
+    /// immutable borrows can be taken out at the same time.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the value is currently mutably borrowed.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::cell::RefCell;
+    ///
+    /// let c = RefCell::new(5);
+    ///
+    /// let borrowed_five = c.borrow();
+    /// let borrowed_five2 = c.borrow();
+    /// ```
+    ///
+    /// An example of panic:
+    ///
+    /// ```
+    /// use std::cell::RefCell;
+    /// use std::thread;
+    ///
+    /// let result = thread::spawn(move || {
+    ///    let c = RefCell::new(5);
+    ///    let m = c.borrow_mut();
+    ///
+    ///    let b = c.borrow(); // this causes a panic
+    /// }).join();
+    ///
+    /// assert!(result.is_err());
+    /// ```
+    #[inline]
+    pub fn borrow(&self) -> Ref<T> {
+        match BorrowRef::new(&self.borrow) {
+            Some(b) => Ref {
+                value: unsafe { &*self.value.get() },
+                borrow: b,
+            },
+            None => panic!("RefCell<T> already mutably borrowed"),
+        }
+    }
+
+    /// Mutably borrows the wrapped value.
+    ///
+    /// The borrow lasts until the returned `RefMut` exits scope. The value
+    /// cannot be borrowed while this borrow is active.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the value is currently borrowed.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::cell::RefCell;
+    ///
+    /// let c = RefCell::new(5);
+    ///
+    /// *c.borrow_mut() = 7;
+    ///
+    /// assert_eq!(*c.borrow(), 7);
+    /// ```
+    ///
+    /// An example of panic:
+    ///
+    /// ```
+    /// use std::cell::RefCell;
+    /// use std::thread;
+    ///
+    /// let result = thread::spawn(move || {
+    ///    let c = RefCell::new(5);
+    ///    let m = c.borrow();
+    ///
+    ///    let b = c.borrow_mut(); // this causes a panic
+    /// }).join();
+    ///
+    /// assert!(result.is_err());
+    /// ```
+    #[inline]
+    pub fn borrow_mut(&self) -> RefMut<T> {
+        match BorrowRefMut::new(&self.borrow) {
+            Some(b) => RefMut {
+                value: unsafe { &mut *self.value.get() },
+                borrow: b,
+            },
+            None => panic!("RefCell<T> already borrowed"),
+        }
+    }
+
+    /// Returns a reference to the underlying `UnsafeCell`.
+    ///
+    /// This can be used to circumvent `RefCell`'s safety checks.
+    ///
+    /// This function is `unsafe` because `UnsafeCell`'s field is public.
+    #[inline]
+    pub unsafe fn as_unsafe_cell(&self) -> &UnsafeCell<T> {
+        &self.value
+    }
+
+    /// Returns a mutable reference to the underlying data.
+    ///
+    /// This call borrows `RefCell` mutably (at compile-time) so there is no
+    /// need for dynamic checks.
+    #[inline]
+    pub fn get_mut(&mut self) -> &mut T {
+        unsafe {
+            &mut *self.value.get()
+        }
+    }
+}
+
+unsafe impl<T: ?Sized> Send for RefCell<T> where T: Send {}
+
+impl<T: Clone> Clone for RefCell<T> {
+    #[inline]
+    fn clone(&self) -> RefCell<T> {
+        RefCell::new(self.borrow().clone())
+    }
+}
+
+impl<T: Default> Default for RefCell<T> {
+    #[inline]
+    fn default() -> RefCell<T> {
+        RefCell::new(Default::default())
+    }
+}
+
+impl<T: ?Sized + PartialEq> PartialEq for RefCell<T> {
+    #[inline]
+    fn eq(&self, other: &RefCell<T>) -> bool {
+        *self.borrow() == *other.borrow()
+    }
+}
+
+impl<T: ?Sized + Eq> Eq for RefCell<T> {}
+
+impl<T: ?Sized + PartialOrd> PartialOrd for RefCell<T> {
+    #[inline]
+    fn partial_cmp(&self, other: &RefCell<T>) -> Option<Ordering> {
+        self.borrow().partial_cmp(&*other.borrow())
+    }
+
+    #[inline]
+    fn lt(&self, other: &RefCell<T>) -> bool {
+        *self.borrow() < *other.borrow()
+    }
+
+    #[inline]
+    fn le(&self, other: &RefCell<T>) -> bool {
+        *self.borrow() <= *other.borrow()
+    }
+
+    #[inline]
+    fn gt(&self, other: &RefCell<T>) -> bool {
+        *self.borrow() > *other.borrow()
+    }
+
+    #[inline]
+    fn ge(&self, other: &RefCell<T>) -> bool {
+        *self.borrow() >= *other.borrow()
+    }
+}
+
+impl<T: ?Sized + Ord> Ord for RefCell<T> {
+    #[inline]
+    fn cmp(&self, other: &RefCell<T>) -> Ordering {
+        self.borrow().cmp(&*other.borrow())
+    }
+}
+
+struct BorrowRef<'b> {
+    borrow: &'b Cell<BorrowFlag>,
+}
+
+impl<'b> BorrowRef<'b> {
+    #[inline]
+    fn new(borrow: &'b Cell<BorrowFlag>) -> Option<BorrowRef<'b>> {
+        match borrow.get() {
+            WRITING => None,
+            b => {
+                borrow.set(b + 1);
+                Some(BorrowRef { borrow: borrow })
+            },
+        }
+    }
+}
+
+impl<'b> Drop for BorrowRef<'b> {
+    #[inline]
+    fn drop(&mut self) {
+        let borrow = self.borrow.get();
+        debug_assert!(borrow != WRITING && borrow != UNUSED);
+        self.borrow.set(borrow - 1);
+    }
+}
+
+impl<'b> Clone for BorrowRef<'b> {
+    #[inline]
+    fn clone(&self) -> BorrowRef<'b> {
+        // Since this Ref exists, we know the borrow flag
+        // is not set to WRITING.
+        let borrow = self.borrow.get();
+        debug_assert!(borrow != UNUSED);
+        // Prevent the borrow counter from overflowing.
+        assert!(borrow != WRITING);
+        self.borrow.set(borrow + 1);
+        BorrowRef { borrow: self.borrow }
+    }
+}
+
+/// Wraps a borrowed reference to a value in a `RefCell` box.
+/// A wrapper type for an immutably borrowed value from a `RefCell<T>`.
+///
+/// See the [module-level documentation](index.html) for more.
+pub struct Ref<'b, T: ?Sized + 'b> {
+    value: &'b T,
+    borrow: BorrowRef<'b>,
+}
+
+impl<'b, T: ?Sized> Deref for Ref<'b, T> {
+    type Target = T;
+
+    #[inline]
+    fn deref(&self) -> &T {
+        self.value
+    }
+}
+
+impl<'b, T: ?Sized> Ref<'b, T> {
+    /// Copies a `Ref`.
+    ///
+    /// The `RefCell` is already immutably borrowed, so this cannot fail.
+    ///
+    /// This is an associated function that needs to be used as
+    /// `Ref::clone(...)`.  A `Clone` implementation or a method would interfere
+    /// with the widespread use of `r.borrow().clone()` to clone the contents of
+    /// a `RefCell`.
+    #[inline]
+    pub fn clone(orig: &Ref<'b, T>) -> Ref<'b, T> {
+        Ref {
+            value: orig.value,
+            borrow: orig.borrow.clone(),
+        }
+    }
+
+    /// Make a new `Ref` for a component of the borrowed data.
+    ///
+    /// The `RefCell` is already immutably borrowed, so this cannot fail.
+    ///
+    /// This is an associated function that needs to be used as `Ref::map(...)`.
+    /// A method would interfere with methods of the same name on the contents
+    /// of a `RefCell` used through `Deref`.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use std::cell::{RefCell, Ref};
+    ///
+    /// let c = RefCell::new((5, 'b'));
+    /// let b1: Ref<(u32, char)> = c.borrow();
+    /// let b2: Ref<u32> = Ref::map(b1, |t| &t.0);
+    /// assert_eq!(*b2, 5)
+    /// ```
+    #[inline]
+    pub fn map<U: ?Sized, F>(orig: Ref<'b, T>, f: F) -> Ref<'b, U>
+        where F: FnOnce(&T) -> &U
+    {
+        Ref {
+            value: f(orig.value),
+            borrow: orig.borrow,
+        }
+    }
+}
+
+impl<'b, T: ?Sized> RefMut<'b, T> {
+    /// Make a new `RefMut` for a component of the borrowed data, e.g. an enum
+    /// variant.
+    ///
+    /// The `RefCell` is already mutably borrowed, so this cannot fail.
+    ///
+    /// This is an associated function that needs to be used as
+    /// `RefMut::map(...)`.  A method would interfere with methods of the same
+    /// name on the contents of a `RefCell` used through `Deref`.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use std::cell::{RefCell, RefMut};
+    ///
+    /// let c = RefCell::new((5, 'b'));
+    /// {
+    ///     let b1: RefMut<(u32, char)> = c.borrow_mut();
+    ///     let mut b2: RefMut<u32> = RefMut::map(b1, |t| &mut t.0);
+    ///     assert_eq!(*b2, 5);
+    ///     *b2 = 42;
+    /// }
+    /// assert_eq!(*c.borrow(), (42, 'b'));
+    /// ```
+    #[inline]
+    pub fn map<U: ?Sized, F>(orig: RefMut<'b, T>, f: F) -> RefMut<'b, U>
+        where F: FnOnce(&mut T) -> &mut U
+    {
+        RefMut {
+            value: f(orig.value),
+            borrow: orig.borrow,
+        }
+    }
+}
+
+struct BorrowRefMut<'b> {
+    borrow: &'b Cell<BorrowFlag>,
+}
+
+impl<'b> Drop for BorrowRefMut<'b> {
+    #[inline]
+    fn drop(&mut self) {
+        let borrow = self.borrow.get();
+        debug_assert!(borrow == WRITING);
+        self.borrow.set(UNUSED);
+    }
+}
+
+impl<'b> BorrowRefMut<'b> {
+    #[inline]
+    fn new(borrow: &'b Cell<BorrowFlag>) -> Option<BorrowRefMut<'b>> {
+        match borrow.get() {
+            UNUSED => {
+                borrow.set(WRITING);
+                Some(BorrowRefMut { borrow: borrow })
+            },
+            _ => None,
+        }
+    }
+}
+
+/// A wrapper type for a mutably borrowed value from a `RefCell<T>`.
+///
+/// See the [module-level documentation](index.html) for more.
+pub struct RefMut<'b, T: ?Sized + 'b> {
+    value: &'b mut T,
+    borrow: BorrowRefMut<'b>,
+}
+
+impl<'b, T: ?Sized> Deref for RefMut<'b, T> {
+    type Target = T;
+
+    #[inline]
+    fn deref(&self) -> &T {
+        self.value
+    }
+}
+
+impl<'b, T: ?Sized> DerefMut for RefMut<'b, T> {
+    #[inline]
+    fn deref_mut(&mut self) -> &mut T {
+        self.value
+    }
+}
diff --git a/src/lib.rs b/src/lib.rs
index be43ca58..d2d36307 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,7 +1,6 @@
 #![crate_name = "bindgen"]
 #![crate_type = "dylib"]
 #![feature(quote)]
-#![feature(borrow_state)]
 
 #![cfg_attr(feature = "clippy", feature(plugin))]
 #![cfg_attr(feature = "clippy", plugin(clippy))]
diff --git a/src/parser.rs b/src/parser.rs
index 3004eb40..12047213 100644
--- a/src/parser.rs
+++ b/src/parser.rs
@@ -1,7 +1,7 @@
 #![allow(non_upper_case_globals)]
 
 use std::collections::{HashMap, HashSet};
-use std::cell::RefCell;
+use hacks::refcell::RefCell;
 use std::rc::Rc;
 use std::path::Path;
 use std::cmp;
@@ -393,7 +393,7 @@ fn conv_decl_ty_resolving_typedefs(ctx: &mut ClangParserCtx,
             // We might incur in double borrows here. If that's the case, we're
             // already scanning the compinfo, and we'd get the args from the
             // ast.
-            use std::cell::BorrowState;
+            use hacks::refcell::BorrowState;
             if !args.is_empty() && ci.borrow_state() == BorrowState::Unused {
                 ci.borrow_mut().args = args;
 
@@ -607,7 +607,7 @@ fn visit_composite(cursor: &Cursor, parent: &Cursor,
                                                     is_class_typedef);
 
 
-            use std::cell::BorrowState;
+            use hacks::refcell::BorrowState;
             if let Some(child_ci) = ty.get_outermost_composite() {
                 if let BorrowState::Unused = child_ci.borrow_state() {
                     let mut child_ci = child_ci.borrow_mut();
diff --git a/src/types.rs b/src/types.rs
index 4527d710..a1d574f2 100644
--- a/src/types.rs
+++ b/src/types.rs
@@ -1,4 +1,5 @@
-use std::cell::{Cell, RefCell};
+use std::cell::Cell;
+use hacks::refcell::RefCell;
 use std::fmt;
 use std::rc::Rc;
 use std::collections::HashMap;