auto merge of #6337 : thestinger/rust/fix_region, r=thestinger

also removes unnecessary casts from the RcMut implementation

Author: bors

doc/tutorial-ffi.md

@@ -157,7 +157,7 @@ pub struct Unique<T> {
     priv ptr: *mut T
 }
 
-pub impl<'self, T: Owned> Unique<T> {
+pub impl<T: Owned> Unique<T> {
     fn new(value: T) -> Unique<T> {
         unsafe {
             let ptr = malloc(core::sys::size_of::<T>() as size_t) as *mut T;
@@ -168,14 +168,14 @@ pub impl<'self, T: Owned> Unique<T> {
         }
     }
 
-    // the 'self lifetime results in the same semantics as `&*x` with ~T
-    fn borrow(&self) -> &'self T {
-        unsafe { cast::transmute(self.ptr) }
+    // the 'r lifetime results in the same semantics as `&*x` with ~T
+    fn borrow<'r>(&'r self) -> &'r T {
+        unsafe { cast::copy_lifetime(self, &*self.ptr) }
     }
 
-    // the 'self lifetime results in the same semantics as `&mut *x` with ~T
-    fn borrow_mut(&mut self) -> &'self mut T {
-        unsafe { cast::transmute(self.ptr) }
+    // the 'r lifetime results in the same semantics as `&mut *x` with ~T
+    fn borrow_mut<'r>(&'r mut self) -> &'r mut T {
+        unsafe { cast::copy_mut_lifetime(self, &mut *self.ptr) }
     }
 }
 

src/libcore/cast.rs

@@ -108,6 +108,12 @@ pub unsafe fn copy_lifetime<'a,S,T>(_ptr: &'a S, ptr: &T) -> &'a T {
     transmute_region(ptr)
 }
 
+/// Transforms lifetime of the second pointer to match the first.
+#[inline(always)]
+pub unsafe fn copy_mut_lifetime<'a,S,T>(_ptr: &'a mut S, ptr: &mut T) -> &'a mut T {
+    transmute_mut_region(ptr)
+}
+
 /// Transforms lifetime of the second pointer to match the first.
 #[inline(always)]
 pub unsafe fn copy_lifetime_vec<'a,S,T>(_ptr: &'a [S], ptr: &T) -> &'a T {

src/libstd/rc.rs

@@ -29,7 +29,7 @@ pub struct Rc<T> {
     priv ptr: *mut RcBox<T>,
 }
 
-pub impl<'self, T: Owned> Rc<T> {
+pub impl<T: Owned> Rc<T> {
     fn new(value: T) -> Rc<T> {
         unsafe {
             let ptr = malloc(sys::size_of::<RcBox<T>>() as size_t) as *mut RcBox<T>;
@@ -40,8 +40,8 @@ pub impl<'self, T: Owned> Rc<T> {
     }
 
     #[inline(always)]
-    fn borrow(&self) -> &'self T {
-        unsafe { cast::transmute_region(&(*self.ptr).value) }
+    fn borrow<'r>(&'r self) -> &'r T {
+        unsafe { cast::copy_lifetime(self, &(*self.ptr).value) }
     }
 }
 
@@ -119,7 +119,7 @@ pub struct RcMut<T> {
     priv ptr: *mut RcMutBox<T>,
 }
 
-pub impl<'self, T: Owned> RcMut<T> {
+pub impl<T: Owned> RcMut<T> {
     fn new(value: T) -> RcMut<T> {
         unsafe {
             let ptr = malloc(sys::size_of::<RcMutBox<T>>() as size_t) as *mut RcMutBox<T>;
@@ -136,7 +136,7 @@ pub impl<'self, T: Owned> RcMut<T> {
             assert!((*self.ptr).borrow != Mutable);
             let previous = (*self.ptr).borrow;
             (*self.ptr).borrow = Immutable;
-            f(cast::transmute_region(&(*self.ptr).value));
+            f(&(*self.ptr).value);
             (*self.ptr).borrow = previous;
         }
     }
@@ -147,7 +147,7 @@ pub impl<'self, T: Owned> RcMut<T> {
         unsafe {
             assert!((*self.ptr).borrow == Nothing);
             (*self.ptr).borrow = Mutable;
-            f(cast::transmute_mut_region(&mut (*self.ptr).value));
+            f(&mut (*self.ptr).value);
             (*self.ptr).borrow = Nothing;
         }
     }