auto merge of #12143 : brson/rust/swap, r=alexcrichton

Thinking about swap as an example of unsafe programming. This cleans it up a bit. It also removes type parametrization over `RawPtr` from the memcpy functions to make this compile.

Author: bors

src/libstd/cast.rs

@@ -10,7 +10,6 @@
 
 //! Unsafe casting functions
 
-use ptr::RawPtr;
 use mem;
 use unstable::intrinsics;
 use ptr::copy_nonoverlapping_memory;
@@ -72,13 +71,13 @@ pub unsafe fn transmute_region<'a,'b,T>(ptr: &'a T) -> &'b T {
 
 /// Coerce an immutable reference to be mutable.
 #[inline]
-pub unsafe fn transmute_mut_unsafe<T,P:RawPtr<T>>(ptr: P) -> *mut T {
+pub unsafe fn transmute_mut_unsafe<T>(ptr: *T) -> *mut T {
     transmute(ptr)
 }
 
 /// Coerce an immutable reference to be mutable.
 #[inline]
-pub unsafe fn transmute_immut_unsafe<T,P:RawPtr<T>>(ptr: P) -> *T {
+pub unsafe fn transmute_immut_unsafe<T>(ptr: *mut T) -> *T {
     transmute(ptr)
 }
 

src/libstd/ptr.rs

@@ -92,8 +92,8 @@ pub fn is_not_null<T,P:RawPtr<T>>(ptr: P) -> bool { ptr.is_not_null() }
  * and destination may overlap.
  */
 #[inline]
-pub unsafe fn copy_memory<T,P:RawPtr<T>>(dst: *mut T, src: P, count: uint) {
-    intrinsics::copy_memory(dst, cast::transmute_immut_unsafe(src), count)
+pub unsafe fn copy_memory<T>(dst: *mut T, src: *T, count: uint) {
+    intrinsics::copy_memory(dst, src, count)
 }
 
 /**
@@ -103,10 +103,10 @@ pub unsafe fn copy_memory<T,P:RawPtr<T>>(dst: *mut T, src: P, count: uint) {
  * and destination may *not* overlap.
  */
 #[inline]
-pub unsafe fn copy_nonoverlapping_memory<T,P:RawPtr<T>>(dst: *mut T,
-                                                        src: P,
-                                                        count: uint) {
-    intrinsics::copy_nonoverlapping_memory(dst, cast::transmute_immut_unsafe(src), count)
+pub unsafe fn copy_nonoverlapping_memory<T>(dst: *mut T,
+                                            src: *T,
+                                            count: uint) {
+    intrinsics::copy_nonoverlapping_memory(dst, src, count)
 }
 
 /**
@@ -137,9 +137,9 @@ pub unsafe fn swap_ptr<T>(x: *mut T, y: *mut T) {
     let t: *mut T = &mut tmp;
 
     // Perform the swap
-    copy_nonoverlapping_memory(t, x, 1);
-    copy_memory(x, y, 1); // `x` and `y` may overlap
-    copy_nonoverlapping_memory(y, t, 1);
+    copy_nonoverlapping_memory(t, &*x, 1);
+    copy_memory(x, &*y, 1); // `x` and `y` may overlap
+    copy_nonoverlapping_memory(y, &*t, 1);
 
     // y and t now point to the same thing, but we need to completely forget `tmp`
     // because it's no longer relevant.

src/libstd/util.rs

@@ -26,19 +26,16 @@ pub fn id<T>(x: T) -> T { x }
 pub fn swap<T>(x: &mut T, y: &mut T) {
     unsafe {
         // Give ourselves some scratch space to work with
-        let mut tmp: T = mem::uninit();
-        let t: *mut T = &mut tmp;
+        let mut t: T = mem::uninit();
 
         // Perform the swap, `&mut` pointers never alias
-        let x_raw: *mut T = x;
-        let y_raw: *mut T = y;
-        ptr::copy_nonoverlapping_memory(t, x_raw, 1);
-        ptr::copy_nonoverlapping_memory(x, y_raw, 1);
-        ptr::copy_nonoverlapping_memory(y, t, 1);
+        ptr::copy_nonoverlapping_memory(&mut t, &*x, 1);
+        ptr::copy_nonoverlapping_memory(x, &*y, 1);
+        ptr::copy_nonoverlapping_memory(y, &t, 1);
 
         // y and t now point to the same thing, but we need to completely forget `tmp`
         // because it's no longer relevant.
-        cast::forget(tmp);
+        cast::forget(t);
     }
 }
 

src/libstd/vec.rs

@@ -1548,7 +1548,7 @@ impl<T> OwnedVector<T> for ~[T] {
             let p = self.as_mut_ptr().offset(i as int);
             // Shift everything over to make space. (Duplicating the
             // `i`th element into two consecutive places.)
-            ptr::copy_memory(p.offset(1), p, len - i);
+            ptr::copy_memory(p.offset(1), &*p, len - i);
             // Write it in, overwriting the first copy of the `i`th
             // element.
             mem::move_val_init(&mut *p, x);
@@ -1567,7 +1567,7 @@ impl<T> OwnedVector<T> for ~[T] {
                 let ret = Some(ptr::read_ptr(ptr as *T));
 
                 // Shift everything down to fill in that spot.
-                ptr::copy_memory(ptr, ptr.offset(1), len - i - 1);
+                ptr::copy_memory(ptr, &*ptr.offset(1), len - i - 1);
                 self.set_len(len - 1);
 
                 ret
@@ -1842,7 +1842,7 @@ fn insertion_sort<T>(v: &mut [T], compare: |&T, &T| -> Ordering) {
             if i != j {
                 let tmp = ptr::read_ptr(read_ptr);
                 ptr::copy_memory(buf_v.offset(j + 1),
-                                 buf_v.offset(j),
+                                 &*buf_v.offset(j),
                                  (i - j) as uint);
                 ptr::copy_nonoverlapping_memory(buf_v.offset(j),
                                                 &tmp as *T,
@@ -1920,7 +1920,7 @@ fn merge_sort<T>(v: &mut [T], compare: |&T, &T| -> Ordering) {
                 // that case, `i == j` so we don't copy. The
                 // `.offset(j)` is always in bounds.
                 ptr::copy_memory(buf_dat.offset(j + 1),
-                                 buf_dat.offset(j),
+                                 &*buf_dat.offset(j),
                                  i - j as uint);
                 ptr::copy_nonoverlapping_memory(buf_dat.offset(j), read_ptr, 1);
             }
@@ -1970,11 +1970,11 @@ fn merge_sort<T>(v: &mut [T], compare: |&T, &T| -> Ordering) {
                     if left == right_start {
                         // the number remaining in this run.
                         let elems = (right_end as uint - right as uint) / mem::size_of::<T>();
-                        ptr::copy_nonoverlapping_memory(out, right, elems);
+                        ptr::copy_nonoverlapping_memory(out, &*right, elems);
                         break;
                     } else if right == right_end {
                         let elems = (right_start as uint - left as uint) / mem::size_of::<T>();
-                        ptr::copy_nonoverlapping_memory(out, left, elems);
+                        ptr::copy_nonoverlapping_memory(out, &*left, elems);
                         break;
                     }
 
@@ -1988,7 +1988,7 @@ fn merge_sort<T>(v: &mut [T], compare: |&T, &T| -> Ordering) {
                     } else {
                         step(&mut left)
                     };
-                    ptr::copy_nonoverlapping_memory(out, to_copy, 1);
+                    ptr::copy_nonoverlapping_memory(out, &*to_copy, 1);
                     step(&mut out);
                 }
             }
@@ -2002,7 +2002,7 @@ fn merge_sort<T>(v: &mut [T], compare: |&T, &T| -> Ordering) {
     // write the result to `v` in one go, so that there are never two copies
     // of the same object in `v`.
     unsafe {
-        ptr::copy_nonoverlapping_memory(v.as_mut_ptr(), buf_dat, len);
+        ptr::copy_nonoverlapping_memory(v.as_mut_ptr(), &*buf_dat, len);
     }
 
     // increment the pointer, returning the old pointer.