auto merge of rust-lang#17494 : aturon/rust/stabilize-mutable-slices,…

… r=alexcrichton

This commit is another in the series of vector slice API stabilization. The focus here is the *mutable* slice API.

Largely, this API inherits the stability attributes [previously assigned](rust-lang#16332) to the analogous methods on immutable slides. It also adds comments to a few `unstable` attributes that were previously missing them.

In addition, the commit adds several `_mut` variants of APIs that were missing:

- `init_mut`
- `head_mut`
- `tail_mut`
- `splitn_mut`
- `rsplitn_mut`

Some of the unsafe APIs -- `unsafe_set`, `init_elem`, and `copy_memory` -- were deprecated in favor of working through `as_mut_ptr`, to simplify the API surface.

Due to deprecations, this is a:

[breaking-change]

src/libcollections/dlist.rs

@@ -844,6 +844,7 @@ mod tests {
     }
 
     #[test]
+    #[allow(deprecated)]
     fn test_append() {
         {
             let mut m = DList::new();

src/libcollections/slice.rs

@@ -850,6 +850,16 @@ mod tests {
         assert_eq!(a.as_slice().head().unwrap(), &11);
     }
 
+    #[test]
+    fn test_head_mut() {
+        let mut a = vec![];
+        assert_eq!(a.as_mut_slice().head_mut(), None);
+        a = vec![11i];
+        assert_eq!(*a.as_mut_slice().head_mut().unwrap(), 11);
+        a = vec![11i, 12];
+        assert_eq!(*a.as_mut_slice().head_mut().unwrap(), 11);
+    }
+
     #[test]
     fn test_tail() {
         let mut a = vec![11i];
@@ -860,22 +870,39 @@ mod tests {
         assert_eq!(a.tail(), b);
     }
 
+    #[test]
+    fn test_tail_mut() {
+        let mut a = vec![11i];
+        let b: &mut [int] = &mut [];
+        assert!(a.as_mut_slice().tail_mut() == b);
+        a = vec![11i, 12];
+        let b: &mut [int] = &mut [12];
+        assert!(a.as_mut_slice().tail_mut() == b);
+    }
+
     #[test]
     #[should_fail]
     fn test_tail_empty() {
         let a: Vec<int> = vec![];
         a.tail();
     }
 
+    #[test]
+    #[should_fail]
+    fn test_tail_mut_empty() {
+        let mut a: Vec<int> = vec![];
+        a.as_mut_slice().tail_mut();
+    }
+
     #[test]
     #[allow(deprecated)]
     fn test_tailn() {
         let mut a = vec![11i, 12, 13];
-        let b: &[int] = &[11, 12, 13];
-        assert_eq!(a.tailn(0), b);
+        let b: &mut [int] = &mut [11, 12, 13];
+        assert!(a.tailn(0) == b);
         a = vec![11i, 12, 13];
-        let b: &[int] = &[13];
-        assert_eq!(a.tailn(2), b);
+        let b: &mut [int] = &mut [13];
+        assert!(a.tailn(2) == b);
     }
 
     #[test]
@@ -896,13 +923,30 @@ mod tests {
         assert_eq!(a.init(), b);
     }
 
+    #[test]
+    fn test_init_mut() {
+        let mut a = vec![11i];
+        let b: &mut [int] = &mut [];
+        assert!(a.as_mut_slice().init_mut() == b);
+        a = vec![11i, 12];
+        let b: &mut [int] = &mut [11];
+        assert!(a.as_mut_slice().init_mut() == b);
+    }
+
     #[test]
     #[should_fail]
     fn test_init_empty() {
         let a: Vec<int> = vec![];
         a.init();
     }
 
+    #[test]
+    #[should_fail]
+    fn test_init_mut_empty() {
+        let mut a: Vec<int> = vec![];
+        a.as_mut_slice().init_mut();
+    }
+
     #[test]
     #[allow(deprecated)]
     fn test_initn() {
@@ -932,6 +976,16 @@ mod tests {
         assert_eq!(a.as_slice().last().unwrap(), &12);
     }
 
+    #[test]
+    fn test_last_mut() {
+        let mut a = vec![];
+        assert_eq!(a.as_mut_slice().last_mut(), None);
+        a = vec![11i];
+        assert_eq!(*a.as_mut_slice().last_mut().unwrap(), 11);
+        a = vec![11i, 12];
+        assert_eq!(*a.as_mut_slice().last_mut().unwrap(), 12);
+    }
+
     #[test]
     fn test_slice() {
         // Test fixed length vector.
@@ -1077,6 +1131,7 @@ mod tests {
     }
 
     #[test]
+    #[allow(deprecated)]
     fn test_grow_set() {
         let mut v = vec![1i, 2, 3];
         v.grow_set(4u, &4, 5);
@@ -1610,6 +1665,7 @@ mod tests {
 
     #[test]
     #[should_fail]
+    #[allow(deprecated)]
     fn test_copy_memory_oob() {
         unsafe {
             let mut a = [1i, 2, 3, 4];
@@ -1793,6 +1849,26 @@ mod tests {
         assert_eq!(xs.splitn(1, |x| *x == 5).collect::<Vec<&[int]>>().as_slice(), splits);
     }
 
+    #[test]
+    fn test_splitnator_mut() {
+        let xs = &mut [1i,2,3,4,5];
+
+        let splits: &[&mut [int]] = &[&mut [1,2,3,4,5]];
+        assert_eq!(xs.splitn_mut(0, |x| *x % 2 == 0).collect::<Vec<&mut [int]>>().as_slice(),
+                   splits);
+        let splits: &[&mut [int]] = &[&mut [1], &mut [3,4,5]];
+        assert_eq!(xs.splitn_mut(1, |x| *x % 2 == 0).collect::<Vec<&mut [int]>>().as_slice(),
+                   splits);
+        let splits: &[&mut [int]] = &[&mut [], &mut [], &mut [], &mut [4,5]];
+        assert_eq!(xs.splitn_mut(3, |_| true).collect::<Vec<&mut [int]>>().as_slice(),
+                   splits);
+
+        let xs: &mut [int] = &mut [];
+        let splits: &[&mut [int]] = &[&mut []];
+        assert_eq!(xs.splitn_mut(1, |x| *x == 5).collect::<Vec<&mut [int]>>().as_slice(),
+                   splits);
+    }
+
     #[test]
     fn test_rsplitator() {
         let xs = &[1i,2,3,4,5];