Adjust Index/IndexMut impls. For generic collections, we take

references. For collections whose keys are integers, we take both
references and by-value.

src/libcollections/btree/map.rs

@@ -914,12 +914,27 @@ impl<K: Debug, V: Debug> Debug for BTreeMap<K, V> {
     }
 }
 
+#[cfg(stage0)]
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<K: Ord, Q: ?Sized, V> Index<Q> for BTreeMap<K, V>
     where K: Borrow<Q>, Q: Ord
 {
     type Output = V;
 
+    #[inline]
+    fn index(&self, key: &Q) -> &V {
+        self.get(key).expect("no entry found for key")
+    }
+}
+
+#[cfg(not(stage0))]
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<'a, K: Ord, Q: ?Sized, V> Index<&'a Q> for BTreeMap<K, V>
+    where K: Borrow<Q>, Q: Ord
+{
+    type Output = V;
+
+    #[inline]
     fn index(&self, key: &Q) -> &V {
         self.get(key).expect("no entry found for key")
     }

src/libcollections/string.rs

@@ -870,34 +870,66 @@ impl<'a> Add<&'a str> for String {
 #[stable(feature = "rust1", since = "1.0.0")]
 impl ops::Index<ops::Range<usize>> for String {
     type Output = str;
+
+    #[cfg(stage0)]
     #[inline]
     fn index(&self, index: &ops::Range<usize>) -> &str {
         &self[..][*index]
     }
+
+    #[cfg(not(stage0))]
+    #[inline]
+    fn index(&self, index: ops::Range<usize>) -> &str {
+        &self[..][index]
+    }
 }
 #[stable(feature = "rust1", since = "1.0.0")]
 impl ops::Index<ops::RangeTo<usize>> for String {
     type Output = str;
+
+    #[cfg(stage0)]
     #[inline]
     fn index(&self, index: &ops::RangeTo<usize>) -> &str {
         &self[..][*index]
     }
+
+    #[cfg(not(stage0))]
+    #[inline]
+    fn index(&self, index: ops::RangeTo<usize>) -> &str {
+        &self[..][index]
+    }
 }
 #[stable(feature = "rust1", since = "1.0.0")]
 impl ops::Index<ops::RangeFrom<usize>> for String {
     type Output = str;
+
+    #[cfg(stage0)]
     #[inline]
     fn index(&self, index: &ops::RangeFrom<usize>) -> &str {
         &self[..][*index]
     }
+
+    #[cfg(not(stage0))]
+    #[inline]
+    fn index(&self, index: ops::RangeFrom<usize>) -> &str {
+        &self[..][index]
+    }
 }
 #[stable(feature = "rust1", since = "1.0.0")]
 impl ops::Index<ops::RangeFull> for String {
     type Output = str;
+
+    #[cfg(stage0)]
     #[inline]
     fn index(&self, _index: &ops::RangeFull) -> &str {
         unsafe { mem::transmute(&*self.vec) }
     }
+
+    #[cfg(not(stage0))]
+    #[inline]
+    fn index(&self, _index: ops::RangeFull) -> &str {
+        unsafe { mem::transmute(&*self.vec) }
+    }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]

src/libcollections/vec.rs

@@ -1323,83 +1323,165 @@ impl<T: Hash> Hash for Vec<T> {
 impl<T> Index<usize> for Vec<T> {
     type Output = T;
 
+
+    #[cfg(stage0)]
     #[inline]
     fn index(&self, index: &usize) -> &T {
         // NB built-in indexing via `&[T]`
         &(**self)[*index]
     }
+
+    #[cfg(not(stage0))]
+    #[inline]
+    fn index(&self, index: usize) -> &T {
+        // NB built-in indexing via `&[T]`
+        &(**self)[index]
+    }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T> IndexMut<usize> for Vec<T> {
+
+    #[cfg(stage0)]
     #[inline]
     fn index_mut(&mut self, index: &usize) -> &mut T {
         // NB built-in indexing via `&mut [T]`
         &mut (**self)[*index]
     }
+
+    #[cfg(not(stage0))]
+    #[inline]
+    fn index_mut(&mut self, index: usize) -> &mut T {
+        // NB built-in indexing via `&mut [T]`
+        &mut (**self)[index]
+    }
 }
 
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T> ops::Index<ops::Range<usize>> for Vec<T> {
     type Output = [T];
+
+    #[cfg(stage0)]
     #[inline]
     fn index(&self, index: &ops::Range<usize>) -> &[T] {
         Index::index(&**self, index)
     }
+
+    #[cfg(not(stage0))]
+    #[inline]
+    fn index(&self, index: ops::Range<usize>) -> &[T] {
+        Index::index(&**self, index)
+    }
 }
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T> ops::Index<ops::RangeTo<usize>> for Vec<T> {
     type Output = [T];
+
+    #[cfg(stage0)]
     #[inline]
     fn index(&self, index: &ops::RangeTo<usize>) -> &[T] {
         Index::index(&**self, index)
     }
+
+    #[cfg(not(stage0))]
+    #[inline]
+    fn index(&self, index: ops::RangeTo<usize>) -> &[T] {
+        Index::index(&**self, index)
+    }
 }
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T> ops::Index<ops::RangeFrom<usize>> for Vec<T> {
     type Output = [T];
+
+    #[cfg(stage0)]
     #[inline]
     fn index(&self, index: &ops::RangeFrom<usize>) -> &[T] {
         Index::index(&**self, index)
     }
+
+    #[cfg(not(stage0))]
+    #[inline]
+    fn index(&self, index: ops::RangeFrom<usize>) -> &[T] {
+        Index::index(&**self, index)
+    }
 }
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T> ops::Index<ops::RangeFull> for Vec<T> {
     type Output = [T];
+
+    #[cfg(stage0)]
     #[inline]
     fn index(&self, _index: &ops::RangeFull) -> &[T] {
         self.as_slice()
     }
+
+    #[cfg(not(stage0))]
+    #[inline]
+    fn index(&self, _index: ops::RangeFull) -> &[T] {
+        self.as_slice()
+    }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T> ops::IndexMut<ops::Range<usize>> for Vec<T> {
+
+    #[cfg(stage0)]
     #[inline]
     fn index_mut(&mut self, index: &ops::Range<usize>) -> &mut [T] {
         IndexMut::index_mut(&mut **self, index)
     }
+
+    #[cfg(not(stage0))]
+    #[inline]
+    fn index_mut(&mut self, index: ops::Range<usize>) -> &mut [T] {
+        IndexMut::index_mut(&mut **self, index)
+    }
 }
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T> ops::IndexMut<ops::RangeTo<usize>> for Vec<T> {
+
+    #[cfg(stage0)]
     #[inline]
     fn index_mut(&mut self, index: &ops::RangeTo<usize>) -> &mut [T] {
         IndexMut::index_mut(&mut **self, index)
     }
+
+    #[cfg(not(stage0))]
+    #[inline]
+    fn index_mut(&mut self, index: ops::RangeTo<usize>) -> &mut [T] {
+        IndexMut::index_mut(&mut **self, index)
+    }
 }
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T> ops::IndexMut<ops::RangeFrom<usize>> for Vec<T> {
+
+    #[cfg(stage0)]
     #[inline]
     fn index_mut(&mut self, index: &ops::RangeFrom<usize>) -> &mut [T] {
         IndexMut::index_mut(&mut **self, index)
     }
+
+    #[cfg(not(stage0))]
+    #[inline]
+    fn index_mut(&mut self, index: ops::RangeFrom<usize>) -> &mut [T] {
+        IndexMut::index_mut(&mut **self, index)
+    }
 }
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T> ops::IndexMut<ops::RangeFull> for Vec<T> {
+
+    #[cfg(stage0)]
     #[inline]
     fn index_mut(&mut self, _index: &ops::RangeFull) -> &mut [T] {
         self.as_mut_slice()
     }
+
+    #[cfg(not(stage0))]
+    #[inline]
+    fn index_mut(&mut self, _index: ops::RangeFull) -> &mut [T] {
+        self.as_mut_slice()
+    }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]

src/libcollections/vec_deque.rs

@@ -1689,18 +1689,32 @@ impl<A: Hash> Hash for VecDeque<A> {
 impl<A> Index<usize> for VecDeque<A> {
     type Output = A;
 
+    #[cfg(stage0)]
     #[inline]
     fn index(&self, i: &usize) -> &A {
         self.get(*i).expect("Out of bounds access")
     }
+
+    #[cfg(not(stage0))]
+    #[inline]
+    fn index(&self, i: usize) -> &A {
+        self.get(i).expect("Out of bounds access")
+    }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<A> IndexMut<usize> for VecDeque<A> {
+    #[cfg(stage0)]
     #[inline]
     fn index_mut(&mut self, i: &usize) -> &mut A {
         self.get_mut(*i).expect("Out of bounds access")
     }
+
+    #[cfg(not(stage0))]
+    #[inline]
+    fn index_mut(&mut self, i: usize) -> &mut A {
+        self.get_mut(i).expect("Out of bounds access")
+    }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]

src/libcollections/vec_map.rs

@@ -798,6 +798,7 @@ impl<V> Extend<(usize, V)> for VecMap<V> {
     }
 }
 
+#[cfg(stage0)]
 impl<V> Index<usize> for VecMap<V> {
     type Output = V;
 
@@ -807,10 +808,49 @@ impl<V> Index<usize> for VecMap<V> {
     }
 }
 
+#[cfg(not(stage0))]
+impl<V> Index<usize> for VecMap<V> {
+    type Output = V;
+
+    #[inline]
+    fn index<'a>(&'a self, i: usize) -> &'a V {
+        self.get(&i).expect("key not present")
+    }
+}
+
+#[cfg(not(stage0))]
+impl<'a,V> Index<&'a usize> for VecMap<V> {
+    type Output = V;
+
+    #[inline]
+    fn index(&self, i: &usize) -> &V {
+        self.get(i).expect("key not present")
+    }
+}
+
+#[cfg(stage0)]
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<V> IndexMut<usize> for VecMap<V> {
     #[inline]
-    fn index_mut<'a>(&'a mut self, i: &usize) -> &'a mut V {
+    fn index_mut(&mut self, i: &usize) -> &mut V {
+        self.get_mut(&i).expect("key not present")
+    }
+}
+
+#[cfg(not(stage0))]
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<V> IndexMut<usize> for VecMap<V> {
+    #[inline]
+    fn index_mut(&mut self, i: usize) -> &mut V {
+        self.get_mut(&i).expect("key not present")
+    }
+}
+
+#[cfg(not(stage0))]
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<'a, V> IndexMut<&'a usize> for VecMap<V> {
+    #[inline]
+    fn index_mut(&mut self, i: &usize) -> &mut V {
         self.get_mut(i).expect("key not present")
     }
 }

src/libcore/ops.rs

@@ -898,7 +898,7 @@ shr_impl_all! { u8 u16 u32 u64 usize i8 i16 i32 i64 isize }
 /// impl Index<Bar> for Foo {
 ///     type Output = Foo;
 ///
-///     fn index<'a>(&'a self, _index: &Bar) -> &'a Foo {
+///     fn index<'a>(&'a self, _index: Bar) -> &'a Foo {
 ///         println!("Indexing!");
 ///         self
 ///     }
@@ -945,13 +945,13 @@ pub trait Index<Idx: ?Sized> {
 /// impl Index<Bar> for Foo {
 ///     type Output = Foo;
 ///
-///     fn index<'a>(&'a self, _index: &Bar) -> &'a Foo {
+///     fn index<'a>(&'a self, _index: Bar) -> &'a Foo {
 ///         self
 ///     }
 /// }
 ///
 /// impl IndexMut<Bar> for Foo {
-///     fn index_mut<'a>(&'a mut self, _index: &Bar) -> &'a mut Foo {
+///     fn index_mut<'a>(&'a mut self, _index: Bar) -> &'a mut Foo {
 ///         println!("Indexing!");
 ///         self
 ///     }

src/libcore/slice.rs

@@ -263,6 +263,7 @@ impl<T> SliceExt for [T] {
     #[inline]
     fn as_mut_slice(&mut self) -> &mut [T] { self }
 
+    #[cfg(stage0)]
     #[inline]
     fn split_at_mut(&mut self, mid: usize) -> (&mut [T], &mut [T]) {
         unsafe {
@@ -273,6 +274,17 @@ impl<T> SliceExt for [T] {
         }
     }
 
+    #[cfg(not(stage0))]
+    #[inline]
+    fn split_at_mut(&mut self, mid: usize) -> (&mut [T], &mut [T]) {
+        unsafe {
+            let self2: &mut [T] = mem::transmute_copy(&self);
+
+            (ops::IndexMut::index_mut(self, ops::RangeTo { end: mid } ),
+             ops::IndexMut::index_mut(self2, ops::RangeFrom { start: mid } ))
+        }
+    }
+
     #[inline]
     fn iter_mut<'a>(&'a mut self) -> IterMut<'a, T> {
         unsafe {
@@ -495,25 +507,45 @@ impl<T> SliceExt for [T] {
 impl<T> ops::Index<usize> for [T] {
     type Output = T;
 
+    #[cfg(stage0)]
     fn index(&self, &index: &usize) -> &T {
         assert!(index < self.len());
 
         unsafe { mem::transmute(self.repr().data.offset(index as isize)) }
     }
+
+    #[cfg(not(stage0))]
+    fn index(&self, index: usize) -> &T {
+        assert!(index < self.len());
+
+        unsafe { mem::transmute(self.repr().data.offset(index as isize)) }
+    }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T> ops::IndexMut<usize> for [T] {
+    #[cfg(stage0)]
+    #[inline]
     fn index_mut(&mut self, &index: &usize) -> &mut T {
         assert!(index < self.len());
 
         unsafe { mem::transmute(self.repr().data.offset(index as isize)) }
     }
+
+    #[cfg(not(stage0))]
+    #[inline]
+    fn index_mut(&mut self, index: usize) -> &mut T {
+        assert!(index < self.len());
+
+        unsafe { mem::transmute(self.repr().data.offset(index as isize)) }
+    }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T> ops::Index<ops::Range<usize>> for [T] {
     type Output = [T];
+
+    #[cfg(stage0)]
     #[inline]
     fn index(&self, index: &ops::Range<usize>) -> &[T] {
         assert!(index.start <= index.end);
@@ -525,34 +557,72 @@ impl<T> ops::Index<ops::Range<usize>> for [T] {
             )
         }
     }
+
+    #[cfg(not(stage0))]
+    #[inline]
+    fn index(&self, index: ops::Range<usize>) -> &[T] {
+        assert!(index.start <= index.end);
+        assert!(index.end <= self.len());
+        unsafe {
+            from_raw_parts (
+                self.as_ptr().offset(index.start as isize),
+                index.end - index.start
+            )
+        }
+    }
 }
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T> ops::Index<ops::RangeTo<usize>> for [T] {
     type Output = [T];
+
+    #[cfg(stage0)]
     #[inline]
     fn index(&self, index: &ops::RangeTo<usize>) -> &[T] {
         self.index(&ops::Range{ start: 0, end: index.end })
     }
+
+    #[cfg(not(stage0))]
+    #[inline]
+    fn index(&self, index: ops::RangeTo<usize>) -> &[T] {
+        self.index(ops::Range{ start: 0, end: index.end })
+    }
 }
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T> ops::Index<ops::RangeFrom<usize>> for [T] {
     type Output = [T];
+
+    #[cfg(stage0)]
     #[inline]
     fn index(&self, index: &ops::RangeFrom<usize>) -> &[T] {
         self.index(&ops::Range{ start: index.start, end: self.len() })
     }
+
+    #[cfg(not(stage0))]
+    #[inline]
+    fn index(&self, index: ops::RangeFrom<usize>) -> &[T] {
+        self.index(ops::Range{ start: index.start, end: self.len() })
+    }
 }
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T> ops::Index<RangeFull> for [T] {
     type Output = [T];
+
+    #[cfg(stage0)]
     #[inline]
     fn index(&self, _index: &RangeFull) -> &[T] {
         self
     }
+
+    #[cfg(not(stage0))]
+    #[inline]
+    fn index(&self, _index: RangeFull) -> &[T] {
+        self
+    }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T> ops::IndexMut<ops::Range<usize>> for [T] {
+    #[cfg(stage0)]
     #[inline]
     fn index_mut(&mut self, index: &ops::Range<usize>) -> &mut [T] {
         assert!(index.start <= index.end);
@@ -564,28 +634,64 @@ impl<T> ops::IndexMut<ops::Range<usize>> for [T] {
             )
         }
     }
+
+    #[cfg(not(stage0))]
+    #[inline]
+    fn index_mut(&mut self, index: ops::Range<usize>) -> &mut [T] {
+        assert!(index.start <= index.end);
+        assert!(index.end <= self.len());
+        unsafe {
+            from_raw_parts_mut(
+                self.as_mut_ptr().offset(index.start as isize),
+                index.end - index.start
+            )
+        }
+    }
 }
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T> ops::IndexMut<ops::RangeTo<usize>> for [T] {
+    #[cfg(stage0)]
     #[inline]
     fn index_mut(&mut self, index: &ops::RangeTo<usize>) -> &mut [T] {
         self.index_mut(&ops::Range{ start: 0, end: index.end })
     }
+
+    #[cfg(not(stage0))]
+    #[inline]
+    fn index_mut(&mut self, index: ops::RangeTo<usize>) -> &mut [T] {
+        self.index_mut(ops::Range{ start: 0, end: index.end })
+    }
 }
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T> ops::IndexMut<ops::RangeFrom<usize>> for [T] {
+    #[cfg(stage0)]
     #[inline]
     fn index_mut(&mut self, index: &ops::RangeFrom<usize>) -> &mut [T] {
         let len = self.len();
         self.index_mut(&ops::Range{ start: index.start, end: len })
     }
+
+    #[cfg(not(stage0))]
+    #[inline]
+    fn index_mut(&mut self, index: ops::RangeFrom<usize>) -> &mut [T] {
+        let len = self.len();
+        self.index_mut(ops::Range{ start: index.start, end: len })
+    }
 }
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T> ops::IndexMut<RangeFull> for [T] {
+
+    #[cfg(stage0)]
     #[inline]
     fn index_mut(&mut self, _index: &RangeFull) -> &mut [T] {
         self
     }
+
+    #[cfg(not(stage0))]
+    #[inline]
+    fn index_mut(&mut self, _index: RangeFull) -> &mut [T] {
+        self
+    }
 }
 
 
@@ -763,37 +869,69 @@ unsafe impl<'a, T: Sync> Send for Iter<'a, T> {}
 #[unstable(feature = "core")]
 impl<'a, T> ops::Index<ops::Range<usize>> for Iter<'a, T> {
     type Output = [T];
+
+    #[cfg(stage0)]
     #[inline]
     fn index(&self, index: &ops::Range<usize>) -> &[T] {
         self.as_slice().index(index)
     }
+
+    #[cfg(not(stage0))]
+    #[inline]
+    fn index(&self, index: ops::Range<usize>) -> &[T] {
+        self.as_slice().index(index)
+    }
 }
 
 #[unstable(feature = "core")]
 impl<'a, T> ops::Index<ops::RangeTo<usize>> for Iter<'a, T> {
     type Output = [T];
+
+    #[cfg(stage0)]
     #[inline]
     fn index(&self, index: &ops::RangeTo<usize>) -> &[T] {
         self.as_slice().index(index)
     }
+
+    #[cfg(not(stage0))]
+    #[inline]
+    fn index(&self, index: ops::RangeTo<usize>) -> &[T] {
+        self.as_slice().index(index)
+    }
 }
 
 #[unstable(feature = "core")]
 impl<'a, T> ops::Index<ops::RangeFrom<usize>> for Iter<'a, T> {
     type Output = [T];
+
+    #[cfg(stage0)]
     #[inline]
     fn index(&self, index: &ops::RangeFrom<usize>) -> &[T] {
         self.as_slice().index(index)
     }
+
+    #[cfg(not(stage0))]
+    #[inline]
+    fn index(&self, index: ops::RangeFrom<usize>) -> &[T] {
+        self.as_slice().index(index)
+    }
 }
 
 #[unstable(feature = "core")]
 impl<'a, T> ops::Index<RangeFull> for Iter<'a, T> {
     type Output = [T];
+
+    #[cfg(stage0)]
     #[inline]
     fn index(&self, _index: &RangeFull) -> &[T] {
         self.as_slice()
     }
+
+    #[cfg(not(stage0))]
+    #[inline]
+    fn index(&self, _index: RangeFull) -> &[T] {
+        self.as_slice()
+    }
 }
 
 impl<'a, T> Iter<'a, T> {
@@ -856,63 +994,126 @@ unsafe impl<'a, T: Send> Send for IterMut<'a, T> {}
 #[unstable(feature = "core")]
 impl<'a, T> ops::Index<ops::Range<usize>> for IterMut<'a, T> {
     type Output = [T];
+
+    #[cfg(stage0)]
     #[inline]
     fn index(&self, index: &ops::Range<usize>) -> &[T] {
         self.index(&RangeFull).index(index)
     }
+
+    #[cfg(not(stage0))]
+    #[inline]
+    fn index(&self, index: ops::Range<usize>) -> &[T] {
+        self.index(RangeFull).index(index)
+    }
 }
 #[unstable(feature = "core")]
 impl<'a, T> ops::Index<ops::RangeTo<usize>> for IterMut<'a, T> {
     type Output = [T];
+
+    #[cfg(stage0)]
     #[inline]
     fn index(&self, index: &ops::RangeTo<usize>) -> &[T] {
         self.index(&RangeFull).index(index)
     }
+
+    #[cfg(not(stage0))]
+    #[inline]
+    fn index(&self, index: ops::RangeTo<usize>) -> &[T] {
+        self.index(RangeFull).index(index)
+    }
 }
 #[unstable(feature = "core")]
 impl<'a, T> ops::Index<ops::RangeFrom<usize>> for IterMut<'a, T> {
     type Output = [T];
+
+    #[cfg(stage0)]
     #[inline]
     fn index(&self, index: &ops::RangeFrom<usize>) -> &[T] {
         self.index(&RangeFull).index(index)
     }
+
+    #[cfg(not(stage0))]
+    #[inline]
+    fn index(&self, index: ops::RangeFrom<usize>) -> &[T] {
+        self.index(RangeFull).index(index)
+    }
 }
 #[unstable(feature = "core")]
 impl<'a, T> ops::Index<RangeFull> for IterMut<'a, T> {
     type Output = [T];
+
+    #[cfg(stage0)]
     #[inline]
     fn index(&self, _index: &RangeFull) -> &[T] {
         make_slice!(T => &[T]: self.ptr, self.end)
     }
+
+    #[cfg(not(stage0))]
+    #[inline]
+    fn index(&self, _index: RangeFull) -> &[T] {
+        make_slice!(T => &[T]: self.ptr, self.end)
+    }
 }
 
 #[unstable(feature = "core")]
 impl<'a, T> ops::IndexMut<ops::Range<usize>> for IterMut<'a, T> {
+    #[cfg(stage0)]
     #[inline]
     fn index_mut(&mut self, index: &ops::Range<usize>) -> &mut [T] {
         self.index_mut(&RangeFull).index_mut(index)
     }
+
+    #[cfg(not(stage0))]
+    #[inline]
+    fn index_mut(&mut self, index: ops::Range<usize>) -> &mut [T] {
+        self.index_mut(RangeFull).index_mut(index)
+    }
 }
 #[unstable(feature = "core")]
 impl<'a, T> ops::IndexMut<ops::RangeTo<usize>> for IterMut<'a, T> {
+
+    #[cfg(stage0)]
     #[inline]
     fn index_mut(&mut self, index: &ops::RangeTo<usize>) -> &mut [T] {
         self.index_mut(&RangeFull).index_mut(index)
     }
+
+    #[cfg(not(stage0))]
+    #[inline]
+    fn index_mut(&mut self, index: ops::RangeTo<usize>) -> &mut [T] {
+        self.index_mut(RangeFull).index_mut(index)
+    }
 }
 #[unstable(feature = "core")]
 impl<'a, T> ops::IndexMut<ops::RangeFrom<usize>> for IterMut<'a, T> {
+
+    #[cfg(stage0)]
     #[inline]
     fn index_mut(&mut self, index: &ops::RangeFrom<usize>) -> &mut [T] {
         self.index_mut(&RangeFull).index_mut(index)
     }
+
+    #[cfg(not(stage0))]
+    #[inline]
+    fn index_mut(&mut self, index: ops::RangeFrom<usize>) -> &mut [T] {
+        self.index_mut(RangeFull).index_mut(index)
+    }
 }
 #[unstable(feature = "core")]
 impl<'a, T> ops::IndexMut<RangeFull> for IterMut<'a, T> {
+
+    #[cfg(stage0)]
     #[inline]
     fn index_mut(&mut self, _index: &RangeFull) -> &mut [T] {
         make_mut_slice!(T => &mut [T]: self.ptr, self.end)
     }
+
+    #[cfg(not(stage0))]
+    #[inline]
+    fn index_mut(&mut self, _index: RangeFull) -> &mut [T] {
+        make_mut_slice!(T => &mut [T]: self.ptr, self.end)
+    }
 }
 
 

src/libcore/str/mod.rs

@@ -1203,6 +1203,7 @@ mod traits {
     /// // byte 100 is outside the string
     /// // &s[3 .. 100];
     /// ```
+    #[cfg(stage0)]
     #[stable(feature = "rust1", since = "1.0.0")]
     impl ops::Index<ops::Range<usize>> for str {
         type Output = str;
@@ -1219,6 +1220,49 @@ mod traits {
         }
     }
 
+    /// Returns a slice of the given string from the byte range
+    /// [`begin`..`end`).
+    ///
+    /// This operation is `O(1)`.
+    ///
+    /// Panics when `begin` and `end` do not point to valid characters
+    /// or point beyond the last character of the string.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// let s = "Löwe 老虎 Léopard";
+    /// assert_eq!(&s[0 .. 1], "L");
+    ///
+    /// assert_eq!(&s[1 .. 9], "öwe 老");
+    ///
+    /// // these will panic:
+    /// // byte 2 lies within `ö`:
+    /// // &s[2 ..3];
+    ///
+    /// // byte 8 lies within `老`
+    /// // &s[1 .. 8];
+    ///
+    /// // byte 100 is outside the string
+    /// // &s[3 .. 100];
+    /// ```
+    #[cfg(not(stage0))]
+    #[stable(feature = "rust1", since = "1.0.0")]
+    impl ops::Index<ops::Range<usize>> for str {
+        type Output = str;
+        #[inline]
+        fn index(&self, index: ops::Range<usize>) -> &str {
+            // is_char_boundary checks that the index is in [0, .len()]
+            if index.start <= index.end &&
+               self.is_char_boundary(index.start) &&
+               self.is_char_boundary(index.end) {
+                unsafe { self.slice_unchecked(index.start, index.end) }
+            } else {
+                super::slice_error_fail(self, index.start, index.end)
+            }
+        }
+    }
+
     /// Returns a slice of the string from the beginning to byte
     /// `end`.
     ///
@@ -1229,6 +1273,8 @@ mod traits {
     #[stable(feature = "rust1", since = "1.0.0")]
     impl ops::Index<ops::RangeTo<usize>> for str {
         type Output = str;
+
+        #[cfg(stage0)]
         #[inline]
         fn index(&self, index: &ops::RangeTo<usize>) -> &str {
             // is_char_boundary checks that the index is in [0, .len()]
@@ -1238,6 +1284,17 @@ mod traits {
                 super::slice_error_fail(self, 0, index.end)
             }
         }
+
+        #[cfg(not(stage0))]
+        #[inline]
+        fn index(&self, index: ops::RangeTo<usize>) -> &str {
+            // is_char_boundary checks that the index is in [0, .len()]
+            if self.is_char_boundary(index.end) {
+                unsafe { self.slice_unchecked(0, index.end) }
+            } else {
+                super::slice_error_fail(self, 0, index.end)
+            }
+        }
     }
 
     /// Returns a slice of the string from `begin` to its end.
@@ -1249,6 +1306,8 @@ mod traits {
     #[stable(feature = "rust1", since = "1.0.0")]
     impl ops::Index<ops::RangeFrom<usize>> for str {
         type Output = str;
+
+        #[cfg(stage0)]
         #[inline]
         fn index(&self, index: &ops::RangeFrom<usize>) -> &str {
             // is_char_boundary checks that the index is in [0, .len()]
@@ -1258,15 +1317,34 @@ mod traits {
                 super::slice_error_fail(self, index.start, self.len())
             }
         }
+
+        #[cfg(not(stage0))]
+        #[inline]
+        fn index(&self, index: ops::RangeFrom<usize>) -> &str {
+            // is_char_boundary checks that the index is in [0, .len()]
+            if self.is_char_boundary(index.start) {
+                unsafe { self.slice_unchecked(index.start, self.len()) }
+            } else {
+                super::slice_error_fail(self, index.start, self.len())
+            }
+        }
     }
 
     #[stable(feature = "rust1", since = "1.0.0")]
     impl ops::Index<ops::RangeFull> for str {
         type Output = str;
+
+        #[cfg(stage0)]
         #[inline]
         fn index(&self, _index: &ops::RangeFull) -> &str {
             self
         }
+
+        #[cfg(not(stage0))]
+        #[inline]
+        fn index(&self, _index: ops::RangeFull) -> &str {
+            self
+        }
     }
 }
 

src/libserialize/json.rs

@@ -1218,6 +1218,7 @@ impl Json {
     }
 }
 
+#[cfg(stage0)]
 impl<'a> Index<&'a str>  for Json {
     type Output = Json;
 
@@ -1226,6 +1227,16 @@ impl<'a> Index<&'a str>  for Json {
     }
 }
 
+#[cfg(not(stage0))]
+impl<'a> Index<&'a str>  for Json {
+    type Output = Json;
+
+    fn index(&self, idx: &'a str) -> &Json {
+        self.find(idx).unwrap()
+    }
+}
+
+#[cfg(stage0)]
 impl Index<uint> for Json {
     type Output = Json;
 
@@ -1237,6 +1248,18 @@ impl Index<uint> for Json {
     }
 }
 
+#[cfg(not(stage0))]
+impl Index<uint> for Json {
+    type Output = Json;
+
+    fn index<'a>(&'a self, idx: uint) -> &'a Json {
+        match self {
+            &Json::Array(ref v) => &v[idx],
+            _ => panic!("can only index Json with uint if it is an array")
+        }
+    }
+}
+
 /// The output of the streaming parser.
 #[derive(PartialEq, Clone, Debug)]
 pub enum JsonEvent {

src/libstd/collections/hash/map.rs

@@ -1088,7 +1088,7 @@ impl<K, V, S> HashMap<K, V, S>
     ///     Some(x) => *x = "b",
     ///     None => (),
     /// }
-    /// assert_eq!(map[1], "b");
+    /// assert_eq!(map[&1], "b");
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn get_mut<Q: ?Sized>(&mut self, k: &Q) -> Option<&mut V>
@@ -1111,7 +1111,7 @@ impl<K, V, S> HashMap<K, V, S>
     ///
     /// map.insert(37, "b");
     /// assert_eq!(map.insert(37, "c"), Some("b"));
-    /// assert_eq!(map[37], "c");
+    /// assert_eq!(map[&37], "c");
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn insert(&mut self, k: K, v: V) -> Option<V> {
@@ -1244,6 +1244,7 @@ impl<K, V, S> Default for HashMap<K, V, S>
     }
 }
 
+#[cfg(stage0)]
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<K, Q: ?Sized, V, S> Index<Q> for HashMap<K, V, S>
     where K: Eq + Hash + Borrow<Q>,
@@ -1258,6 +1259,21 @@ impl<K, Q: ?Sized, V, S> Index<Q> for HashMap<K, V, S>
     }
 }
 
+#[cfg(not(stage0))]
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<'a, K, Q: ?Sized, V, S> Index<&'a Q> for HashMap<K, V, S>
+    where K: Eq + Hash + Borrow<Q>,
+          Q: Eq + Hash,
+          S: HashState,
+{
+    type Output = V;
+
+    #[inline]
+    fn index(&self, index: &Q) -> &V {
+        self.get(index).expect("no entry found for key")
+    }
+}
+
 /// HashMap iterator.
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct Iter<'a, K: 'a, V: 'a> {
@@ -2185,7 +2201,7 @@ mod test_map {
         map.insert(2, 1);
         map.insert(3, 4);
 
-        assert_eq!(map[2], 1);
+        assert_eq!(map[&2], 1);
     }
 
     #[test]
@@ -2197,7 +2213,7 @@ mod test_map {
         map.insert(2, 1);
         map.insert(3, 4);
 
-        map[4];
+        map[&4];
     }
 
     #[test]

src/libstd/ffi/os_str.rs

@@ -103,6 +103,7 @@ impl OsString {
     }
 }
 
+#[cfg(stage0)]
 #[stable(feature = "rust1", since = "1.0.0")]
 impl ops::Index<ops::RangeFull> for OsString {
     type Output = OsStr;
@@ -113,6 +114,17 @@ impl ops::Index<ops::RangeFull> for OsString {
     }
 }
 
+#[cfg(not(stage0))]
+#[stable(feature = "rust1", since = "1.0.0")]
+impl ops::Index<ops::RangeFull> for OsString {
+    type Output = OsStr;
+
+    #[inline]
+    fn index(&self, _index: ops::RangeFull) -> &OsStr {
+        unsafe { mem::transmute(self.inner.as_slice()) }
+    }
+}
+
 #[stable(feature = "rust1", since = "1.0.0")]
 impl ops::Deref for OsString {
     type Target = OsStr;

src/libstd/sys/common/wtf8.rs

@@ -634,6 +634,7 @@ impl Wtf8 {
 ///
 /// Panics when `begin` and `end` do not point to code point boundaries,
 /// or point beyond the end of the string.
+#[cfg(stage0)]
 impl ops::Index<ops::Range<usize>> for Wtf8 {
     type Output = Wtf8;
 
@@ -650,12 +651,36 @@ impl ops::Index<ops::Range<usize>> for Wtf8 {
     }
 }
 
+/// Return a slice of the given string for the byte range [`begin`..`end`).
+///
+/// # Panics
+///
+/// Panics when `begin` and `end` do not point to code point boundaries,
+/// or point beyond the end of the string.
+#[cfg(not(stage0))]
+impl ops::Index<ops::Range<usize>> for Wtf8 {
+    type Output = Wtf8;
+
+    #[inline]
+    fn index(&self, range: ops::Range<usize>) -> &Wtf8 {
+        // is_code_point_boundary checks that the index is in [0, .len()]
+        if range.start <= range.end &&
+           is_code_point_boundary(self, range.start) &&
+           is_code_point_boundary(self, range.end) {
+            unsafe { slice_unchecked(self, range.start, range.end) }
+        } else {
+            slice_error_fail(self, range.start, range.end)
+        }
+    }
+}
+
 /// Return a slice of the given string from byte `begin` to its end.
 ///
 /// # Panics
 ///
 /// Panics when `begin` is not at a code point boundary,
 /// or is beyond the end of the string.
+#[cfg(stage0)]
 impl ops::Index<ops::RangeFrom<usize>> for Wtf8 {
     type Output = Wtf8;
 
@@ -670,12 +695,34 @@ impl ops::Index<ops::RangeFrom<usize>> for Wtf8 {
     }
 }
 
+/// Return a slice of the given string from byte `begin` to its end.
+///
+/// # Panics
+///
+/// Panics when `begin` is not at a code point boundary,
+/// or is beyond the end of the string.
+#[cfg(not(stage0))]
+impl ops::Index<ops::RangeFrom<usize>> for Wtf8 {
+    type Output = Wtf8;
+
+    #[inline]
+    fn index(&self, range: ops::RangeFrom<usize>) -> &Wtf8 {
+        // is_code_point_boundary checks that the index is in [0, .len()]
+        if is_code_point_boundary(self, range.start) {
+            unsafe { slice_unchecked(self, range.start, self.len()) }
+        } else {
+            slice_error_fail(self, range.start, self.len())
+        }
+    }
+}
+
 /// Return a slice of the given string from its beginning to byte `end`.
 ///
 /// # Panics
 ///
 /// Panics when `end` is not at a code point boundary,
 /// or is beyond the end of the string.
+#[cfg(stage0)]
 impl ops::Index<ops::RangeTo<usize>> for Wtf8 {
     type Output = Wtf8;
 
@@ -690,6 +737,28 @@ impl ops::Index<ops::RangeTo<usize>> for Wtf8 {
     }
 }
 
+/// Return a slice of the given string from its beginning to byte `end`.
+///
+/// # Panics
+///
+/// Panics when `end` is not at a code point boundary,
+/// or is beyond the end of the string.
+#[cfg(not(stage0))]
+impl ops::Index<ops::RangeTo<usize>> for Wtf8 {
+    type Output = Wtf8;
+
+    #[inline]
+    fn index(&self, range: ops::RangeTo<usize>) -> &Wtf8 {
+        // is_code_point_boundary checks that the index is in [0, .len()]
+        if is_code_point_boundary(self, range.end) {
+            unsafe { slice_unchecked(self, 0, range.end) }
+        } else {
+            slice_error_fail(self, 0, range.end)
+        }
+    }
+}
+
+#[cfg(stage0)]
 impl ops::Index<ops::RangeFull> for Wtf8 {
     type Output = Wtf8;
 
@@ -699,6 +768,16 @@ impl ops::Index<ops::RangeFull> for Wtf8 {
     }
 }
 
+#[cfg(not(stage0))]
+impl ops::Index<ops::RangeFull> for Wtf8 {
+    type Output = Wtf8;
+
+    #[inline]
+    fn index(&self, _range: ops::RangeFull) -> &Wtf8 {
+        self
+    }
+}
+
 #[inline]
 fn decode_surrogate(second_byte: u8, third_byte: u8) -> u16 {
     // The first byte is assumed to be 0xED