Fallout from stabilization

58 files changed, 105 insertions, 103 deletions

diff --git a/src/libcollections/binary_heap.rs b/src/libcollections/binary_heap.rs
index 8efc4cd50c1..ed931028446 100644
--- a/src/libcollections/binary_heap.rs
+++ b/src/libcollections/binary_heap.rs
@@ -585,10 +585,10 @@ impl<T> DoubleEndedIterator<T> for MoveItems<T> {
     fn next_back(&mut self) -> Option<T> { self.iter.next_back() }
 }
 
-impl<T> ExactSize<T> for MoveItems<T> {}
+impl<T> ExactSizeIterator<T> for MoveItems<T> {}
 
 impl<T: Ord> FromIterator<T> for BinaryHeap<T> {
-    fn from_iter<Iter: Iterator<T>>(mut iter: Iter) -> BinaryHeap<T> {
+    fn from_iter<Iter: Iterator<T>>(iter: Iter) -> BinaryHeap<T> {
         let vec: Vec<T> = iter.collect();
         BinaryHeap::from_vec(vec)
     }
diff --git a/src/libcollections/bit.rs b/src/libcollections/bit.rs
index 64abc78daf3..903a9bd9823 100644
--- a/src/libcollections/bit.rs
+++ b/src/libcollections/bit.rs
@@ -68,7 +68,7 @@ use core::prelude::*;
 use core::cmp;
 use core::default::Default;
 use core::fmt;
-use core::iter::{Chain, Enumerate, Repeat, Skip, Take};
+use core::iter::{Chain, Enumerate, Repeat, Skip, Take, repeat};
 use core::iter;
 use core::num::Int;
 use core::slice;
@@ -88,11 +88,11 @@ fn match_words <'a,'b>(a: &'a Bitv, b: &'b Bitv) -> (MatchWords<'a>, MatchWords<
 
     // have to uselessly pretend to pad the longer one for type matching
     if a_len < b_len {
-        (a.mask_words(0).chain(Repeat::new(0u32).enumerate().take(b_len).skip(a_len)),
-         b.mask_words(0).chain(Repeat::new(0u32).enumerate().take(0).skip(0)))
+        (a.mask_words(0).chain(repeat(0u32).enumerate().take(b_len).skip(a_len)),
+         b.mask_words(0).chain(repeat(0u32).enumerate().take(0).skip(0)))
     } else {
-        (a.mask_words(0).chain(Repeat::new(0u32).enumerate().take(0).skip(0)),
-         b.mask_words(0).chain(Repeat::new(0u32).enumerate().take(a_len).skip(b_len)))
+        (a.mask_words(0).chain(repeat(0u32).enumerate().take(0).skip(0)),
+         b.mask_words(0).chain(repeat(0u32).enumerate().take(a_len).skip(b_len)))
     }
 }
 
@@ -943,7 +943,7 @@ impl<'a> DoubleEndedIterator<bool> for Bits<'a> {
     }
 }
 
-impl<'a> ExactSize<bool> for Bits<'a> {}
+impl<'a> ExactSizeIterator<bool> for Bits<'a> {}
 
 impl<'a> RandomAccessIterator<bool> for Bits<'a> {
     #[inline]
diff --git a/src/libcollections/btree/map.rs b/src/libcollections/btree/map.rs
index adb9a9ae5bd..8a6d26c26bf 100644
--- a/src/libcollections/btree/map.rs
+++ b/src/libcollections/btree/map.rs
@@ -863,7 +863,7 @@ impl<K, V, E, T: Traverse<E> + DoubleEndedIterator<TraversalItem<K, V, E>>>
     // Note that the design of these iterators permits an *arbitrary* initial pair of min and max,
     // making these arbitrary sub-range iterators. However the logic to construct these paths
     // efficiently is fairly involved, so this is a FIXME. The sub-range iterators also wouldn't be
-    // able to accurately predict size, so those iterators can't implement ExactSize.
+    // able to accurately predict size, so those iterators can't implement ExactSizeIterator.
     fn next(&mut self) -> Option<(K, V)> {
         loop {
             // We want the smallest element, so try to get the top of the left stack
@@ -963,7 +963,7 @@ impl<'a, K, V> Iterator<(&'a K, &'a V)> for Entries<'a, K, V> {
 impl<'a, K, V> DoubleEndedIterator<(&'a K, &'a V)> for Entries<'a, K, V> {
     fn next_back(&mut self) -> Option<(&'a K, &'a V)> { self.inner.next_back() }
 }
-impl<'a, K, V> ExactSize<(&'a K, &'a V)> for Entries<'a, K, V> {}
+impl<'a, K, V> ExactSizeIterator<(&'a K, &'a V)> for Entries<'a, K, V> {}
 
 
 impl<'a, K, V> Iterator<(&'a K, &'a mut V)> for MutEntries<'a, K, V> {
@@ -973,7 +973,7 @@ impl<'a, K, V> Iterator<(&'a K, &'a mut V)> for MutEntries<'a, K, V> {
 impl<'a, K, V> DoubleEndedIterator<(&'a K, &'a mut V)> for MutEntries<'a, K, V> {
     fn next_back(&mut self) -> Option<(&'a K, &'a mut V)> { self.inner.next_back() }
 }
-impl<'a, K, V> ExactSize<(&'a K, &'a mut V)> for MutEntries<'a, K, V> {}
+impl<'a, K, V> ExactSizeIterator<(&'a K, &'a mut V)> for MutEntries<'a, K, V> {}
 
 
 impl<K, V> Iterator<(K, V)> for MoveEntries<K, V> {
@@ -983,7 +983,7 @@ impl<K, V> Iterator<(K, V)> for MoveEntries<K, V> {
 impl<K, V> DoubleEndedIterator<(K, V)> for MoveEntries<K, V> {
     fn next_back(&mut self) -> Option<(K, V)> { self.inner.next_back() }
 }
-impl<K, V> ExactSize<(K, V)> for MoveEntries<K, V> {}
+impl<K, V> ExactSizeIterator<(K, V)> for MoveEntries<K, V> {}
 
 
 
diff --git a/src/libcollections/dlist.rs b/src/libcollections/dlist.rs
index 19216b32ce7..3f95bda663e 100644
--- a/src/libcollections/dlist.rs
+++ b/src/libcollections/dlist.rs
@@ -607,7 +607,7 @@ impl<'a, A> DoubleEndedIterator<&'a A> for Items<'a, A> {
     }
 }
 
-impl<'a, A> ExactSize<&'a A> for Items<'a, A> {}
+impl<'a, A> ExactSizeIterator<&'a A> for Items<'a, A> {}
 
 impl<'a, A> Iterator<&'a mut A> for MutItems<'a, A> {
     #[inline]
@@ -645,7 +645,7 @@ impl<'a, A> DoubleEndedIterator<&'a mut A> for MutItems<'a, A> {
     }
 }
 
-impl<'a, A> ExactSize<&'a mut A> for MutItems<'a, A> {}
+impl<'a, A> ExactSizeIterator<&'a mut A> for MutItems<'a, A> {}
 
 /// Allows mutating a `DList` while iterating.
 pub trait ListInsertion<A> {
diff --git a/src/libcollections/ring_buf.rs b/src/libcollections/ring_buf.rs
index 643b500ec3e..8f0b0d41b03 100644
--- a/src/libcollections/ring_buf.rs
+++ b/src/libcollections/ring_buf.rs
@@ -695,8 +695,7 @@ impl<'a, T> DoubleEndedIterator<&'a T> for Items<'a, T> {
     }
 }
 
-
-impl<'a, T> ExactSize<&'a T> for Items<'a, T> {}
+impl<'a, T> ExactSizeIterator<&'a T> for Items<'a, T> {}
 
 impl<'a, T> RandomAccessIterator<&'a T> for Items<'a, T> {
     #[inline]
@@ -763,7 +762,7 @@ impl<'a, T> DoubleEndedIterator<&'a mut T> for MutItems<'a, T> {
     }
 }
 
-impl<'a, T> ExactSize<&'a mut T> for MutItems<'a, T> {}
+impl<'a, T> ExactSizeIterator<&'a mut T> for MutItems<'a, T> {}
 
 impl<A: PartialEq> PartialEq for RingBuf<A> {
     fn eq(&self, other: &RingBuf<A>) -> bool {
@@ -1322,7 +1321,7 @@ mod tests {
         let u: Vec<int> = deq.iter().map(|&x| x).collect();
         assert_eq!(u, v);
 
-        let mut seq = iter::count(0u, 2).take(256);
+        let seq = iter::count(0u, 2).take(256);
         let deq: RingBuf<uint> = seq.collect();
         for (i, &x) in deq.iter().enumerate() {
             assert_eq!(2*i, x);
diff --git a/src/libcollections/slice.rs b/src/libcollections/slice.rs
index ab5ac5bf9e1..06e1ee0fc0f 100644
--- a/src/libcollections/slice.rs
+++ b/src/libcollections/slice.rs
@@ -94,7 +94,7 @@ use core::cmp;
 use core::kinds::Sized;
 use core::mem::size_of;
 use core::mem;
-use core::prelude::{Clone, Greater, Iterator, Less, None, Option};
+use core::prelude::{Clone, Greater, Iterator, IteratorExt, Less, None, Option};
 use core::prelude::{Ord, Ordering, RawPtr, Some, range};
 use core::ptr;
 use core::iter::{range_step, MultiplicativeIterator};
diff --git a/src/libcollections/str.rs b/src/libcollections/str.rs
index 9982eaefff8..32059f7808f 100644
--- a/src/libcollections/str.rs
+++ b/src/libcollections/str.rs
@@ -61,7 +61,7 @@ use core::cmp;
 use core::iter::AdditiveIterator;
 use core::kinds::Sized;
 use core::prelude::{Char, Clone, Eq, Equiv};
-use core::prelude::{Iterator, SlicePrelude, None, Option, Ord, Ordering};
+use core::prelude::{Iterator, IteratorExt, SlicePrelude, None, Option, Ord, Ordering};
 use core::prelude::{PartialEq, PartialOrd, Result, AsSlice, Some, Tuple2};
 use core::prelude::{range};
 
@@ -794,7 +794,7 @@ mod tests {
     use std::cmp::{Equal, Greater, Less, Ord, PartialOrd, Equiv};
     use std::option::{Some, None};
     use std::ptr::RawPtr;
-    use std::iter::{Iterator, DoubleEndedIterator};
+    use std::iter::{Iterator, IteratorExt, DoubleEndedIteratorExt};
 
     use super::*;
     use std::slice::{AsSlice, SlicePrelude};
@@ -2143,12 +2143,15 @@ mod tests {
         let gr_inds = s.grapheme_indices(true).rev().collect::<Vec<(uint, &str)>>();
         let b: &[_] = &[(11, "\r\n"), (6, "ö̲"), (3, "é"), (0u, "a̐")];
         assert_eq!(gr_inds.as_slice(), b);
-        let mut gr_inds = s.grapheme_indices(true);
-        let e1 = gr_inds.size_hint();
-        assert_eq!(e1, (1, Some(13)));
-        let c = gr_inds.count();
-        assert_eq!(c, 4);
-        let e2 = gr_inds.size_hint();
+        let mut gr_inds_iter = s.grapheme_indices(true);
+        {
+            let gr_inds = gr_inds_iter.by_ref();
+            let e1 = gr_inds.size_hint();
+            assert_eq!(e1, (1, Some(13)));
+            let c = gr_inds.count();
+            assert_eq!(c, 4);
+        }
+        let e2 = gr_inds_iter.size_hint();
         assert_eq!(e2, (0, Some(0)));
 
         // make sure the reverse iterator does the right thing with "\n" at beginning of string
@@ -2285,7 +2288,7 @@ mod bench {
     use test::Bencher;
     use test::black_box;
     use super::*;
-    use std::iter::{Iterator, DoubleEndedIterator};
+    use std::iter::{IteratorExt, DoubleEndedIteratorExt};
     use std::str::StrPrelude;
     use std::slice::SlicePrelude;
 
diff --git a/src/libcollections/vec.rs b/src/libcollections/vec.rs
index a3291e01942..8b4428849d7 100644
--- a/src/libcollections/vec.rs
+++ b/src/libcollections/vec.rs
@@ -1319,7 +1319,7 @@ impl<T> DoubleEndedIterator<T> for MoveItems<T> {
     }
 }
 
-impl<T> ExactSize<T> for MoveItems<T> {}
+impl<T> ExactSizeIterator<T> for MoveItems<T> {}
 
 #[unsafe_destructor]
 impl<T> Drop for MoveItems<T> {
diff --git a/src/libcore/fmt/float.rs b/src/libcore/fmt/float.rs
index 1760c4d8e66..31a46c26e2a 100644
--- a/src/libcore/fmt/float.rs
+++ b/src/libcore/fmt/float.rs
@@ -17,7 +17,7 @@ pub use self::SignFormat::*;
 use char;
 use char::Char;
 use fmt;
-use iter::{range, DoubleEndedIterator};
+use iter::{range, DoubleEndedIteratorExt};
 use num::{Float, FPNaN, FPInfinite, ToPrimitive};
 use num::cast;
 use result::Ok;
diff --git a/src/libcore/fmt/mod.rs b/src/libcore/fmt/mod.rs
index 6e77b0a7c79..605148beb90 100644
--- a/src/libcore/fmt/mod.rs
+++ b/src/libcore/fmt/mod.rs
@@ -14,7 +14,7 @@
 
 use any;
 use cell::{Cell, Ref, RefMut};
-use iter::{Iterator, range};
+use iter::{Iterator, IteratorExt, range};
 use kinds::{Copy, Sized};
 use mem;
 use option::{Option, Some, None};
diff --git a/src/libcore/fmt/num.rs b/src/libcore/fmt/num.rs
index 1c856a6e208..a441ced03b2 100644
--- a/src/libcore/fmt/num.rs
+++ b/src/libcore/fmt/num.rs
@@ -15,7 +15,7 @@
 #![allow(unsigned_negation)]
 
 use fmt;
-use iter::DoubleEndedIterator;
+use iter::DoubleEndedIteratorExt;
 use num::{Int, cast};
 use slice::SlicePrelude;
 
diff --git a/src/libcore/num/mod.rs b/src/libcore/num/mod.rs
index 07f2e154c76..ce61bd97e13 100644
--- a/src/libcore/num/mod.rs
+++ b/src/libcore/num/mod.rs
@@ -25,7 +25,7 @@ use clone::Clone;
 use cmp::{PartialEq, Eq};
 use cmp::{PartialOrd, Ord};
 use intrinsics;
-use iter::Iterator;
+use iter::IteratorExt;
 use kinds::Copy;
 use mem::size_of;
 use ops::{Add, Sub, Mul, Div, Rem, Neg};
diff --git a/src/libcore/option.rs b/src/libcore/option.rs
index fcf2dab6908..7d7b41bf7bf 100644
--- a/src/libcore/option.rs
+++ b/src/libcore/option.rs
@@ -147,7 +147,7 @@ pub use self::Option::*;
 
 use cmp::{Eq, Ord};
 use default::Default;
-use iter::{Iterator, DoubleEndedIterator, FromIterator, ExactSize};
+use iter::{Iterator, IteratorExt, DoubleEndedIterator, FromIterator, ExactSizeIterator};
 use mem;
 use result::{Result, Ok, Err};
 use slice;
@@ -797,7 +797,7 @@ impl<A> DoubleEndedIterator<A> for Item<A> {
     }
 }
 
-impl<A> ExactSize<A> for Item<A> {}
+impl<A> ExactSizeIterator<A> for Item<A> {}
 
 /////////////////////////////////////////////////////////////////////////////
 // FromIterator
diff --git a/src/libcore/prelude.rs b/src/libcore/prelude.rs
index 9f883d60496..6678a20087b 100644
--- a/src/libcore/prelude.rs
+++ b/src/libcore/prelude.rs
@@ -39,7 +39,7 @@ pub use ops::{Slice, SliceMut};
 pub use ops::{Fn, FnMut, FnOnce};
 
 // Reexported functions
-pub use iter::{range, repeat};
+pub use iter::range;
 pub use mem::drop;
 pub use str::from_str;
 
@@ -50,9 +50,10 @@ pub use clone::Clone;
 pub use cmp::{PartialEq, PartialOrd, Eq, Ord};
 pub use cmp::{Ordering, Equiv};
 pub use cmp::Ordering::{Less, Equal, Greater};
-pub use iter::{FromIterator, Extend};
-pub use iter::{Iterator, DoubleEndedIterator, RandomAccessIterator, CloneableIterator};
-pub use iter::{OrdIterator, MutableDoubleEndedIterator, ExactSize};
+pub use iter::{FromIterator, Extend, IteratorExt};
+pub use iter::{Iterator, DoubleEndedIterator, DoubleEndedIteratorExt, RandomAccessIterator};
+pub use iter::{IteratorCloneExt, CloneIteratorExt};
+pub use iter::{IteratorOrdExt, MutableDoubleEndedIterator, ExactSizeIterator};
 pub use num::{ToPrimitive, FromPrimitive};
 pub use option::Option;
 pub use option::Option::{Some, None};
diff --git a/src/libcore/result.rs b/src/libcore/result.rs
index 3240b4207a1..202ac464497 100644
--- a/src/libcore/result.rs
+++ b/src/libcore/result.rs
@@ -235,7 +235,7 @@ pub use self::Result::*;
 use std::fmt::Show;
 use slice;
 use slice::AsSlice;
-use iter::{Iterator, DoubleEndedIterator, FromIterator, ExactSize};
+use iter::{Iterator, IteratorExt, DoubleEndedIterator, FromIterator, ExactSizeIterator};
 use option::{None, Option, Some};
 
 /// `Result` is a type that represents either success (`Ok`) or failure (`Err`).
@@ -831,7 +831,7 @@ impl<A> DoubleEndedIterator<A> for Item<A> {
     }
 }
 
-impl<A> ExactSize<A> for Item<A> {}
+impl<A> ExactSizeIterator<A> for Item<A> {}
 
 /////////////////////////////////////////////////////////////////////////////
 // FromIterator
diff --git a/src/libcore/slice.rs b/src/libcore/slice.rs
index 6625d19781a..36464e4d29e 100644
--- a/src/libcore/slice.rs
+++ b/src/libcore/slice.rs
@@ -1160,7 +1160,7 @@ impl<'a, T> Items<'a, T> {
 iterator!{struct Items -> *const T, &'a T}
 
 #[experimental = "needs review"]
-impl<'a, T> ExactSize<&'a T> for Items<'a, T> {}
+impl<'a, T> ExactSizeIterator<&'a T> for Items<'a, T> {}
 
 #[experimental = "needs review"]
 impl<'a, T> Clone for Items<'a, T> {
@@ -1255,7 +1255,7 @@ impl<'a, T> MutItems<'a, T> {
 iterator!{struct MutItems -> *mut T, &'a mut T}
 
 #[experimental = "needs review"]
-impl<'a, T> ExactSize<&'a mut T> for MutItems<'a, T> {}
+impl<'a, T> ExactSizeIterator<&'a mut T> for MutItems<'a, T> {}
 
 /// An abstraction over the splitting iterators, so that splitn, splitn_mut etc
 /// can be implemented once.
diff --git a/src/libcore/str.rs b/src/libcore/str.rs
index bb7710c2acc..b9586399aec 100644
--- a/src/libcore/str.rs
+++ b/src/libcore/str.rs
@@ -23,9 +23,9 @@ use char::Char;
 use char;
 use cmp::{Eq, mod};
 use default::Default;
+use iter::{Map, Iterator, IteratorExt, DoubleEndedIterator};
+use iter::{DoubleEndedIteratorExt, ExactSizeIterator};
 use iter::range;
-use iter::{DoubleEndedIterator, ExactSize};
-use iter::{Map, Iterator};
 use kinds::Sized;
 use mem;
 use num::Int;
@@ -1210,7 +1210,7 @@ Section: Trait implementations
 #[allow(missing_docs)]
 pub mod traits {
     use cmp::{Ord, Ordering, Less, Equal, Greater, PartialEq, PartialOrd, Equiv, Eq};
-    use iter::Iterator;
+    use iter::IteratorExt;
     use option::{Option, Some};
     use ops;
     use str::{Str, StrPrelude, eq_slice};
diff --git a/src/libgetopts/lib.rs b/src/libgetopts/lib.rs
index a182f582b5f..74165dcabc4 100644
--- a/src/libgetopts/lib.rs
+++ b/src/libgetopts/lib.rs
@@ -710,7 +710,7 @@ pub fn usage(brief: &str, opts: &[OptGroup]) -> String {
 
     let desc_sep = format!("\n{}", " ".repeat(24));
 
-    let mut rows = opts.iter().map(|optref| {
+    let rows = opts.iter().map(|optref| {
         let OptGroup{short_name,
                      long_name,
                      hint,
diff --git a/src/librand/isaac.rs b/src/librand/isaac.rs
index 02dd53e4214..517b50c49c7 100644
--- a/src/librand/isaac.rs
+++ b/src/librand/isaac.rs
@@ -11,8 +11,8 @@
 //! The ISAAC random number generator.
 
 use core::prelude::*;
-use core::iter::{range_step, Repeat};
 use core::slice;
+use core::iter::{range_step, repeat};
 
 use {Rng, SeedableRng, Rand};
 
@@ -205,7 +205,7 @@ impl<'a> SeedableRng<&'a [u32]> for IsaacRng {
     fn reseed(&mut self, seed: &'a [u32]) {
         // make the seed into [seed[0], seed[1], ..., seed[seed.len()
         // - 1], 0, 0, ...], to fill rng.rsl.
-        let seed_iter = seed.iter().map(|&x| x).chain(Repeat::new(0u32));
+        let seed_iter = seed.iter().map(|&x| x).chain(repeat(0u32));
 
         for (rsl_elem, seed_elem) in self.rsl.iter_mut().zip(seed_iter) {
             *rsl_elem = seed_elem;
@@ -438,7 +438,7 @@ impl<'a> SeedableRng<&'a [u64]> for Isaac64Rng {
     fn reseed(&mut self, seed: &'a [u64]) {
         // make the seed into [seed[0], seed[1], ..., seed[seed.len()
         // - 1], 0, 0, ...], to fill rng.rsl.
-        let seed_iter = seed.iter().map(|&x| x).chain(Repeat::new(0u64));
+        let seed_iter = seed.iter().map(|&x| x).chain(repeat(0u64));
 
         for (rsl_elem, seed_elem) in self.rsl.iter_mut().zip(seed_iter) {
             *rsl_elem = seed_elem;
diff --git a/src/librustc/middle/cfg/construct.rs b/src/librustc/middle/cfg/construct.rs
index 61c56cf9ecc..b42fb8ccc41 100644
--- a/src/librustc/middle/cfg/construct.rs
+++ b/src/librustc/middle/cfg/construct.rs
@@ -154,7 +154,6 @@ impl<'a, 'tcx> CFGBuilder<'a, 'tcx> {
                                           pats: I,
                                           pred: CFGIndex) -> CFGIndex {
         //! Handles case where all of the patterns must match.
-        let mut pats = pats;
         pats.fold(pred, |pred, pat| self.pat(&**pat, pred))
     }
 
@@ -527,7 +526,7 @@ impl<'a, 'tcx> CFGBuilder<'a, 'tcx> {
     }
 
     fn exprs<'a, I: Iterator<&'a ast::Expr>>(&mut self,
-                                             mut exprs: I,
+                                             exprs: I,
                                              pred: CFGIndex) -> CFGIndex {
         //! Constructs graph for `exprs` evaluated in order
         exprs.fold(pred, |p, e| self.expr(e, p))
diff --git a/src/librustc/middle/check_match.rs b/src/librustc/middle/check_match.rs
index 806fea3b54f..bcfc003480f 100644
--- a/src/librustc/middle/check_match.rs
+++ b/src/librustc/middle/check_match.rs
@@ -93,7 +93,7 @@ impl<'a> fmt::Show for Matrix<'a> {
 }
 
 impl<'a> FromIterator<Vec<&'a Pat>> for Matrix<'a> {
-    fn from_iter<T: Iterator<Vec<&'a Pat>>>(mut iterator: T) -> Matrix<'a> {
+    fn from_iter<T: Iterator<Vec<&'a Pat>>>(iterator: T) -> Matrix<'a> {
         Matrix(iterator.collect())
     }
 }
@@ -1091,4 +1091,3 @@ impl<'a, 'b, 'tcx, 'v> Visitor<'v> for AtBindingPatternVisitor<'a, 'b, 'tcx> {
         }
     }
 }
-
diff --git a/src/librustc/middle/const_eval.rs b/src/librustc/middle/const_eval.rs
index 98ac7e413ca..7b442fedc24 100644
--- a/src/librustc/middle/const_eval.rs
+++ b/src/librustc/middle/const_eval.rs
@@ -80,7 +80,7 @@ pub fn join(a: constness, b: constness) -> constness {
     }
 }
 
-pub fn join_all<It: Iterator<constness>>(mut cs: It) -> constness {
+pub fn join_all<It: Iterator<constness>>(cs: It) -> constness {
     cs.fold(integral_const, |a, b| join(a, b))
 }
 
diff --git a/src/librustc/middle/dependency_format.rs b/src/librustc/middle/dependency_format.rs
index e8e90e74989..3cb628c2e65 100644
--- a/src/librustc/middle/dependency_format.rs
+++ b/src/librustc/middle/dependency_format.rs
@@ -233,7 +233,7 @@ fn add_library(sess: &session::Session,
 
 fn attempt_static(sess: &session::Session) -> Option<DependencyList> {
     let crates = sess.cstore.get_used_crates(cstore::RequireStatic);
-    if crates.iter().all(|&(_, ref p)| p.is_some()) {
+    if crates.iter().by_ref().all(|&(_, ref p)| p.is_some()) {
         Some(crates.into_iter().map(|_| Some(cstore::RequireStatic)).collect())
     } else {
         None
diff --git a/src/librustc/middle/entry.rs b/src/librustc/middle/entry.rs
index fd0162b30d8..417e5336249 100644
--- a/src/librustc/middle/entry.rs
+++ b/src/librustc/middle/entry.rs
@@ -80,7 +80,7 @@ fn find_item(item: &Item, ctxt: &mut EntryContext) {
     match item.node {
         ItemFn(..) => {
             if item.ident.name == ctxt.main_name {
-                 ctxt.ast_map.with_path(item.id, |mut path| {
+                 ctxt.ast_map.with_path(item.id, |path| {
                         if path.count() == 1 {
                             // This is a top-level function so can be 'main'
                             if ctxt.main_fn.is_none() {
diff --git a/src/librustc/middle/pat_util.rs b/src/librustc/middle/pat_util.rs
index a51956797ca..8d4fbfd4cbc 100644
--- a/src/librustc/middle/pat_util.rs
+++ b/src/librustc/middle/pat_util.rs
@@ -132,7 +132,7 @@ pub fn simple_identifier<'a>(pat: &'a ast::Pat) -> Option<&'a ast::Ident> {
 }
 
 pub fn def_to_path(tcx: &ty::ctxt, id: ast::DefId) -> ast::Path {
-    ty::with_path(tcx, id, |mut path| ast::Path {
+    ty::with_path(tcx, id, |path| ast::Path {
         global: false,
         segments: path.last().map(|elem| ast::PathSegment {
             identifier: ast::Ident::new(elem.name()),
diff --git a/src/librustc/middle/ty.rs b/src/librustc/middle/ty.rs
index 98b958749d5..2c8465e62d7 100644
--- a/src/librustc/middle/ty.rs
+++ b/src/librustc/middle/ty.rs
@@ -3106,7 +3106,7 @@ pub fn is_type_representable<'tcx>(cx: &ctxt<'tcx>, sp: Span, ty: Ty<'tcx>)
     // Iterate until something non-representable is found
     fn find_nonrepresentable<'tcx, It: Iterator<Ty<'tcx>>>(cx: &ctxt<'tcx>, sp: Span,
                                                            seen: &mut Vec<Ty<'tcx>>,
-                                                           mut iter: It)
+                                                           iter: It)
                                                            -> Representability {
         iter.fold(Representable,
                   |r, ty| cmp::max(r, is_type_structurally_recursive(cx, sp, seen, ty)))
@@ -3164,7 +3164,7 @@ pub fn is_type_representable<'tcx>(cx: &ctxt<'tcx>, sp: Span, ty: Ty<'tcx>)
                 let types_a = substs_a.types.get_slice(subst::TypeSpace);
                 let types_b = substs_b.types.get_slice(subst::TypeSpace);
 
-                let mut pairs = types_a.iter().zip(types_b.iter());
+                let pairs = types_a.iter().zip(types_b.iter());
 
                 pairs.all(|(&a, &b)| same_type(a, b))
             }
diff --git a/src/librustc/middle/typeck/check/mod.rs b/src/librustc/middle/typeck/check/mod.rs
index d38c5bc0ca9..754bdc8c8ea 100644
--- a/src/librustc/middle/typeck/check/mod.rs
+++ b/src/librustc/middle/typeck/check/mod.rs
@@ -4177,7 +4177,7 @@ fn check_expr_with_unifier<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
       }
       ast::ExprMethodCall(ident, ref tps, ref args) => {
         check_method_call(fcx, expr, ident, args.as_slice(), tps.as_slice(), lvalue_pref);
-        let mut arg_tys = args.iter().map(|a| fcx.expr_ty(&**a));
+        let arg_tys = args.iter().map(|a| fcx.expr_ty(&**a));
         let  args_err = arg_tys.fold(false,
              |rest_err, a| {
               rest_err || ty::type_is_error(a)});
diff --git a/src/librustc_trans/save/recorder.rs b/src/librustc_trans/save/recorder.rs
index e245878dd87..2102133f97d 100644
--- a/src/librustc_trans/save/recorder.rs
+++ b/src/librustc_trans/save/recorder.rs
@@ -170,7 +170,7 @@ impl<'a> FmtStrs<'a> {
         });
 
         let pairs = fields.iter().zip(values);
-        let mut strs = pairs.map(|(f, v)| format!(",{},\"{}\"", f, escape(
+        let strs = pairs.map(|(f, v)| format!(",{},\"{}\"", f, escape(
             if *f == "qualname" && v.len() > 0 {
                 let mut n = self.krate.clone();
                 n.push_str("::");
diff --git a/src/librustc_trans/trans/base.rs b/src/librustc_trans/trans/base.rs
index bdf2eca21d6..6fe5298393e 100644
--- a/src/librustc_trans/trans/base.rs
+++ b/src/librustc_trans/trans/base.rs
@@ -2696,7 +2696,7 @@ fn exported_name<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>, id: ast::NodeId,
         // Use provided name
         Some(name) => name.get().to_string(),
 
-        _ => ccx.tcx().map.with_path(id, |mut path| {
+        _ => ccx.tcx().map.with_path(id, |path| {
             if attr::contains_name(attrs, "no_mangle") {
                 // Don't mangle
                 path.last().unwrap().to_string()
diff --git a/src/librustdoc/clean/inline.rs b/src/librustdoc/clean/inline.rs
index 16edccd1543..a646b7e1ccb 100644
--- a/src/librustdoc/clean/inline.rs
+++ b/src/librustdoc/clean/inline.rs
@@ -151,7 +151,7 @@ pub fn build_external_trait(cx: &DocContext, tcx: &ty::ctxt,
     let def = ty::lookup_trait_def(tcx, did);
     let trait_items = ty::trait_items(tcx, did).clean(cx);
     let provided = ty::provided_trait_methods(tcx, did);
-    let mut items = trait_items.into_iter().map(|trait_item| {
+    let items = trait_items.into_iter().map(|trait_item| {
         if provided.iter().any(|a| a.def_id == trait_item.def_id) {
             clean::ProvidedMethod(trait_item)
         } else {
diff --git a/src/librustdoc/html/format.rs b/src/librustdoc/html/format.rs
index 43aef11ce5c..d523992b4c6 100644
--- a/src/librustdoc/html/format.rs
+++ b/src/librustdoc/html/format.rs
@@ -422,7 +422,7 @@ impl fmt::Show for clean::Type {
                        bounds = if decl.bounds.len() == 0 {
                            "".to_string()
                        } else {
-                           let mut m = decl.bounds
+                           let m = decl.bounds
                                            .iter()
                                            .map(|s| s.to_string());
                            format!(
diff --git a/src/librustdoc/html/markdown.rs b/src/librustdoc/html/markdown.rs
index 11dc8f4f660..df25daa3ca1 100644
--- a/src/librustdoc/html/markdown.rs
+++ b/src/librustdoc/html/markdown.rs
@@ -183,7 +183,7 @@ pub fn render(w: &mut fmt::Formatter, s: &str, print_toc: bool) -> fmt::Result {
                 }
             };
 
-            let mut lines = origtext.lines().filter(|l| {
+            let lines = origtext.lines().filter(|l| {
                 stripped_filtered_line(*l).is_none()
             });
             let text = lines.collect::<Vec<&str>>().connect("\n");
@@ -325,7 +325,7 @@ pub fn find_testable_code(doc: &str, tests: &mut ::test::Collector) {
             let opaque = opaque as *mut hoedown_html_renderer_state;
             let tests = &mut *((*opaque).opaque as *mut ::test::Collector);
             let text = str::from_utf8(text).unwrap();
-            let mut lines = text.lines().map(|l| {
+            let lines = text.lines().map(|l| {
                 stripped_filtered_line(l).unwrap_or(l)
             });
             let text = lines.collect::<Vec<&str>>().connect("\n");
diff --git a/src/librustrt/task.rs b/src/librustrt/task.rs
index 63fa3938fc8..325bdc284ac 100644
--- a/src/librustrt/task.rs
+++ b/src/librustrt/task.rs
@@ -19,7 +19,7 @@ use alloc::arc::Arc;
 use alloc::boxed::Box;
 use core::any::Any;
 use core::atomic::{AtomicUint, SeqCst};
-use core::iter::Take;
+use core::iter::{IteratorExt, Take};
 use core::kinds::marker;
 use core::mem;
 use core::prelude::{Clone, Drop, Err, Iterator, None, Ok, Option, Send, Some};
diff --git a/src/libstd/ascii.rs b/src/libstd/ascii.rs
index 9754e673d38..403ca9d1432 100644
--- a/src/libstd/ascii.rs
+++ b/src/libstd/ascii.rs
@@ -17,7 +17,7 @@
 
 use core::kinds::Sized;
 use fmt;
-use iter::Iterator;
+use iter::IteratorExt;
 use mem;
 use option::{Option, Some, None};
 use slice::{SlicePrelude, AsSlice};
diff --git a/src/libstd/collections/hash/map.rs b/src/libstd/collections/hash/map.rs
index 662ae913764..9c7967d17bb 100644
--- a/src/libstd/collections/hash/map.rs
+++ b/src/libstd/collections/hash/map.rs
@@ -20,7 +20,7 @@ use cmp::{max, Eq, Equiv, PartialEq};
 use default::Default;
 use fmt::{mod, Show};
 use hash::{Hash, Hasher, RandomSipHasher};
-use iter::{mod, Iterator, FromIterator, Extend};
+use iter::{mod, Iterator, IteratorExt, FromIterator, Extend};
 use kinds::Sized;
 use mem::{mod, replace};
 use num::UnsignedInt;
diff --git a/src/libstd/collections/hash/set.rs b/src/libstd/collections/hash/set.rs
index 2fbcb464358..f6d526cca39 100644
--- a/src/libstd/collections/hash/set.rs
+++ b/src/libstd/collections/hash/set.rs
@@ -17,7 +17,7 @@ use default::Default;
 use fmt::Show;
 use fmt;
 use hash::{Hash, Hasher, RandomSipHasher};
-use iter::{Iterator, FromIterator, FilterMap, Chain, Repeat, Zip, Extend};
+use iter::{Iterator, IteratorExt, FromIterator, FilterMap, Chain, Repeat, Zip, Extend, repeat};
 use iter;
 use option::{Some, None};
 use result::{Ok, Err};
@@ -262,7 +262,7 @@ impl<T: Eq + Hash<S>, S, H: Hasher<S>> HashSet<T, H> {
     /// ```
     #[unstable = "matches collection reform specification, waiting for dust to settle"]
     pub fn difference<'a>(&'a self, other: &'a HashSet<T, H>) -> SetAlgebraItems<'a, T, H> {
-        Repeat::new(other).zip(self.iter())
+        repeat(other).zip(self.iter())
             .filter_map(|(other, elt)| {
                 if !other.contains(elt) { Some(elt) } else { None }
             })
@@ -314,7 +314,7 @@ impl<T: Eq + Hash<S>, S, H: Hasher<S>> HashSet<T, H> {
     #[unstable = "matches collection reform specification, waiting for dust to settle"]
     pub fn intersection<'a>(&'a self, other: &'a HashSet<T, H>)
         -> SetAlgebraItems<'a, T, H> {
-        Repeat::new(other).zip(self.iter())
+        repeat(other).zip(self.iter())
             .filter_map(|(other, elt)| {
                 if other.contains(elt) { Some(elt) } else { None }
             })
diff --git a/src/libstd/dynamic_lib.rs b/src/libstd/dynamic_lib.rs
index 0f119d44485..4b868f6a95b 100644
--- a/src/libstd/dynamic_lib.rs
+++ b/src/libstd/dynamic_lib.rs
@@ -21,7 +21,7 @@ A simple wrapper over the platform's dynamic library facilities
 
 use clone::Clone;
 use c_str::ToCStr;
-use iter::Iterator;
+use iter::IteratorExt;
 use mem;
 use ops::*;
 use option::*;
@@ -280,7 +280,7 @@ pub mod dl {
 #[cfg(target_os = "windows")]
 pub mod dl {
     use c_str::ToCStr;
-    use iter::Iterator;
+    use iter::IteratorExt;
     use libc;
     use os;
     use ptr;
diff --git a/src/libstd/io/buffered.rs b/src/libstd/io/buffered.rs
index 148323762c8..025033a112c 100644
--- a/src/libstd/io/buffered.rs
+++ b/src/libstd/io/buffered.rs
@@ -14,7 +14,7 @@
 
 use cmp;
 use io::{Reader, Writer, Stream, Buffer, DEFAULT_BUF_SIZE, IoResult};
-use iter::ExactSize;
+use iter::ExactSizeIterator;
 use ops::Drop;
 use option::{Some, None, Option};
 use result::{Ok, Err};
diff --git a/src/libstd/io/mod.rs b/src/libstd/io/mod.rs
index 681400e9db5..a25674030ae 100644
--- a/src/libstd/io/mod.rs
+++ b/src/libstd/io/mod.rs
@@ -233,7 +233,7 @@ use default::Default;
 use error::{FromError, Error};
 use fmt;
 use int;
-use iter::Iterator;
+use iter::{Iterator, IteratorExt};
 use mem::transmute;
 use ops::{BitOr, BitXor, BitAnd, Sub, Not};
 use option::{Option, Some, None};
diff --git a/src/libstd/io/net/addrinfo.rs b/src/libstd/io/net/addrinfo.rs
index 13f602de03a..d6a48fd39e6 100644
--- a/src/libstd/io/net/addrinfo.rs
+++ b/src/libstd/io/net/addrinfo.rs
@@ -23,7 +23,7 @@ pub use self::SocketType::*;
 pub use self::Flag::*;
 pub use self::Protocol::*;
 
-use iter::Iterator;
+use iter::IteratorExt;
 use io::{IoResult};
 use io::net::ip::{SocketAddr, IpAddr};
 use option::{Option, Some, None};
diff --git a/src/libstd/io/net/ip.rs b/src/libstd/io/net/ip.rs
index d87768a0860..4812e911cc4 100644
--- a/src/libstd/io/net/ip.rs
+++ b/src/libstd/io/net/ip.rs
@@ -20,7 +20,7 @@ pub use self::IpAddr::*;
 use fmt;
 use io::{mod, IoResult, IoError};
 use io::net;
-use iter::Iterator;
+use iter::{Iterator, IteratorExt};
 use option::{Option, None, Some};
 use result::{Ok, Err};
 use str::{FromStr, StrPrelude};
diff --git a/src/libstd/io/net/tcp.rs b/src/libstd/io/net/tcp.rs
index cbac6b48b83..8ba91684d04 100644
--- a/src/libstd/io/net/tcp.rs
+++ b/src/libstd/io/net/tcp.rs
@@ -19,7 +19,6 @@
 
 use clone::Clone;
 use io::IoResult;
-use iter::Iterator;
 use result::Err;
 use io::net::ip::{SocketAddr, ToSocketAddr};
 use io::{Reader, Writer, Listener, Acceptor};
diff --git a/src/libstd/io/stdio.rs b/src/libstd/io/stdio.rs
index d450e9f1dce..e6dd20f63fb 100644
--- a/src/libstd/io/stdio.rs
+++ b/src/libstd/io/stdio.rs
@@ -35,7 +35,6 @@ use failure::LOCAL_STDERR;
 use fmt;
 use io::{Reader, Writer, IoResult, IoError, OtherIoError,
          standard_error, EndOfFile, LineBufferedWriter, BufferedReader};
-use iter::Iterator;
 use kinds::Send;
 use libc;
 use mem;
diff --git a/src/libstd/os.rs b/src/libstd/os.rs
index 9b50361ec1f..3019e86575a 100644
--- a/src/libstd/os.rs
+++ b/src/libstd/os.rs
@@ -39,7 +39,7 @@ use clone::Clone;
 use error::{FromError, Error};
 use fmt;
 use io::{IoResult, IoError};
-use iter::Iterator;
+use iter::{Iterator, IteratorExt};
 use libc::{c_void, c_int};
 use libc;
 use boxed::Box;
diff --git a/src/libstd/path/mod.rs b/src/libstd/path/mod.rs
index a185a29a700..078a9b1518f 100644
--- a/src/libstd/path/mod.rs
+++ b/src/libstd/path/mod.rs
@@ -71,7 +71,7 @@ use core::kinds::Sized;
 use c_str::CString;
 use clone::Clone;
 use fmt;
-use iter::Iterator;
+use iter::IteratorExt;
 use option::{Option, None, Some};
 use str;
 use str::{MaybeOwned, Str, StrPrelude};
diff --git a/src/libstd/path/posix.rs b/src/libstd/path/posix.rs
index 2b444fdc32b..027ac029288 100644
--- a/src/libstd/path/posix.rs
+++ b/src/libstd/path/posix.rs
@@ -15,9 +15,10 @@ use clone::Clone;
 use cmp::{PartialEq, Eq, PartialOrd, Ord, Ordering};
 use hash;
 use io::Writer;
-use iter::{DoubleEndedIterator, AdditiveIterator, Extend, Iterator, Map};
-use kinds::Sized;
+use iter::{DoubleEndedIteratorExt, AdditiveIterator, Extend};
+use iter::{Iterator, IteratorExt, Map};
 use option::{Option, None, Some};
+use kinds::Sized;
 use str::{FromStr, Str};
 use str;
 use slice::{CloneSliceAllocPrelude, Splits, AsSlice, VectorVector,
diff --git a/src/libstd/path/windows.rs b/src/libstd/path/windows.rs
index 9f81de72980..334227f42bb 100644
--- a/src/libstd/path/windows.rs
+++ b/src/libstd/path/windows.rs
@@ -20,7 +20,8 @@ use clone::Clone;
 use cmp::{PartialEq, Eq, PartialOrd, Ord, Ordering};
 use hash;
 use io::Writer;
-use iter::{AdditiveIterator, DoubleEndedIterator, Extend, Iterator, Map};
+use iter::{AdditiveIterator, DoubleEndedIteratorExt, Extend};
+use iter::{Iterator, IteratorExt, Map};
 use mem;
 use option::{Option, Some, None};
 use slice::{AsSlice, SlicePrelude};
diff --git a/src/libstd/prelude.rs b/src/libstd/prelude.rs
index 65f45c3f97e..82691b111a8 100644
--- a/src/libstd/prelude.rs
+++ b/src/libstd/prelude.rs
@@ -50,7 +50,7 @@
 #[doc(no_inline)] pub use ops::{Fn, FnMut, FnOnce};
 
 // Reexported functions
-#[doc(no_inline)] pub use iter::{range, repeat};
+#[doc(no_inline)] pub use iter::range;
 #[doc(no_inline)] pub use mem::drop;
 #[doc(no_inline)] pub use str::from_str;
 
@@ -64,10 +64,11 @@
 #[doc(no_inline)] pub use cmp::{PartialEq, PartialOrd, Eq, Ord};
 #[doc(no_inline)] pub use cmp::{Ordering, Equiv};
 #[doc(no_inline)] pub use cmp::Ordering::{Less, Equal, Greater};
-#[doc(no_inline)] pub use iter::{FromIterator, Extend, ExactSize};
-#[doc(no_inline)] pub use iter::{Iterator, DoubleEndedIterator};
-#[doc(no_inline)] pub use iter::{RandomAccessIterator, CloneableIterator};
-#[doc(no_inline)] pub use iter::{OrdIterator, MutableDoubleEndedIterator};
+#[doc(no_inline)] pub use iter::{FromIterator, Extend, ExactSizeIterator};
+#[doc(no_inline)] pub use iter::{Iterator, IteratorExt, DoubleEndedIterator};
+#[doc(no_inline)] pub use iter::{DoubleEndedIteratorExt, CloneIteratorExt};
+#[doc(no_inline)] pub use iter::{RandomAccessIterator, IteratorCloneExt};
+#[doc(no_inline)] pub use iter::{IteratorOrdExt, MutableDoubleEndedIterator};
 #[doc(no_inline)] pub use num::{ToPrimitive, FromPrimitive};
 #[doc(no_inline)] pub use boxed::Box;
 #[doc(no_inline)] pub use option::Option;
diff --git a/src/libstd/rand/mod.rs b/src/libstd/rand/mod.rs
index f9f9147b107..da690f5d154 100644
--- a/src/libstd/rand/mod.rs
+++ b/src/libstd/rand/mod.rs
@@ -224,7 +224,7 @@
 use cell::RefCell;
 use clone::Clone;
 use io::IoResult;
-use iter::Iterator;
+use iter::{Iterator, IteratorExt};
 use mem;
 use rc::Rc;
 use result::{Ok, Err};
diff --git a/src/libstd/rt/backtrace.rs b/src/libstd/rt/backtrace.rs
index 81022994387..4f6c1f8a2c6 100644
--- a/src/libstd/rt/backtrace.rs
+++ b/src/libstd/rt/backtrace.rs
@@ -13,7 +13,7 @@
 #![allow(non_camel_case_types)]
 
 use io::{IoResult, Writer};
-use iter::Iterator;
+use iter::{Iterator, IteratorExt};
 use option::{Some, None};
 use os;
 use result::{Ok, Err};
@@ -388,7 +388,7 @@ mod imp {
 
     #[cfg(not(any(target_os = "macos", target_os = "ios")))]
     fn print(w: &mut Writer, idx: int, addr: *mut libc::c_void) -> IoResult<()> {
-        use iter::Iterator;
+        use iter::IteratorExt;
         use os;
         use path::GenericPath;
         use ptr::RawPtr;
diff --git a/src/libstd/sys/windows/c.rs b/src/libstd/sys/windows/c.rs
index b8e9b1dca3a..e46765f25b8 100644
--- a/src/libstd/sys/windows/c.rs
+++ b/src/libstd/sys/windows/c.rs
@@ -131,7 +131,7 @@ extern "system" {
 
 pub mod compat {
     use intrinsics::{atomic_store_relaxed, transmute};
-    use iter::Iterator;
+    use iter::IteratorExt;
     use libc::types::os::arch::extra::{LPCWSTR, HMODULE, LPCSTR, LPVOID};
     use prelude::*;
 
diff --git a/src/libstd/sys/windows/process.rs b/src/libstd/sys/windows/process.rs
index 3fb5ee34356..4a6ae0b7e9e 100644
--- a/src/libstd/sys/windows/process.rs
+++ b/src/libstd/sys/windows/process.rs
@@ -124,7 +124,7 @@ impl Process {
         use libc::funcs::extra::msvcrt::get_osfhandle;
 
         use mem;
-        use iter::Iterator;
+        use iter::{Iterator, IteratorExt};
         use str::StrPrelude;
 
         if cfg.gid().is_some() || cfg.uid().is_some() {
diff --git a/src/libsyntax/ast_map/mod.rs b/src/libsyntax/ast_map/mod.rs
index 8a2202d28d5..6b97b931ef7 100644
--- a/src/libsyntax/ast_map/mod.rs
+++ b/src/libsyntax/ast_map/mod.rs
@@ -87,7 +87,7 @@ impl<'a, T: Copy> Iterator<T> for Values<'a, T> {
 /// The type of the iterator used by with_path.
 pub type PathElems<'a, 'b> = iter::Chain<Values<'a, PathElem>, LinkedPath<'b>>;
 
-pub fn path_to_string<PI: Iterator<PathElem>>(mut path: PI) -> String {
+pub fn path_to_string<PI: Iterator<PathElem>>(path: PI) -> String {
     let itr = token::get_ident_interner();
 
     path.fold(String::new(), |mut s, e| {
diff --git a/src/libsyntax/config.rs b/src/libsyntax/config.rs
index 257bfd69f43..4f718555d53 100644
--- a/src/libsyntax/config.rs
+++ b/src/libsyntax/config.rs
@@ -131,7 +131,7 @@ fn fold_item_underscore(cx: &mut Context, item: ast::Item_) -> ast::Item_ {
             ast::ItemStruct(fold_struct(cx, def), generics)
         }
         ast::ItemEnum(def, generics) => {
-            let mut variants = def.variants.into_iter().filter_map(|v| {
+            let variants = def.variants.into_iter().filter_map(|v| {
                 if !(cx.in_cfg)(v.node.attrs.as_slice()) {
                     None
                 } else {
@@ -273,4 +273,3 @@ fn in_cfg(diagnostic: &SpanHandler, cfg: &[P<ast::MetaItem>], attrs: &[ast::Attr
         attr::cfg_matches(diagnostic, cfg, &*mis[0])
     })
 }
-
diff --git a/src/libsyntax/ext/base.rs b/src/libsyntax/ext/base.rs
index 1cbc2b98c93..8d0d399fa31 100644
--- a/src/libsyntax/ext/base.rs
+++ b/src/libsyntax/ext/base.rs
@@ -210,7 +210,7 @@ pub struct MacItems {
 }
 
 impl MacItems {
-    pub fn new<I: Iterator<P<ast::Item>>>(mut it: I) -> Box<MacResult+'static> {
+    pub fn new<I: Iterator<P<ast::Item>>>(it: I) -> Box<MacResult+'static> {
         box MacItems { items: it.collect() } as Box<MacResult+'static>
     }
 }
diff --git a/src/libsyntax/ext/format.rs b/src/libsyntax/ext/format.rs
index b04a800a32d..490246f8246 100644
--- a/src/libsyntax/ext/format.rs
+++ b/src/libsyntax/ext/format.rs
@@ -580,7 +580,7 @@ impl<'a, 'b> Context<'a, 'b> {
         let slicename = self.ecx.ident_of("__args_vec");
         {
             let args = names.into_iter().map(|a| a.unwrap());
-            let mut args = locals.into_iter().chain(args);
+            let args = locals.into_iter().chain(args);
             let args = self.ecx.expr_vec_slice(self.fmtsp, args.collect());
             lets.push(self.ecx.stmt_let(self.fmtsp, false, slicename, args));
         }
diff --git a/src/libsyntax/owned_slice.rs b/src/libsyntax/owned_slice.rs
index f622e2d6112..b31b20c80c2 100644
--- a/src/libsyntax/owned_slice.rs
+++ b/src/libsyntax/owned_slice.rs
@@ -145,7 +145,7 @@ impl<T: PartialEq> PartialEq for OwnedSlice<T> {
 impl<T: Eq> Eq for OwnedSlice<T> {}
 
 impl<T> FromIterator<T> for OwnedSlice<T> {
-    fn from_iter<I: Iterator<T>>(mut iter: I) -> OwnedSlice<T> {
+    fn from_iter<I: Iterator<T>>(iter: I) -> OwnedSlice<T> {
         OwnedSlice::from_vec(iter.collect())
     }
 }
diff --git a/src/libunicode/u_str.rs b/src/libunicode/u_str.rs
index 56b1f0907d5..03a50409d7e 100644
--- a/src/libunicode/u_str.rs
+++ b/src/libunicode/u_str.rs
@@ -20,7 +20,8 @@
 use self::GraphemeState::*;
 use core::cmp;
 use core::slice::SlicePrelude;
-use core::iter::{Filter, AdditiveIterator, Iterator, DoubleEndedIterator};
+use core::iter::{Filter, AdditiveIterator, Iterator, IteratorExt};
+use core::iter::{DoubleEndedIterator, DoubleEndedIteratorExt};
 use core::kinds::Sized;
 use core::option::{Option, None, Some};
 use core::str::{CharSplits, StrPrelude};