Removed many pointless calls to *iter() and iter_mut()

src/compiletest/runtest.rs

@@ -285,8 +285,8 @@ fn run_pretty_test(config: &Config, props: &TestProps, testfile: &Path) {
                             format!("--target={}", config.target),
                             "-L".to_string(),
                             aux_dir.to_str().unwrap().to_string());
-        args.extend(split_maybe_args(&config.target_rustcflags).into_iter());
-        args.extend(split_maybe_args(&props.compile_flags).into_iter());
+        args.extend(split_maybe_args(&config.target_rustcflags));
+        args.extend(split_maybe_args(&props.compile_flags));
         return ProcArgs {
             prog: config.rustc_path.to_str().unwrap().to_string(),
             args: args,
@@ -333,8 +333,8 @@ actual:\n\
                             config.build_base.to_str().unwrap().to_string(),
                             "-L".to_string(),
                             aux_dir.to_str().unwrap().to_string());
-        args.extend(split_maybe_args(&config.target_rustcflags).into_iter());
-        args.extend(split_maybe_args(&props.compile_flags).into_iter());
+        args.extend(split_maybe_args(&config.target_rustcflags));
+        args.extend(split_maybe_args(&props.compile_flags));
         // FIXME (#9639): This needs to handle non-utf8 paths
         return ProcArgs {
             prog: config.rustc_path.to_str().unwrap().to_string(),
@@ -380,7 +380,7 @@ fn run_debuginfo_gdb_test(config: &Config, props: &TestProps, testfile: &Path) {
             script_str.push_str(&format!("set solib-search-path \
                                          ./{}/stage2/lib/rustlib/{}/lib/\n",
                                          config.host, config.target));
-            for line in breakpoint_lines.iter() {
+            for line in &breakpoint_lines {
                 script_str.push_str(&format!("break {:?}:{}\n",
                                              testfile.file_name().unwrap()
                                                      .to_string_lossy(),
@@ -1171,7 +1171,7 @@ fn document(config: &Config, props: &TestProps,
                         out_dir.to_str().unwrap().to_string(),
                         testfile.to_str().unwrap().to_string()];
     args.extend(extra_args.iter().cloned());
-    args.extend(split_maybe_args(&props.compile_flags).into_iter());
+    args.extend(split_maybe_args(&props.compile_flags));
     let args = ProcArgs {
         prog: config.rustdoc_path.to_str().unwrap().to_string(),
         args: args,
@@ -1236,7 +1236,7 @@ fn compose_and_run_compiler(config: &Config, props: &TestProps,
                 vec!("--crate-type=dylib".to_string())
             }
         };
-        crate_type.extend(extra_link_args.clone().into_iter());
+        crate_type.extend(extra_link_args.clone());
         let aux_args =
             make_compile_args(config,
                               &aux_props,
@@ -1334,11 +1334,11 @@ fn make_compile_args<F>(config: &Config,
     };
     args.push(path.to_str().unwrap().to_string());
     if props.force_host {
-        args.extend(split_maybe_args(&config.host_rustcflags).into_iter());
+        args.extend(split_maybe_args(&config.host_rustcflags));
     } else {
-        args.extend(split_maybe_args(&config.target_rustcflags).into_iter());
+        args.extend(split_maybe_args(&config.target_rustcflags));
     }
-    args.extend(split_maybe_args(&props.compile_flags).into_iter());
+    args.extend(split_maybe_args(&props.compile_flags));
     return ProcArgs {
         prog: config.rustc_path.to_str().unwrap().to_string(),
         args: args,
@@ -1373,7 +1373,7 @@ fn make_run_args(config: &Config, props: &TestProps, testfile: &Path)
     args.push(exe_file.to_str().unwrap().to_string());
 
     // Add the arguments in the run_flags directive
-    args.extend(split_maybe_args(&props.run_flags).into_iter());
+    args.extend(split_maybe_args(&props.run_flags));
 
     let prog = args.remove(0);
     return ProcArgs {
@@ -1683,7 +1683,7 @@ fn compile_test_and_save_ir(config: &Config, props: &TestProps,
                              aux_dir.to_str().unwrap().to_string());
     let llvm_args = vec!("--emit=llvm-ir".to_string(),
                          "--crate-type=lib".to_string());
-    link_args.extend(llvm_args.into_iter());
+    link_args.extend(llvm_args);
     let args = make_compile_args(config,
                                  props,
                                  link_args,

src/error-index-generator/main.rs

@@ -73,7 +73,7 @@ r##"<!DOCTYPE html>
 
     try!(write!(&mut output_file, "<h1>Rust Compiler Error Index</h1>\n"));
 
-    for (err_code, info) in err_map.iter() {
+    for (err_code, info) in err_map {
         // Enclose each error in a div so they can be shown/hidden en masse.
         let desc_desc = match info.description {
             Some(_) => "error-described",

src/liballoc/rc.rs

@@ -130,7 +130,7 @@
 //!     gadget_owner.gadgets.borrow_mut().push(gadget2.clone().downgrade());
 //!
 //!     // Iterate over our Gadgets, printing their details out
-//!     for gadget_opt in gadget_owner.gadgets.borrow().iter() {
+//!     for gadget_opt in &*gadget_owner.gadgets.borrow() {
 //!
 //!         // gadget_opt is a Weak<Gadget>. Since weak pointers can't guarantee
 //!         // that their object is still allocated, we need to call upgrade()

src/libcollections/binary_heap.rs

@@ -85,7 +85,7 @@
 //!
 //!         // For each node we can reach, see if we can find a way with
 //!         // a lower cost going through this node
-//!         for edge in adj_list[position].iter() {
+//!         for edge in &adj_list[position] {
 //!             let next = State { cost: cost + edge.cost, position: edge.node };
 //!
 //!             // If so, add it to the frontier and continue
@@ -450,7 +450,7 @@ impl<T: Ord> BinaryHeap<T> {
     /// let vec = heap.into_vec();
     ///
     /// // Will print in some order
-    /// for x in vec.iter() {
+    /// for x in vec {
     ///     println!("{}", x);
     /// }
     /// ```

src/libcollections/bit.rs

@@ -266,9 +266,9 @@ impl BitVec {
     /// # #![feature(collections)]
     /// use std::collections::BitVec;
     ///
-    /// let mut bv = BitVec::from_elem(10, false);
+    /// let bv = BitVec::from_elem(10, false);
     /// assert_eq!(bv.len(), 10);
-    /// for x in bv.iter() {
+    /// for x in &bv {
     ///     assert_eq!(x, false);
     /// }
     /// ```
@@ -1245,7 +1245,7 @@ impl<'a> IntoIterator for &'a BitVec {
 /// s.union_with(&other);
 ///
 /// // Print 0, 1, 3 in some order
-/// for x in s.iter() {
+/// for x in &s {
 ///     println!("{}", x);
 /// }
 ///
@@ -1370,7 +1370,7 @@ impl BitSet {
     /// let s = BitSet::from_bit_vec(bv);
     ///
     /// // Print 1, 2 in arbitrary order
-    /// for x in s.iter() {
+    /// for x in &s {
     ///     println!("{}", x);
     /// }
     /// ```

src/libcollections/btree/map.rs

@@ -907,7 +907,7 @@ impl<K: Ord, V> Default for BTreeMap<K, V> {
 impl<K: PartialEq, V: PartialEq> PartialEq for BTreeMap<K, V> {
     fn eq(&self, other: &BTreeMap<K, V>) -> bool {
         self.len() == other.len() &&
-            self.iter().zip(other.iter()).all(|(a, b)| a == b)
+            self.iter().zip(other).all(|(a, b)| a == b)
     }
 }
 
@@ -1544,7 +1544,7 @@ impl<K: Ord, V> BTreeMap<K, V> {
     /// for (_, balance) in map.range_mut(Included(&"B"), Excluded(&"Cheryl")) {
     ///     *balance += 100;
     /// }
-    /// for (name, balance) in map.iter() {
+    /// for (name, balance) in &map {
     ///     println!("{} => {}", name, balance);
     /// }
     /// ```

src/libcollections/linked_list.rs

@@ -265,7 +265,7 @@ impl<T> LinkedList<T> {
     ///
     /// a.append(&mut b);
     ///
-    /// for e in a.iter() {
+    /// for e in &a {
     ///     println!("{}", e); // prints 1, then 2, then 3, then 4
     /// }
     /// println!("{}", b.len()); // prints 0
@@ -1189,7 +1189,7 @@ mod tests {
         check_links(&m);
 
         let mut i = 0;
-        for (a, &b) in m.into_iter().zip(v.iter()) {
+        for (a, &b) in m.into_iter().zip(&v) {
             i += 1;
             assert_eq!(a, b);
         }

src/libcollections/slice.rs

@@ -971,7 +971,7 @@ impl<T> [T] {
                reason = "uncertain about this API approach")]
     #[inline]
     pub fn move_from(&mut self, mut src: Vec<T>, start: usize, end: usize) -> usize {
-        for (a, b) in self.iter_mut().zip(src[start .. end].iter_mut()) {
+        for (a, b) in self.iter_mut().zip(&mut src[start .. end]) {
             mem::swap(a, b);
         }
         cmp::min(self.len(), end-start)

src/libcollections/str.rs

@@ -1890,7 +1890,7 @@ impl str {
     #[stable(feature = "unicode_case_mapping", since = "1.2.0")]
     pub fn to_uppercase(&self) -> String {
         let mut s = String::with_capacity(self.len());
-        s.extend(self[..].chars().flat_map(|c| c.to_uppercase()));
+        s.extend(self.chars().flat_map(|c| c.to_uppercase()));
         return s;
     }
 

src/libcollections/vec.rs

@@ -1331,7 +1331,7 @@ impl<T:Clone> Clone for Vec<T> {
         }
 
         // reuse the contained values' allocations/resources.
-        for (place, thing) in self.iter_mut().zip(other.iter()) {
+        for (place, thing) in self.iter_mut().zip(other) {
             place.clone_from(thing)
         }
 

src/libcollections/vec_deque.rs

@@ -1443,7 +1443,7 @@ impl<T: Clone> VecDeque<T> {
     /// buf.push_back(15);
     /// buf.resize(2, 0);
     /// buf.resize(6, 20);
-    /// for (a, b) in [5, 10, 20, 20, 20, 20].iter().zip(buf.iter()) {
+    /// for (a, b) in [5, 10, 20, 20, 20, 20].iter().zip(&buf) {
     ///     assert_eq!(a, b);
     /// }
     /// ```
@@ -1681,7 +1681,7 @@ impl<'a, T: 'a> ExactSizeIterator for Drain<'a, T> {}
 impl<A: PartialEq> PartialEq for VecDeque<A> {
     fn eq(&self, other: &VecDeque<A>) -> bool {
         self.len() == other.len() &&
-            self.iter().zip(other.iter()).all(|(a, b)| a.eq(b))
+            self.iter().zip(other).all(|(a, b)| a.eq(b))
     }
 }
 

src/libcollections/vec_map.rs

@@ -54,7 +54,7 @@ use vec::Vec;
 /// assert_eq!(months.get(&3), Some(&"Venus"));
 ///
 /// // Print out all months
-/// for (key, value) in months.iter() {
+/// for (key, value) in &months {
 ///     println!("month {} is {}", key, value);
 /// }
 ///
@@ -287,7 +287,7 @@ impl<V> VecMap<V> {
     ///     *value = "x";
     /// }
     ///
-    /// for (key, value) in map.iter() {
+    /// for (key, value) in &map {
     ///     assert_eq!(value, &"x");
     /// }
     /// ```

src/libcollectionstest/bit/vec.rs

@@ -625,7 +625,7 @@ fn test_bit_vec_grow() {
 fn test_bit_vec_extend() {
     let mut bit_vec = BitVec::from_bytes(&[0b10110110, 0b00000000, 0b11111111]);
     let ext = BitVec::from_bytes(&[0b01001001, 0b10010010, 0b10111101]);
-    bit_vec.extend(ext.iter());
+    bit_vec.extend(&ext);
     assert_eq!(bit_vec, BitVec::from_bytes(&[0b10110110, 0b00000000, 0b11111111,
                                  0b01001001, 0b10010010, 0b10111101]));
 }

src/libcollectionstest/btree/set.rs

@@ -147,7 +147,7 @@ fn test_zip() {
 
     let x = x;
     let y = y;
-    let mut z = x.iter().zip(y.iter());
+    let mut z = x.iter().zip(&y);
 
     // FIXME: #5801: this needs a type hint to compile...
     let result: Option<(&usize, & &'static str)> = z.next();

src/libcollectionstest/string.rs

@@ -344,7 +344,7 @@ fn test_from_iterator() {
     assert_eq!(s, c);
 
     let mut d = t.to_string();
-    d.extend(vec![u].into_iter());
+    d.extend(vec![u]);
     assert_eq!(s, d);
 }
 

src/libcollectionstest/vec.rs

@@ -699,7 +699,7 @@ fn do_bench_from_iter(b: &mut Bencher, src_len: usize) {
     b.bytes = src_len as u64;
 
     b.iter(|| {
-        let dst: Vec<_> = FromIterator::from_iter(src.clone().into_iter());
+        let dst: Vec<_> = FromIterator::from_iter(src.clone());
         assert_eq!(dst.len(), src_len);
         assert!(dst.iter().enumerate().all(|(i, x)| i == *x));
     });
@@ -733,7 +733,7 @@ fn do_bench_extend(b: &mut Bencher, dst_len: usize, src_len: usize) {
 
     b.iter(|| {
         let mut dst = dst.clone();
-        dst.extend(src.clone().into_iter());
+        dst.extend(src.clone());
         assert_eq!(dst.len(), dst_len + src_len);
         assert!(dst.iter().enumerate().all(|(i, x)| i == *x));
     });
@@ -831,7 +831,7 @@ fn do_bench_push_all_move(b: &mut Bencher, dst_len: usize, src_len: usize) {
 
     b.iter(|| {
         let mut dst = dst.clone();
-        dst.extend(src.clone().into_iter());
+        dst.extend(src.clone());
         assert_eq!(dst.len(), dst_len + src_len);
         assert!(dst.iter().enumerate().all(|(i, x)| i == *x));
     });

src/libcore/iter.rs

@@ -177,7 +177,7 @@ pub trait Iterator {
     /// ```
     /// let a = [0];
     /// let b = [1];
-    /// let mut it = a.iter().chain(b.iter());
+    /// let mut it = a.iter().chain(&b);
     /// assert_eq!(it.next(), Some(&0));
     /// assert_eq!(it.next(), Some(&1));
     /// assert!(it.next().is_none());
@@ -200,7 +200,7 @@ pub trait Iterator {
     /// ```
     /// let a = [0];
     /// let b = [1];
-    /// let mut it = a.iter().zip(b.iter());
+    /// let mut it = a.iter().zip(&b);
     /// assert_eq!(it.next(), Some((&0, &1)));
     /// assert!(it.next().is_none());
     /// ```
@@ -585,9 +585,9 @@ pub trait Iterator {
 
         for x in self {
             if f(&x) {
-                left.extend(Some(x).into_iter())
+                left.extend(Some(x))
             } else {
-                right.extend(Some(x).into_iter())
+                right.extend(Some(x))
             }
         }
 
@@ -994,8 +994,8 @@ pub trait Iterator {
         us.extend(SizeHint(lo, hi, marker::PhantomData));
 
         for (t, u) in self {
-            ts.extend(Some(t).into_iter());
-            us.extend(Some(u).into_iter());
+            ts.extend(Some(t));
+            us.extend(Some(u));
         }
 
         (ts, us)

src/libcore/num/flt2dec/bignum.rs

@@ -146,7 +146,7 @@ macro_rules! define_bignum {
 
                 let mut sz = cmp::max(self.size, other.size);
                 let mut carry = false;
-                for (a, b) in self.base[..sz].iter_mut().zip(other.base[..sz].iter()) {
+                for (a, b) in self.base[..sz].iter_mut().zip(&other.base[..sz]) {
                     let (c, v) = (*a).full_add(*b, carry);
                     *a = v;
                     carry = c;
@@ -166,7 +166,7 @@ macro_rules! define_bignum {
 
                 let sz = cmp::max(self.size, other.size);
                 let mut noborrow = true;
-                for (a, b) in self.base[..sz].iter_mut().zip(other.base[..sz].iter()) {
+                for (a, b) in self.base[..sz].iter_mut().zip(&other.base[..sz]) {
                     let (c, v) = (*a).full_add(!*b, noborrow);
                     *a = v;
                     noborrow = c;
@@ -183,7 +183,7 @@ macro_rules! define_bignum {
 
                 let mut sz = self.size;
                 let mut carry = 0;
-                for a in self.base[..sz].iter_mut() {
+                for a in &mut self.base[..sz] {
                     let (c, v) = (*a).full_mul(other, carry);
                     *a = v;
                     carry = c;

src/libcore/option.rs

@@ -124,7 +124,7 @@
 //! // but to start with we've just got `None`.
 //! let mut name_of_biggest_animal = None;
 //! let mut size_of_biggest_animal = 0;
-//! for big_thing in all_the_big_things.iter() {
+//! for big_thing in &all_the_big_things {
 //!     match *big_thing {
 //!         Kingdom::Animal(size, name) if size > size_of_biggest_animal => {
 //!             // Now we've found the name of some big animal

src/libcoretest/iter.rs

@@ -82,7 +82,7 @@ fn test_iterator_chain() {
     let xs = [0, 1, 2, 3, 4, 5];
     let ys = [30, 40, 50, 60];
     let expected = [0, 1, 2, 3, 4, 5, 30, 40, 50, 60];
-    let it = xs.iter().chain(ys.iter());
+    let it = xs.iter().chain(&ys);
     let mut i = 0;
     for &x in it {
         assert_eq!(x, expected[i]);
@@ -107,11 +107,11 @@ fn test_iterator_chain_nth() {
     let zs = [];
     let expected = [0, 1, 2, 3, 4, 5, 30, 40, 50, 60];
     for (i, x) in expected.iter().enumerate() {
-        assert_eq!(Some(x), xs.iter().chain(ys.iter()).nth(i));
+        assert_eq!(Some(x), xs.iter().chain(&ys).nth(i));
     }
-    assert_eq!(zs.iter().chain(xs.iter()).nth(0), Some(&0));
+    assert_eq!(zs.iter().chain(&xs).nth(0), Some(&0));
 
-    let mut it = xs.iter().chain(zs.iter());
+    let mut it = xs.iter().chain(&zs);
     assert_eq!(it.nth(5), Some(&5));
     assert_eq!(it.next(), None);
 }
@@ -121,10 +121,10 @@ fn test_iterator_chain_last() {
     let xs = [0, 1, 2, 3, 4, 5];
     let ys = [30, 40, 50, 60];
     let zs = [];
-    assert_eq!(xs.iter().chain(ys.iter()).last(), Some(&60));
-    assert_eq!(zs.iter().chain(ys.iter()).last(), Some(&60));
-    assert_eq!(ys.iter().chain(zs.iter()).last(), Some(&60));
-    assert_eq!(zs.iter().chain(zs.iter()).last(), None);
+    assert_eq!(xs.iter().chain(&ys).last(), Some(&60));
+    assert_eq!(zs.iter().chain(&ys).last(), Some(&60));
+    assert_eq!(ys.iter().chain(&zs).last(), Some(&60));
+    assert_eq!(zs.iter().chain(&zs).last(), None);
 }
 
 #[test]
@@ -132,8 +132,8 @@ fn test_iterator_chain_count() {
     let xs = [0, 1, 2, 3, 4, 5];
     let ys = [30, 40, 50, 60];
     let zs = [];
-    assert_eq!(xs.iter().chain(ys.iter()).count(), 10);
-    assert_eq!(zs.iter().chain(ys.iter()).count(), 4);
+    assert_eq!(xs.iter().chain(&ys).count(), 10);
+    assert_eq!(zs.iter().chain(&ys).count(), 4);
 }
 
 #[test]
@@ -571,8 +571,8 @@ fn test_iterator_size_hint() {
     assert_eq!(vi.clone().take_while(|_| false).size_hint(), (0, Some(10)));
     assert_eq!(vi.clone().skip_while(|_| false).size_hint(), (0, Some(10)));
     assert_eq!(vi.clone().enumerate().size_hint(), (10, Some(10)));
-    assert_eq!(vi.clone().chain(v2.iter()).size_hint(), (13, Some(13)));
-    assert_eq!(vi.clone().zip(v2.iter()).size_hint(), (3, Some(3)));
+    assert_eq!(vi.clone().chain(v2).size_hint(), (13, Some(13)));
+    assert_eq!(vi.clone().zip(v2).size_hint(), (3, Some(3)));
     assert_eq!(vi.clone().scan(0, |_,_| Some(0)).size_hint(), (0, Some(10)));
     assert_eq!(vi.clone().filter(|_| false).size_hint(), (0, Some(10)));
     assert_eq!(vi.clone().map(|&i| i+1).size_hint(), (10, Some(10)));
@@ -742,7 +742,7 @@ fn test_double_ended_filter_map() {
 fn test_double_ended_chain() {
     let xs = [1, 2, 3, 4, 5];
     let ys = [7, 9, 11];
-    let mut it = xs.iter().chain(ys.iter()).rev();
+    let mut it = xs.iter().chain(&ys).rev();
     assert_eq!(it.next().unwrap(), &11);
     assert_eq!(it.next().unwrap(), &9);
     assert_eq!(it.next_back().unwrap(), &1);
@@ -807,7 +807,7 @@ fn check_randacc_iter<A, T>(a: T, len: usize) where
 fn test_double_ended_flat_map() {
     let u = [0,1];
     let v = [5,6,7,8];
-    let mut it = u.iter().flat_map(|x| v[*x..v.len()].iter());
+    let mut it = u.iter().flat_map(|x| &v[*x..v.len()]);
     assert_eq!(it.next_back().unwrap(), &8);
     assert_eq!(it.next().unwrap(),      &5);
     assert_eq!(it.next_back().unwrap(), &7);
@@ -824,7 +824,7 @@ fn test_double_ended_flat_map() {
 fn test_random_access_chain() {
     let xs = [1, 2, 3, 4, 5];
     let ys = [7, 9, 11];
-    let mut it = xs.iter().chain(ys.iter());
+    let mut it = xs.iter().chain(&ys);
     assert_eq!(it.idx(0).unwrap(), &1);
     assert_eq!(it.idx(5).unwrap(), &7);
     assert_eq!(it.idx(7).unwrap(), &11);
@@ -862,7 +862,7 @@ fn test_random_access_rev() {
 fn test_random_access_zip() {
     let xs = [1, 2, 3, 4, 5];
     let ys = [7, 9, 11];
-    check_randacc_iter(xs.iter().zip(ys.iter()), cmp::min(xs.len(), ys.len()));
+    check_randacc_iter(xs.iter().zip(&ys), cmp::min(xs.len(), ys.len()));
 }
 
 #[test]

src/libcoretest/option.rs

@@ -72,7 +72,7 @@ fn test_option_dance() {
     let x = Some(());
     let mut y = Some(5);
     let mut y2 = 0;
-    for _x in x.iter() {
+    for _x in x {
         y2 = y.take().unwrap();
     }
     assert_eq!(y2, 5);

src/libgetopts/lib.rs

@@ -953,7 +953,7 @@ fn test_split_within() {
     fn t(s: &str, i: usize, u: &[String]) {
         let mut v = Vec::new();
         each_split_within(s, i, |s| { v.push(s.to_string()); true });
-        assert!(v.iter().zip(u.iter()).all(|(a,b)| a == b));
+        assert!(v.iter().zip(u).all(|(a,b)| a == b));
     }
     t("", 0, &[]);
     t("", 15, &[]);

src/libgraphviz/lib.rs

@@ -74,7 +74,7 @@
 //!         // (assumes that |N| \approxeq |E|)
 //!         let &Edges(ref v) = self;
 //!         let mut nodes = Vec::with_capacity(v.len());
-//!         for &(s,t) in v.iter() {
+//!         for &(s,t) in v {
 //!             nodes.push(s); nodes.push(t);
 //!         }
 //!         nodes.sort();

src/librand/chacha.rs

@@ -174,7 +174,7 @@ impl<'a> SeedableRng<&'a [u32]> for ChaChaRng {
         self.init(&[0; KEY_WORDS]);
         // set key in place
         let key = &mut self.state[4 .. 4+KEY_WORDS];
-        for (k, s) in key.iter_mut().zip(seed.iter()) {
+        for (k, s) in key.iter_mut().zip(seed) {
             *k = *s;
         }
     }

src/librand/isaac.rs

@@ -140,7 +140,7 @@ impl IsaacRng {
         }
 
         let r = [(0, MIDPOINT), (MIDPOINT, 0)];
-        for &(mr_offset, m2_offset) in r.iter() {
+        for &(mr_offset, m2_offset) in &r {
 
             macro_rules! rngstepp {
                 ($j:expr, $shift:expr) => {{
@@ -379,7 +379,7 @@ impl Isaac64Rng {
             }
         }
 
-        for &(mr_offset, m2_offset) in MP_VEC.iter() {
+        for &(mr_offset, m2_offset) in &MP_VEC {
             for base in (0..MIDPOINT / 4).map(|i| i * 4) {
 
                 macro_rules! rngstepp {

src/librustc/ast_map/mod.rs

@@ -404,7 +404,7 @@ impl<'ast> Map<'ast> {
 
     fn path_to_str_with_ident(&self, id: NodeId, i: Ident) -> String {
         self.with_path(id, |path| {
-            path_to_string(path.chain(Some(PathName(i.name)).into_iter()))
+            path_to_string(path.chain(Some(PathName(i.name))))
         })
     }
 

src/librustc/metadata/creader.rs

@@ -698,7 +698,7 @@ pub fn import_codemap(local_codemap: &codemap::CodeMap,
             return false;
         }
 
-        for (&line1, &line2) in lines1.iter().zip(lines2.iter()) {
+        for (&line1, &line2) in lines1.iter().zip(&*lines2) {
             if (line1 - fm1.start_pos) != (line2 - fm2.start_pos) {
                 return false;
             }
@@ -711,7 +711,7 @@ pub fn import_codemap(local_codemap: &codemap::CodeMap,
             return false;
         }
 
-        for (mb1, mb2) in multibytes1.iter().zip(multibytes2.iter()) {
+        for (mb1, mb2) in multibytes1.iter().zip(&*multibytes2) {
             if (mb1.bytes != mb2.bytes) ||
                ((mb1.pos - fm1.start_pos) != (mb2.pos - fm2.start_pos)) {
                 return false;

src/librustc/metadata/encoder.rs

@@ -723,14 +723,14 @@ fn encode_generics<'a, 'tcx>(rbml_w: &mut Encoder,
         abbrevs: &ecx.type_abbrevs
     };
 
-    for param in generics.types.iter() {
+    for param in &generics.types {
         rbml_w.start_tag(tag_type_param_def);
         tyencode::enc_type_param_def(rbml_w, ty_str_ctxt, param);
         rbml_w.end_tag();
     }
 
     // Region parameters
-    for param in generics.regions.iter() {
+    for param in &generics.regions {
         rbml_w.start_tag(tag_region_param_def);
 
         rbml_w.start_tag(tag_region_param_def_ident);
@@ -838,7 +838,7 @@ fn encode_info_for_associated_const(ecx: &EncodeContext,
     encode_stability(rbml_w, stab);
 
     let elem = ast_map::PathName(associated_const.name);
-    encode_path(rbml_w, impl_path.chain(Some(elem).into_iter()));
+    encode_path(rbml_w, impl_path.chain(Some(elem)));
 
     if let Some(ii) = impl_item_opt {
         encode_attributes(rbml_w, &ii.attrs);
@@ -871,7 +871,7 @@ fn encode_info_for_method<'a, 'tcx>(ecx: &EncodeContext<'a, 'tcx>,
     encode_bounds_and_type_for_item(rbml_w, ecx, m.def_id.local_id());
 
     let elem = ast_map::PathName(m.name);
-    encode_path(rbml_w, impl_path.chain(Some(elem).into_iter()));
+    encode_path(rbml_w, impl_path.chain(Some(elem)));
     if let Some(impl_item) = impl_item_opt {
         if let ast::MethodImplItem(ref sig, _) = impl_item.node {
             encode_attributes(rbml_w, &impl_item.attrs);
@@ -917,7 +917,7 @@ fn encode_info_for_associated_type<'a, 'tcx>(ecx: &EncodeContext<'a, 'tcx>,
     encode_stability(rbml_w, stab);
 
     let elem = ast_map::PathName(associated_type.name);
-    encode_path(rbml_w, impl_path.chain(Some(elem).into_iter()));
+    encode_path(rbml_w, impl_path.chain(Some(elem)));
 
     if let Some(ii) = impl_item_opt {
         encode_attributes(rbml_w, &ii.attrs);
@@ -955,7 +955,7 @@ fn encode_repr_attrs(rbml_w: &mut Encoder,
     let mut repr_attrs = Vec::new();
     for attr in attrs {
         repr_attrs.extend(attr::find_repr_attrs(ecx.tcx.sess.diagnostic(),
-                                                attr).into_iter());
+                                                attr));
     }
     rbml_w.start_tag(tag_items_data_item_repr);
     repr_attrs.encode(rbml_w);
@@ -1409,7 +1409,7 @@ fn encode_info_for_item(ecx: &EncodeContext,
 
                     let elem = ast_map::PathName(associated_const.name);
                     encode_path(rbml_w,
-                                path.clone().chain(Some(elem).into_iter()));
+                                path.clone().chain(Some(elem)));
 
                     encode_item_sort(rbml_w, 'C');
                     encode_family(rbml_w, 'C');
@@ -1426,7 +1426,7 @@ fn encode_info_for_item(ecx: &EncodeContext,
 
                     let elem = ast_map::PathName(method_ty.name);
                     encode_path(rbml_w,
-                                path.clone().chain(Some(elem).into_iter()));
+                                path.clone().chain(Some(elem)));
 
                     match method_ty.explicit_self {
                         ty::StaticExplicitSelfCategory => {
@@ -1449,7 +1449,7 @@ fn encode_info_for_item(ecx: &EncodeContext,
 
                     let elem = ast_map::PathName(associated_type.name);
                     encode_path(rbml_w,
-                                path.clone().chain(Some(elem).into_iter()));
+                                path.clone().chain(Some(elem)));
 
                     encode_item_sort(rbml_w, 't');
                     encode_family(rbml_w, 'y');
@@ -1822,8 +1822,8 @@ fn encode_lang_items(ecx: &EncodeContext, rbml_w: &mut Encoder) {
 fn encode_native_libraries(ecx: &EncodeContext, rbml_w: &mut Encoder) {
     rbml_w.start_tag(tag_native_libraries);
 
-    for &(ref lib, kind) in ecx.tcx.sess.cstore.get_used_libraries()
-                               .borrow().iter() {
+    for &(ref lib, kind) in &*ecx.tcx.sess.cstore.get_used_libraries()
+                               .borrow() {
         match kind {
             cstore::NativeStatic => {} // these libraries are not propagated
             cstore::NativeFramework | cstore::NativeUnknown => {

src/librustc/metadata/loader.rs

@@ -438,7 +438,7 @@ impl<'a> Context<'a> {
                 FileMatches
             }).unwrap_or(FileDoesntMatch)
         });
-        self.rejected_via_kind.extend(staticlibs.into_iter());
+        self.rejected_via_kind.extend(staticlibs);
 
         // We have now collected all known libraries into a set of candidates
         // keyed of the filename hash listed. For each filename, we also have a

src/librustc/metadata/macro_import.rs

@@ -164,14 +164,14 @@ impl<'a> MacroLoader<'a> {
         }
 
         if let Some(sel) = import.as_ref() {
-            for (name, span) in sel.iter() {
+            for (name, span) in sel {
                 if !seen.contains(name) {
                     self.sess.span_err(*span, "imported macro not found");
                 }
             }
         }
 
-        for (name, span) in reexport.iter() {
+        for (name, span) in &reexport {
             if !seen.contains(name) {
                 self.sess.span_err(*span, "reexported macro not found");
             }

src/librustc/middle/astencode.rs

@@ -1126,7 +1126,7 @@ fn encode_side_tables_for_id(ecx: &e::EncodeContext,
         })
     }
 
-    for &qualif in tcx.const_qualif_map.borrow().get(&id).iter() {
+    if let Some(qualif) = tcx.const_qualif_map.borrow().get(&id) {
         rbml_w.tag(c::tag_table_const_qualif, |rbml_w| {
             rbml_w.id(id);
             qualif.encode(rbml_w).unwrap()

src/librustc/middle/cfg/construct.rs

@@ -338,7 +338,7 @@ impl<'a, 'tcx> CFGBuilder<'a, 'tcx> {
 
             ast::ExprRange(ref start, ref end) => {
                 let fields = start.as_ref().map(|e| &**e).into_iter()
-                    .chain(end.as_ref().map(|e| &**e).into_iter());
+                    .chain(end.as_ref().map(|e| &**e));
                 self.straightline(expr, pred, fields)
             }
 

src/librustc/middle/check_const.rs

@@ -409,7 +409,7 @@ impl<'a, 'tcx, 'v> Visitor<'v> for CheckCrateVisitor<'a, 'tcx> {
         // Special-case some expressions to avoid certain flags bubbling up.
         match ex.node {
             ast::ExprCall(ref callee, ref args) => {
-                for arg in args.iter() {
+                for arg in args {
                     self.visit_expr(&**arg)
                 }
 
@@ -435,7 +435,7 @@ impl<'a, 'tcx, 'v> Visitor<'v> for CheckCrateVisitor<'a, 'tcx> {
                 // Compute the most demanding borrow from all the arms'
                 // patterns and set that on the discriminator.
                 let mut borrow = None;
-                for pat in arms.iter().flat_map(|arm| arm.pats.iter()) {
+                for pat in arms.iter().flat_map(|arm| &arm.pats) {
                     let pat_borrow = self.rvalue_borrows.remove(&pat.id);
                     match (borrow, pat_borrow) {
                         (None, _) | (_, Some(ast::MutMutable)) => {

src/librustc/middle/check_match.rs

@@ -187,7 +187,7 @@ fn check_expr(cx: &mut MatchCheckCtxt, ex: &ast::Expr) {
 
             for pat in inlined_arms
                 .iter()
-                .flat_map(|&(ref pats, _)| pats.iter()) {
+                .flat_map(|&(ref pats, _)| pats) {
                 // Third, check legality of move bindings.
                 check_legality_of_bindings_in_at_patterns(cx, &**pat);
 
@@ -220,7 +220,7 @@ fn check_expr(cx: &mut MatchCheckCtxt, ex: &ast::Expr) {
             let matrix: Matrix = inlined_arms
                 .iter()
                 .filter(|&&(_, guard)| guard.is_none())
-                .flat_map(|arm| arm.0.iter())
+                .flat_map(|arm| &arm.0)
                 .map(|pat| vec![&**pat])
                 .collect();
             check_exhaustive(cx, ex.span, &matrix, source);
@@ -583,7 +583,7 @@ fn construct_witness(cx: &MatchCheckCtxt, ctor: &Constructor,
 fn missing_constructor(cx: &MatchCheckCtxt, &Matrix(ref rows): &Matrix,
                        left_ty: Ty, max_slice_length: usize) -> Option<Constructor> {
     let used_constructors: Vec<Constructor> = rows.iter()
-        .flat_map(|row| pat_constructors(cx, row[0], left_ty, max_slice_length).into_iter())
+        .flat_map(|row| pat_constructors(cx, row[0], left_ty, max_slice_length))
         .collect();
     all_constructors(cx, left_ty, max_slice_length)
         .into_iter()
@@ -705,7 +705,7 @@ fn is_useful(cx: &MatchCheckCtxt,
                         let wild_pats: Vec<_> = repeat(DUMMY_WILD_PAT).take(arity).collect();
                         let enum_pat = construct_witness(cx, &constructor, wild_pats, left_ty);
                         let mut new_pats = vec![enum_pat];
-                        new_pats.extend(pats.into_iter());
+                        new_pats.extend(pats);
                         UsefulWithWitness(new_pats)
                     },
                     result => result

src/librustc/middle/dataflow.rs

@@ -634,7 +634,7 @@ fn bitwise<Op:BitwiseOperator>(out_vec: &mut [usize],
                                op: &Op) -> bool {
     assert_eq!(out_vec.len(), in_vec.len());
     let mut changed = false;
-    for (out_elt, in_elt) in out_vec.iter_mut().zip(in_vec.iter()) {
+    for (out_elt, in_elt) in out_vec.iter_mut().zip(in_vec) {
         let old_val = *out_elt;
         let new_val = op.join(old_val, *in_elt);
         *out_elt = new_val;

src/librustc/middle/expr_use_visitor.rs

@@ -212,11 +212,11 @@ enum OverloadedCallType {
 impl OverloadedCallType {
     fn from_trait_id(tcx: &ty::ctxt, trait_id: ast::DefId)
                      -> OverloadedCallType {
-        for &(maybe_function_trait, overloaded_call_type) in [
+        for &(maybe_function_trait, overloaded_call_type) in &[
             (tcx.lang_items.fn_once_trait(), FnOnceOverloadedCall),
             (tcx.lang_items.fn_mut_trait(), FnMutOverloadedCall),
             (tcx.lang_items.fn_trait(), FnOverloadedCall)
-        ].iter() {
+        ] {
             match maybe_function_trait {
                 Some(function_trait) if function_trait == trait_id => {
                     return overloaded_call_type

src/librustc/middle/implicator.rs

@@ -276,7 +276,7 @@ impl<'a, 'tcx> Implicator<'a, 'tcx> {
 
         let variances = ty::item_variances(self.tcx(), def_id);
 
-        for (&region, &variance) in substs.regions().iter().zip(variances.regions.iter()) {
+        for (&region, &variance) in substs.regions().iter().zip(&variances.regions) {
             match variance {
                 ty::Contravariant | ty::Invariant => {
                     // If any data with this lifetime is reachable
@@ -287,7 +287,7 @@ impl<'a, 'tcx> Implicator<'a, 'tcx> {
             }
         }
 
-        for (&ty, &variance) in substs.types.iter().zip(variances.types.iter()) {
+        for (&ty, &variance) in substs.types.iter().zip(&variances.types) {
             match variance {
                 ty::Covariant | ty::Invariant => {
                     // If any data of this type is reachable within,

src/librustc/middle/infer/higher_ranked/mod.rs

@@ -443,7 +443,7 @@ impl<'a,'tcx> InferCtxtExt for InferCtxt<'a,'tcx> {
         let escaping_region_vars: FnvHashSet<_> =
             escaping_types
             .iter()
-            .flat_map(|&t| ty_fold::collect_regions(self.tcx, &t).into_iter())
+            .flat_map(|&t| ty_fold::collect_regions(self.tcx, &t))
             .collect();
 
         region_vars.retain(|&region_vid| {

src/librustc/middle/region.rs

@@ -372,22 +372,22 @@ struct RegionResolutionVisitor<'a> {
 
 impl RegionMaps {
     pub fn each_encl_scope<E>(&self, mut e:E) where E: FnMut(&CodeExtent, &CodeExtent) {
-        for (child, parent) in self.scope_map.borrow().iter() {
+        for (child, parent) in &*self.scope_map.borrow() {
             e(child, parent)
         }
     }
     pub fn each_var_scope<E>(&self, mut e:E) where E: FnMut(&ast::NodeId, &CodeExtent) {
-        for (child, parent) in self.var_map.borrow().iter() {
+        for (child, parent) in &*self.var_map.borrow() {
             e(child, parent)
         }
     }
     pub fn each_rvalue_scope<E>(&self, mut e:E) where E: FnMut(&ast::NodeId, &CodeExtent) {
-        for (child, parent) in self.rvalue_scopes.borrow().iter() {
+        for (child, parent) in &*self.rvalue_scopes.borrow() {
             e(child, parent)
         }
     }
     pub fn each_terminating_scope<E>(&self, mut e:E) where E: FnMut(&CodeExtent) {
-        for scope in self.terminating_scopes.borrow().iter() {
+        for scope in &*self.terminating_scopes.borrow() {
             e(scope)
         }
     }

src/librustc/middle/stability.rs

@@ -485,7 +485,7 @@ pub fn check_pat(tcx: &ty::ctxt, pat: &ast::Pat,
     match pat.node {
         // Foo(a, b, c)
         ast::PatEnum(_, Some(ref pat_fields)) => {
-            for (field, struct_field) in pat_fields.iter().zip(struct_fields.iter()) {
+            for (field, struct_field) in pat_fields.iter().zip(&struct_fields) {
                 // a .. pattern is fine, but anything positional is
                 // not.
                 if let ast::PatWild(ast::PatWildMulti) = field.node {
@@ -595,14 +595,14 @@ pub fn check_unused_or_stable_features(sess: &Session,
 
     let stable_msg = "this feature is stable. attribute no longer needed";
 
-    for &span in sess.features.borrow().declared_stable_lang_features.iter() {
+    for &span in &sess.features.borrow().declared_stable_lang_features {
         sess.add_lint(lint::builtin::STABLE_FEATURES,
                       ast::CRATE_NODE_ID,
                       span,
                       stable_msg.to_string());
     }
 
-    for (used_lib_feature, level) in lib_features_used.iter() {
+    for (used_lib_feature, level) in lib_features_used {
         match remaining_lib_features.remove(used_lib_feature) {
             Some(span) => {
                 if *level == attr::Stable {
@@ -616,7 +616,7 @@ pub fn check_unused_or_stable_features(sess: &Session,
         }
     }
 
-    for (_, &span) in remaining_lib_features.iter() {
+    for &span in remaining_lib_features.values() {
         sess.add_lint(lint::builtin::UNUSED_FEATURES,
                       ast::CRATE_NODE_ID,
                       span,

src/librustc/middle/subst.rs

@@ -279,8 +279,8 @@ impl<T> VecPerParamSpace<T> {
         let self_limit = type_limit + s.len();
 
         let mut content = t;
-        content.extend(s.into_iter());
-        content.extend(f.into_iter());
+        content.extend(s);
+        content.extend(f);
 
         VecPerParamSpace {
             type_limit: type_limit,

src/librustc/middle/traits/coherence.rs

@@ -85,7 +85,7 @@ fn overlap(selcx: &mut SelectionContext,
     let infcx = selcx.infcx();
     let opt_failing_obligation =
         a_obligations.iter()
-                     .chain(b_obligations.iter())
+                     .chain(&b_obligations)
                      .map(|o| infcx.resolve_type_vars_if_possible(o))
                      .find(|o| !selcx.evaluate_obligation(o));
 
@@ -159,8 +159,8 @@ fn impl_trait_ref_and_oblig<'a,'tcx>(selcx: &mut SelectionContext<'a,'tcx>,
 
     let impl_obligations: Vec<_> =
         impl_obligations.into_iter()
-        .chain(normalization_obligations1.into_iter())
-        .chain(normalization_obligations2.into_iter())
+        .chain(normalization_obligations1)
+        .chain(normalization_obligations2)
         .collect();
 
     (impl_trait_ref, impl_obligations)
@@ -209,7 +209,7 @@ fn orphan_check_trait_ref<'tcx>(tcx: &ty::ctxt<'tcx>,
     // First, create an ordered iterator over all the type parameters to the trait, with the self
     // type appearing first.
     let input_tys = Some(trait_ref.self_ty());
-    let input_tys = input_tys.iter().chain(trait_ref.substs.types.get_slice(TypeSpace).iter());
+    let input_tys = input_tys.iter().chain(trait_ref.substs.types.get_slice(TypeSpace));
 
     // Find the first input type that either references a type parameter OR
     // some local type.
@@ -255,7 +255,7 @@ fn uncovered_tys<'tcx>(tcx: &ty::ctxt<'tcx>,
         vec![]
     } else if fundamental_ty(tcx, ty) {
         ty.walk_shallow()
-          .flat_map(|t| uncovered_tys(tcx, t, infer_is_local).into_iter())
+          .flat_map(|t| uncovered_tys(tcx, t, infer_is_local))
           .collect()
     } else {
         vec![ty]

src/librustc/middle/traits/fulfill.rs

@@ -399,7 +399,7 @@ fn process_predicate<'a,'tcx>(selcx: &mut SelectionContext<'a,'tcx>,
                    result.repr(tcx));
             match result {
                 Ok(Some(obligations)) => {
-                    new_obligations.extend(obligations.into_iter());
+                    new_obligations.extend(obligations);
                     true
                 }
                 Ok(None) => {

src/librustc/middle/traits/object_safety.rs

@@ -80,7 +80,7 @@ pub fn object_safety_violations<'tcx>(tcx: &ty::ctxt<'tcx>,
                                       -> Vec<ObjectSafetyViolation<'tcx>>
 {
     traits::supertrait_def_ids(tcx, trait_def_id)
-        .flat_map(|def_id| object_safety_violations_for_trait(tcx, def_id).into_iter())
+        .flat_map(|def_id| object_safety_violations_for_trait(tcx, def_id))
         .collect()
 }
 

src/librustc/middle/traits/project.rs

@@ -280,7 +280,7 @@ impl<'a,'b,'tcx> TypeFolder<'tcx> for AssociatedTypeNormalizer<'a,'b,'tcx> {
                                               data.clone(),
                                               self.cause.clone(),
                                               self.depth);
-                self.obligations.extend(obligations.into_iter());
+                self.obligations.extend(obligations);
                 ty
             }
 
@@ -376,7 +376,7 @@ fn opt_normalize_projection_type<'a,'b,'tcx>(
                        normalized_ty.repr(tcx),
                        depth);
 
-                obligations.extend(normalizer.obligations.into_iter());
+                obligations.extend(normalizer.obligations);
                 Some(Normalized {
                     value: normalized_ty,
                     obligations: obligations,
@@ -872,7 +872,7 @@ fn confirm_impl_candidate<'cx,'tcx>(
 
     // It is not in the impl - get the default from the trait.
     let trait_ref = obligation.predicate.trait_ref;
-    for trait_item in ty::trait_items(selcx.tcx(), trait_ref.def_id).iter() {
+    for trait_item in &*ty::trait_items(selcx.tcx(), trait_ref.def_id) {
         if let &ty::TypeTraitItem(ref assoc_ty) = trait_item {
             if assoc_ty.name == obligation.predicate.item_name {
                 if let Some(ty) = assoc_ty.ty {

src/librustc/middle/traits/select.rs

@@ -1750,7 +1750,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                 let types: Vec<Ty> =
                     ty::substd_enum_variants(self.tcx(), def_id, substs)
                     .iter()
-                    .flat_map(|variant| variant.args.iter())
+                    .flat_map(|variant| &variant.args)
                     .cloned()
                     .collect();
                 nominal(bound, types)
@@ -1893,7 +1893,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
             ty::ty_enum(def_id, substs) => {
                 Some(ty::substd_enum_variants(self.tcx(), def_id, substs)
                      .iter()
-                     .flat_map(|variant| variant.args.iter())
+                     .flat_map(|variant| &variant.args)
                      .map(|&ty| ty)
                      .collect())
             }
@@ -1960,7 +1960,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
 
         // Flatten those vectors (couldn't do it above due `collect`)
         match obligations {
-            Ok(obligations) => obligations.into_iter().flat_map(|o| o.into_iter()).collect(),
+            Ok(obligations) => obligations.into_iter().flat_map(|o| o).collect(),
             Err(ErrorReported) => Vec::new(),
         }
     }
@@ -2689,7 +2689,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         // simplified, do not match.
 
         obligation.predicate.0.input_types().iter()
-            .zip(impl_trait_ref.input_types().iter())
+            .zip(impl_trait_ref.input_types())
             .any(|(&obligation_ty, &impl_ty)| {
                 let simplified_obligation_ty =
                     fast_reject::simplify_type(self.tcx(), obligation_ty, true);

src/librustc/middle/traits/util.rs

@@ -135,7 +135,7 @@ impl<'cx, 'tcx> Elaborator<'cx, 'tcx> {
                 // Sized { }`.
                 predicates.retain(|r| self.visited.insert(r));
 
-                self.stack.extend(predicates.into_iter());
+                self.stack.extend(predicates);
             }
             ty::Predicate::Equate(..) => {
                 // Currently, we do not "elaborate" predicates like

src/librustc/middle/ty.rs

@@ -2154,7 +2154,7 @@ impl<'tcx> Predicate<'tcx> {
                 let trait_inputs = data.0.projection_ty.trait_ref.substs.types.as_slice();
                 trait_inputs.iter()
                             .cloned()
-                            .chain(Some(data.0.ty).into_iter())
+                            .chain(Some(data.0.ty))
                             .collect()
             }
         };
@@ -2571,7 +2571,7 @@ impl<'tcx> TraitDef<'tcx> {
     pub fn for_each_impl<F: FnMut(DefId)>(&self, tcx: &ctxt<'tcx>, mut f: F)  {
         ty::populate_implementations_for_trait_if_necessary(tcx, self.trait_ref.def_id);
 
-        for &impl_def_id in self.blanket_impls.borrow().iter() {
+        for &impl_def_id in &*self.blanket_impls.borrow() {
             f(impl_def_id);
         }
 
@@ -2589,7 +2589,7 @@ impl<'tcx> TraitDef<'tcx> {
     {
         ty::populate_implementations_for_trait_if_necessary(tcx, self.trait_ref.def_id);
 
-        for &impl_def_id in self.blanket_impls.borrow().iter() {
+        for &impl_def_id in &*self.blanket_impls.borrow() {
             f(impl_def_id);
         }
 
@@ -3068,7 +3068,7 @@ impl FlagComputation {
         match substs.regions {
             subst::ErasedRegions => {}
             subst::NonerasedRegions(ref regions) => {
-                for &r in regions.iter() {
+                for &r in regions {
                     self.add_region(r);
                 }
             }
@@ -4199,7 +4199,7 @@ pub fn is_type_representable<'tcx>(cx: &ctxt<'tcx>, sp: Span, ty: Ty<'tcx>)
             ty_enum(did, substs) => {
                 let vs = enum_variants(cx, did);
                 let iter = vs.iter()
-                    .flat_map(|variant| { variant.args.iter() })
+                    .flat_map(|variant| &variant.args)
                     .map(|aty| { aty.subst_spanned(cx, substs, Some(sp)) });
 
                 find_nonrepresentable(cx, sp, seen, iter)
@@ -4233,7 +4233,7 @@ 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 mut pairs = types_a.iter().zip(types_b);
 
                 pairs.all(|(&a, &b)| same_type(a, b))
             }
@@ -4509,7 +4509,7 @@ pub fn named_element_ty<'tcx>(cx: &ctxt<'tcx>,
             let variant_info = enum_variant_with_id(cx, def_id, variant_def_id);
             variant_info.arg_names.as_ref()
                 .expect("must have struct enum variant if accessing a named fields")
-                .iter().zip(variant_info.args.iter())
+                .iter().zip(&variant_info.args)
                 .find(|&(&name, _)| name == n)
                 .map(|(_name, arg_t)| arg_t.subst(cx, substs))
         }
@@ -5401,7 +5401,7 @@ pub fn associated_type_parameter_index(cx: &ctxt,
                                        trait_def: &TraitDef,
                                        associated_type_id: ast::DefId)
                                        -> usize {
-    for type_parameter_def in trait_def.generics.types.iter() {
+    for type_parameter_def in &trait_def.generics.types {
         if type_parameter_def.def_id == associated_type_id {
             return type_parameter_def.index as usize
         }
@@ -6607,8 +6607,8 @@ pub fn hash_crate_independent<'tcx>(tcx: &ctxt<'tcx>, ty: Ty<'tcx>, svh: &Svh) -
                     hash!(data.bounds);
 
                     let principal = anonymize_late_bound_regions(tcx, &data.principal).0;
-                    for subty in principal.substs.types.iter() {
-                        helper(tcx, *subty, svh, state);
+                    for subty in &principal.substs.types {
+                        helper(tcx, subty, svh, state);
                     }
 
                     return false;
@@ -6933,7 +6933,7 @@ pub fn accumulate_lifetimes_in_type(accumulator: &mut Vec<ty::Region>,
         match substs.regions {
             subst::ErasedRegions => {}
             subst::NonerasedRegions(ref regions) => {
-                for region in regions.iter() {
+                for region in regions {
                     accumulator.push(*region)
                 }
             }

src/librustc/middle/ty_relate/mod.rs

@@ -274,8 +274,7 @@ fn relate_arg_vecs<'a,'tcx:'a,R>(relation: &mut R,
         return Err(ty::terr_arg_count);
     }
 
-    a_args.iter()
-          .zip(b_args.iter())
+    a_args.iter().zip(b_args)
           .map(|(a, b)| relation.relate_with_variance(ty::Contravariant, a, b))
           .collect()
 }
@@ -355,8 +354,7 @@ impl<'a,'tcx:'a> Relate<'a,'tcx> for Vec<ty::PolyProjectionPredicate<'tcx>> {
         if a.len() != b.len() {
             Err(ty::terr_projection_bounds_length(expected_found(relation, &a.len(), &b.len())))
         } else {
-            a.iter()
-                .zip(b.iter())
+            a.iter().zip(b)
                 .map(|(a, b)| relation.relate(a, b))
                 .collect()
         }
@@ -539,8 +537,7 @@ pub fn super_relate_tys<'a,'tcx:'a,R>(relation: &mut R,
         (&ty::ty_tup(ref as_), &ty::ty_tup(ref bs)) =>
         {
             if as_.len() == bs.len() {
-                let ts = try!(as_.iter()
-                                 .zip(bs.iter())
+                let ts = try!(as_.iter().zip(bs)
                                  .map(|(a, b)| relation.relate(a, b))
                                  .collect::<Result<_, _>>());
                 Ok(ty::mk_tup(tcx, ts))

src/librustc/util/ppaux.rs

@@ -470,15 +470,15 @@ pub fn parameterized<'tcx,GG>(cx: &ctxt<'tcx>,
                 strings.push(format!(".."));
             }
             subst::NonerasedRegions(ref regions) => {
-                for region in regions.iter() {
+                for region in regions {
                     strings.push(region.repr(cx));
                 }
             }
         }
-        for ty in substs.types.iter() {
+        for ty in &substs.types {
             strings.push(ty.repr(cx));
         }
-        for projection in projections.iter() {
+        for projection in projections {
             strings.push(format!("{}={}",
                                  projection.projection_ty.item_name.user_string(cx),
                                  projection.ty.user_string(cx)));
@@ -495,7 +495,7 @@ pub fn parameterized<'tcx,GG>(cx: &ctxt<'tcx>,
     match substs.regions {
         subst::ErasedRegions => { }
         subst::NonerasedRegions(ref regions) => {
-            for &r in regions.iter() {
+            for &r in regions {
                 let s = region_to_string(cx, "", false, r);
                 if s.is_empty() {
                     // This happens when the value of the region
@@ -523,7 +523,7 @@ pub fn parameterized<'tcx,GG>(cx: &ctxt<'tcx>,
     let ty_params = generics.types.get_slice(subst::TypeSpace);
     let has_defaults = ty_params.last().map_or(false, |def| def.default.is_some());
     let num_defaults = if has_defaults {
-        ty_params.iter().zip(tps.iter()).rev().take_while(|&(def, &actual)| {
+        ty_params.iter().zip(tps).rev().take_while(|&(def, &actual)| {
             match def.default {
                 Some(default) => {
                     if !has_self && ty::type_has_self(default) {

src/librustc_borrowck/borrowck/gather_loans/move_error.rs

@@ -99,7 +99,7 @@ fn group_errors_with_same_origin<'tcx>(errors: &Vec<MoveError<'tcx>>)
         for ge in &mut *grouped_errors {
             if move_from_id == ge.move_from.id && error.move_to.is_some() {
                 debug!("appending move_to to list");
-                ge.move_to_places.extend(move_to.into_iter());
+                ge.move_to_places.extend(move_to);
                 return
             }
         }

src/librustc_driver/driver.rs

@@ -484,7 +484,7 @@ pub fn phase_2_configure_and_expand(sess: &Session,
                 let mut new_path = sess.host_filesearch(PathKind::All)
                                        .get_dylib_search_paths();
                 new_path.extend(env::split_paths(&_old_path));
-                env::set_var("PATH", &env::join_paths(new_path.iter()).unwrap());
+                env::set_var("PATH", &env::join_paths(new_path).unwrap());
             }
             let features = sess.features.borrow();
             let cfg = syntax::ext::expand::ExpansionConfig {
@@ -765,7 +765,7 @@ pub fn phase_6_link_output(sess: &Session,
     let old_path = env::var_os("PATH").unwrap_or(OsString::new());
     let mut new_path = sess.host_filesearch(PathKind::All).get_tools_search_paths();
     new_path.extend(env::split_paths(&old_path));
-    env::set_var("PATH", &env::join_paths(new_path.iter()).unwrap());
+    env::set_var("PATH", &env::join_paths(&new_path).unwrap());
 
     time(sess.time_passes(), "linking", (), |_|
          link::link_binary(sess,
@@ -895,7 +895,7 @@ pub fn collect_crate_types(session: &Session,
     // will be found in crate attributes.
     let mut base = session.opts.crate_types.clone();
     if base.is_empty() {
-        base.extend(attr_types.into_iter());
+        base.extend(attr_types);
         if base.is_empty() {
             base.push(link::default_output_for_target(session));
         }

src/librustc_driver/lib.rs

@@ -566,7 +566,7 @@ Available lint options:
     let plugin_groups = sort_lint_groups(plugin_groups);
     let builtin_groups = sort_lint_groups(builtin_groups);
 
-    let max_name_len = plugin.iter().chain(builtin.iter())
+    let max_name_len = plugin.iter().chain(&builtin)
         .map(|&s| s.name.chars().count())
         .max().unwrap_or(0);
     let padded = |x: &str| {
@@ -593,7 +593,7 @@ Available lint options:
 
 
 
-    let max_name_len = plugin_groups.iter().chain(builtin_groups.iter())
+    let max_name_len = plugin_groups.iter().chain(&builtin_groups)
         .map(|&(s, _)| s.chars().count())
         .max().unwrap_or(0);
     let padded = |x: &str| {

src/librustc_lint/builtin.rs

@@ -645,7 +645,7 @@ impl LintPass for UnusedAttributes {
         }
 
         let plugin_attributes = cx.sess().plugin_attributes.borrow_mut();
-        for &(ref name, ty) in plugin_attributes.iter() {
+        for &(ref name, ty) in &*plugin_attributes {
             if ty == AttributeType::Whitelisted && attr.check_name(&*name) {
                 break;
             }
@@ -2249,7 +2249,7 @@ impl LintPass for DropWithReprExtern {
         lint_array!(DROP_WITH_REPR_EXTERN)
     }
     fn check_crate(&mut self, ctx: &Context, _: &ast::Crate) {
-        for dtor_did in ctx.tcx.destructors.borrow().iter() {
+        for dtor_did in &*ctx.tcx.destructors.borrow() {
             let (drop_impl_did, dtor_self_type) =
                 if dtor_did.krate == ast::LOCAL_CRATE {
                     let impl_did = ctx.tcx.map.get_parent_did(dtor_did.node);

src/librustc_resolve/lib.rs

@@ -215,7 +215,7 @@ impl<'a, 'v, 'tcx> Visitor<'v> for Resolver<'a, 'tcx> {
         // `visit::walk_variant` without the discriminant expression.
         match variant.node.kind {
             ast::TupleVariantKind(ref variant_arguments) => {
-                for variant_argument in variant_arguments.iter() {
+                for variant_argument in variant_arguments {
                     self.visit_ty(&*variant_argument.ty);
                 }
             }

src/librustc_trans/back/link.rs

@@ -355,7 +355,7 @@ pub fn mangle_internal_name_by_type_and_seq<'a, 'tcx>(ccx: &CrateContext<'a, 'tc
 }
 
 pub fn mangle_internal_name_by_path_and_seq(path: PathElems, flav: &str) -> String {
-    mangle(path.chain(Some(gensym_name(flav)).into_iter()), None)
+    mangle(path.chain(Some(gensym_name(flav))), None)
 }
 
 pub fn get_cc_prog(sess: &Session) -> String {
@@ -761,7 +761,7 @@ fn link_staticlib(sess: &Session, obj_filename: &Path, out_filename: &Path) {
         ab.add_rlib(&p, &name[..], sess.lto()).unwrap();
 
         let native_libs = csearch::get_native_libraries(&sess.cstore, cnum);
-        all_native_libs.extend(native_libs.into_iter());
+        all_native_libs.extend(native_libs);
     }
 
     ab.update_symbols();
@@ -918,7 +918,7 @@ fn link_args(cmd: &mut Linker,
         let empty_vec = Vec::new();
         let empty_str = String::new();
         let args = sess.opts.cg.link_args.as_ref().unwrap_or(&empty_vec);
-        let mut args = args.iter().chain(used_link_args.iter());
+        let mut args = args.iter().chain(&*used_link_args);
         let relocation_model = sess.opts.cg.relocation_model.as_ref()
                                    .unwrap_or(&empty_str);
         if (t.options.relocation_model == "pic" || *relocation_model == "pic")

src/librustc_trans/save/dump_csv.rs

@@ -138,7 +138,7 @@ impl <'l, 'tcx> DumpCsvVisitor<'l, 'tcx> {
         let mut result: Vec<(Span, String)> = vec!();
 
         let mut segs = vec!();
-        for (i, (seg, span)) in path.segments.iter().zip(spans.iter()).enumerate() {
+        for (i, (seg, span)) in path.segments.iter().zip(&spans).enumerate() {
             segs.push(seg.clone());
             let sub_path = ast::Path{span: *span, // span for the last segment
                                      global: path.global,
@@ -476,14 +476,14 @@ impl <'l, 'tcx> DumpCsvVisitor<'l, 'tcx> {
         // the first few to match the number of generics we're looking for.
         let param_sub_spans = self.span.spans_for_ty_params(full_span,
                                                            (generics.ty_params.len() as isize));
-        for (param, param_ss) in generics.ty_params.iter().zip(param_sub_spans.iter()) {
+        for (param, param_ss) in generics.ty_params.iter().zip(param_sub_spans) {
             // Append $id to name to make sure each one is unique
             let name = format!("{}::{}${}",
                                prefix,
-                               escape(self.span.snippet(*param_ss)),
+                               escape(self.span.snippet(param_ss)),
                                id);
             self.fmt.typedef_str(full_span,
-                                 Some(*param_ss),
+                                 Some(param_ss),
                                  param.id,
                                  &name,
                                  "");

src/librustc_trans/trans/_match.rs

@@ -1501,7 +1501,7 @@ fn trans_match_inner<'blk, 'tcx>(scope_cx: Block<'blk, 'tcx>,
     };
 
     let mut matches = Vec::new();
-    for (arm_data, pats) in arm_datas.iter().zip(arm_pats.iter()) {
+    for (arm_data, pats) in arm_datas.iter().zip(&arm_pats) {
         matches.extend(pats.iter().map(|p| Match {
             pats: vec![&**p],
             data: arm_data,
@@ -1833,7 +1833,7 @@ fn bind_irrefutable_pat<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
                 .iter()
                 .chain(slice.iter())
                 .chain(after.iter())
-                .zip(extracted.vals.into_iter())
+                .zip(extracted.vals)
                 .fold(bcx, |bcx, (inner, elem)|
                     bind_irrefutable_pat(bcx, &**inner, elem, cleanup_scope)
                 );

src/librustc_trans/trans/adt.rs

@@ -1199,7 +1199,7 @@ fn build_const_struct<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
     // offset of current value
     let mut offset = 0;
     let mut cfields = Vec::new();
-    for (&val, &target_offset) in vals.iter().zip(target_offsets.iter()) {
+    for (&val, target_offset) in vals.iter().zip(target_offsets) {
         if !st.packed {
             let val_align = machine::llalign_of_min(ccx, val_ty(val));
             offset = roundup(offset, val_align);

src/librustc_trans/trans/asm.rs

@@ -88,7 +88,7 @@ pub fn trans_inline_asm<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, ia: &ast::InlineAsm)
 
     let all_constraints= constraints.iter()
                                     .map(|s| s.to_string())
-                                    .chain(ext_constraints.into_iter())
+                                    .chain(ext_constraints)
                                     .chain(clobbers)
                                     .chain(arch_clobbers.iter()
                                                .map(|s| s.to_string()))

src/librustc_trans/trans/builder.rs

@@ -561,7 +561,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         // we care about.
         if ixs.len() < 16 {
             let mut small_vec = [ C_i32(self.ccx, 0); 16 ];
-            for (small_vec_e, &ix) in small_vec.iter_mut().zip(ixs.iter()) {
+            for (small_vec_e, &ix) in small_vec.iter_mut().zip(ixs) {
                 *small_vec_e = C_i32(self.ccx, ix as i32);
             }
             self.inbounds_gep(base, &small_vec[..ixs.len()])

src/librustc_trans/trans/debuginfo/create_scope_map.rs

@@ -257,7 +257,7 @@ fn walk_pattern(cx: &CrateContext,
             for &codemap::Spanned {
                 node: ast::FieldPat { pat: ref sub_pat, .. },
                 ..
-            } in field_pats.iter() {
+            } in field_pats {
                 walk_pattern(cx, &**sub_pat, scope_stack, scope_map);
             }
         }

src/librustc_trans/trans/debuginfo/metadata.rs

@@ -1557,7 +1557,7 @@ fn describe_enum_variant<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
 
     // Build an array of (field name, field type) pairs to be captured in the factory closure.
     let args: Vec<(String, Ty)> = arg_names.iter()
-        .zip(struct_def.fields.iter())
+        .zip(&struct_def.fields)
         .map(|(s, &t)| (s.to_string(), t))
         .collect();
 

src/librustc_trans/trans/debuginfo/type_names.rs

@@ -216,7 +216,7 @@ pub fn push_debuginfo_type_name<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
 
         output.push('<');
 
-        for &type_parameter in substs.types.iter() {
+        for &type_parameter in &substs.types {
             push_debuginfo_type_name(cx, type_parameter, true, output);
             output.push_str(", ");
         }

src/librustc_trans/trans/expr.rs

@@ -526,7 +526,7 @@ fn coerce_unsized<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
             };
             assert!(coerce_index < src_fields.len() && src_fields.len() == target_fields.len());
 
-            let iter = src_fields.iter().zip(target_fields.iter()).enumerate();
+            let iter = src_fields.iter().zip(target_fields).enumerate();
             for (i, (src_ty, target_ty)) in iter {
                 let ll_source = adt::trans_field_ptr(bcx, &repr_source, source.val, 0, i);
                 let ll_target = adt::trans_field_ptr(bcx, &repr_target, target.val, 0, i);
@@ -1547,7 +1547,7 @@ pub fn trans_adt<'a, 'blk, 'tcx>(mut bcx: Block<'blk, 'tcx>,
         }
 
         // Finally, move scratch field values into actual field locations
-        for (i, datum) in scratch_vals.into_iter() {
+        for (i, datum) in scratch_vals {
             let dest = adt::trans_field_ptr(bcx, &*repr, addr, discr, i);
             bcx = datum.store_to(bcx, dest);
         }

src/librustc_trans/trans/foreign.rs

@@ -454,7 +454,7 @@ fn gate_simd_ffi(tcx: &ty::ctxt, decl: &ast::FnDecl, ty: &ty::BareFnTy) {
             }
         };
         let sig = &ty.sig.0;
-        for (input, ty) in decl.inputs.iter().zip(sig.inputs.iter()) {
+        for (input, ty) in decl.inputs.iter().zip(&sig.inputs) {
             check(&*input.ty, *ty)
         }
         if let ast::Return(ref ty) = decl.output {
@@ -600,7 +600,7 @@ pub fn trans_rust_fn_with_foreign_abi<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
 
         let ps = ccx.tcx().map.with_path(id, |path| {
             let abi = Some(ast_map::PathName(special_idents::clownshoe_abi.name));
-            link::mangle(path.chain(abi.into_iter()), hash)
+            link::mangle(path.chain(abi), hash)
         });
 
         // Compute the type that the function would have if it were just a

src/librustc_trans/trans/inline.rs

@@ -106,7 +106,7 @@ fn instantiate_inline(ccx: &CrateContext, fn_id: ast::DefId)
             ast::ItemEnum(_, _) => {
               let vs_here = ty::enum_variants(ccx.tcx(), local_def(item.id));
               let vs_there = ty::enum_variants(ccx.tcx(), parent_id);
-              for (here, there) in vs_here.iter().zip(vs_there.iter()) {
+              for (here, there) in vs_here.iter().zip(&*vs_there) {
                   if there.id == fn_id { my_id = here.id.node; }
                   ccx.external().borrow_mut().insert(there.id, Some(here.id.node));
               }

src/librustc_typeck/astconv.rs

@@ -508,7 +508,7 @@ fn find_implied_output_region(input_tys: &[Ty], input_pats: Vec<String>)
     let mut lifetimes_for_params: Vec<(String, usize)> = Vec::new();
     let mut possible_implied_output_region = None;
 
-    for (input_type, input_pat) in input_tys.iter().zip(input_pats.into_iter()) {
+    for (input_type, input_pat) in input_tys.iter().zip(input_pats) {
         let mut accumulator = Vec::new();
         ty::accumulate_lifetimes_in_type(&mut accumulator, *input_type);
 

src/librustc_typeck/check/_match.rs

@@ -250,7 +250,7 @@ pub fn check_pat<'a, 'tcx>(pcx: &pat_ctxt<'a, 'tcx>,
             let pat_ty = ty::mk_tup(tcx, element_tys.clone());
             fcx.write_ty(pat.id, pat_ty);
             demand::eqtype(fcx, pat.span, expected, pat_ty);
-            for (element_pat, element_ty) in elements.iter().zip(element_tys.into_iter()) {
+            for (element_pat, element_ty) in elements.iter().zip(element_tys) {
                 check_pat(pcx, &**element_pat, element_ty);
             }
         }
@@ -697,8 +697,8 @@ pub fn check_pat_enum<'a, 'tcx>(pcx: &pat_ctxt<'a, 'tcx>,
 
     if let Some(subpats) = subpats {
         if subpats.len() == arg_tys.len() {
-            for (subpat, arg_ty) in subpats.iter().zip(arg_tys.iter()) {
-                check_pat(pcx, &**subpat, *arg_ty);
+            for (subpat, arg_ty) in subpats.iter().zip(arg_tys) {
+                check_pat(pcx, &**subpat, arg_ty);
             }
         } else if arg_tys.is_empty() {
             span_err!(tcx.sess, pat.span, E0024,

src/librustc_typeck/check/callee.rs

@@ -184,11 +184,11 @@ fn try_overloaded_call_traits<'a,'tcx>(fcx: &FnCtxt<'a, 'tcx>,
                                        -> Option<ty::MethodCallee<'tcx>>
 {
     // Try the options that are least restrictive on the caller first.
-    for &(opt_trait_def_id, method_name) in [
+    for &(opt_trait_def_id, method_name) in &[
         (fcx.tcx().lang_items.fn_trait(), token::intern("call")),
         (fcx.tcx().lang_items.fn_mut_trait(), token::intern("call_mut")),
         (fcx.tcx().lang_items.fn_once_trait(), token::intern("call_once")),
-    ].iter() {
+    ] {
         let trait_def_id = match opt_trait_def_id {
             Some(def_id) => def_id,
             None => continue,
@@ -379,7 +379,7 @@ impl<'tcx> DeferredCallResolution<'tcx> for CallResolution<'tcx> {
                        method_callee.repr(fcx.tcx()));
 
                 for (&method_arg_ty, &self_arg_ty) in
-                    method_sig.inputs[1..].iter().zip(self.fn_sig.inputs.iter())
+                    method_sig.inputs[1..].iter().zip(&self.fn_sig.inputs)
                 {
                     demand::eqtype(fcx, self.call_expr.span, self_arg_ty, method_arg_ty);
                 }

src/librustc_typeck/check/dropck.rs

@@ -475,7 +475,7 @@ fn iterate_over_potentially_unsafe_regions_in_type<'a, 'tcx>(
 
                     let fields =
                         ty::lookup_struct_fields(rcx.tcx(), struct_did);
-                    for field in fields.iter() {
+                    for field in &fields {
                         let field_type =
                             ty::lookup_field_type(rcx.tcx(),
                                                   struct_did,
@@ -507,7 +507,7 @@ fn iterate_over_potentially_unsafe_regions_in_type<'a, 'tcx>(
                         ty::substd_enum_variants(rcx.tcx(),
                                                  enum_did,
                                                  substs);
-                    for variant_info in all_variant_info.iter() {
+                    for variant_info in &all_variant_info {
                         for (i, arg_type) in variant_info.args.iter().enumerate() {
                             try!(iterate_over_potentially_unsafe_regions_in_type(
                                 rcx,

src/librustc_typeck/check/mod.rs

@@ -482,7 +482,7 @@ pub fn check_item_types(ccx: &CrateCtxt) {
 
     ccx.tcx.sess.abort_if_errors();
 
-    for drop_method_did in ccx.tcx.destructors.borrow().iter() {
+    for drop_method_did in &*ccx.tcx.destructors.borrow() {
         if drop_method_did.krate == ast::LOCAL_CRATE {
             let drop_impl_did = ccx.tcx.map.get_parent_did(drop_method_did.node);
             match dropck::check_drop_impl(ccx.tcx, drop_impl_did) {
@@ -679,7 +679,7 @@ fn check_fn<'a, 'tcx>(ccx: &'a CrateCtxt<'a, 'tcx>,
         let mut visit = GatherLocalsVisitor { fcx: &fcx, };
 
         // Add formal parameters.
-        for (arg_ty, input) in arg_tys.iter().zip(decl.inputs.iter()) {
+        for (arg_ty, input) in arg_tys.iter().zip(&decl.inputs) {
             // Create type variables for each argument.
             pat_util::pat_bindings(
                 &tcx.def_map,
@@ -706,8 +706,8 @@ fn check_fn<'a, 'tcx>(ccx: &'a CrateCtxt<'a, 'tcx>,
         ty::FnDiverging => NoExpectation
     });
 
-    for (input, arg) in decl.inputs.iter().zip(arg_tys.iter()) {
-        fcx.write_ty(input.id, *arg);
+    for (input, arg) in decl.inputs.iter().zip(arg_tys) {
+        fcx.write_ty(input.id, arg);
     }
 
     fcx
@@ -1753,7 +1753,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                                            substs: &Substs<'tcx>,
                                            expr: &ast::Expr)
     {
-        for &ty in substs.types.iter() {
+        for &ty in &substs.types {
             let default_bound = ty::ReScope(CodeExtent::from_node_id(expr.id));
             let cause = traits::ObligationCause::new(expr.span, self.body_id,
                                                      traits::MiscObligation);
@@ -4292,7 +4292,7 @@ pub fn check_enum_variants<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>,
         // we need not check for that.
         let variants = ty::enum_variants(ccx.tcx, def_id);
 
-        for (v, variant) in vs.iter().zip(variants.iter()) {
+        for (v, variant) in vs.iter().zip(&*variants) {
             let current_disr_val = variant.disr_val;
 
             // Check for duplicate discriminant values
@@ -4563,7 +4563,7 @@ pub fn instantiate_path<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
     // provided (if any) into their appropriate spaces. We'll also report
     // errors if type parameters are provided in an inappropriate place.
     let mut substs = Substs::empty();
-    for (opt_space, segment) in segment_spaces.iter().zip(segments.iter()) {
+    for (opt_space, segment) in segment_spaces.iter().zip(segments) {
         match *opt_space {
             None => {
                 check_path_args(fcx.tcx(), slice::ref_slice(segment),

src/librustc_typeck/check/regionck.rs

@@ -637,7 +637,7 @@ fn visit_expr(rcx: &mut Rcx, expr: &ast::Expr) {
             // outlive the operation you are performing.
             let lhs_ty = rcx.resolve_expr_type_adjusted(&**lhs);
             let rhs_ty = rcx.resolve_expr_type_adjusted(&**rhs);
-            for &ty in [lhs_ty, rhs_ty].iter() {
+            for &ty in &[lhs_ty, rhs_ty] {
                 type_must_outlive(rcx,
                                   infer::Operand(expr.span),
                                   ty,

src/librustc_typeck/check/upvar.rs

@@ -235,7 +235,7 @@ impl<'a,'tcx> AdjustBorrowKind<'a,'tcx> {
         if self.closures_with_inferred_kinds.contains(&id) {
             let mut deferred_call_resolutions =
                 self.fcx.remove_deferred_call_resolutions(closure_def_id);
-            for deferred_call_resolution in deferred_call_resolutions.iter_mut() {
+            for deferred_call_resolution in &mut deferred_call_resolutions {
                 deferred_call_resolution.resolve(self.fcx);
             }
         }

src/librustc_typeck/check/wf.rs

@@ -375,7 +375,7 @@ impl<'ccx, 'tcx> CheckTypeWellFormedVisitor<'ccx, 'tcx> {
 fn reject_non_type_param_bounds<'tcx>(tcx: &ty::ctxt<'tcx>,
                                       span: Span,
                                       predicates: &ty::GenericPredicates<'tcx>) {
-    for predicate in predicates.predicates.iter() {
+    for predicate in &predicates.predicates {
         match predicate {
             &ty::Predicate::Trait(ty::Binder(ref tr)) => {
                 let found_param = tr.input_types().iter()
@@ -514,7 +514,7 @@ impl<'cx,'tcx> BoundsChecker<'cx,'tcx> {
                 traits::ItemObligation(trait_ref.def_id)),
             &bounds);
 
-        for &ty in trait_ref.substs.types.iter() {
+        for &ty in &trait_ref.substs.types {
             self.check_traits_in_ty(ty);
         }
     }

src/librustc_typeck/collect.rs

@@ -260,7 +260,7 @@ impl<'a,'tcx> CrateCtxt<'a,'tcx> {
             }
         }
 
-        for request in cycle[1..].iter() {
+        for request in &cycle[1..] {
             match *request {
                 AstConvRequest::GetItemTypeScheme(def_id) |
                 AstConvRequest::GetTraitDef(def_id) => {
@@ -443,7 +443,7 @@ impl<'a,'b,'tcx,A,B> GetTypeParameterBounds<'tcx> for (&'a A,&'b B)
                                  -> Vec<ty::Predicate<'tcx>>
     {
         let mut v = self.0.get_type_parameter_bounds(astconv, span, node_id);
-        v.extend(self.1.get_type_parameter_bounds(astconv, span, node_id).into_iter());
+        v.extend(self.1.get_type_parameter_bounds(astconv, span, node_id));
         v
     }
 }
@@ -516,8 +516,8 @@ impl<'tcx> GetTypeParameterBounds<'tcx> for ast::Generics {
             self.ty_params
                 .iter()
                 .filter(|p| p.id == node_id)
-                .flat_map(|p| p.bounds.iter())
-                .flat_map(|b| predicates_from_bound(astconv, ty, b).into_iter());
+                .flat_map(|p| &*p.bounds)
+                .flat_map(|b| predicates_from_bound(astconv, ty, b));
 
         let from_where_clauses =
             self.where_clause
@@ -528,8 +528,8 @@ impl<'tcx> GetTypeParameterBounds<'tcx> for ast::Generics {
                     _ => None
                 })
                 .filter(|bp| is_param(astconv.tcx(), &bp.bounded_ty, node_id))
-                .flat_map(|bp| bp.bounds.iter())
-                .flat_map(|b| predicates_from_bound(astconv, ty, b).into_iter());
+                .flat_map(|bp| &*bp.bounds)
+                .flat_map(|b| predicates_from_bound(astconv, ty, b));
 
         from_ty_params.chain(from_where_clauses).collect()
     }
@@ -1188,7 +1188,7 @@ fn ensure_super_predicates_step(ccx: &CrateCtxt,
         let superbounds2 = generics.get_type_parameter_bounds(&ccx.icx(scope), item.span, item.id);
 
         // Combine the two lists to form the complete set of superbounds:
-        let superbounds = superbounds1.into_iter().chain(superbounds2.into_iter()).collect();
+        let superbounds = superbounds1.into_iter().chain(superbounds2).collect();
         let superpredicates = ty::GenericPredicates {
             predicates: VecPerParamSpace::new(superbounds, vec![], vec![])
         };
@@ -1928,7 +1928,7 @@ fn compute_object_lifetime_default<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>,
     let inline_bounds = from_bounds(ccx, param_bounds);
     let where_bounds = from_predicates(ccx, param_id, &where_clause.predicates);
     let all_bounds: HashSet<_> = inline_bounds.into_iter()
-                                              .chain(where_bounds.into_iter())
+                                              .chain(where_bounds)
                                               .collect();
     return if all_bounds.len() > 1 {
         Some(ty::ObjectLifetimeDefault::Ambiguous)
@@ -2026,7 +2026,7 @@ fn predicates_from_bound<'tcx>(astconv: &AstConv<'tcx>,
             let pred = conv_poly_trait_ref(astconv, param_ty, tr, &mut projections);
             projections.into_iter()
                        .map(|p| p.as_predicate())
-                       .chain(Some(pred.as_predicate()).into_iter())
+                       .chain(Some(pred.as_predicate()))
                        .collect()
         }
         ast::RegionTyParamBound(ref lifetime) => {
@@ -2096,7 +2096,7 @@ fn compute_type_scheme_of_foreign_fn_decl<'a, 'tcx>(
     abi: abi::Abi)
     -> ty::TypeScheme<'tcx>
 {
-    for i in decl.inputs.iter() {
+    for i in &decl.inputs {
         match (*i).pat.node {
             ast::PatIdent(_, _, _) => (),
             ast::PatWild(ast::PatWildSingle) => (),
@@ -2300,7 +2300,7 @@ fn enforce_impl_params_are_constrained<'tcx>(tcx: &ty::ctxt<'tcx>,
                       ty::TypeTraitItem(ref assoc_ty) => assoc_ty.ty,
                       ty::ConstTraitItem(..) | ty::MethodTraitItem(..) => None
                   })
-                  .flat_map(|ty| ctp::parameters_for_type(ty).into_iter())
+                  .flat_map(|ty| ctp::parameters_for_type(ty))
                   .filter_map(|p| match p {
                       ctp::Parameter::Type(_) => None,
                       ctp::Parameter::Region(r) => Some(r),

src/librustc_typeck/constrained_type_params.rs

@@ -21,7 +21,7 @@ pub enum Parameter {
 
 pub fn parameters_for_type<'tcx>(ty: Ty<'tcx>) -> Vec<Parameter> {
     ty.walk()
-      .flat_map(|ty| parameters_for_type_shallow(ty).into_iter())
+      .flat_map(|ty| parameters_for_type_shallow(ty))
       .collect()
 }
 
@@ -31,7 +31,7 @@ pub fn parameters_for_trait_ref<'tcx>(trait_ref: &ty::TraitRef<'tcx>) -> Vec<Par
 
     let type_parameters =
         trait_ref.substs.types.iter()
-                              .flat_map(|ty| parameters_for_type(ty).into_iter());
+                              .flat_map(|ty| parameters_for_type(ty));
 
     region_parameters.extend(type_parameters);
 

src/librustdoc/clean/inline.rs

@@ -83,17 +83,17 @@ fn try_inline_def(cx: &DocContext, tcx: &ty::ctxt,
         }
         def::DefStruct(did) => {
             record_extern_fqn(cx, did, clean::TypeStruct);
-            ret.extend(build_impls(cx, tcx, did).into_iter());
+            ret.extend(build_impls(cx, tcx, did));
             clean::StructItem(build_struct(cx, tcx, did))
         }
         def::DefTy(did, false) => {
             record_extern_fqn(cx, did, clean::TypeTypedef);
-            ret.extend(build_impls(cx, tcx, did).into_iter());
+            ret.extend(build_impls(cx, tcx, did));
             build_type(cx, tcx, did)
         }
         def::DefTy(did, true) => {
             record_extern_fqn(cx, did, clean::TypeEnum);
-            ret.extend(build_impls(cx, tcx, did).into_iter());
+            ret.extend(build_impls(cx, tcx, did));
             build_type(cx, tcx, did)
         }
         // Assume that the enum type is reexported next to the variant, and
@@ -228,7 +228,7 @@ pub fn build_impls(cx: &DocContext, tcx: &ty::ctxt,
     match tcx.inherent_impls.borrow().get(&did) {
         None => {}
         Some(i) => {
-            for &did in i.iter() {
+            for &did in &**i {
                 build_impl(cx, tcx, did, &mut impls);
             }
         }
@@ -451,7 +451,7 @@ fn build_module(cx: &DocContext, tcx: &ty::ctxt,
                 decoder::DlDef(def) if vis == ast::Public => {
                     if !visited.insert(def) { return }
                     match try_inline_def(cx, tcx, def) {
-                        Some(i) => items.extend(i.into_iter()),
+                        Some(i) => items.extend(i),
                         None => {}
                     }
                 }

src/librustdoc/clean/mod.rs

@@ -190,7 +190,7 @@ impl<'a, 'tcx> Clean<Crate> for visit_ast::RustdocVisitor<'a, 'tcx> {
                     inner: PrimitiveItem(prim),
                 });
             }
-            m.items.extend(tmp.into_iter());
+            m.items.extend(tmp);
         }
 
         let src = match cx.input {
@@ -382,17 +382,17 @@ impl Clean<Item> for doctree::Module {
 
         let mut items: Vec<Item> = vec![];
         items.extend(self.extern_crates.iter().map(|x| x.clean(cx)));
-        items.extend(self.imports.iter().flat_map(|x| x.clean(cx).into_iter()));
+        items.extend(self.imports.iter().flat_map(|x| x.clean(cx)));
         items.extend(self.structs.iter().map(|x| x.clean(cx)));
         items.extend(self.enums.iter().map(|x| x.clean(cx)));
         items.extend(self.fns.iter().map(|x| x.clean(cx)));
-        items.extend(self.foreigns.iter().flat_map(|x| x.clean(cx).into_iter()));
+        items.extend(self.foreigns.iter().flat_map(|x| x.clean(cx)));
         items.extend(self.mods.iter().map(|x| x.clean(cx)));
         items.extend(self.typedefs.iter().map(|x| x.clean(cx)));
         items.extend(self.statics.iter().map(|x| x.clean(cx)));
         items.extend(self.constants.iter().map(|x| x.clean(cx)));
         items.extend(self.traits.iter().map(|x| x.clean(cx)));
-        items.extend(self.impls.iter().flat_map(|x| x.clean(cx).into_iter()));
+        items.extend(self.impls.iter().flat_map(|x| x.clean(cx)));
         items.extend(self.macros.iter().map(|x| x.clean(cx)));
         items.extend(self.def_traits.iter().map(|x| x.clean(cx)));
 
@@ -1884,7 +1884,7 @@ impl<'tcx> Clean<Item> for ty::VariantInfo<'tcx> {
                 StructVariant(VariantStruct {
                     struct_type: doctree::Plain,
                     fields_stripped: false,
-                    fields: s.iter().zip(self.args.iter()).map(|(name, ty)| {
+                    fields: s.iter().zip(&self.args).map(|(name, ty)| {
                         Item {
                             source: Span::empty(),
                             name: Some(name.clean(cx)),
@@ -2375,7 +2375,7 @@ impl Clean<Vec<Item>> for doctree::Import {
                     for path in list {
                         match inline::try_inline(cx, path.node.id(), None) {
                             Some(items) => {
-                                ret.extend(items.into_iter());
+                                ret.extend(items);
                             }
                             None => {
                                 remaining.push(path.clean(cx));

src/librustdoc/clean/simplify.rs

@@ -139,7 +139,7 @@ pub fn where_clauses(cx: &DocContext, clauses: Vec<WP>) -> Vec<WP> {
 }
 
 pub fn ty_params(mut params: Vec<clean::TyParam>) -> Vec<clean::TyParam> {
-    for param in params.iter_mut() {
+    for param in &mut params {
         param.bounds = ty_bounds(mem::replace(&mut param.bounds, Vec::new()));
     }
     return params;
@@ -165,7 +165,7 @@ fn trait_is_same_or_supertrait(cx: &DocContext, child: ast::DefId,
             } if *s == "Self" => Some(bounds),
             _ => None,
         }
-    }).flat_map(|bounds| bounds.iter()).any(|bound| {
+    }).flat_map(|bounds| bounds).any(|bound| {
         let poly_trait = match *bound {
             clean::TraitBound(ref t, _) => t,
             _ => return false,

src/librustdoc/html/render.rs

@@ -2414,7 +2414,7 @@ fn render_impl(w: &mut fmt::Formatter, i: &Impl, link: AssocItemLink,
     }
 
     try!(write!(w, "<div class='impl-items'>"));
-    for trait_item in i.impl_.items.iter() {
+    for trait_item in &i.impl_.items {
         try!(doctraititem(w, trait_item, link, render_header));
     }
 

src/librustdoc/test.rs

@@ -75,7 +75,7 @@ pub fn run(input: &str,
     rustc_lint::register_builtins(&mut sess.lint_store.borrow_mut(), Some(&sess));
 
     let mut cfg = config::build_configuration(&sess);
-    cfg.extend(config::parse_cfgspecs(cfgs).into_iter());
+    cfg.extend(config::parse_cfgspecs(cfgs));
     let krate = driver::phase_1_parse_input(&sess, cfg, &input);
     let krate = driver::phase_2_configure_and_expand(&sess, krate,
                                                      "rustdoc-test", None)
@@ -129,12 +129,13 @@ fn scrape_test_config(krate: &::syntax::ast::Crate) -> TestOptions {
         attrs: Vec::new(),
     };
 
-    let attrs = krate.attrs.iter().filter(|a| a.check_name("doc"))
+    let attrs = krate.attrs.iter()
+                     .filter(|a| a.check_name("doc"))
                      .filter_map(|a| a.meta_item_list())
-                     .flat_map(|l| l.iter())
+                     .flat_map(|l| l)
                      .filter(|a| a.check_name("test"))
                      .filter_map(|a| a.meta_item_list())
-                     .flat_map(|l| l.iter());
+                     .flat_map(|l| l);
     for attr in attrs {
         if attr.check_name("no_crate_inject") {
             opts.no_crate_inject = true;
@@ -239,7 +240,7 @@ fn runtest(test: &str, cratename: &str, libs: SearchPaths,
         let path = env::var_os(var).unwrap_or(OsString::new());
         let mut path = env::split_paths(&path).collect::<Vec<_>>();
         path.insert(0, libdir.clone());
-        env::join_paths(path.iter()).unwrap()
+        env::join_paths(path).unwrap()
     };
     cmd.env(var, &newpath);
 

src/libstd/ascii.rs

@@ -226,7 +226,7 @@ impl AsciiExt for [u8] {
     #[inline]
     fn eq_ignore_ascii_case(&self, other: &[u8]) -> bool {
         self.len() == other.len() &&
-        self.iter().zip(other.iter()).all(|(a, b)| {
+        self.iter().zip(other).all(|(a, b)| {
             a.eq_ignore_ascii_case(b)
         })
     }

src/libstd/collections/hash/map.rs

@@ -906,7 +906,7 @@ impl<K, V, S> HashMap<K, V, S>
     ///     *val *= 2;
     /// }
     ///
-    /// for (key, val) in map.iter() {
+    /// for (key, val) in &map {
     ///     println!("key: {} val: {}", key, val);
     /// }
     /// ```

src/libstd/collections/hash/set.rs

@@ -647,7 +647,7 @@ impl<'a, 'b, T, S> BitOr<&'b HashSet<T, S>> for &'a HashSet<T, S>
     ///
     /// let mut i = 0;
     /// let expected = [1, 2, 3, 4, 5];
-    /// for x in set.iter() {
+    /// for x in &set {
     ///     assert!(expected.contains(x));
     ///     i += 1;
     /// }
@@ -679,7 +679,7 @@ impl<'a, 'b, T, S> BitAnd<&'b HashSet<T, S>> for &'a HashSet<T, S>
     ///
     /// let mut i = 0;
     /// let expected = [2, 3];
-    /// for x in set.iter() {
+    /// for x in &set {
     ///     assert!(expected.contains(x));
     ///     i += 1;
     /// }
@@ -711,7 +711,7 @@ impl<'a, 'b, T, S> BitXor<&'b HashSet<T, S>> for &'a HashSet<T, S>
     ///
     /// let mut i = 0;
     /// let expected = [1, 2, 4, 5];
-    /// for x in set.iter() {
+    /// for x in &set {
     ///     assert!(expected.contains(x));
     ///     i += 1;
     /// }
@@ -743,7 +743,7 @@ impl<'a, 'b, T, S> Sub<&'b HashSet<T, S>> for &'a HashSet<T, S>
     ///
     /// let mut i = 0;
     /// let expected = [1, 2];
-    /// for x in set.iter() {
+    /// for x in &set {
     ///     assert!(expected.contains(x));
     ///     i += 1;
     /// }
@@ -838,7 +838,7 @@ impl<T, S> IntoIterator for HashSet<T, S>
     /// let v: Vec<String> = set.into_iter().collect();
     ///
     /// // Will print in an arbitrary order.
-    /// for x in v.iter() {
+    /// for x in &v {
     ///     println!("{}", x);
     /// }
     /// ```

src/libstd/collections/mod.rs

@@ -252,6 +252,7 @@
 //! contents by-value. This is great when the collection itself is no longer
 //! needed, and the values are needed elsewhere. Using `extend` with `into_iter`
 //! is the main way that contents of one collection are moved into another.
+//! `extend` automatically calls `into_iter`, and takes any `T: IntoIterator`.
 //! Calling `collect` on an iterator itself is also a great way to convert one
 //! collection into another. Both of these methods should internally use the
 //! capacity management tools discussed in the previous section to do this as
@@ -260,7 +261,7 @@
 //! ```
 //! let mut vec1 = vec![1, 2, 3, 4];
 //! let vec2 = vec![10, 20, 30, 40];
-//! vec1.extend(vec2.into_iter());
+//! vec1.extend(vec2);
 //! ```
 //!
 //! ```
@@ -339,7 +340,7 @@
 //! assert_eq!(count.get(&'s'), Some(&8));
 //!
 //! println!("Number of occurrences of each character");
-//! for (char, count) in count.iter() {
+//! for (char, count) in &count {
 //!     println!("{}: {}", char, count);
 //! }
 //! ```
@@ -362,7 +363,7 @@
 //! // Our clients.
 //! let mut blood_alcohol = BTreeMap::new();
 //!
-//! for id in orders.into_iter() {
+//! for id in orders {
 //!     // If this is the first time we've seen this customer, initialize them
 //!     // with no blood alcohol. Otherwise, just retrieve them.
 //!     let person = blood_alcohol.entry(id).or_insert(Person{id: id, blood_alcohol: 0.0});

src/libstd/dynamic_lib.rs

@@ -294,7 +294,7 @@ mod dl {
         let result = match filename {
             Some(filename) => {
                 let filename_str: Vec<_> =
-                    filename.encode_wide().chain(Some(0).into_iter()).collect();
+                    filename.encode_wide().chain(Some(0)).collect();
                 let result = unsafe {
                     LoadLibraryW(filename_str.as_ptr() as *const libc::c_void)
                 };

src/libstd/env.rs

@@ -365,7 +365,7 @@ pub struct JoinPathsError {
 /// if let Some(path) = env::var_os("PATH") {
 ///     let mut paths = env::split_paths(&path).collect::<Vec<_>>();
 ///     paths.push(PathBuf::from("/home/xyz/bin"));
-///     let new_path = env::join_paths(paths.iter()).unwrap();
+///     let new_path = env::join_paths(paths).unwrap();
 ///     env::set_var("PATH", &new_path);
 /// }
 /// ```

src/libstd/io/util.rs

@@ -78,7 +78,7 @@ pub fn repeat(byte: u8) -> Repeat { Repeat { byte: byte } }
 #[stable(feature = "rust1", since = "1.0.0")]
 impl Read for Repeat {
     fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
-        for slot in buf.iter_mut() {
+        for slot in &mut *buf {
             *slot = self.byte;
         }
         Ok(buf.len())

src/libstd/net/parser.rs

@@ -63,7 +63,7 @@ impl<'a> Parser<'a> {
     // Return result of first successful parser
     fn read_or<T>(&mut self, parsers: &mut [Box<FnMut(&mut Parser) -> Option<T> + 'static>])
                -> Option<T> {
-        for pf in parsers.iter_mut() {
+        for pf in parsers {
             match self.read_atomically(|p: &mut Parser| pf(p)) {
                 Some(r) => return Some(r),
                 None => {}

src/libstd/sys/windows/fs.rs

@@ -368,7 +368,7 @@ impl fmt::Debug for File {
 }
 
 pub fn to_utf16(s: &Path) -> Vec<u16> {
-    s.as_os_str().encode_wide().chain(Some(0).into_iter()).collect()
+    s.as_os_str().encode_wide().chain(Some(0)).collect()
 }
 
 impl FileAttr {

src/libsyntax/ast_util.rs

@@ -615,7 +615,7 @@ pub fn path_name_eq(a : &ast::Path, b : &ast::Path) -> bool {
 // are two arrays of segments equal when compared unhygienically?
 pub fn segments_name_eq(a : &[ast::PathSegment], b : &[ast::PathSegment]) -> bool {
     a.len() == b.len() &&
-    a.iter().zip(b.iter()).all(|(s, t)| {
+    a.iter().zip(b).all(|(s, t)| {
         s.identifier.name == t.identifier.name &&
         // FIXME #7743: ident -> name problems in lifetime comparison?
         // can types contain idents?

src/libsyntax/attr.rs

@@ -414,7 +414,7 @@ fn find_stability_generic<'a,
                 let mut feature = None;
                 let mut since = None;
                 let mut reason = None;
-                for meta in metas.iter() {
+                for meta in metas {
                     if meta.name() == "feature" {
                         match meta.value_str() {
                             Some(v) => feature = Some(v),

src/libsyntax/diagnostic.rs

@@ -595,7 +595,7 @@ fn highlight_lines(err: &mut EmitterWriter,
     let display_line_strings = &line_strings[..display_lines];
 
     // Print the offending lines
-    for (line_info, line) in display_line_infos.iter().zip(display_line_strings.iter()) {
+    for (line_info, line) in display_line_infos.iter().zip(display_line_strings) {
         try!(write!(&mut err.dst, "{}:{} {}\n",
                     fm.name,
                     line_info.line_index + 1,

src/libsyntax/ext/deriving/generic/mod.rs

@@ -549,10 +549,10 @@ impl<'a> TraitDef<'a> {
                 .map(|ty_param| ty_param.ident.name)
                 .collect();
 
-            for field_ty in field_tys.into_iter() {
+            for field_ty in field_tys {
                 let tys = find_type_parameters(&*field_ty, &ty_param_names);
 
-                for ty in tys.into_iter() {
+                for ty in tys {
                     let mut bounds: Vec<_> = self.additional_bounds.iter().map(|p| {
                         cx.typarambound(p.to_path(cx, self.span, type_ident, generics))
                     }).collect();
@@ -672,7 +672,7 @@ impl<'a> TraitDef<'a> {
                        generics: &Generics) -> P<ast::Item> {
         let mut field_tys = Vec::new();
 
-        for variant in enum_def.variants.iter() {
+        for variant in &enum_def.variants {
             match variant.node.kind {
                 ast::VariantKind::TupleVariantKind(ref args) => {
                     field_tys.extend(args.iter()
@@ -967,7 +967,7 @@ impl<'a> MethodDef<'a> {
         // make a series of nested matches, to destructure the
         // structs. This is actually right-to-left, but it shouldn't
         // matter.
-        for (arg_expr, pat) in self_args.iter().zip(patterns.iter()) {
+        for (arg_expr, pat) in self_args.iter().zip(patterns) {
             body = cx.expr_match(trait_.span, arg_expr.clone(),
                                      vec!( cx.arm(trait_.span, vec!(pat.clone()), body) ))
         }
@@ -1226,7 +1226,7 @@ impl<'a> MethodDef<'a> {
             let target_type_name =
                 find_repr_type_name(&cx.parse_sess.span_diagnostic, type_attrs);
 
-            for (&ident, self_arg) in vi_idents.iter().zip(self_args.iter()) {
+            for (&ident, self_arg) in vi_idents.iter().zip(&self_args) {
                 let path = vec![cx.ident_of_std("core"),
                                 cx.ident_of("intrinsics"),
                                 cx.ident_of("discriminant_value")];
@@ -1465,7 +1465,7 @@ impl<'a> TraitDef<'a> {
         // struct_type is definitely not Unknown, since struct_def.fields
         // must be nonempty to reach here
         let pattern = if struct_type == Record {
-            let field_pats = subpats.into_iter().zip(ident_expr.iter())
+            let field_pats = subpats.into_iter().zip(&ident_expr)
                                     .map(|(pat, &(_, id, _, _))| {
                 // id is guaranteed to be Some
                 codemap::Spanned {

src/libsyntax/ext/expand.rs

@@ -183,7 +183,7 @@ pub fn expand_expr(e: P<ast::Expr>, fld: &mut MacroExpander) -> P<ast::Expr> {
 
             let mut arms = Vec::with_capacity(else_if_arms.len() + 2);
             arms.push(pat_arm);
-            arms.extend(else_if_arms.into_iter());
+            arms.extend(else_if_arms);
             arms.push(else_arm);
 
             let match_expr = fld.cx.expr(span,
@@ -779,7 +779,7 @@ fn expand_non_macro_stmt(Spanned {node, span: stmt_span}: Stmt, fld: &mut MacroE
                     };
                     // add them to the existing pending renames:
                     fld.cx.syntax_env.info().pending_renames
-                          .extend(new_pending_renames.into_iter());
+                          .extend(new_pending_renames);
                     Local {
                         id: id,
                         ty: expanded_ty,

src/libsyntax/ext/quote.rs

@@ -49,7 +49,7 @@ pub mod rt {
 
     impl<T: ToTokens> ToTokens for Vec<T> {
         fn to_tokens(&self, cx: &ExtCtxt) -> Vec<TokenTree> {
-            self.iter().flat_map(|t| t.to_tokens(cx).into_iter()).collect()
+            self.iter().flat_map(|t| t.to_tokens(cx)).collect()
         }
     }
 
@@ -387,7 +387,7 @@ pub fn expand_quote_matcher(cx: &mut ExtCtxt,
                             -> Box<base::MacResult+'static> {
     let (cx_expr, tts) = parse_arguments_to_quote(cx, tts);
     let mut vector = mk_stmts_let(cx, sp);
-    vector.extend(statements_mk_tts(cx, &tts[..], true).into_iter());
+    vector.extend(statements_mk_tts(cx, &tts[..], true));
     let block = cx.expr_block(
         cx.block_all(sp,
                      vector,
@@ -593,7 +593,7 @@ fn expr_mk_token(cx: &ExtCtxt, sp: Span, tok: &token::Token) -> P<ast::Expr> {
 fn statements_mk_tt(cx: &ExtCtxt, tt: &ast::TokenTree, matcher: bool) -> Vec<P<ast::Stmt>> {
     match *tt {
         ast::TtToken(sp, SubstNt(ident, _)) => {
-            // tt.extend($ident.to_tokens(ext_cx).into_iter())
+            // tt.extend($ident.to_tokens(ext_cx))
 
             let e_to_toks =
                 cx.expr_method_call(sp,
@@ -633,8 +633,8 @@ fn statements_mk_tt(cx: &ExtCtxt, tt: &ast::TokenTree, matcher: bool) -> Vec<P<a
         ast::TtDelimited(_, ref delimed) => {
             statements_mk_tt(cx, &delimed.open_tt(), matcher).into_iter()
                 .chain(delimed.tts.iter()
-                                  .flat_map(|tt| statements_mk_tt(cx, tt, matcher).into_iter()))
-                .chain(statements_mk_tt(cx, &delimed.close_tt(), matcher).into_iter())
+                                  .flat_map(|tt| statements_mk_tt(cx, tt, matcher)))
+                .chain(statements_mk_tt(cx, &delimed.close_tt(), matcher))
                 .collect()
         },
         ast::TtSequence(sp, ref seq) => {
@@ -646,7 +646,7 @@ fn statements_mk_tt(cx: &ExtCtxt, tt: &ast::TokenTree, matcher: bool) -> Vec<P<a
 
             let stmt_let_tt = cx.stmt_let(sp, true, id_ext("tt"), cx.expr_vec_ng(sp));
             let mut tts_stmts = vec![stmt_let_tt];
-            tts_stmts.extend(statements_mk_tts(cx, &seq.tts[..], matcher).into_iter());
+            tts_stmts.extend(statements_mk_tts(cx, &seq.tts[..], matcher));
             let e_tts = cx.expr_block(cx.block(sp, tts_stmts,
                                                    Some(cx.expr_ident(sp, id_ext("tt")))));
             let e_separator = match seq.separator {
@@ -748,7 +748,7 @@ fn mk_stmts_let(cx: &ExtCtxt, sp: Span) -> Vec<P<ast::Stmt>> {
 fn statements_mk_tts(cx: &ExtCtxt, tts: &[ast::TokenTree], matcher: bool) -> Vec<P<ast::Stmt>> {
     let mut ss = Vec::new();
     for tt in tts {
-        ss.extend(statements_mk_tt(cx, tt, matcher).into_iter());
+        ss.extend(statements_mk_tt(cx, tt, matcher));
     }
     ss
 }
@@ -758,7 +758,7 @@ fn expand_tts(cx: &ExtCtxt, sp: Span, tts: &[ast::TokenTree])
     let (cx_expr, tts) = parse_arguments_to_quote(cx, tts);
 
     let mut vector = mk_stmts_let(cx, sp);
-    vector.extend(statements_mk_tts(cx, &tts[..], false).into_iter());
+    vector.extend(statements_mk_tts(cx, &tts[..], false));
     let block = cx.expr_block(
         cx.block_all(sp,
                      vector,
@@ -780,7 +780,7 @@ fn expand_wrapper(cx: &ExtCtxt,
         // make item: `use ...;`
         let path = path.iter().map(|s| s.to_string()).collect();
         cx.stmt_item(sp, cx.item_use_glob(sp, ast::Inherited, ids_ext(path)))
-    }).chain(Some(stmt_let_ext_cx).into_iter()).collect();
+    }).chain(Some(stmt_let_ext_cx)).collect();
 
     cx.expr_block(cx.block_all(sp, stmts, Some(expr)))
 }

src/libsyntax/feature_gate.rs

@@ -385,7 +385,7 @@ impl<'a> Context<'a> {
                 return;
             }
         }
-        for &(ref n, ref ty) in self.plugin_attributes.iter() {
+        for &(ref n, ref ty) in self.plugin_attributes {
             if &*n == name {
                 // Plugins can't gate attributes, so we don't check for it
                 // unlike the code above; we only use this loop to

src/libsyntax/fold.rs

@@ -353,7 +353,7 @@ pub fn noop_fold_view_path<T: Folder>(view_path: P<ViewPath>, fld: &mut T) -> P<
 }
 
 pub fn fold_attrs<T: Folder>(attrs: Vec<Attribute>, fld: &mut T) -> Vec<Attribute> {
-    attrs.into_iter().flat_map(|x| fld.fold_attribute(x).into_iter()).collect()
+    attrs.into_iter().flat_map(|x| fld.fold_attribute(x)).collect()
 }
 
 pub fn noop_fold_arm<T: Folder>(Arm {attrs, pats, guard, body}: Arm, fld: &mut T) -> Arm {

src/libsyntax/parse/parser.rs

@@ -1060,7 +1060,7 @@ impl<'a> Parser<'a> {
             };
             let all_bounds =
                 Some(TraitTyParamBound(poly_trait_ref, TraitBoundModifier::None)).into_iter()
-                .chain(other_bounds.into_vec().into_iter())
+                .chain(other_bounds.into_vec())
                 .collect();
             Ok(ast::TyPolyTraitRef(all_bounds))
         }
@@ -2058,7 +2058,7 @@ impl<'a> Parser<'a> {
                             |p| Ok(try!(p.parse_expr_nopanic()))
                                 ));
                         let mut exprs = vec!(first_expr);
-                        exprs.extend(remaining_exprs.into_iter());
+                        exprs.extend(remaining_exprs);
                         ex = ExprVec(exprs);
                     } else {
                         // Vector with one element.
@@ -4423,7 +4423,7 @@ impl<'a> Parser<'a> {
             (name, ConstImplItem(typ, expr))
         } else {
             let (name, inner_attrs, node) = try!(self.parse_impl_method(vis));
-            attrs.extend(inner_attrs.into_iter());
+            attrs.extend(inner_attrs);
             (name, node)
         };
 
@@ -5068,7 +5068,7 @@ impl<'a> Parser<'a> {
 
         let abi = opt_abi.unwrap_or(abi::C);
 
-        attrs.extend(self.parse_inner_attributes().into_iter());
+        attrs.extend(self.parse_inner_attributes());
 
         let mut foreign_items = vec![];
         while let Some(item) = try!(self.parse_foreign_item()) {
@@ -5244,7 +5244,7 @@ impl<'a> Parser<'a> {
                 try!(self.bump());
                 let mut attrs = attrs;
                 mem::swap(&mut item.attrs, &mut attrs);
-                item.attrs.extend(attrs.into_iter());
+                item.attrs.extend(attrs);
                 return Ok(Some(P(item)));
             }
             None => {}