for x in xs.iter() -> for x in &xs

src/compiletest/compiletest.rs

@@ -276,7 +276,7 @@ pub fn make_tests(config: &Config) -> Vec<test::TestDescAndFn> {
            config.src_base.display());
     let mut tests = Vec::new();
     let dirs = fs::readdir(&config.src_base).unwrap();
-    for file in dirs.iter() {
+    for file in &dirs {
         let file = file.clone();
         debug!("inspecting file {:?}", file.display());
         if is_test(config, &file) {
@@ -304,13 +304,13 @@ pub fn is_test(config: &Config, testfile: &Path) -> bool {
 
     let mut valid = false;
 
-    for ext in valid_extensions.iter() {
+    for ext in &valid_extensions {
         if name.ends_with(ext.as_slice()) {
             valid = true;
         }
     }
 
-    for pre in invalid_prefixes.iter() {
+    for pre in &invalid_prefixes {
         if name.starts_with(pre.as_slice()) {
             valid = false;
         }

src/compiletest/procsrv.rs

@@ -46,7 +46,7 @@ pub fn run(lib_path: &str,
 
     match cmd.spawn() {
         Ok(mut process) => {
-            for input in input.iter() {
+            if let Some(input) = input {
                 process.stdin.as_mut().unwrap().write_all(input.as_bytes()).unwrap();
             }
             let ProcessOutput { status, output, error } =
@@ -78,7 +78,7 @@ pub fn run_background(lib_path: &str,
 
     match cmd.spawn() {
         Ok(mut process) => {
-            for input in input.iter() {
+            if let Some(input) = input {
                 process.stdin.as_mut().unwrap().write_all(input.as_bytes()).unwrap();
             }
 

src/compiletest/runtest.rs

@@ -547,7 +547,7 @@ fn run_debuginfo_gdb_test(config: &Config, props: &TestProps, testfile: &Path) {
                                          exe_file.as_str().unwrap().replace("\\", "\\\\"))[]);
 
             // Add line breakpoints
-            for line in breakpoint_lines.iter() {
+            for line in &breakpoint_lines {
                 script_str.push_str(&format!("break '{}':{}\n",
                                              testfile.filename_display(),
                                              *line)[]);
@@ -683,13 +683,13 @@ fn run_debuginfo_lldb_test(config: &Config, props: &TestProps, testfile: &Path)
     script_str.push_str("type category enable Rust\n");
 
     // Set breakpoints on every line that contains the string "#break"
-    for line in breakpoint_lines.iter() {
+    for line in &breakpoint_lines {
         script_str.push_str(format!("breakpoint set --line {}\n",
                                     line).as_slice());
     }
 
     // Append the other commands
-    for line in commands.iter() {
+    for line in &commands {
         script_str.push_str(line.as_slice());
         script_str.push_str("\n");
     }
@@ -847,7 +847,7 @@ fn check_debugger_output(debugger_run_result: &ProcRes, check_lines: &[String])
             let mut rest = line.trim();
             let mut first = true;
             let mut failed = false;
-            for frag in check_fragments[i].iter() {
+            for frag in &check_fragments[i] {
                 let found = if first {
                     if rest.starts_with(frag.as_slice()) {
                         Some(0)
@@ -915,7 +915,7 @@ fn check_error_patterns(props: &TestProps,
                               missing_patterns[0]).as_slice(),
                       proc_res);
     } else {
-        for pattern in missing_patterns.iter() {
+        for pattern in missing_patterns {
             error(format!("error pattern '{}' not found!",
                           *pattern).as_slice());
         }
@@ -935,7 +935,7 @@ fn check_no_compiler_crash(proc_res: &ProcRes) {
 fn check_forbid_output(props: &TestProps,
                        output_to_check: &str,
                        proc_res: &ProcRes) {
-    for pat in props.forbid_output.iter() {
+    for pat in &props.forbid_output {
         if output_to_check.contains(pat.as_slice()) {
             fatal_proc_rec("forbidden pattern found in compiler output", proc_res);
         }
@@ -1173,7 +1173,7 @@ fn compose_and_run_compiler(
     // FIXME (#9639): This needs to handle non-utf8 paths
     let extra_link_args = vec!("-L".to_string(), aux_dir.as_str().unwrap().to_string());
 
-    for rel_ab in props.aux_builds.iter() {
+    for rel_ab in &props.aux_builds {
         let abs_ab = config.aux_base.join(rel_ab.as_slice());
         let aux_props = header::load_props(&abs_ab);
         let mut crate_type = if aux_props.no_prefer_dynamic {
@@ -1510,7 +1510,7 @@ fn _arm_exec_compiled_test(config: &Config,
     runargs.push(format!("{}", config.adb_test_dir));
     runargs.push(format!("{}", prog_short));
 
-    for tv in args.args.iter() {
+    for tv in &args.args {
         runargs.push(tv.to_string());
     }
     procsrv::run("",
@@ -1591,7 +1591,7 @@ fn _arm_push_aux_shared_library(config: &Config, testfile: &Path) {
     let tdir = aux_output_dir_name(config, testfile);
 
     let dirs = fs::readdir(&tdir).unwrap();
-    for file in dirs.iter() {
+    for file in &dirs {
         if file.extension_str() == Some("so") {
             // FIXME (#9639): This needs to handle non-utf8 paths
             let copy_result = procsrv::run("",

src/compiletest/util.rs

@@ -26,7 +26,7 @@ static OS_TABLE: &'static [(&'static str, &'static str)] = &[
 ];
 
 pub fn get_os(triple: &str) -> &'static str {
-    for &(triple_os, os) in OS_TABLE.iter() {
+    for &(triple_os, os) in OS_TABLE {
         if triple.contains(triple_os) {
             return os
         }

src/libarena/lib.rs

@@ -127,7 +127,7 @@ impl Drop for Arena {
     fn drop(&mut self) {
         unsafe {
             destroy_chunk(&*self.head.borrow());
-            for chunk in self.chunks.borrow().iter() {
+            for chunk in &*self.chunks.borrow() {
                 if !chunk.is_copy.get() {
                     destroy_chunk(chunk);
                 }

src/libcollections/bench.rs

@@ -73,7 +73,7 @@ pub fn find_rand_n<M, T, I, F>(n: uint,
     let mut keys = (0..n).map(|_| rng.gen::<uint>() % n)
                               .collect::<Vec<_>>();
 
-    for k in keys.iter() {
+    for k in &keys {
         insert(map, *k);
     }
 

src/libcollections/binary_heap.rs

@@ -696,7 +696,7 @@ mod tests {
         let iterout = [9, 5, 3];
         let heap = BinaryHeap::from_vec(data);
         let mut i = 0;
-        for el in heap.iter() {
+        for el in &heap {
             assert_eq!(*el, iterout[i]);
             i += 1;
         }
@@ -884,7 +884,7 @@ mod tests {
 
         let mut q: BinaryHeap<uint> = xs.iter().rev().map(|&x| x).collect();
 
-        for &x in xs.iter() {
+        for &x in &xs {
             assert_eq!(q.pop().unwrap(), x);
         }
     }

src/libcollections/bit.rs

@@ -976,7 +976,7 @@ impl Ord for Bitv {
 #[stable(feature = "rust1", since = "1.0.0")]
 impl fmt::Debug for Bitv {
     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
-        for bit in self.iter() {
+        for bit in self {
             try!(write!(fmt, "{}", if bit { 1u32 } else { 0u32 }));
         }
         Ok(())
@@ -1743,7 +1743,7 @@ impl fmt::Debug for BitvSet {
     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
         try!(write!(fmt, "BitvSet {{"));
         let mut first = true;
-        for n in self.iter() {
+        for n in self {
             if !first {
                 try!(write!(fmt, ", "));
             }
@@ -1756,7 +1756,7 @@ impl fmt::Debug for BitvSet {
 
 impl<S: hash::Writer + hash::Hasher> hash::Hash<S> for BitvSet {
     fn hash(&self, state: &mut S) {
-        for pos in self.iter() {
+        for pos in self {
             pos.hash(state);
         }
     }
@@ -2600,7 +2600,7 @@ mod bitv_bench {
         b.iter(|| {
             let mut sum = 0u;
             for _ in 0u..10 {
-                for pres in bitv.iter() {
+                for pres in &bitv {
                     sum += pres as uint;
                 }
             }
@@ -2613,7 +2613,7 @@ mod bitv_bench {
         let bitv = Bitv::from_elem(BENCH_BITS, false);
         b.iter(|| {
             let mut sum = 0u;
-            for pres in bitv.iter() {
+            for pres in &bitv {
                 sum += pres as uint;
             }
             sum
@@ -2674,8 +2674,8 @@ mod bitv_set_test {
     fn test_bitv_set_frombitv_init() {
         let bools = [true, false];
         let lengths = [10, 64, 100];
-        for &b in bools.iter() {
-            for &l in lengths.iter() {
+        for &b in &bools {
+            for &l in &lengths {
                 let bitset = BitvSet::from_bitv(Bitv::from_elem(l, b));
                 assert_eq!(bitset.contains(&1u), b);
                 assert_eq!(bitset.contains(&(l-1u)), b);
@@ -3062,7 +3062,7 @@ mod bitv_set_bench {
                                               |idx| {idx % 3 == 0}));
         b.iter(|| {
             let mut sum = 0u;
-            for idx in bitv.iter() {
+            for idx in &bitv {
                 sum += idx as uint;
             }
             sum

src/libcollections/btree/map.rs

@@ -856,7 +856,7 @@ impl<K: Ord, V> Extend<(K, V)> for BTreeMap<K, V> {
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<S: Hasher, K: Hash<S>, V: Hash<S>> Hash<S> for BTreeMap<K, V> {
     fn hash(&self, state: &mut S) {
-        for elt in self.iter() {
+        for elt in self {
             elt.hash(state);
         }
     }
@@ -1946,7 +1946,7 @@ mod bench {
         }
 
         b.iter(|| {
-            for entry in map.iter() {
+            for entry in &map {
                 black_box(entry);
             }
         });

src/libcollections/btree/node.rs

@@ -435,13 +435,13 @@ impl<K: Clone, V: Clone> Clone for Node<K, V> {
             let mut vals = RawItems::from_parts(ret.vals().as_ptr(), 0);
             let mut edges = RawItems::from_parts(ret.edges().as_ptr(), 0);
 
-            for key in self.keys().iter() {
+            for key in self.keys() {
                 keys.push(key.clone())
             }
-            for val in self.vals().iter() {
+            for val in self.vals() {
                 vals.push(val.clone())
             }
-            for edge in self.edges().iter() {
+            for edge in self.edges() {
                 edges.push(edge.clone())
             }
 

src/libcollections/btree/set.rs

@@ -791,8 +791,8 @@ mod test {
         let mut set_a = BTreeSet::new();
         let mut set_b = BTreeSet::new();
 
-        for x in a.iter() { assert!(set_a.insert(*x)) }
-        for y in b.iter() { assert!(set_b.insert(*y)) }
+        for x in a { assert!(set_a.insert(*x)) }
+        for y in b { assert!(set_b.insert(*y)) }
 
         let mut i = 0;
         f(&set_a, &set_b, Counter { i: &mut i, expected: expected });
@@ -894,7 +894,7 @@ mod test {
 
         let set: BTreeSet<int> = xs.iter().map(|&x| x).collect();
 
-        for x in xs.iter() {
+        for x in &xs {
             assert!(set.contains(x));
         }
     }

src/libcollections/dlist.rs

@@ -917,7 +917,7 @@ impl<A: fmt::Debug> fmt::Debug for DList<A> {
 impl<S: Writer + Hasher, A: Hash<S>> Hash<S> for DList<A> {
     fn hash(&self, state: &mut S) {
         self.len().hash(state);
-        for elt in self.iter() {
+        for elt in self {
             elt.hash(state);
         }
     }

src/libcollections/enum_set.rs

@@ -36,7 +36,7 @@ impl<E:CLike + fmt::Debug> fmt::Debug for EnumSet<E> {
     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
         try!(write!(fmt, "EnumSet {{"));
         let mut first = true;
-        for e in self.iter() {
+        for e in self {
             if !first {
                 try!(write!(fmt, ", "));
             }

src/libcollections/ring_buf.rs

@@ -1573,7 +1573,7 @@ impl<A: Ord> Ord for RingBuf<A> {
 impl<S: Writer + Hasher, A: Hash<S>> Hash<S> for RingBuf<A> {
     fn hash(&self, state: &mut S) {
         self.len().hash(state);
-        for elt in self.iter() {
+        for elt in self {
             elt.hash(state);
         }
     }
@@ -1856,7 +1856,7 @@ mod tests {
 
         b.iter(|| {
             let mut sum = 0;
-            for &i in ring.iter() {
+            for &i in &ring {
                 sum += i;
             }
             test::black_box(sum);

src/libcollections/slice.rs

@@ -1118,7 +1118,7 @@ impl<T: Clone, V: AsSlice<T>> SliceConcatExt<T, Vec<T>> for [V] {
     fn concat(&self) -> Vec<T> {
         let size = self.iter().fold(0u, |acc, v| acc + v.as_slice().len());
         let mut result = Vec::with_capacity(size);
-        for v in self.iter() {
+        for v in self {
             result.push_all(v.as_slice())
         }
         result
@@ -1128,7 +1128,7 @@ impl<T: Clone, V: AsSlice<T>> SliceConcatExt<T, Vec<T>> for [V] {
         let size = self.iter().fold(0u, |acc, v| acc + v.as_slice().len());
         let mut result = Vec::with_capacity(size + self.len());
         let mut first = true;
-        for v in self.iter() {
+        for v in self {
             if first { first = false } else { result.push(sep.clone()) }
             result.push_all(v.as_slice())
         }
@@ -2681,13 +2681,13 @@ mod tests {
         assert_eq!(v.len(), 3);
         let mut cnt = 0u;
 
-        for f in v.iter() {
+        for f in &v {
             assert!(*f == Foo);
             cnt += 1;
         }
         assert_eq!(cnt, 3);
 
-        for f in v[1..3].iter() {
+        for f in &v[1..3] {
             assert!(*f == Foo);
             cnt += 1;
         }
@@ -2707,7 +2707,7 @@ mod tests {
 
         let xs: [Foo; 3] = [Foo, Foo, Foo];
         cnt = 0;
-        for f in xs.iter() {
+        for f in &xs {
             assert!(*f == Foo);
             cnt += 1;
         }
@@ -2858,7 +2858,7 @@ mod bench {
 
         b.iter(|| {
             let mut sum = 0;
-            for x in v.iter() {
+            for x in &v {
                 sum += *x;
             }
             // sum == 11806, to stop dead code elimination.

src/libcollections/str.rs

@@ -99,7 +99,7 @@ impl<S: Str> SliceConcatExt<str, String> for [S] {
         let len = s.iter().map(|s| s.as_slice().len()).sum();
         let mut result = String::with_capacity(len);
 
-        for s in s.iter() {
+        for s in s {
             result.push_str(s.as_slice())
         }
 
@@ -125,7 +125,7 @@ impl<S: Str> SliceConcatExt<str, String> for [S] {
         let mut result = String::with_capacity(len);
         let mut first = true;
 
-        for s in s.iter() {
+        for s in s {
             if first {
                 first = false;
             } else {
@@ -2005,7 +2005,7 @@ mod tests {
         let s = "ศไทย中华Việt Nam";
         let v = vec!['ศ','ไ','ท','ย','中','华','V','i','ệ','t',' ','N','a','m'];
         let mut pos = 0;
-        for ch in v.iter() {
+        for ch in &v {
             assert!(s.char_at(pos) == *ch);
             pos += ch.to_string().len();
         }
@@ -2703,7 +2703,7 @@ mod tests {
             &["\u{378}\u{308}\u{903}"], &["\u{378}\u{308}", "\u{903}"]),
         ];
 
-        for &(s, g) in test_same.iter() {
+        for &(s, g) in &test_same[] {
             // test forward iterator
             assert!(order::equals(s.graphemes(true), g.iter().map(|&x| x)));
             assert!(order::equals(s.graphemes(false), g.iter().map(|&x| x)));
@@ -2713,7 +2713,7 @@ mod tests {
             assert!(order::equals(s.graphemes(false).rev(), g.iter().rev().map(|&x| x)));
         }
 
-        for &(s, gt, gf) in test_diff.iter() {
+        for &(s, gt, gf) in &test_diff {
             // test forward iterator
             assert!(order::equals(s.graphemes(true), gt.iter().map(|&x| x)));
             assert!(order::equals(s.graphemes(false), gf.iter().map(|&x| x)));

src/libcollections/string.rs

@@ -1118,7 +1118,7 @@ mod tests {
              (String::from_str("\u{20000}"),
               vec![0xD840, 0xDC00])];
 
-        for p in pairs.iter() {
+        for p in &pairs {
             let (s, u) = (*p).clone();
             let s_as_utf16 = s.utf16_units().collect::<Vec<u16>>();
             let u_as_string = String::from_utf16(u.as_slice()).unwrap();

src/libcollections/vec.rs

@@ -1547,7 +1547,7 @@ impl<T> Drop for Vec<T> {
         // zeroed (when moving out, because of #[unsafe_no_drop_flag]).
         if self.cap != 0 {
             unsafe {
-                for x in self.iter() {
+                for x in &*self {
                     ptr::read(x);
                 }
                 dealloc(*self.ptr, self.cap)
@@ -2129,7 +2129,7 @@ mod tests {
         v.push(());
         assert_eq!(v.iter().count(), 2);
 
-        for &() in v.iter() {}
+        for &() in &v {}
 
         assert_eq!(v.iter_mut().count(), 2);
         v.push(());

src/libcollections/vec_map.rs

@@ -90,7 +90,7 @@ impl<S: Writer + Hasher, V: Hash<S>> Hash<S> for VecMap<V> {
         // In order to not traverse the `VecMap` twice, count the elements
         // during iteration.
         let mut count: uint = 0;
-        for elt in self.iter() {
+        for elt in self {
             elt.hash(state);
             count += 1;
         }
@@ -1112,7 +1112,7 @@ mod test_map {
 
         let map: VecMap<char> = xs.iter().map(|&x| x).collect();
 
-        for &(k, v) in xs.iter() {
+        for &(k, v) in &xs {
             assert_eq!(map.get(&k), Some(&v));
         }
     }

src/libcore/fmt/mod.rs

@@ -888,7 +888,7 @@ impl<T: Debug> Debug for [T] {
             try!(write!(f, "["));
         }
         let mut is_first = true;
-        for x in self.iter() {
+        for x in self {
             if is_first {
                 is_first = false;
             } else {

src/libcore/hash/mod.rs

@@ -205,7 +205,7 @@ impl<S: Writer + Hasher, T: Hash<S>> Hash<S> for [T] {
     #[inline]
     fn hash(&self, state: &mut S) {
         self.len().hash(state);
-        for elt in self.iter() {
+        for elt in self {
             elt.hash(state);
         }
     }

src/libcoretest/cmp.rs

@@ -66,11 +66,11 @@ fn test_partial_min() {
         (1.0f64, NAN, None)
     ];
 
-    for &(a, b, result) in data_integer.iter() {
+    for &(a, b, result) in &data_integer {
         assert!(partial_min(a, b) == result);
     }
 
-    for &(a, b, result) in data_float.iter() {
+    for &(a, b, result) in &data_float {
         assert!(partial_min(a, b) == result);
     }
 }
@@ -99,11 +99,11 @@ fn test_partial_max() {
         (1.0f64, NAN, None)
     ];
 
-    for &(a, b, result) in data_integer.iter() {
+    for &(a, b, result) in &data_integer {
         assert!(partial_max(a, b) == result);
     }
 
-    for &(a, b, result) in data_float.iter() {
+    for &(a, b, result) in &data_float {
         assert!(partial_max(a, b) == result);
     }
 }

src/libcoretest/hash/mod.rs

@@ -25,7 +25,7 @@ impl Default for MyHasher {
 impl Writer for MyHasher {
     // Most things we'll just add up the bytes.
     fn write(&mut self, buf: &[u8]) {
-        for byte in buf.iter() {
+        for byte in buf {
             self.hash += *byte as u64;
         }
     }

src/libcoretest/hash/sip.rs

@@ -109,7 +109,7 @@ fn test_siphash() {
 
     fn to_hex_str(r: &[u8; 8]) -> String {
         let mut s = String::new();
-        for b in r.iter() {
+        for b in r {
             s.push_str(format!("{}", fmt::radix(*b, 16)).as_slice());
         }
         s
@@ -130,7 +130,7 @@ fn test_siphash() {
     fn result_str(h: u64) -> String {
         let r = result_bytes(h);
         let mut s = String::new();
-        for b in r.iter() {
+        for b in &r {
             s.push_str(format!("{}", fmt::radix(*b, 16)).as_slice());
         }
         s

src/libgetopts/lib.rs

@@ -315,7 +315,7 @@ impl Matches {
 
     /// Returns true if any of several options were matched.
     pub fn opts_present(&self, names: &[String]) -> bool {
-        for nm in names.iter() {
+        for nm in names {
             match find_opt(self.opts.as_slice(), Name::from_str(&nm[])) {
                 Some(id) if !self.vals[id].is_empty() => return true,
                 _ => (),
@@ -326,7 +326,7 @@ impl Matches {
 
     /// Returns the string argument supplied to one of several matching options or `None`.
     pub fn opts_str(&self, names: &[String]) -> Option<String> {
-        for nm in names.iter() {
+        for nm in names {
             match self.opt_val(&nm[]) {
                 Some(Val(ref s)) => return Some(s.clone()),
                 _ => ()
@@ -342,7 +342,7 @@ impl Matches {
     pub fn opt_strs(&self, nm: &str) -> Vec<String> {
         let mut acc: Vec<String> = Vec::new();
         let r = self.opt_vals(nm);
-        for v in r.iter() {
+        for v in &r {
             match *v {
                 Val(ref s) => acc.push((*s).clone()),
                 _ => ()
@@ -395,7 +395,7 @@ fn find_opt(opts: &[Opt], nm: Name) -> Option<uint> {
     }
 
     // Search in aliases.
-    for candidate in opts.iter() {
+    for candidate in opts {
         if candidate.aliases.iter().position(|opt| opt.name == nm).is_some() {
             return opts.iter().position(|opt| opt.name == candidate.name);
         }
@@ -648,7 +648,7 @@ pub fn getopts(args: &[String], optgrps: &[OptGroup]) -> Result {
                 }
             }
             let mut name_pos = 0;
-            for nm in names.iter() {
+            for nm in &names {
                 name_pos += 1;
                 let optid = match find_opt(opts.as_slice(), (*nm).clone()) {
                   Some(id) => id,

src/libgraphviz/lib.rs

@@ -548,7 +548,7 @@ pub fn render_opts<'a, N:Clone+'a, E:Clone+'a, G:Labeller<'a,N,E>+GraphWalk<'a,N
               options: &[RenderOption]) -> old_io::IoResult<()>
 {
     fn writeln<W:Writer>(w: &mut W, arg: &[&str]) -> old_io::IoResult<()> {
-        for &s in arg.iter() { try!(w.write_str(s)); }
+        for &s in arg { try!(w.write_str(s)); }
         w.write_char('\n')
     }
 
@@ -557,7 +557,7 @@ pub fn render_opts<'a, N:Clone+'a, E:Clone+'a, G:Labeller<'a,N,E>+GraphWalk<'a,N
     }
 
     try!(writeln(w, &["digraph ", g.graph_id().as_slice(), " {"]));
-    for n in g.nodes().iter() {
+    for n in &*g.nodes() {
         try!(indent(w));
         let id = g.node_id(n);
         if options.contains(&RenderOption::NoNodeLabels) {
@@ -569,7 +569,7 @@ pub fn render_opts<'a, N:Clone+'a, E:Clone+'a, G:Labeller<'a,N,E>+GraphWalk<'a,N
         }
     }
 
-    for e in g.edges().iter() {
+    for e in &*g.edges() {
         let escaped_label = g.edge_label(e).escape();
         try!(indent(w));
         let source = g.source(e);

src/librand/distributions/mod.rs

@@ -305,7 +305,7 @@ mod tests {
 
                 let mut rng = CountingRng { i: 0 };
 
-                for &val in expected.iter() {
+                for &val in &expected {
                     assert_eq!(wc.ind_sample(&mut rng), val)
                 }
             }}

src/librand/distributions/range.rs

@@ -188,7 +188,7 @@ mod tests {
                    let v: &[($ty, $ty)] = &[(0, 10),
                                             (10, 127),
                                             (Int::min_value(), Int::max_value())];
-                   for &(low, high) in v.iter() {
+                   for &(low, high) in v {
                         let mut sampler: Range<$ty> = Range::new(low, high);
                         for _ in 0u..1000 {
                             let v = sampler.sample(&mut rng);
@@ -214,7 +214,7 @@ mod tests {
                                             (-1e35, -1e25),
                                             (1e-35, 1e-25),
                                             (-1e35, 1e35)];
-                   for &(low, high) in v.iter() {
+                   for &(low, high) in v {
                         let mut sampler: Range<$ty> = Range::new(low, high);
                         for _ in 0u..1000 {
                             let v = sampler.sample(&mut rng);

src/librand/isaac.rs

@@ -134,7 +134,7 @@ 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) => {{
@@ -373,7 +373,7 @@ 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/librand/reseeding.rs

@@ -225,7 +225,7 @@ mod test {
         // To test that `fill_bytes` actually did something, check that the
         // average of `v` is not 0.
         let mut sum = 0.0;
-        for &x in v.iter() {
+        for &x in &v {
             sum += x as f64;
         }
         assert!(sum / v.len() as f64 != 0.0);

src/librustc/lint/builtin.rs

@@ -459,7 +459,7 @@ impl LintPass for ImproperCTypes {
         }
 
         fn check_foreign_fn(cx: &Context, decl: &ast::FnDecl) {
-            for input in decl.inputs.iter() {
+            for input in &decl.inputs {
                 check_ty(cx, &*input.ty);
             }
             if let ast::Return(ref ret_ty) = decl.output {
@@ -469,7 +469,7 @@ impl LintPass for ImproperCTypes {
 
         match it.node {
             ast::ItemForeignMod(ref nmod) if nmod.abi != abi::RustIntrinsic => {
-                for ni in nmod.items.iter() {
+                for ni in &nmod.items {
                     match ni.node {
                         ast::ForeignItemFn(ref decl, _) => check_foreign_fn(cx, &**decl),
                         ast::ForeignItemStatic(ref t, _) => check_ty(cx, &**t)
@@ -532,7 +532,7 @@ impl LintPass for BoxPointers {
         // If it's a struct, we also have to check the fields' types
         match it.node {
             ast::ItemStruct(ref struct_def, _) => {
-                for struct_field in struct_def.fields.iter() {
+                for struct_field in &struct_def.fields {
                     self.check_heap_type(cx, struct_field.span,
                                          ty::node_id_to_type(cx.tcx, struct_field.node.id));
                 }
@@ -683,7 +683,7 @@ impl LintPass for UnusedAttributes {
             "no_builtins",
         ];
 
-        for &name in ATTRIBUTE_WHITELIST.iter() {
+        for &name in ATTRIBUTE_WHITELIST {
             if attr.check_name(name) {
                 break;
             }
@@ -785,7 +785,7 @@ impl LintPass for UnusedResults {
         }
 
         fn check_must_use(cx: &Context, attrs: &[ast::Attribute], sp: Span) -> bool {
-            for attr in attrs.iter() {
+            for attr in attrs {
                 if attr.check_name("must_use") {
                     let mut msg = "unused result which must be used".to_string();
                     // check for #[must_use="..."]
@@ -869,7 +869,7 @@ impl LintPass for NonCamelCaseTypes {
             ast::ItemEnum(ref enum_definition, _) => {
                 if has_extern_repr { return }
                 self.check_case(cx, "type", it.ident, it.span);
-                for variant in enum_definition.variants.iter() {
+                for variant in &enum_definition.variants {
                     self.check_case(cx, "variant", variant.node.name, variant.span);
                 }
             }
@@ -878,7 +878,7 @@ impl LintPass for NonCamelCaseTypes {
     }
 
     fn check_generics(&mut self, cx: &Context, it: &ast::Generics) {
-        for gen in it.ty_params.iter() {
+        for gen in &*it.ty_params {
             self.check_case(cx, "type parameter", gen.ident, gen.span);
         }
     }
@@ -1048,7 +1048,7 @@ impl LintPass for NonSnakeCase {
 
     fn check_struct_def(&mut self, cx: &Context, s: &ast::StructDef,
             _: ast::Ident, _: &ast::Generics, _: ast::NodeId) {
-        for sf in s.fields.iter() {
+        for sf in &s.fields {
             if let ast::StructField_ { kind: ast::NamedField(ident, _), .. } = sf.node {
                 self.check_snake_case(cx, "structure field", ident, sf.span);
             }
@@ -1346,7 +1346,7 @@ impl UnusedMut {
         // avoid false warnings in match arms with multiple patterns
 
         let mut mutables = FnvHashMap();
-        for p in pats.iter() {
+        for p in pats {
             pat_util::pat_bindings(&cx.tcx.def_map, &**p, |mode, id, _, path1| {
                 let ident = path1.node;
                 if let ast::BindByValue(ast::MutMutable) = mode {
@@ -1361,7 +1361,7 @@ impl UnusedMut {
         }
 
         let used_mutables = cx.tcx.used_mut_nodes.borrow();
-        for (_, v) in mutables.iter() {
+        for (_, v) in &mutables {
             if !v.iter().any(|e| used_mutables.contains(e)) {
                 cx.span_lint(UNUSED_MUT, cx.tcx.map.span(v[0]),
                              "variable does not need to be mutable");
@@ -1377,7 +1377,7 @@ impl LintPass for UnusedMut {
 
     fn check_expr(&mut self, cx: &Context, e: &ast::Expr) {
         if let ast::ExprMatch(_, ref arms, _) = e.node {
-            for a in arms.iter() {
+            for a in arms {
                 self.check_unused_mut_pat(cx, &a.pats[])
             }
         }
@@ -1394,7 +1394,7 @@ impl LintPass for UnusedMut {
     fn check_fn(&mut self, cx: &Context,
                 _: visit::FnKind, decl: &ast::FnDecl,
                 _: &ast::Block, _: Span, _: ast::NodeId) {
-        for a in decl.inputs.iter() {
+        for a in &decl.inputs {
             self.check_unused_mut_pat(cx, slice::ref_slice(&a.pat));
         }
     }
@@ -1871,7 +1871,7 @@ impl LintPass for UnconditionalRecursion {
             if cx.current_level(UNCONDITIONAL_RECURSION) != Level::Allow {
                 let sess = cx.sess();
                 // offer some help to the programmer.
-                for call in self_call_spans.iter() {
+                for call in &self_call_spans {
                     sess.span_note(*call, "recursive call site")
                 }
                 sess.span_help(sp, "a `loop` may express intention better if this is on purpose")

src/librustc/lint/context.rs

@@ -116,7 +116,7 @@ impl LintStore {
 
     pub fn register_pass(&mut self, sess: Option<&Session>,
                          from_plugin: bool, pass: LintPassObject) {
-        for &lint in pass.get_lints().iter() {
+        for &lint in pass.get_lints() {
             self.lints.push((*lint, from_plugin));
 
             let id = LintId::of(*lint);
@@ -260,7 +260,7 @@ impl LintStore {
     }
 
     pub fn process_command_line(&mut self, sess: &Session) {
-        for &(ref lint_name, level) in sess.opts.lint_opts.iter() {
+        for &(ref lint_name, level) in &sess.opts.lint_opts {
             match self.find_lint(&lint_name[], sess, None) {
                 Some(lint_id) => self.set_level(lint_id, (level, CommandLine)),
                 None => {
@@ -340,7 +340,7 @@ macro_rules! run_lints { ($cx:expr, $f:ident, $($args:expr),*) => ({
 pub fn gather_attrs(attrs: &[ast::Attribute])
                     -> Vec<Result<(InternedString, Level, Span), Span>> {
     let mut out = vec!();
-    for attr in attrs.iter() {
+    for attr in attrs {
         let level = match Level::from_str(attr.name().get()) {
             None => continue,
             Some(lvl) => lvl,
@@ -357,7 +357,7 @@ pub fn gather_attrs(attrs: &[ast::Attribute])
             }
         };
 
-        for meta in metas.iter() {
+        for meta in metas {
             out.push(match meta.node {
                 ast::MetaWord(ref lint_name) => Ok((lint_name.clone(), level, meta.span)),
                 _ => Err(meta.span),
@@ -794,8 +794,8 @@ pub fn check_crate(tcx: &ty::ctxt,
 
     // If we missed any lints added to the session, then there's a bug somewhere
     // in the iteration code.
-    for (id, v) in tcx.sess.lints.borrow().iter() {
-        for &(lint, span, ref msg) in v.iter() {
+    for (id, v) in &*tcx.sess.lints.borrow() {
+        for &(lint, span, ref msg) in v {
             tcx.sess.span_bug(span,
                               format!("unprocessed lint {} at {}: {}",
                                       lint.as_str(), tcx.map.node_to_string(*id), *msg).as_slice())

src/librustc/metadata/creader.rs

@@ -162,7 +162,7 @@ impl<'a> CrateReader<'a> {
             dump_crates(&self.sess.cstore);
         }
 
-        for &(ref name, kind) in self.sess.opts.libs.iter() {
+        for &(ref name, kind) in &self.sess.opts.libs {
             register_native_lib(self.sess, None, name.clone(), kind);
         }
     }
@@ -235,7 +235,7 @@ impl<'a> CrateReader<'a> {
                         None
                     })
                     .collect::<Vec<&ast::Attribute>>();
-                for m in link_args.iter() {
+                for m in &link_args {
                     match m.value_str() {
                         Some(linkarg) => self.sess.cstore.add_used_link_args(linkarg.get()),
                         None => { /* fallthrough */ }
@@ -250,7 +250,7 @@ impl<'a> CrateReader<'a> {
                         None
                     })
                     .collect::<Vec<&ast::Attribute>>();
-                for m in link_args.iter() {
+                for m in &link_args {
                     match m.meta_item_list() {
                         Some(items) => {
                             let kind = items.iter().find(|k| {

src/librustc/metadata/csearch.rs

@@ -382,7 +382,7 @@ pub fn get_stability(cstore: &cstore::CStore,
 pub fn is_staged_api(cstore: &cstore::CStore, def: ast::DefId) -> bool {
     let cdata = cstore.get_crate_data(def.krate);
     let attrs = decoder::get_crate_attributes(cdata.data());
-    for attr in attrs.iter() {
+    for attr in &attrs {
         if attr.name().get() == "staged_api" {
             match attr.node.value.node { ast::MetaWord(_) => return true, _ => (/*pass*/) }
         }

src/librustc/metadata/cstore.rs

@@ -113,7 +113,7 @@ impl CStore {
     pub fn iter_crate_data<I>(&self, mut i: I) where
         I: FnMut(ast::CrateNum, &crate_metadata),
     {
-        for (&k, v) in self.metas.borrow().iter() {
+        for (&k, v) in &*self.metas.borrow() {
             i(k, &**v);
         }
     }
@@ -122,7 +122,7 @@ impl CStore {
     pub fn iter_crate_data_origins<I>(&self, mut i: I) where
         I: FnMut(ast::CrateNum, &crate_metadata, Option<CrateSource>),
     {
-        for (&k, v) in self.metas.borrow().iter() {
+        for (&k, v) in &*self.metas.borrow() {
             let origin = self.get_used_crate_source(k);
             origin.as_ref().map(|cs| { assert!(k == cs.cnum); });
             i(k, &**v, origin);
@@ -167,12 +167,12 @@ impl CStore {
                  ordering: &mut Vec<ast::CrateNum>) {
             if ordering.contains(&cnum) { return }
             let meta = cstore.get_crate_data(cnum);
-            for (_, &dep) in meta.cnum_map.iter() {
+            for (_, &dep) in &meta.cnum_map {
                 visit(cstore, dep, ordering);
             }
             ordering.push(cnum);
         };
-        for (&num, _) in self.metas.borrow().iter() {
+        for (&num, _) in &*self.metas.borrow() {
             visit(self, num, &mut ordering);
         }
         ordering.reverse();

src/librustc/metadata/decoder.rs

@@ -1022,7 +1022,7 @@ pub fn get_methods_if_impl(intr: Rc<IdentInterner>,
     });
 
     let mut impl_methods = Vec::new();
-    for impl_method_id in impl_method_ids.iter() {
+    for impl_method_id in &impl_method_ids {
         let impl_method_doc = lookup_item(impl_method_id.node, cdata.data());
         let family = item_family(impl_method_doc);
         match family {
@@ -1189,7 +1189,7 @@ fn list_crate_attributes(md: rbml::Doc, hash: &Svh,
     try!(write!(out, "=Crate Attributes ({})=\n", *hash));
 
     let r = get_attributes(md);
-    for attr in r.iter() {
+    for attr in &r {
         try!(write!(out, "{}\n", pprust::attribute_to_string(attr)));
     }
 
@@ -1232,7 +1232,7 @@ pub fn get_crate_deps(data: &[u8]) -> Vec<CrateDep> {
 
 fn list_crate_deps(data: &[u8], out: &mut old_io::Writer) -> old_io::IoResult<()> {
     try!(write!(out, "=External Dependencies=\n"));
-    for dep in get_crate_deps(data).iter() {
+    for dep in &get_crate_deps(data) {
         try!(write!(out, "{} {}-{}\n", dep.cnum, dep.name, dep.hash));
     }
     try!(write!(out, "\n"));

src/librustc/metadata/encoder.rs

@@ -288,7 +288,7 @@ fn encode_parent_item(rbml_w: &mut Encoder, id: DefId) {
 fn encode_struct_fields(rbml_w: &mut Encoder,
                         fields: &[ty::field_ty],
                         origin: DefId) {
-    for f in fields.iter() {
+    for f in fields {
         if f.name == special_idents::unnamed_field.name {
             rbml_w.start_tag(tag_item_unnamed_field);
         } else {
@@ -316,7 +316,7 @@ fn encode_enum_variant_info(ecx: &EncodeContext,
     let mut i = 0;
     let vi = ty::enum_variants(ecx.tcx,
                                DefId { krate: ast::LOCAL_CRATE, node: id });
-    for variant in variants.iter() {
+    for variant in variants {
         let def_id = local_def(variant.node.id);
         index.push(entry {
             val: variant.node.id as i64,
@@ -367,7 +367,7 @@ fn encode_path<PI: Iterator<Item=PathElem>>(rbml_w: &mut Encoder, path: PI) {
     let path = path.collect::<Vec<_>>();
     rbml_w.start_tag(tag_path);
     rbml_w.wr_tagged_u32(tag_path_len, path.len() as u32);
-    for pe in path.iter() {
+    for pe in &path {
         let tag = match *pe {
             ast_map::PathMod(_) => tag_path_elem_mod,
             ast_map::PathName(_) => tag_path_elem_name
@@ -402,8 +402,8 @@ fn encode_reexported_static_base_methods(ecx: &EncodeContext,
     let impl_items = ecx.tcx.impl_items.borrow();
     match ecx.tcx.inherent_impls.borrow().get(&exp.def_id) {
         Some(implementations) => {
-            for base_impl_did in implementations.iter() {
-                for &method_did in (*impl_items)[*base_impl_did].iter() {
+            for base_impl_did in &**implementations {
+                for &method_did in &*(*impl_items)[*base_impl_did] {
                     let impl_item = ty::impl_or_trait_item(
                         ecx.tcx,
                         method_did.def_id());
@@ -431,7 +431,7 @@ fn encode_reexported_static_trait_methods(ecx: &EncodeContext,
                                           -> bool {
     match ecx.tcx.trait_items_cache.borrow().get(&exp.def_id) {
         Some(trait_items) => {
-            for trait_item in trait_items.iter() {
+            for trait_item in &**trait_items {
                 if let ty::MethodTraitItem(ref m) = *trait_item {
                     encode_reexported_static_method(rbml_w,
                                                     exp,
@@ -517,9 +517,9 @@ fn encode_reexports(ecx: &EncodeContext,
                     path: PathElems) {
     debug!("(encoding info for module) encoding reexports for {}", id);
     match ecx.reexports.get(&id) {
-        Some(ref exports) => {
+        Some(exports) => {
             debug!("(encoding info for module) found reexports for {}", id);
-            for exp in exports.iter() {
+            for exp in exports {
                 debug!("(encoding info for module) reexport '{}' ({}/{}) for \
                         {}",
                        exp.name,
@@ -559,7 +559,7 @@ fn encode_info_for_mod(ecx: &EncodeContext,
     debug!("(encoding info for module) encoding info for module ID {}", id);
 
     // Encode info about all the module children.
-    for item in md.items.iter() {
+    for item in &md.items {
         rbml_w.start_tag(tag_mod_child);
         rbml_w.wr_str(&def_to_string(local_def(item.id))[]);
         rbml_w.end_tag();
@@ -665,9 +665,9 @@ fn encode_parent_sort(rbml_w: &mut Encoder, sort: char) {
 
 fn encode_provided_source(rbml_w: &mut Encoder,
                           source_opt: Option<DefId>) {
-    for source in source_opt.iter() {
+    if let Some(source) = source_opt {
         rbml_w.start_tag(tag_item_method_provided_source);
-        let s = def_to_string(*source);
+        let s = def_to_string(source);
         rbml_w.writer.write_all(s.as_bytes());
         rbml_w.end_tag();
     }
@@ -684,7 +684,7 @@ fn encode_info_for_struct(ecx: &EncodeContext,
     let mut index = Vec::new();
      /* We encode both private and public fields -- need to include
         private fields to get the offsets right */
-    for field in fields.iter() {
+    for field in fields {
         let nm = field.name;
         let id = field.id.node;
 
@@ -783,7 +783,7 @@ fn encode_generics<'a, 'tcx>(rbml_w: &mut Encoder,
         rbml_w.wr_tagged_u64(tag_region_param_def_index,
                              param.index as u64);
 
-        for &bound_region in param.bounds.iter() {
+        for &bound_region in &param.bounds {
             encode_region(ecx, rbml_w, bound_region);
         }
 
@@ -911,7 +911,7 @@ fn encode_info_for_associated_type(ecx: &EncodeContext,
 fn encode_method_argument_names(rbml_w: &mut Encoder,
                                 decl: &ast::FnDecl) {
     rbml_w.start_tag(tag_method_argument_names);
-    for arg in decl.inputs.iter() {
+    for arg in &decl.inputs {
         rbml_w.start_tag(tag_method_argument_name);
         if let ast::PatIdent(_, ref path1, _) = arg.pat.node {
             let name = token::get_ident(path1.node);
@@ -926,7 +926,7 @@ fn encode_repr_attrs(rbml_w: &mut Encoder,
                      ecx: &EncodeContext,
                      attrs: &[ast::Attribute]) {
     let mut repr_attrs = Vec::new();
-    for attr in attrs.iter() {
+    for attr in attrs {
         repr_attrs.extend(attr::find_repr_attrs(ecx.tcx.sess.diagnostic(),
                                                 attr).into_iter());
     }
@@ -962,7 +962,7 @@ fn encode_inherent_implementations(ecx: &EncodeContext,
     match ecx.tcx.inherent_impls.borrow().get(&def_id) {
         None => {}
         Some(implementations) => {
-            for &impl_def_id in implementations.iter() {
+            for &impl_def_id in &**implementations {
                 rbml_w.start_tag(tag_items_data_item_inherent_impl);
                 encode_def_id(rbml_w, impl_def_id);
                 rbml_w.end_tag();
@@ -978,7 +978,7 @@ fn encode_extension_implementations(ecx: &EncodeContext,
     match ecx.tcx.trait_impls.borrow().get(&trait_def_id) {
         None => {}
         Some(implementations) => {
-            for &impl_def_id in implementations.borrow().iter() {
+            for &impl_def_id in &*implementations.borrow() {
                 rbml_w.start_tag(tag_items_data_item_extension_impl);
                 encode_def_id(rbml_w, impl_def_id);
                 rbml_w.end_tag();
@@ -1091,7 +1091,7 @@ fn encode_info_for_item(ecx: &EncodeContext,
         encode_path(rbml_w, path);
 
         // Encode all the items in this module.
-        for foreign_item in fm.items.iter() {
+        for foreign_item in &fm.items {
             rbml_w.start_tag(tag_mod_child);
             rbml_w.wr_str(&def_to_string(local_def(foreign_item.id))[]);
             rbml_w.end_tag();
@@ -1123,7 +1123,7 @@ fn encode_info_for_item(ecx: &EncodeContext,
         encode_name(rbml_w, item.ident.name);
         encode_attributes(rbml_w, &item.attrs[]);
         encode_repr_attrs(rbml_w, ecx, &item.attrs[]);
-        for v in (*enum_definition).variants.iter() {
+        for v in &enum_definition.variants {
             encode_variant_id(rbml_w, local_def(v.node.id));
         }
         encode_inlined_item(ecx, rbml_w, IIItemRef(item));
@@ -1216,7 +1216,7 @@ fn encode_info_for_item(ecx: &EncodeContext,
             }
             _ => {}
         }
-        for &item_def_id in items.iter() {
+        for &item_def_id in items {
             rbml_w.start_tag(tag_item_impl_item);
             match item_def_id {
                 ty::MethodTraitItemId(item_def_id) => {
@@ -1230,7 +1230,7 @@ fn encode_info_for_item(ecx: &EncodeContext,
             }
             rbml_w.end_tag();
         }
-        for ast_trait_ref in opt_trait.iter() {
+        if let Some(ref ast_trait_ref) = *opt_trait {
             let trait_ref = ty::node_id_to_trait_ref(
                 tcx, ast_trait_ref.ref_id);
             encode_trait_ref(rbml_w, ecx, &*trait_ref, tag_item_trait_ref);
@@ -1314,7 +1314,7 @@ fn encode_info_for_item(ecx: &EncodeContext,
         encode_attributes(rbml_w, &item.attrs[]);
         encode_visibility(rbml_w, vis);
         encode_stability(rbml_w, stab);
-        for &method_def_id in ty::trait_item_def_ids(tcx, def_id).iter() {
+        for &method_def_id in &*ty::trait_item_def_ids(tcx, def_id) {
             rbml_w.start_tag(tag_item_trait_item);
             match method_def_id {
                 ty::MethodTraitItemId(method_def_id) => {
@@ -1599,10 +1599,10 @@ fn encode_index<T, F>(rbml_w: &mut Encoder, index: Vec<entry<T>>, mut write_fn:
     rbml_w.start_tag(tag_index);
     let mut bucket_locs = Vec::new();
     rbml_w.start_tag(tag_index_buckets);
-    for bucket in buckets.iter() {
+    for bucket in &buckets {
         bucket_locs.push(rbml_w.writer.tell().unwrap());
         rbml_w.start_tag(tag_index_buckets_bucket);
-        for elt in bucket.iter() {
+        for elt in bucket {
             rbml_w.start_tag(tag_index_buckets_bucket_elt);
             assert!(elt.pos < 0xffff_ffff);
             {
@@ -1616,7 +1616,7 @@ fn encode_index<T, F>(rbml_w: &mut Encoder, index: Vec<entry<T>>, mut write_fn:
     }
     rbml_w.end_tag();
     rbml_w.start_tag(tag_index_table);
-    for pos in bucket_locs.iter() {
+    for pos in &bucket_locs {
         assert!(*pos < 0xffff_ffff);
         let wr: &mut SeekableMemWriter = rbml_w.writer;
         wr.write_be_u32(*pos as u32);
@@ -1660,7 +1660,7 @@ fn encode_meta_item(rbml_w: &mut Encoder, mi: &ast::MetaItem) {
         rbml_w.start_tag(tag_meta_item_name);
         rbml_w.writer.write_all(name.get().as_bytes());
         rbml_w.end_tag();
-        for inner_item in items.iter() {
+        for inner_item in items {
             encode_meta_item(rbml_w, &**inner_item);
         }
         rbml_w.end_tag();
@@ -1670,7 +1670,7 @@ fn encode_meta_item(rbml_w: &mut Encoder, mi: &ast::MetaItem) {
 
 fn encode_attributes(rbml_w: &mut Encoder, attrs: &[ast::Attribute]) {
     rbml_w.start_tag(tag_attributes);
-    for attr in attrs.iter() {
+    for attr in attrs {
         rbml_w.start_tag(tag_attribute);
         rbml_w.wr_tagged_u8(tag_attribute_is_sugared_doc, attr.node.is_sugared_doc as u8);
         encode_meta_item(rbml_w, &*attr.node.value);
@@ -1694,7 +1694,7 @@ fn encode_paren_sugar(rbml_w: &mut Encoder, paren_sugar: bool) {
 
 fn encode_associated_type_names(rbml_w: &mut Encoder, names: &[ast::Name]) {
     rbml_w.start_tag(tag_associated_type_names);
-    for &name in names.iter() {
+    for &name in names {
         rbml_w.wr_tagged_str(tag_associated_type_name, token::get_name(name).get());
     }
     rbml_w.end_tag();
@@ -1726,7 +1726,7 @@ fn encode_crate_deps(rbml_w: &mut Encoder, cstore: &cstore::CStore) {
 
         // Sanity-check the crate numbers
         let mut expected_cnum = 1;
-        for n in deps.iter() {
+        for n in &deps {
             assert_eq!(n.cnum, expected_cnum);
             expected_cnum += 1;
         }
@@ -1740,7 +1740,7 @@ fn encode_crate_deps(rbml_w: &mut Encoder, cstore: &cstore::CStore) {
     // but is enough to get transitive crate dependencies working.
     rbml_w.start_tag(tag_crate_deps);
     let r = get_ordered_deps(cstore);
-    for dep in r.iter() {
+    for dep in &r {
         encode_crate_dep(rbml_w, (*dep).clone());
     }
     rbml_w.end_tag();
@@ -1749,8 +1749,8 @@ fn encode_crate_deps(rbml_w: &mut Encoder, cstore: &cstore::CStore) {
 fn encode_lang_items(ecx: &EncodeContext, rbml_w: &mut Encoder) {
     rbml_w.start_tag(tag_lang_items);
 
-    for (i, def_id) in ecx.tcx.lang_items.items() {
-        for id in def_id.iter() {
+    for (i, &def_id) in ecx.tcx.lang_items.items() {
+        if let Some(id) = def_id {
             if id.krate == ast::LOCAL_CRATE {
                 rbml_w.start_tag(tag_lang_items_item);
 
@@ -1773,7 +1773,7 @@ fn encode_lang_items(ecx: &EncodeContext, rbml_w: &mut Encoder) {
         }
     }
 
-    for i in ecx.tcx.lang_items.missing.iter() {
+    for i in &ecx.tcx.lang_items.missing {
         rbml_w.wr_tagged_u32(tag_lang_items_missing, *i as u32);
     }
 
@@ -1817,7 +1817,7 @@ fn encode_plugin_registrar_fn(ecx: &EncodeContext, rbml_w: &mut Encoder) {
 fn encode_macro_defs(rbml_w: &mut Encoder,
                      krate: &ast::Crate) {
     rbml_w.start_tag(tag_macro_defs);
-    for def in krate.exported_macros.iter() {
+    for def in &krate.exported_macros {
         rbml_w.start_tag(tag_macro_def);
 
         encode_name(rbml_w, def.ident.name);
@@ -1911,7 +1911,7 @@ fn encode_misc_info(ecx: &EncodeContext,
                     rbml_w: &mut Encoder) {
     rbml_w.start_tag(tag_misc_info);
     rbml_w.start_tag(tag_misc_info_crate_items);
-    for item in krate.module.items.iter() {
+    for item in &krate.module.items {
         rbml_w.start_tag(tag_mod_child);
         rbml_w.wr_str(&def_to_string(local_def(item.id))[]);
         rbml_w.end_tag();
@@ -1935,7 +1935,7 @@ fn encode_misc_info(ecx: &EncodeContext,
 fn encode_reachable_extern_fns(ecx: &EncodeContext, rbml_w: &mut Encoder) {
     rbml_w.start_tag(tag_reachable_extern_fns);
 
-    for id in ecx.reachable.iter() {
+    for id in ecx.reachable {
         if let Some(ast_map::NodeItem(i)) = ecx.tcx.map.find(*id) {
             if let ast::ItemFn(_, _, abi, ref generics, _) = i.node {
                 if abi != abi::Rust && !generics.is_type_parameterized() {
@@ -2150,7 +2150,7 @@ fn encode_metadata_inner(wr: &mut SeekableMemWriter,
     stats.total_bytes = rbml_w.writer.tell().unwrap();
 
     if tcx.sess.meta_stats() {
-        for e in rbml_w.writer.get_ref().iter() {
+        for e in rbml_w.writer.get_ref() {
             if *e == 0 {
                 stats.zero_bytes += 1;
             }

src/librustc/metadata/filesearch.rs

@@ -66,7 +66,7 @@ impl<'a> FileSearch<'a> {
         // Try RUST_PATH
         if !found {
             let rustpath = rust_path();
-            for path in rustpath.iter() {
+            for path in &rustpath {
                 let tlib_path = make_rustpkg_lib_path(
                     self.sysroot, path, self.triple);
                 debug!("is {} in visited_dirs? {}", tlib_path.display(),
@@ -243,8 +243,7 @@ pub fn rust_path() -> Vec<Path> {
         }
         cwd.pop();
     }
-    let h = os::homedir();
-    for h in h.iter() {
+    if let Some(h) = os::homedir() {
         let p = h.join(".rust");
         if !env_rust_path.contains(&p) && p.exists() {
             env_rust_path.push(p);

src/librustc/metadata/loader.rs

@@ -452,7 +452,7 @@ impl<'a> Context<'a> {
                     &format!("multiple matching crates for `{}`",
                             self.crate_name)[]);
                 self.sess.note("candidates:");
-                for lib in libraries.iter() {
+                for lib in &libraries {
                     match lib.dylib {
                         Some((ref p, _)) => {
                             self.sess.note(&format!("path: {}",

src/librustc/metadata/tydecode.rs

@@ -249,7 +249,7 @@ fn parse_vec_per_param_space<'a, 'tcx, T, F>(st: &mut PState<'a, 'tcx>,
     F: FnMut(&mut PState<'a, 'tcx>) -> T,
 {
     let mut r = VecPerParamSpace::empty();
-    for &space in subst::ParamSpace::all().iter() {
+    for &space in &subst::ParamSpace::all() {
         assert_eq!(next(st), '[');
         while peek(st) != ']' {
             r.push(space, f(st));

src/librustc/metadata/tyencode.rs

@@ -97,7 +97,7 @@ pub fn enc_ty<'a, 'tcx>(w: &mut SeekableMemWriter, cx: &ctxt<'a, 'tcx>, t: Ty<'t
         }
         ty::ty_tup(ref ts) => {
             mywrite!(w, "T[");
-            for t in ts.iter() { enc_ty(w, cx, *t); }
+            for t in ts { enc_ty(w, cx, *t); }
             mywrite!(w, "]");
         }
         ty::ty_uniq(typ) => { mywrite!(w, "~"); enc_ty(w, cx, typ); }
@@ -206,9 +206,9 @@ fn enc_vec_per_param_space<'a, 'tcx, T, F>(w: &mut SeekableMemWriter,
                                            mut op: F) where
     F: FnMut(&mut SeekableMemWriter, &ctxt<'a, 'tcx>, &T),
 {
-    for &space in subst::ParamSpace::all().iter() {
+    for &space in &subst::ParamSpace::all() {
         mywrite!(w, "[");
-        for t in v.get_slice(space).iter() {
+        for t in v.get_slice(space) {
             op(w, cx, t);
         }
         mywrite!(w, "]");
@@ -337,7 +337,7 @@ pub fn enc_closure_ty<'a, 'tcx>(w: &mut SeekableMemWriter, cx: &ctxt<'a, 'tcx>,
 fn enc_fn_sig<'a, 'tcx>(w: &mut SeekableMemWriter, cx: &ctxt<'a, 'tcx>,
                         fsig: &ty::PolyFnSig<'tcx>) {
     mywrite!(w, "[");
-    for ty in fsig.0.inputs.iter() {
+    for ty in &fsig.0.inputs {
         enc_ty(w, cx, *ty);
     }
     mywrite!(w, "]");
@@ -357,7 +357,7 @@ fn enc_fn_sig<'a, 'tcx>(w: &mut SeekableMemWriter, cx: &ctxt<'a, 'tcx>,
 }
 
 pub fn enc_builtin_bounds(w: &mut SeekableMemWriter, _cx: &ctxt, bs: &ty::BuiltinBounds) {
-    for bound in bs.iter() {
+    for bound in bs {
         match bound {
             ty::BoundSend => mywrite!(w, "S"),
             ty::BoundSized => mywrite!(w, "Z"),
@@ -383,17 +383,17 @@ pub fn enc_bounds<'a, 'tcx>(w: &mut SeekableMemWriter, cx: &ctxt<'a, 'tcx>,
                             bs: &ty::ParamBounds<'tcx>) {
     enc_builtin_bounds(w, cx, &bs.builtin_bounds);
 
-    for &r in bs.region_bounds.iter() {
+    for &r in &bs.region_bounds {
         mywrite!(w, "R");
         enc_region(w, cx, r);
     }
 
-    for tp in bs.trait_bounds.iter() {
+    for tp in &bs.trait_bounds {
         mywrite!(w, "I");
         enc_trait_ref(w, cx, &*tp.0);
     }
 
-    for tp in bs.projection_bounds.iter() {
+    for tp in &bs.projection_bounds {
         mywrite!(w, "P");
         enc_projection_predicate(w, cx, &tp.0);
     }

src/librustc/middle/astencode.rs

@@ -766,7 +766,7 @@ fn encode_vec_per_param_space<T, F>(rbml_w: &mut Encoder,
                                     mut f: F) where
     F: FnMut(&mut Encoder, &T),
 {
-    for &space in subst::ParamSpace::all().iter() {
+    for &space in &subst::ParamSpace::all() {
         rbml_w.emit_from_vec(v.get_slice(space),
                              |rbml_w, n| Ok(f(rbml_w, n))).unwrap();
     }
@@ -1156,14 +1156,14 @@ fn encode_side_tables_for_id(ecx: &e::EncodeContext,
 
     debug!("Encoding side tables for id {}", id);
 
-    for def in tcx.def_map.borrow().get(&id).iter() {
+    if let Some(def) = tcx.def_map.borrow().get(&id) {
         rbml_w.tag(c::tag_table_def, |rbml_w| {
             rbml_w.id(id);
             rbml_w.tag(c::tag_table_val, |rbml_w| (*def).encode(rbml_w).unwrap());
         })
     }
 
-    for &ty in tcx.node_types.borrow().get(&id).iter() {
+    if let Some(ty) = tcx.node_types.borrow().get(&id) {
         rbml_w.tag(c::tag_table_node_type, |rbml_w| {
             rbml_w.id(id);
             rbml_w.tag(c::tag_table_val, |rbml_w| {
@@ -1172,7 +1172,7 @@ fn encode_side_tables_for_id(ecx: &e::EncodeContext,
         })
     }
 
-    for &item_substs in tcx.item_substs.borrow().get(&id).iter() {
+    if let Some(item_substs) = tcx.item_substs.borrow().get(&id) {
         rbml_w.tag(c::tag_table_item_subst, |rbml_w| {
             rbml_w.id(id);
             rbml_w.tag(c::tag_table_val, |rbml_w| {
@@ -1181,7 +1181,7 @@ fn encode_side_tables_for_id(ecx: &e::EncodeContext,
         })
     }
 
-    for &fv in tcx.freevars.borrow().get(&id).iter() {
+    if let Some(fv) = tcx.freevars.borrow().get(&id) {
         rbml_w.tag(c::tag_table_freevars, |rbml_w| {
             rbml_w.id(id);
             rbml_w.tag(c::tag_table_val, |rbml_w| {
@@ -1191,7 +1191,7 @@ fn encode_side_tables_for_id(ecx: &e::EncodeContext,
             })
         });
 
-        for freevar in fv.iter() {
+        for freevar in fv {
             rbml_w.tag(c::tag_table_upvar_capture_map, |rbml_w| {
                 rbml_w.id(id);
                 rbml_w.tag(c::tag_table_val, |rbml_w| {
@@ -1209,7 +1209,7 @@ fn encode_side_tables_for_id(ecx: &e::EncodeContext,
     }
 
     let lid = ast::DefId { krate: ast::LOCAL_CRATE, node: id };
-    for &type_scheme in tcx.tcache.borrow().get(&lid).iter() {
+    if let Some(type_scheme) = tcx.tcache.borrow().get(&lid) {
         rbml_w.tag(c::tag_table_tcache, |rbml_w| {
             rbml_w.id(id);
             rbml_w.tag(c::tag_table_val, |rbml_w| {
@@ -1218,7 +1218,7 @@ fn encode_side_tables_for_id(ecx: &e::EncodeContext,
         })
     }
 
-    for &type_param_def in tcx.ty_param_defs.borrow().get(&id).iter() {
+    if let Some(type_param_def) = tcx.ty_param_defs.borrow().get(&id) {
         rbml_w.tag(c::tag_table_param_defs, |rbml_w| {
             rbml_w.id(id);
             rbml_w.tag(c::tag_table_val, |rbml_w| {
@@ -1228,7 +1228,7 @@ fn encode_side_tables_for_id(ecx: &e::EncodeContext,
     }
 
     let method_call = MethodCall::expr(id);
-    for &method in tcx.method_map.borrow().get(&method_call).iter() {
+    if let Some(method) = tcx.method_map.borrow().get(&method_call) {
         rbml_w.tag(c::tag_table_method_map, |rbml_w| {
             rbml_w.id(id);
             rbml_w.tag(c::tag_table_val, |rbml_w| {
@@ -1237,7 +1237,7 @@ fn encode_side_tables_for_id(ecx: &e::EncodeContext,
         })
     }
 
-    for &trait_ref in tcx.object_cast_map.borrow().get(&id).iter() {
+    if let Some(trait_ref) = tcx.object_cast_map.borrow().get(&id) {
         rbml_w.tag(c::tag_table_object_cast_map, |rbml_w| {
             rbml_w.id(id);
             rbml_w.tag(c::tag_table_val, |rbml_w| {
@@ -1246,11 +1246,11 @@ fn encode_side_tables_for_id(ecx: &e::EncodeContext,
         })
     }
 
-    for &adjustment in tcx.adjustments.borrow().get(&id).iter() {
+    if let Some(adjustment) = tcx.adjustments.borrow().get(&id) {
         match *adjustment {
             _ if ty::adjust_is_object(adjustment) => {
                 let method_call = MethodCall::autoobject(id);
-                for &method in tcx.method_map.borrow().get(&method_call).iter() {
+                if let Some(method) = tcx.method_map.borrow().get(&method_call) {
                     rbml_w.tag(c::tag_table_method_map, |rbml_w| {
                         rbml_w.id(id);
                         rbml_w.tag(c::tag_table_val, |rbml_w| {
@@ -1263,7 +1263,7 @@ fn encode_side_tables_for_id(ecx: &e::EncodeContext,
                 assert!(!ty::adjust_is_object(adjustment));
                 for autoderef in 0..adj.autoderefs {
                     let method_call = MethodCall::autoderef(id, autoderef);
-                    for &method in tcx.method_map.borrow().get(&method_call).iter() {
+                    if let Some(method) = tcx.method_map.borrow().get(&method_call) {
                         rbml_w.tag(c::tag_table_method_map, |rbml_w| {
                             rbml_w.id(id);
                             rbml_w.tag(c::tag_table_val, |rbml_w| {
@@ -1287,7 +1287,7 @@ fn encode_side_tables_for_id(ecx: &e::EncodeContext,
         })
     }
 
-    for &closure_type in tcx.closure_tys.borrow().get(&ast_util::local_def(id)).iter() {
+    if let Some(closure_type) = tcx.closure_tys.borrow().get(&ast_util::local_def(id)) {
         rbml_w.tag(c::tag_table_closure_tys, |rbml_w| {
             rbml_w.id(id);
             rbml_w.tag(c::tag_table_val, |rbml_w| {
@@ -1296,11 +1296,11 @@ fn encode_side_tables_for_id(ecx: &e::EncodeContext,
         })
     }
 
-    for &&closure_kind in tcx.closure_kinds.borrow().get(&ast_util::local_def(id)).iter() {
+    if let Some(closure_kind) = tcx.closure_kinds.borrow().get(&ast_util::local_def(id)) {
         rbml_w.tag(c::tag_table_closure_kinds, |rbml_w| {
             rbml_w.id(id);
             rbml_w.tag(c::tag_table_val, |rbml_w| {
-                encode_closure_kind(rbml_w, closure_kind)
+                encode_closure_kind(rbml_w, *closure_kind)
             })
         })
     }

src/librustc/middle/cfg/construct.rs

@@ -68,7 +68,7 @@ fn add_initial_dummy_node(g: &mut CFGGraph) -> CFGIndex {
 impl<'a, 'tcx> CFGBuilder<'a, 'tcx> {
     fn block(&mut self, blk: &ast::Block, pred: CFGIndex) -> CFGIndex {
         let mut stmts_exit = pred;
-        for stmt in blk.stmts.iter() {
+        for stmt in &blk.stmts {
             stmts_exit = self.stmt(&**stmt, stmts_exit);
         }
 
@@ -166,7 +166,7 @@ impl<'a, 'tcx> CFGBuilder<'a, 'tcx> {
             self.pat(&*pats[0], pred)
         } else {
             let collect = self.add_dummy_node(&[]);
-            for pat in pats.iter() {
+            for pat in pats {
                 let pat_exit = self.pat(&**pat, pred);
                 self.add_contained_edge(pat_exit, collect);
             }
@@ -325,7 +325,7 @@ impl<'a, 'tcx> CFGBuilder<'a, 'tcx> {
 
                 let expr_exit = self.add_node(expr.id, &[]);
                 let mut cond_exit = discr_exit;
-                for arm in arms.iter() {
+                for arm in arms {
                     cond_exit = self.add_dummy_node(&[cond_exit]);        // 2
                     let pats_exit = self.pats_any(&arm.pats[],
                                                   cond_exit);            // 3
@@ -522,7 +522,7 @@ impl<'a, 'tcx> CFGBuilder<'a, 'tcx> {
             assert!(!self.exit_map.contains_key(&id));
             self.exit_map.insert(id, node);
         }
-        for &pred in preds.iter() {
+        for &pred in preds {
             self.add_contained_edge(pred, node);
         }
         node
@@ -574,7 +574,7 @@ impl<'a, 'tcx> CFGBuilder<'a, 'tcx> {
             Some(_) => {
                 match self.tcx.def_map.borrow().get(&expr.id) {
                     Some(&def::DefLabel(loop_id)) => {
-                        for l in self.loop_scopes.iter() {
+                        for l in &self.loop_scopes {
                             if l.loop_id == loop_id {
                                 return *l;
                             }

src/librustc/middle/check_const.rs

@@ -46,7 +46,7 @@ impl<'a, 'tcx, 'v> Visitor<'v> for CheckCrateVisitor<'a, 'tcx> {
             }
             ast::ItemEnum(ref enum_definition, _) => {
                 self.inside_const(|v| {
-                    for var in enum_definition.variants.iter() {
+                    for var in &enum_definition.variants {
                         if let Some(ref ex) = var.node.disr_expr {
                             v.visit_expr(&**ex);
                         }
@@ -137,7 +137,7 @@ fn check_expr(v: &mut CheckCrateVisitor, e: &ast::Expr) {
         }
         ast::ExprBlock(ref block) => {
             // Check all statements in the block
-            for stmt in block.stmts.iter() {
+            for stmt in &block.stmts {
                 let block_span_err = |&: span|
                     span_err!(v.tcx.sess, span, E0016,
                               "blocks in constants are limited to items and \

src/librustc/middle/check_match.rs

@@ -157,7 +157,7 @@ fn check_expr(cx: &mut MatchCheckCtxt, ex: &ast::Expr) {
     visit::walk_expr(cx, ex);
     match ex.node {
         ast::ExprMatch(ref scrut, ref arms, source) => {
-            for arm in arms.iter() {
+            for arm in arms {
                 // First, check legality of move bindings.
                 check_legality_of_move_bindings(cx,
                                                 arm.guard.is_some(),
@@ -285,8 +285,8 @@ fn check_arms(cx: &MatchCheckCtxt,
               source: ast::MatchSource) {
     let mut seen = Matrix(vec![]);
     let mut printed_if_let_err = false;
-    for &(ref pats, guard) in arms.iter() {
-        for pat in pats.iter() {
+    for &(ref pats, guard) in arms {
+        for pat in pats {
             let v = vec![&**pat];
 
             match is_useful(cx, &seen, &v[], LeaveOutWitness) {
@@ -979,7 +979,7 @@ fn check_fn(cx: &mut MatchCheckCtxt,
 
     visit::walk_fn(cx, kind, decl, body, sp);
 
-    for input in decl.inputs.iter() {
+    for input in &decl.inputs {
         is_refutable(cx, &*input.pat, |pat| {
             span_err!(cx.tcx.sess, input.pat.span, E0006,
                 "refutable pattern in function argument: `{}` not covered",
@@ -1012,7 +1012,7 @@ fn check_legality_of_move_bindings(cx: &MatchCheckCtxt,
     let tcx = cx.tcx;
     let def_map = &tcx.def_map;
     let mut by_ref_span = None;
-    for pat in pats.iter() {
+    for pat in pats {
         pat_bindings(def_map, &**pat, |bm, _, span, _path| {
             match bm {
                 ast::BindByRef(_) => {
@@ -1039,7 +1039,7 @@ fn check_legality_of_move_bindings(cx: &MatchCheckCtxt,
         }
     };
 
-    for pat in pats.iter() {
+    for pat in pats {
         walk_pat(&**pat, |p| {
             if pat_is_binding(def_map, &*p) {
                 match p.node {

src/librustc/middle/const_eval.rs

@@ -104,7 +104,7 @@ fn lookup_variant_by_id<'a>(tcx: &'a ty::ctxt,
                             -> Option<&'a Expr> {
     fn variant_expr<'a>(variants: &'a [P<ast::Variant>], id: ast::NodeId)
                         -> Option<&'a Expr> {
-        for variant in variants.iter() {
+        for variant in variants {
             if variant.node.id == id {
                 return variant.node.disr_expr.as_ref().map(|e| &**e);
             }

src/librustc/middle/dataflow.rs

@@ -399,7 +399,7 @@ impl<'a, 'tcx, O:DataFlowOperator> DataFlowContext<'a, 'tcx, O> {
             let mut orig_kills = self.kills[start.. end].to_vec();
 
             let mut changed = false;
-            for &node_id in edge.data.exiting_scopes.iter() {
+            for &node_id in &edge.data.exiting_scopes {
                 let opt_cfg_idx = self.nodeid_to_index.get(&node_id).map(|&i|i);
                 match opt_cfg_idx {
                     Some(cfg_idx) => {
@@ -550,7 +550,7 @@ fn bits_to_string(words: &[uint]) -> String {
 
     // Note: this is a little endian printout of bytes.
 
-    for &word in words.iter() {
+    for &word in words {
         let mut v = word;
         for _ in 0..uint::BYTES {
             result.push(sep);

src/librustc/middle/dead.rs

@@ -173,7 +173,7 @@ impl<'a, 'tcx> MarkSymbolVisitor<'a, 'tcx> {
             }
         };
         let fields = ty::lookup_struct_fields(self.tcx, id);
-        for pat in pats.iter() {
+        for pat in pats {
             let field_id = fields.iter()
                 .find(|field| field.name == pat.node.ident.name).unwrap().id;
             self.live_symbols.insert(field_id.node);
@@ -356,7 +356,7 @@ impl<'v> Visitor<'v> for LifeSeeder {
                 self.worklist.extend(enum_def.variants.iter().map(|variant| variant.node.id));
             }
             ast::ItemImpl(_, _, _, Some(ref _trait_ref), _, ref impl_items) => {
-                for impl_item in impl_items.iter() {
+                for impl_item in impl_items {
                     match *impl_item {
                         ast::MethodImplItem(ref method) => {
                             self.worklist.push(method.id);
@@ -397,10 +397,10 @@ fn create_and_seed_worklist(tcx: &ty::ctxt,
     // depending on whether a crate is built as bin or lib, and we want
     // the warning to be consistent, we also seed the worklist with
     // exported symbols.
-    for id in exported_items.iter() {
+    for id in exported_items {
         worklist.push(*id);
     }
-    for id in reachable_symbols.iter() {
+    for id in reachable_symbols {
         worklist.push(*id);
     }
 
@@ -499,8 +499,8 @@ impl<'a, 'tcx> DeadVisitor<'a, 'tcx> {
         match self.tcx.inherent_impls.borrow().get(&local_def(id)) {
             None => (),
             Some(impl_list) => {
-                for impl_did in impl_list.iter() {
-                    for item_did in (*impl_items)[*impl_did].iter() {
+                for impl_did in &**impl_list {
+                    for item_did in &(*impl_items)[*impl_did] {
                         if self.live_symbols.contains(&item_did.def_id()
                                                                .node) {
                             return true;
@@ -536,7 +536,7 @@ impl<'a, 'tcx, 'v> Visitor<'v> for DeadVisitor<'a, 'tcx> {
         } else {
             match item.node {
                 ast::ItemEnum(ref enum_def, _) => {
-                    for variant in enum_def.variants.iter() {
+                    for variant in &enum_def.variants {
                         if self.should_warn_about_variant(&variant.node) {
                             self.warn_dead_code(variant.node.id, variant.span,
                                                 variant.node.name, "variant");

src/librustc/middle/dependency_format.rs

@@ -85,7 +85,7 @@ pub type Dependencies = FnvHashMap<config::CrateType, DependencyList>;
 
 pub fn calculate(tcx: &ty::ctxt) {
     let mut fmts = tcx.dependency_formats.borrow_mut();
-    for &ty in tcx.sess.crate_types.borrow().iter() {
+    for &ty in &*tcx.sess.crate_types.borrow() {
         fmts.insert(ty, calculate_type(&tcx.sess, ty));
     }
     tcx.sess.abort_if_errors();
@@ -148,7 +148,7 @@ fn calculate_type(sess: &session::Session,
             debug!("adding dylib: {}", data.name);
             add_library(sess, cnum, cstore::RequireDynamic, &mut formats);
             let deps = csearch::get_dylib_dependency_formats(&sess.cstore, cnum);
-            for &(depnum, style) in deps.iter() {
+            for &(depnum, style) in &deps {
                 debug!("adding {:?}: {}", style,
                        sess.cstore.get_crate_data(depnum).name.clone());
                 add_library(sess, depnum, style, &mut formats);

src/librustc/middle/entry.rs

@@ -139,7 +139,7 @@ fn configure_main(this: &mut EntryContext) {
                                but you have one or more functions named 'main' that are not \
                                defined at the crate level. Either move the definition or \
                                attach the `#[main]` attribute to override this behavior.");
-            for &(_, span) in this.non_main_fns.iter() {
+            for &(_, span) in &this.non_main_fns {
                 this.session.span_note(span, "here is a function named 'main'");
             }
             this.session.abort_if_errors();

src/librustc/middle/expr_use_visitor.rs

@@ -342,7 +342,7 @@ impl<'d,'t,'tcx,TYPER:mc::Typer<'tcx>> ExprUseVisitor<'d,'t,'tcx,TYPER> {
     fn walk_arg_patterns(&mut self,
                          decl: &ast::FnDecl,
                          body: &ast::Block) {
-        for arg in decl.inputs.iter() {
+        for arg in &decl.inputs {
             let arg_ty = return_if_err!(self.typer.node_ty(arg.pat.id));
 
             let fn_body_scope = region::CodeExtent::from_node_id(body.id);
@@ -372,7 +372,7 @@ impl<'d,'t,'tcx,TYPER:mc::Typer<'tcx>> ExprUseVisitor<'d,'t,'tcx,TYPER> {
     }
 
     fn consume_exprs(&mut self, exprs: &Vec<P<ast::Expr>>) {
-        for expr in exprs.iter() {
+        for expr in exprs {
             self.consume_expr(&**expr);
         }
     }
@@ -476,7 +476,7 @@ impl<'d,'t,'tcx,TYPER:mc::Typer<'tcx>> ExprUseVisitor<'d,'t,'tcx,TYPER> {
             ast::ExprIf(ref cond_expr, ref then_blk, ref opt_else_expr) => {
                 self.consume_expr(&**cond_expr);
                 self.walk_block(&**then_blk);
-                for else_expr in opt_else_expr.iter() {
+                if let Some(ref else_expr) = *opt_else_expr {
                     self.consume_expr(&**else_expr);
                 }
             }
@@ -490,7 +490,7 @@ impl<'d,'t,'tcx,TYPER:mc::Typer<'tcx>> ExprUseVisitor<'d,'t,'tcx,TYPER> {
                 self.borrow_expr(&**discr, ty::ReEmpty, ty::ImmBorrow, MatchDiscriminant);
 
                 // treatment of the discriminant is handled while walking the arms.
-                for arm in arms.iter() {
+                for arm in arms {
                     let mode = self.arm_move_mode(discr_cmt.clone(), arm);
                     let mode = mode.match_mode();
                     self.walk_arm(discr_cmt.clone(), arm, mode);
@@ -511,11 +511,11 @@ impl<'d,'t,'tcx,TYPER:mc::Typer<'tcx>> ExprUseVisitor<'d,'t,'tcx,TYPER> {
             }
 
             ast::ExprInlineAsm(ref ia) => {
-                for &(_, ref input) in ia.inputs.iter() {
+                for &(_, ref input) in &ia.inputs {
                     self.consume_expr(&**input);
                 }
 
-                for &(_, ref output, is_rw) in ia.outputs.iter() {
+                for &(_, ref output, is_rw) in &ia.outputs {
                     self.mutate_expr(expr, &**output,
                                            if is_rw { WriteAndRead } else { JustWrite });
                 }
@@ -572,7 +572,7 @@ impl<'d,'t,'tcx,TYPER:mc::Typer<'tcx>> ExprUseVisitor<'d,'t,'tcx,TYPER> {
             }
 
             ast::ExprRet(ref opt_expr) => {
-                for expr in opt_expr.iter() {
+                if let Some(ref expr) = *opt_expr {
                     self.consume_expr(&**expr);
                 }
             }
@@ -715,11 +715,11 @@ impl<'d,'t,'tcx,TYPER:mc::Typer<'tcx>> ExprUseVisitor<'d,'t,'tcx,TYPER> {
     fn walk_block(&mut self, blk: &ast::Block) {
         debug!("walk_block(blk.id={})", blk.id);
 
-        for stmt in blk.stmts.iter() {
+        for stmt in &blk.stmts {
             self.walk_stmt(&**stmt);
         }
 
-        for tail_expr in blk.expr.iter() {
+        if let Some(ref tail_expr) = blk.expr {
             self.consume_expr(&**tail_expr);
         }
     }
@@ -729,7 +729,7 @@ impl<'d,'t,'tcx,TYPER:mc::Typer<'tcx>> ExprUseVisitor<'d,'t,'tcx,TYPER> {
                         fields: &Vec<ast::Field>,
                         opt_with: &Option<P<ast::Expr>>) {
         // Consume the expressions supplying values for each field.
-        for field in fields.iter() {
+        for field in fields {
             self.consume_expr(&*field.expr);
         }
 
@@ -762,7 +762,7 @@ impl<'d,'t,'tcx,TYPER:mc::Typer<'tcx>> ExprUseVisitor<'d,'t,'tcx,TYPER> {
         };
 
         // Consume those fields of the with expression that are needed.
-        for with_field in with_fields.iter() {
+        for with_field in &with_fields {
             if !contains_field_named(with_field, fields) {
                 let cmt_field = self.mc.cat_field(&*with_expr,
                                                   with_cmt.clone(),
@@ -908,7 +908,7 @@ impl<'d,'t,'tcx,TYPER:mc::Typer<'tcx>> ExprUseVisitor<'d,'t,'tcx,TYPER> {
         match pass_args {
             PassArgs::ByValue => {
                 self.consume_expr(receiver);
-                for &arg in rhs.iter() {
+                for &arg in &rhs {
                     self.consume_expr(arg);
                 }
 
@@ -926,7 +926,7 @@ impl<'d,'t,'tcx,TYPER:mc::Typer<'tcx>> ExprUseVisitor<'d,'t,'tcx,TYPER> {
         let r = ty::ReScope(region::CodeExtent::from_node_id(expr.id));
         let bk = ty::ImmBorrow;
 
-        for &arg in rhs.iter() {
+        for &arg in &rhs {
             self.borrow_expr(arg, r, bk, OverloadedOperator);
         }
         return true;
@@ -934,18 +934,18 @@ impl<'d,'t,'tcx,TYPER:mc::Typer<'tcx>> ExprUseVisitor<'d,'t,'tcx,TYPER> {
 
     fn arm_move_mode(&mut self, discr_cmt: mc::cmt<'tcx>, arm: &ast::Arm) -> TrackMatchMode<Span> {
         let mut mode = Unknown;
-        for pat in arm.pats.iter() {
+        for pat in &arm.pats {
             self.determine_pat_move_mode(discr_cmt.clone(), &**pat, &mut mode);
         }
         mode
     }
 
     fn walk_arm(&mut self, discr_cmt: mc::cmt<'tcx>, arm: &ast::Arm, mode: MatchMode) {
-        for pat in arm.pats.iter() {
+        for pat in &arm.pats {
             self.walk_pat(discr_cmt.clone(), &**pat, mode);
         }
 
-        for guard in arm.guard.iter() {
+        if let Some(ref guard) = arm.guard {
             self.consume_expr(&**guard);
         }
 
@@ -1195,7 +1195,7 @@ impl<'d,'t,'tcx,TYPER:mc::Typer<'tcx>> ExprUseVisitor<'d,'t,'tcx,TYPER> {
         debug!("walk_captures({})", closure_expr.repr(self.tcx()));
 
         ty::with_freevars(self.tcx(), closure_expr.id, |freevars| {
-            for freevar in freevars.iter() {
+            for freevar in freevars {
                 let id_var = freevar.def.def_id().node;
                 let upvar_id = ty::UpvarId { var_id: id_var,
                                              closure_expr_id: closure_expr.id };

src/librustc/middle/infer/combine.rs

@@ -116,7 +116,7 @@ pub trait Combine<'tcx> : Sized {
     {
         let mut substs = subst::Substs::empty();
 
-        for &space in subst::ParamSpace::all().iter() {
+        for &space in &subst::ParamSpace::all() {
             let a_tps = a_subst.types.get_slice(space);
             let b_tps = b_subst.types.get_slice(space);
             let tps = try!(self.tps(space, a_tps, b_tps));
@@ -129,7 +129,7 @@ pub trait Combine<'tcx> : Sized {
             }
 
             (&NonerasedRegions(ref a), &NonerasedRegions(ref b)) => {
-                for &space in subst::ParamSpace::all().iter() {
+                for &space in &subst::ParamSpace::all() {
                     let a_regions = a.get_slice(space);
                     let b_regions = b.get_slice(space);
 
@@ -139,7 +139,7 @@ pub trait Combine<'tcx> : Sized {
                             variances.regions.get_slice(space)
                         }
                         None => {
-                            for _ in a_regions.iter() {
+                            for _ in a_regions {
                                 invariance.push(ty::Invariant);
                             }
                             &invariance[]

src/librustc/middle/infer/error_reporting.rs

@@ -170,7 +170,7 @@ impl<'a, 'tcx> ErrorReporting<'tcx> for InferCtxt<'a, 'tcx> {
                             errors: &Vec<RegionResolutionError<'tcx>>) {
         let p_errors = self.process_errors(errors);
         let errors = if p_errors.is_empty() { errors } else { &p_errors };
-        for error in errors.iter() {
+        for error in errors {
             match error.clone() {
                 ConcreteFailure(origin, sub, sup) => {
                     self.report_concrete_failure(origin, sub, sup);
@@ -222,7 +222,7 @@ impl<'a, 'tcx> ErrorReporting<'tcx> for InferCtxt<'a, 'tcx> {
         let mut trace_origins = Vec::new();
         let mut same_regions = Vec::new();
         let mut processed_errors = Vec::new();
-        for error in errors.iter() {
+        for error in errors {
             match error.clone() {
                 ConcreteFailure(origin, sub, sup) => {
                     debug!("processing ConcreteFailure");
@@ -257,7 +257,7 @@ impl<'a, 'tcx> ErrorReporting<'tcx> for InferCtxt<'a, 'tcx> {
         }
         if !same_regions.is_empty() {
             let common_scope_id = same_regions[0].scope_id;
-            for sr in same_regions.iter() {
+            for sr in &same_regions {
                 // Since ProcessedErrors is used to reconstruct the function
                 // declaration, we want to make sure that they are, in fact,
                 // from the same scope
@@ -796,11 +796,11 @@ impl<'a, 'tcx> ErrorReporting<'tcx> for InferCtxt<'a, 'tcx> {
                                var_origins: &[RegionVariableOrigin],
                                trace_origins: &[(TypeTrace<'tcx>, ty::type_err<'tcx>)],
                                same_regions: &[SameRegions]) {
-        for vo in var_origins.iter() {
+        for vo in var_origins {
             self.report_inference_failure(vo.clone());
         }
         self.give_suggestion(same_regions);
-        for &(ref trace, terr) in trace_origins.iter() {
+        for &(ref trace, terr) in trace_origins {
             self.report_type_error(trace.clone(), &terr);
         }
     }
@@ -916,7 +916,7 @@ impl<'a, 'tcx> Rebuilder<'a, 'tcx> {
         let mut ty_params = self.generics.ty_params.clone();
         let where_clause = self.generics.where_clause.clone();
         let mut kept_lifetimes = HashSet::new();
-        for sr in self.same_regions.iter() {
+        for sr in self.same_regions {
             self.cur_anon.set(0);
             self.offset_cur_anon();
             let (anon_nums, region_names) =
@@ -958,7 +958,7 @@ impl<'a, 'tcx> Rebuilder<'a, 'tcx> {
             // vector of string and then sort them. However, it makes the
             // choice of lifetime name deterministic and thus easier to test.
             let mut names = Vec::new();
-            for rn in region_names.iter() {
+            for rn in region_names {
                 let lt_name = token::get_name(*rn).get().to_string();
                 names.push(lt_name);
             }
@@ -973,7 +973,7 @@ impl<'a, 'tcx> Rebuilder<'a, 'tcx> {
                                    -> (HashSet<u32>, HashSet<ast::Name>) {
         let mut anon_nums = HashSet::new();
         let mut region_names = HashSet::new();
-        for br in same_regions.regions.iter() {
+        for br in &same_regions.regions {
             match *br {
                 ty::BrAnon(i) => {
                     anon_nums.insert(i);
@@ -989,8 +989,8 @@ impl<'a, 'tcx> Rebuilder<'a, 'tcx> {
 
     fn extract_all_region_names(&self) -> HashSet<ast::Name> {
         let mut all_region_names = HashSet::new();
-        for sr in self.same_regions.iter() {
-            for br in sr.regions.iter() {
+        for sr in self.same_regions {
+            for br in &sr.regions {
                 match *br {
                     ty::BrNamed(_, name) => {
                         all_region_names.insert(name);
@@ -1123,11 +1123,11 @@ impl<'a, 'tcx> Rebuilder<'a, 'tcx> {
                         where_clause: ast::WhereClause)
                         -> ast::Generics {
         let mut lifetimes = Vec::new();
-        for lt in add.iter() {
+        for lt in add {
             lifetimes.push(ast::LifetimeDef { lifetime: *lt,
                                               bounds: Vec::new() });
         }
-        for lt in generics.lifetimes.iter() {
+        for lt in &generics.lifetimes {
             if keep.contains(&lt.lifetime.name) ||
                 !remove.contains(&lt.lifetime.name) {
                 lifetimes.push((*lt).clone());
@@ -1147,7 +1147,7 @@ impl<'a, 'tcx> Rebuilder<'a, 'tcx> {
                        region_names: &HashSet<ast::Name>)
                        -> Vec<ast::Arg> {
         let mut new_inputs = Vec::new();
-        for arg in inputs.iter() {
+        for arg in inputs {
             let new_ty = self.rebuild_arg_ty_or_output(&*arg.ty, lifetime,
                                                        anon_nums, region_names);
             let possibly_new_arg = ast::Arg {
@@ -1729,7 +1729,7 @@ struct LifeGiver {
 impl LifeGiver {
     fn with_taken(taken: &[ast::LifetimeDef]) -> LifeGiver {
         let mut taken_ = HashSet::new();
-        for lt in taken.iter() {
+        for lt in taken {
             let lt_name = token::get_name(lt.lifetime.name).get().to_string();
             taken_.insert(lt_name);
         }

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

@@ -176,7 +176,7 @@ impl<'tcx,C> HigherRankedRelations<'tcx> for C
             // in both A and B.  Replace the variable with the "first"
             // bound region from A that we find it to be associated
             // with.
-            for (a_br, a_r) in a_map.iter() {
+            for (a_br, a_r) in a_map {
                 if tainted.iter().any(|x| x == a_r) {
                     debug!("generalize_region(r0={:?}): \
                             replacing with {:?}, tainted={:?}",
@@ -258,7 +258,7 @@ impl<'tcx,C> HigherRankedRelations<'tcx> for C
             let mut a_r = None;
             let mut b_r = None;
             let mut only_new_vars = true;
-            for r in tainted.iter() {
+            for r in &tainted {
                 if is_var_in_set(a_vars, *r) {
                     if a_r.is_some() {
                         return fresh_bound_variable(infcx, debruijn);
@@ -315,7 +315,7 @@ impl<'tcx,C> HigherRankedRelations<'tcx> for C
                       a_map: &FnvHashMap<ty::BoundRegion, ty::Region>,
                       r: ty::Region) -> ty::Region
         {
-            for (a_br, a_r) in a_map.iter() {
+            for (a_br, a_r) in a_map {
                 if *a_r == r {
                     return ty::ReLateBound(ty::DebruijnIndex::new(1), *a_br);
                 }
@@ -497,9 +497,9 @@ pub fn leak_check<'a,'tcx>(infcx: &InferCtxt<'a,'tcx>,
            skol_map.repr(infcx.tcx));
 
     let new_vars = infcx.region_vars_confined_to_snapshot(snapshot);
-    for (&skol_br, &skol) in skol_map.iter() {
+    for (&skol_br, &skol) in skol_map {
         let tainted = infcx.tainted_regions(snapshot, skol);
-        for &tainted_region in tainted.iter() {
+        for &tainted_region in &tainted {
             // Each skolemized should only be relatable to itself
             // or new variables:
             match tainted_region {

src/librustc/middle/infer/mod.rs

@@ -998,8 +998,8 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
                     mk_msg(resolved_expected.map(|t| self.ty_to_string(t)), actual_ty),
                     error_str)[]);
 
-                for err in err.iter() {
-                    ty::note_and_explain_type_err(self.tcx, *err)
+                if let Some(err) = err {
+                    ty::note_and_explain_type_err(self.tcx, err)
                 }
             }
         }

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

@@ -667,7 +667,7 @@ impl<'a, 'tcx> RegionVarBindings<'a, 'tcx> {
                                     a, b);
                             }
                             VerifyGenericBound(_, _, a, ref bs) => {
-                                for &b in bs.iter() {
+                                for &b in bs {
                                     consider_adding_bidirectional_edges(
                                         &mut result_set, r,
                                         a, b);
@@ -1200,7 +1200,7 @@ impl<'a, 'tcx> RegionVarBindings<'a, 'tcx> {
                                       errors: &mut Vec<RegionResolutionError<'tcx>>)
     {
         let mut reg_reg_dups = FnvHashSet();
-        for verify in self.verifys.borrow().iter() {
+        for verify in &*self.verifys.borrow() {
             match *verify {
                 VerifyRegSubReg(ref origin, sub, sup) => {
                     if self.is_subregion_of(sub, sup) {
@@ -1333,7 +1333,7 @@ impl<'a, 'tcx> RegionVarBindings<'a, 'tcx> {
         }
         let dummy_idx = graph.add_node(());
 
-        for (constraint, _) in constraints.iter() {
+        for (constraint, _) in &*constraints {
             match *constraint {
                 ConstrainVarSubVar(a_id, b_id) => {
                     graph.add_edge(NodeIndex(a_id.index as uint),
@@ -1393,8 +1393,8 @@ impl<'a, 'tcx> RegionVarBindings<'a, 'tcx> {
         lower_bounds.sort_by(|a, b| { free_regions_first(a, b) });
         upper_bounds.sort_by(|a, b| { free_regions_first(a, b) });
 
-        for lower_bound in lower_bounds.iter() {
-            for upper_bound in upper_bounds.iter() {
+        for lower_bound in &lower_bounds {
+            for upper_bound in &upper_bounds {
                 if !self.is_subregion_of(lower_bound.region,
                                          upper_bound.region) {
                     errors.push(SubSupConflict(
@@ -1435,8 +1435,8 @@ impl<'a, 'tcx> RegionVarBindings<'a, 'tcx> {
             return;
         }
 
-        for upper_bound_1 in upper_bounds.iter() {
-            for upper_bound_2 in upper_bounds.iter() {
+        for upper_bound_1 in &upper_bounds {
+            for upper_bound_2 in &upper_bounds {
                 match self.glb_concrete_regions(upper_bound_1.region,
                                                 upper_bound_2.region) {
                   Ok(_) => {}
@@ -1554,7 +1554,7 @@ impl<'a, 'tcx> RegionVarBindings<'a, 'tcx> {
             changed = false;
             iteration += 1;
             debug!("---- {} Iteration {}{}", "#", tag, iteration);
-            for (constraint, _) in self.constraints.borrow().iter() {
+            for (constraint, _) in &*self.constraints.borrow() {
                 let edge_changed = body(constraint);
                 if edge_changed {
                     debug!("Updated due to constraint {}",

src/librustc/middle/infer/type_variable.rs

@@ -105,7 +105,7 @@ impl<'tcx> TypeVariableTable<'tcx> {
                                already instantiated")
         };
 
-        for &(dir, vid) in relations.iter() {
+        for &(dir, vid) in &relations {
             stack.push((ty, dir, vid));
         }
 
@@ -165,7 +165,7 @@ impl<'tcx> TypeVariableTable<'tcx> {
         let mut escaping_types = Vec::new();
         let actions_since_snapshot = self.values.actions_since_snapshot(&s.snapshot);
         debug!("actions_since_snapshot.len() = {}", actions_since_snapshot.len());
-        for action in actions_since_snapshot.iter() {
+        for action in actions_since_snapshot {
             match *action {
                 sv::UndoLog::NewElem(index) => {
                     // if any new variables were created during the

src/librustc/middle/lang_items.rs

@@ -120,7 +120,7 @@ impl LanguageItems {
             (self.fn_once_trait(), ty::FnOnceClosureKind),
             ];
 
-        for &(opt_def_id, kind) in def_id_kinds.iter() {
+        for &(opt_def_id, kind) in &def_id_kinds {
             if Some(id) == opt_def_id {
                 return Some(kind);
             }
@@ -217,7 +217,7 @@ impl<'a> LanguageItemCollector<'a> {
 }
 
 pub fn extract(attrs: &[ast::Attribute]) -> Option<InternedString> {
-    for attribute in attrs.iter() {
+    for attribute in attrs {
         match attribute.value_str() {
             Some(ref value) if attribute.check_name("lang") => {
                 return Some(value.clone());

src/librustc/middle/liveness.rs

@@ -378,7 +378,7 @@ fn visit_fn(ir: &mut IrMaps,
 
     debug!("creating fn_maps: {:?}", &fn_maps as *const IrMaps);
 
-    for arg in decl.inputs.iter() {
+    for arg in &decl.inputs {
         pat_util::pat_bindings(&ir.tcx.def_map,
                                &*arg.pat,
                                |_bm, arg_id, _x, path1| {
@@ -427,7 +427,7 @@ fn visit_local(ir: &mut IrMaps, local: &ast::Local) {
 }
 
 fn visit_arm(ir: &mut IrMaps, arm: &ast::Arm) {
-    for pat in arm.pats.iter() {
+    for pat in &arm.pats {
         pat_util::pat_bindings(&ir.tcx.def_map, &**pat, |bm, p_id, sp, path1| {
             debug!("adding local variable {} from match with bm {:?}",
                    p_id, bm);
@@ -464,7 +464,7 @@ fn visit_expr(ir: &mut IrMaps, expr: &Expr) {
         // construction site.
         let mut call_caps = Vec::new();
         ty::with_freevars(ir.tcx, expr.id, |freevars| {
-            for fv in freevars.iter() {
+            for fv in freevars {
                 if let DefLocal(rv) = fv.def {
                     let fv_ln = ir.add_live_node(FreeVarNode(fv.span));
                     call_caps.push(CaptureInfo {ln: fv_ln,
@@ -1049,7 +1049,7 @@ impl<'a, 'tcx> Liveness<'a, 'tcx> {
             let ln = self.live_node(expr.id, expr.span);
             self.init_empty(ln, succ);
             let mut first_merge = true;
-            for arm in arms.iter() {
+            for arm in arms {
                 let body_succ =
                     self.propagate_through_expr(&*arm.body, succ);
                 let guard_succ =
@@ -1445,12 +1445,12 @@ fn check_expr(this: &mut Liveness, expr: &Expr) {
       }
 
       ast::ExprInlineAsm(ref ia) => {
-        for &(_, ref input) in ia.inputs.iter() {
+        for &(_, ref input) in &ia.inputs {
           this.visit_expr(&**input);
         }
 
         // Output operands must be lvalues
-        for &(_, ref out, _) in ia.outputs.iter() {
+        for &(_, ref out, _) in &ia.outputs {
           this.check_lvalue(&**out);
           this.visit_expr(&**out);
         }
@@ -1590,7 +1590,7 @@ impl<'a, 'tcx> Liveness<'a, 'tcx> {
     }
 
     fn warn_about_unused_args(&self, decl: &ast::FnDecl, entry_ln: LiveNode) {
-        for arg in decl.inputs.iter() {
+        for arg in &decl.inputs {
             pat_util::pat_bindings(&self.ir.tcx.def_map,
                                    &*arg.pat,
                                    |_bm, p_id, sp, path1| {
@@ -1620,7 +1620,7 @@ impl<'a, 'tcx> Liveness<'a, 'tcx> {
                          -> bool {
         if !self.used_on_entry(ln, var) {
             let r = self.should_warn(var);
-            for name in r.iter() {
+            if let Some(name) = r {
 
                 // annoying: for parameters in funcs like `fn(x: int)
                 // {ret}`, there is only one node, so asking about
@@ -1634,10 +1634,10 @@ impl<'a, 'tcx> Liveness<'a, 'tcx> {
                 if is_assigned {
                     self.ir.tcx.sess.add_lint(lint::builtin::UNUSED_VARIABLES, id, sp,
                         format!("variable `{}` is assigned to, but never used",
-                                *name));
+                                name));
                 } else {
                     self.ir.tcx.sess.add_lint(lint::builtin::UNUSED_VARIABLES, id, sp,
-                        format!("unused variable: `{}`", *name));
+                        format!("unused variable: `{}`", name));
                 }
             }
             true
@@ -1653,9 +1653,9 @@ impl<'a, 'tcx> Liveness<'a, 'tcx> {
                               var: Variable) {
         if self.live_on_exit(ln, var).is_none() {
             let r = self.should_warn(var);
-            for name in r.iter() {
+            if let Some(name) = r {
                 self.ir.tcx.sess.add_lint(lint::builtin::UNUSED_ASSIGNMENTS, id, sp,
-                    format!("value assigned to `{}` is never read", *name));
+                    format!("value assigned to `{}` is never read", name));
             }
         }
     }

src/librustc/middle/mem_categorization.rs

@@ -1208,7 +1208,7 @@ impl<'t,'tcx,TYPER:Typer<'tcx>> MemCategorizationContext<'t,TYPER> {
                     }
                 }
                 Some(&def::DefConst(..)) => {
-                    for subpat in subpats.iter() {
+                    for subpat in subpats {
                         try!(self.cat_pattern_(cmt.clone(), &**subpat, op));
                     }
                 }
@@ -1230,7 +1230,7 @@ impl<'t,'tcx,TYPER:Typer<'tcx>> MemCategorizationContext<'t,TYPER> {
 
           ast::PatStruct(_, ref field_pats, _) => {
             // {f1: p1, ..., fN: pN}
-            for fp in field_pats.iter() {
+            for fp in field_pats {
                 let field_ty = try!(self.pat_ty(&*fp.node.pat)); // see (*2)
                 let cmt_field = self.cat_field(pat, cmt.clone(), fp.node.ident.name, field_ty);
                 try!(self.cat_pattern_(cmt_field, &*fp.node.pat, op));
@@ -1259,15 +1259,15 @@ impl<'t,'tcx,TYPER:Typer<'tcx>> MemCategorizationContext<'t,TYPER> {
 
           ast::PatVec(ref before, ref slice, ref after) => {
               let elt_cmt = try!(self.cat_index(pat, try!(self.deref_vec(pat, cmt))));
-              for before_pat in before.iter() {
+              for before_pat in before {
                   try!(self.cat_pattern_(elt_cmt.clone(), &**before_pat, op));
               }
-              for slice_pat in slice.iter() {
+              if let Some(ref slice_pat) = *slice {
                   let slice_ty = try!(self.pat_ty(&**slice_pat));
                   let slice_cmt = self.cat_rvalue_node(pat.id(), pat.span(), slice_ty);
                   try!(self.cat_pattern_(slice_cmt, &**slice_pat, op));
               }
-              for after_pat in after.iter() {
+              for after_pat in after {
                   try!(self.cat_pattern_(elt_cmt.clone(), &**after_pat, op));
               }
           }

src/librustc/middle/reachable.rs

@@ -353,7 +353,7 @@ impl<'a, 'tcx> ReachableContext<'a, 'tcx> {
     // this properly would result in the necessity of computing *type*
     // reachability, which might result in a compile time loss.
     fn mark_destructors_reachable(&mut self) {
-        for (_, destructor_def_id) in self.tcx.destructor_for_type.borrow().iter() {
+        for (_, destructor_def_id) in &*self.tcx.destructor_for_type.borrow() {
             if destructor_def_id.krate == ast::LOCAL_CRATE {
                 self.reachable_symbols.insert(destructor_def_id.node);
             }
@@ -371,7 +371,7 @@ pub fn find_reachable(tcx: &ty::ctxt,
     //         other crates link to us, they're going to expect to be able to
     //         use the lang items, so we need to be sure to mark them as
     //         exported.
-    for id in exported_items.iter() {
+    for id in exported_items {
         reachable_context.worklist.push(*id);
     }
     for (_, item) in tcx.lang_items.items() {

src/librustc/middle/recursion_limit.rs

@@ -20,7 +20,7 @@ use syntax::ast;
 use syntax::attr::AttrMetaMethods;
 
 pub fn update_recursion_limit(sess: &Session, krate: &ast::Crate) {
-    for attr in krate.attrs.iter() {
+    for attr in &krate.attrs {
         if !attr.check_name("recursion_limit") {
             continue;
         }

src/librustc/middle/region.rs

@@ -888,14 +888,14 @@ fn resolve_local(visitor: &mut RegionResolutionVisitor, local: &ast::Local) {
                 record_rvalue_scope(visitor, &**subexpr, blk_id);
             }
             ast::ExprStruct(_, ref fields, _) => {
-                for field in fields.iter() {
+                for field in fields {
                     record_rvalue_scope_if_borrow_expr(
                         visitor, &*field.expr, blk_id);
                 }
             }
             ast::ExprVec(ref subexprs) |
             ast::ExprTup(ref subexprs) => {
-                for subexpr in subexprs.iter() {
+                for subexpr in subexprs {
                     record_rvalue_scope_if_borrow_expr(
                         visitor, &**subexpr, blk_id);
                 }

src/librustc/middle/resolve_lifetime.rs

@@ -187,14 +187,14 @@ impl<'a, 'v> Visitor<'v> for LifetimeContext<'a> {
     }
 
     fn visit_generics(&mut self, generics: &ast::Generics) {
-        for ty_param in generics.ty_params.iter() {
+        for ty_param in &*generics.ty_params {
             visit::walk_ty_param_bounds_helper(self, &ty_param.bounds);
             match ty_param.default {
                 Some(ref ty) => self.visit_ty(&**ty),
                 None => {}
             }
         }
-        for predicate in generics.where_clause.predicates.iter() {
+        for predicate in &generics.where_clause.predicates {
             match predicate {
                 &ast::WherePredicate::BoundPredicate(ast::WhereBoundPredicate{ ref bounded_ty,
                                                                                ref bounds,
@@ -207,7 +207,7 @@ impl<'a, 'v> Visitor<'v> for LifetimeContext<'a> {
                                                                                 .. }) => {
 
                     self.visit_lifetime_ref(lifetime);
-                    for bound in bounds.iter() {
+                    for bound in bounds {
                         self.visit_lifetime_ref(bound);
                     }
                 }
@@ -229,7 +229,7 @@ impl<'a, 'v> Visitor<'v> for LifetimeContext<'a> {
 
         self.with(LateScope(&trait_ref.bound_lifetimes, self.scope), |old_scope, this| {
             this.check_lifetime_defs(old_scope, &trait_ref.bound_lifetimes);
-            for lifetime in trait_ref.bound_lifetimes.iter() {
+            for lifetime in &trait_ref.bound_lifetimes {
                 this.visit_lifetime_def(lifetime);
             }
             this.visit_trait_ref(&trait_ref.trait_ref)
@@ -408,7 +408,7 @@ impl<'a> LifetimeContext<'a> {
             let lifetime_i = &lifetimes[i];
 
             let special_idents = [special_idents::static_lifetime];
-            for lifetime in lifetimes.iter() {
+            for lifetime in lifetimes {
                 if special_idents.iter().any(|&i| i.name == lifetime.lifetime.name) {
                     span_err!(self.sess, lifetime.lifetime.span, E0262,
                         "illegal lifetime parameter name: `{}`",
@@ -431,7 +431,7 @@ impl<'a> LifetimeContext<'a> {
             // It is a soft error to shadow a lifetime within a parent scope.
             self.check_lifetime_def_for_shadowing(old_scope, &lifetime_i.lifetime);
 
-            for bound in lifetime_i.bounds.iter() {
+            for bound in &lifetime_i.bounds {
                 self.resolve_lifetime_ref(bound);
             }
         }
@@ -535,10 +535,10 @@ fn early_bound_lifetime_names(generics: &ast::Generics) -> Vec<ast::Name> {
         let mut collector =
             FreeLifetimeCollector { early_bound: &mut early_bound,
                                     late_bound: &mut late_bound };
-        for ty_param in generics.ty_params.iter() {
+        for ty_param in &*generics.ty_params {
             visit::walk_ty_param_bounds_helper(&mut collector, &ty_param.bounds);
         }
-        for predicate in generics.where_clause.predicates.iter() {
+        for predicate in &generics.where_clause.predicates {
             match predicate {
                 &ast::WherePredicate::BoundPredicate(ast::WhereBoundPredicate{ref bounds,
                                                                               ref bounded_ty,
@@ -551,7 +551,7 @@ fn early_bound_lifetime_names(generics: &ast::Generics) -> Vec<ast::Name> {
                                                                                 ..}) => {
                     collector.visit_lifetime_ref(lifetime);
 
-                    for bound in bounds.iter() {
+                    for bound in bounds {
                         collector.visit_lifetime_ref(bound);
                     }
                 }
@@ -562,11 +562,11 @@ fn early_bound_lifetime_names(generics: &ast::Generics) -> Vec<ast::Name> {
 
     // Any lifetime that either has a bound or is referenced by a
     // bound is early.
-    for lifetime_def in generics.lifetimes.iter() {
+    for lifetime_def in &generics.lifetimes {
         if !lifetime_def.bounds.is_empty() {
             shuffle(&mut early_bound, &mut late_bound,
                     lifetime_def.lifetime.name);
-            for bound in lifetime_def.bounds.iter() {
+            for bound in &lifetime_def.bounds {
                 shuffle(&mut early_bound, &mut late_bound,
                         bound.name);
             }

src/librustc/middle/stability.rs

@@ -148,7 +148,7 @@ impl Index {
     /// Construct the stability index for a crate being compiled.
     pub fn build(sess: &Session, krate: &Crate) -> Index {
         let mut staged_api = false;
-        for attr in krate.attrs.iter() {
+        for attr in &krate.attrs {
             if attr.name().get() == "staged_api" {
                 match attr.node.value.node {
                     ast::MetaWord(_) => {
@@ -273,7 +273,7 @@ pub fn check_item(tcx: &ty::ctxt, item: &ast::Item,
             maybe_do_stability_check(tcx, id, item.span, cb);
         }
         ast::ItemTrait(_, _, ref supertraits, _) => {
-            for t in supertraits.iter() {
+            for t in &**supertraits {
                 if let ast::TraitTyParamBound(ref t, _) = *t {
                     let id = ty::trait_ref_to_def_id(tcx, &t.trait_ref);
                     maybe_do_stability_check(tcx, id, t.trait_ref.path.span, cb);
@@ -410,11 +410,11 @@ pub fn check_unused_features(sess: &Session,
     let mut active_lib_features: FnvHashMap<InternedString, Span>
         = lib_features.clone().into_iter().collect();
 
-    for used_feature in used_lib_features.iter() {
+    for used_feature in used_lib_features {
         active_lib_features.remove(used_feature);
     }
 
-    for (_, &span) in active_lib_features.iter() {
+    for (_, &span) in &active_lib_features {
         sess.add_lint(lint::builtin::UNUSED_FEATURES,
                       ast::CRATE_NODE_ID,
                       span,

src/librustc/middle/subst.rs

@@ -241,7 +241,7 @@ pub struct SeparateVecsPerParamSpace<T> {
 impl<T: fmt::Debug> fmt::Debug for VecPerParamSpace<T> {
     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
         try!(write!(fmt, "VecPerParamSpace {{"));
-        for space in ParamSpace::all().iter() {
+        for space in &ParamSpace::all() {
             try!(write!(fmt, "{:?}: {:?}, ", *space, self.get_slice(*space)));
         }
         try!(write!(fmt, "}}"));

src/librustc/middle/traits/doc.rs

@@ -35,7 +35,7 @@ provide an impl. To see what I mean, consider the body of `clone_slice`:
 
     fn clone_slice<T:Clone>(x: &[T]) -> Vec<T> {
         let mut v = Vec::new();
-        for e in x.iter() {
+        for e in &x {
             v.push((*e).clone()); // (*)
         }
     }

src/librustc/middle/traits/error_reporting.rs

@@ -28,7 +28,7 @@ use util::ppaux::{Repr, UserString};
 
 pub fn report_fulfillment_errors<'a, 'tcx>(infcx: &InferCtxt<'a, 'tcx>,
                                            errors: &Vec<FulfillmentError<'tcx>>) {
-    for error in errors.iter() {
+    for error in errors {
         report_fulfillment_error(infcx, error);
     }
 }
@@ -68,7 +68,7 @@ fn report_on_unimplemented<'a, 'tcx>(infcx: &InferCtxt<'a, 'tcx>,
                                      span: Span) -> Option<String> {
     let def_id = trait_ref.def_id;
     let mut report = None;
-    for item in ty::get_attrs(infcx.tcx, def_id).iter() {
+    for item in &*ty::get_attrs(infcx.tcx, def_id) {
         if item.check_name("rustc_on_unimplemented") {
             let err_sp = if item.meta().span == DUMMY_SP {
                 span

src/librustc/middle/traits/object_safety.rs

@@ -176,7 +176,7 @@ fn object_safety_violations_for_method<'tcx>(tcx: &ty::ctxt<'tcx>,
     // The `Self` type is erased, so it should not appear in list of
     // arguments or return type apart from the receiver.
     let ref sig = method.fty.sig;
-    for &input_ty in sig.0.inputs[1..].iter() {
+    for &input_ty in &sig.0.inputs[1..] {
         if contains_illegal_self_type_reference(tcx, trait_def_id, input_ty) {
             return Some(MethodViolationCode::ReferencesSelf);
         }

src/librustc/middle/traits/project.rs

@@ -802,7 +802,7 @@ fn confirm_impl_candidate<'cx,'tcx>(
 
     let impl_items = &impl_items_map[impl_vtable.impl_def_id];
     let mut impl_ty = None;
-    for impl_item in impl_items.iter() {
+    for impl_item in impl_items {
         let assoc_type = match impl_or_trait_items_map[impl_item.def_id()] {
             ty::TypeTraitItem(ref assoc_type) => assoc_type.clone(),
             ty::MethodTraitItem(..) => { continue; }

src/librustc/middle/traits/select.rs

@@ -1089,7 +1089,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         debug!("assemble_candidates_from_impls(self_ty={})", self_ty.repr(self.tcx()));
 
         let all_impls = self.all_impls(obligation.predicate.def_id());
-        for &impl_def_id in all_impls.iter() {
+        for &impl_def_id in &all_impls {
             self.infcx.probe(|snapshot| {
                 let (skol_obligation_trait_pred, skol_map) =
                     self.infcx().skolemize_late_bound_regions(&obligation.predicate, snapshot);

src/librustc/middle/traits/util.rs

@@ -343,7 +343,7 @@ pub fn get_vtable_index_of_object_method<'tcx>(tcx: &ty::ctxt<'tcx>,
         }
 
         let trait_items = ty::trait_items(tcx, bound_ref.def_id());
-        for trait_item in trait_items.iter() {
+        for trait_item in &**trait_items {
             match *trait_item {
                 ty::MethodTraitItem(_) => method_count += 1,
                 ty::TypeTraitItem(_) => {}

src/librustc/middle/ty.rs

@@ -872,7 +872,7 @@ macro_rules! sty_debug_print {
                 $(let mut $variant = total;)*
 
 
-                for (_, t) in tcx.interner.borrow().iter() {
+                for (_, t) in &*tcx.interner.borrow() {
                     let variant = match t.sty {
                         ty::ty_bool | ty::ty_char | ty::ty_int(..) | ty::ty_uint(..) |
                             ty::ty_float(..) | ty::ty_str => continue,
@@ -2579,7 +2579,7 @@ impl FlagComputation {
             &ty_trait(box TyTrait { ref principal, ref bounds }) => {
                 let mut computation = FlagComputation::new();
                 computation.add_substs(principal.0.substs);
-                for projection_bound in bounds.projection_bounds.iter() {
+                for projection_bound in &bounds.projection_bounds {
                     let mut proj_computation = FlagComputation::new();
                     proj_computation.add_projection_predicate(&projection_bound.0);
                     computation.add_bound_computation(&proj_computation);
@@ -2618,7 +2618,7 @@ impl FlagComputation {
     }
 
     fn add_tys(&mut self, tys: &[Ty]) {
-        for &ty in tys.iter() {
+        for &ty in tys {
             self.add_ty(ty);
         }
     }
@@ -3530,7 +3530,7 @@ pub fn type_contents<'tcx>(cx: &ctxt<'tcx>, ty: Ty<'tcx>) -> TypeContents {
         // make no assumptions (other than that it cannot have an
         // in-scope type parameter within, which makes no sense).
         let mut tc = TC::All - TC::InteriorParam;
-        for bound in bounds.builtin_bounds.iter() {
+        for bound in &bounds.builtin_bounds {
             tc = tc - match bound {
                 BoundSync | BoundSend | BoundCopy => TC::None,
                 BoundSized => TC::Nonsized,
@@ -4644,7 +4644,7 @@ pub fn stmt_node_id(s: &ast::Stmt) -> ast::NodeId {
 pub fn field_idx_strict(tcx: &ctxt, name: ast::Name, fields: &[field])
                      -> uint {
     let mut i = 0;
-    for f in fields.iter() { if f.name == name { return i; } i += 1; }
+    for f in fields { if f.name == name { return i; } i += 1; }
     tcx.sess.bug(&format!(
         "no field named `{}` found in the list of fields `{:?}`",
         token::get_name(name),
@@ -5468,25 +5468,25 @@ pub fn predicates<'tcx>(
 {
     let mut vec = Vec::new();
 
-    for builtin_bound in bounds.builtin_bounds.iter() {
+    for builtin_bound in &bounds.builtin_bounds {
         match traits::trait_ref_for_builtin_bound(tcx, builtin_bound, param_ty) {
             Ok(trait_ref) => { vec.push(trait_ref.as_predicate()); }
             Err(ErrorReported) => { }
         }
     }
 
-    for &region_bound in bounds.region_bounds.iter() {
+    for &region_bound in &bounds.region_bounds {
         // account for the binder being introduced below; no need to shift `param_ty`
         // because, at present at least, it can only refer to early-bound regions
         let region_bound = ty_fold::shift_region(region_bound, 1);
         vec.push(ty::Binder(ty::OutlivesPredicate(param_ty, region_bound)).as_predicate());
     }
 
-    for bound_trait_ref in bounds.trait_bounds.iter() {
+    for bound_trait_ref in &bounds.trait_bounds {
         vec.push(bound_trait_ref.as_predicate());
     }
 
-    for projection in bounds.projection_bounds.iter() {
+    for projection in &bounds.projection_bounds {
         vec.push(projection.as_predicate());
     }
 
@@ -5931,17 +5931,17 @@ pub fn populate_implementations_for_type_if_necessary(tcx: &ctxt,
 
         // Record the trait->implementation mappings, if applicable.
         let associated_traits = csearch::get_impl_trait(tcx, impl_def_id);
-        for trait_ref in associated_traits.iter() {
+        if let Some(ref trait_ref) = associated_traits {
             record_trait_implementation(tcx, trait_ref.def_id, impl_def_id);
         }
 
         // For any methods that use a default implementation, add them to
         // the map. This is a bit unfortunate.
-        for impl_item_def_id in impl_items.iter() {
+        for impl_item_def_id in &impl_items {
             let method_def_id = impl_item_def_id.def_id();
             match impl_or_trait_item(tcx, method_def_id) {
                 MethodTraitItem(method) => {
-                    for &source in method.provided_source.iter() {
+                    if let Some(source) = method.provided_source {
                         tcx.provided_method_sources
                            .borrow_mut()
                            .insert(method_def_id, source);
@@ -5985,11 +5985,11 @@ pub fn populate_implementations_for_trait_if_necessary(
 
         // For any methods that use a default implementation, add them to
         // the map. This is a bit unfortunate.
-        for impl_item_def_id in impl_items.iter() {
+        for impl_item_def_id in &impl_items {
             let method_def_id = impl_item_def_id.def_id();
             match impl_or_trait_item(tcx, method_def_id) {
                 MethodTraitItem(method) => {
-                    for &source in method.provided_source.iter() {
+                    if let Some(source) = method.provided_source {
                         tcx.provided_method_sources
                            .borrow_mut()
                            .insert(method_def_id, source);
@@ -6121,7 +6121,7 @@ pub fn hash_crate_independent<'tcx>(tcx: &ctxt<'tcx>, ty: Ty<'tcx>, svh: &Svh) -
         };
         let fn_sig = |&: state: &mut SipHasher, sig: &Binder<FnSig<'tcx>>| {
             let sig = anonymize_late_bound_regions(tcx, sig).0;
-            for a in sig.inputs.iter() { helper(tcx, *a, svh, state); }
+            for a in &sig.inputs { helper(tcx, *a, svh, state); }
             if let ty::FnConverging(output) = sig.output {
                 helper(tcx, output, svh, state);
             }
@@ -6270,7 +6270,7 @@ pub fn construct_free_substs<'a,'tcx>(
                           free_id: ast::NodeId,
                           region_params: &[RegionParameterDef])
     {
-        for r in region_params.iter() {
+        for r in region_params {
             regions.push(r.space, ty::free_region_from_def(free_id, r));
         }
     }
@@ -6278,7 +6278,7 @@ pub fn construct_free_substs<'a,'tcx>(
     fn push_types_from_defs<'tcx>(tcx: &ty::ctxt<'tcx>,
                                   types: &mut VecPerParamSpace<Ty<'tcx>>,
                                   defs: &[TypeParameterDef<'tcx>]) {
-        for def in defs.iter() {
+        for def in defs {
             debug!("construct_parameter_environment(): push_types_from_defs: def={:?}",
                    def.repr(tcx));
             let ty = ty::mk_param_from_def(tcx, def);
@@ -6351,7 +6351,7 @@ pub fn construct_parameter_environment<'a,'tcx>(
     fn record_region_bounds<'tcx>(tcx: &ty::ctxt<'tcx>, predicates: &[ty::Predicate<'tcx>]) {
         debug!("record_region_bounds(predicates={:?})", predicates.repr(tcx));
 
-        for predicate in predicates.iter() {
+        for predicate in predicates {
             match *predicate {
                 Predicate::Projection(..) |
                 Predicate::Trait(..) |
@@ -6870,7 +6870,7 @@ pub fn can_type_implement_copy<'a,'tcx>(param_env: &ParameterEnvironment<'a, 'tc
     let did = match self_type.sty {
         ty::ty_struct(struct_did, substs) => {
             let fields = ty::struct_fields(tcx, struct_did, substs);
-            for field in fields.iter() {
+            for field in &fields {
                 if type_moves_by_default(param_env, span, field.mt.ty) {
                     return Err(FieldDoesNotImplementCopy(field.name))
                 }
@@ -6879,8 +6879,8 @@ pub fn can_type_implement_copy<'a,'tcx>(param_env: &ParameterEnvironment<'a, 'tc
         }
         ty::ty_enum(enum_did, substs) => {
             let enum_variants = ty::enum_variants(tcx, enum_did);
-            for variant in enum_variants.iter() {
-                for variant_arg_type in variant.args.iter() {
+            for variant in &*enum_variants {
+                for variant_arg_type in &variant.args {
                     let substd_arg_type =
                         variant_arg_type.subst(tcx, substs);
                     if type_moves_by_default(param_env, span, substd_arg_type) {

src/librustc/middle/weak_lang_items.rs

@@ -78,7 +78,7 @@ fn verify(sess: &Session, items: &lang_items::LanguageItems) {
 
     let mut missing = HashSet::new();
     sess.cstore.iter_crate_data(|cnum, _| {
-        for item in csearch::get_missing_lang_items(&sess.cstore, cnum).iter() {
+        for item in &csearch::get_missing_lang_items(&sess.cstore, cnum) {
             missing.insert(*item);
         }
     });

src/librustc/plugin/build.rs

@@ -48,7 +48,7 @@ pub fn find_plugin_registrar(diagnostic: &diagnostic::SpanHandler,
         },
         _ => {
             diagnostic.handler().err("multiple plugin registration functions found");
-            for &(_, span) in finder.registrars.iter() {
+            for &(_, span) in &finder.registrars {
                 diagnostic.span_note(span, "one is here");
             }
             diagnostic.handler().abort_if_errors();

src/librustc/plugin/load.rs

@@ -73,7 +73,7 @@ pub fn load_plugins(sess: &Session, krate: &ast::Crate,
     // We need to error on `#[macro_use] extern crate` when it isn't at the
     // crate root, because `$crate` won't work properly. Identify these by
     // spans, because the crate map isn't set up yet.
-    for item in krate.module.items.iter() {
+    for item in &krate.module.items {
         if let ast::ItemExternCrate(_) = item.node {
             loader.span_whitelist.insert(item.span);
         }
@@ -82,7 +82,7 @@ pub fn load_plugins(sess: &Session, krate: &ast::Crate,
     visit::walk_crate(&mut loader, krate);
 
     if let Some(plugins) = addl_plugins {
-        for plugin in plugins.iter() {
+        for plugin in &plugins {
             loader.load_plugin(CrateOrString::Str(plugin.as_slice()),
                                                   None, None, None)
         }
@@ -107,7 +107,7 @@ impl<'a, 'v> Visitor<'v> for PluginLoader<'a> {
         let mut plugin_attr = None;
         let mut macro_selection = Some(HashSet::new());  // None => load all
         let mut reexport = HashSet::new();
-        for attr in item.attrs.iter() {
+        for attr in &item.attrs {
             let mut used = true;
             match attr.name().get() {
                 "phase" => {
@@ -127,7 +127,7 @@ impl<'a, 'v> Visitor<'v> for PluginLoader<'a> {
                         macro_selection = None;
                     }
                     if let (Some(sel), Some(names)) = (macro_selection.as_mut(), names) {
-                        for name in names.iter() {
+                        for name in names {
                             if let ast::MetaWord(ref name) = name.node {
                                 sel.insert(name.clone());
                             } else {
@@ -145,7 +145,7 @@ impl<'a, 'v> Visitor<'v> for PluginLoader<'a> {
                         }
                     };
 
-                    for name in names.iter() {
+                    for name in names {
                         if let ast::MetaWord(ref name) = name.node {
                             reexport.insert(name.clone());
                         } else {

src/librustc/session/config.rs

@@ -306,7 +306,7 @@ macro_rules! options {
             let value = iter.next();
             let option_to_lookup = key.replace("-", "_");
             let mut found = false;
-            for &(candidate, setter, opt_type_desc, _) in $stat.iter() {
+            for &(candidate, setter, opt_type_desc, _) in $stat {
                 if option_to_lookup != candidate { continue }
                 if !setter(&mut op, value) {
                     match (value, opt_type_desc) {
@@ -830,7 +830,7 @@ pub fn build_session_options(matches: &getopts::Matches) -> Options {
     let mut lint_opts = vec!();
     let mut describe_lints = false;
 
-    for &level in [lint::Allow, lint::Warn, lint::Deny, lint::Forbid].iter() {
+    for &level in &[lint::Allow, lint::Warn, lint::Deny, lint::Forbid] {
         for lint_name in matches.opt_strs(level.as_str()).into_iter() {
             if lint_name == "help" {
                 describe_lints = true;
@@ -853,7 +853,7 @@ pub fn build_session_options(matches: &getopts::Matches) -> Options {
     let mut output_types = Vec::new();
     if !debugging_opts.parse_only && !no_trans {
         let unparsed_output_types = matches.opt_strs("emit");
-        for unparsed_output_type in unparsed_output_types.iter() {
+        for unparsed_output_type in &unparsed_output_types {
             for part in unparsed_output_type.split(',') {
                 let output_type = match part.as_slice() {
                     "asm" => OutputTypeAssembly,
@@ -923,7 +923,7 @@ pub fn build_session_options(matches: &getopts::Matches) -> Options {
     };
 
     let mut search_paths = SearchPaths::new();
-    for s in matches.opt_strs("L").iter() {
+    for s in &matches.opt_strs("L") {
         search_paths.add_path(&s[]);
     }
 
@@ -997,7 +997,7 @@ pub fn build_session_options(matches: &getopts::Matches) -> Options {
     };
 
     let mut externs = HashMap::new();
-    for arg in matches.opt_strs("extern").iter() {
+    for arg in &matches.opt_strs("extern") {
         let mut parts = arg.splitn(1, '=');
         let name = match parts.next() {
             Some(s) => s,
@@ -1049,7 +1049,7 @@ pub fn build_session_options(matches: &getopts::Matches) -> Options {
 pub fn parse_crate_types_from_list(list_list: Vec<String>) -> Result<Vec<CrateType>, String> {
 
     let mut crate_types: Vec<CrateType> = Vec::new();
-    for unparsed_crate_type in list_list.iter() {
+    for unparsed_crate_type in &list_list {
         for part in unparsed_crate_type.split(',') {
             let new_part = match part {
                 "lib"       => default_lib_output(),

src/librustc/util/common.rs

@@ -163,7 +163,7 @@ pub fn can_reach<T, S>(edges_map: &HashMap<T, Vec<T>, S>, source: T,
     while i < queue.len() {
         match edges_map.get(&queue[i]) {
             Some(edges) => {
-                for target in edges.iter() {
+                for target in edges {
                     if *target == destination {
                         return true;
                     }

src/librustc/util/nodemap.rs

@@ -62,7 +62,7 @@ impl Hasher for FnvHasher {
 impl Writer for FnvHasher {
     fn write(&mut self, bytes: &[u8]) {
         let FnvHasher(mut hash) = *self;
-        for byte in bytes.iter() {
+        for byte in bytes {
             hash = hash ^ (*byte as u64);
             hash = hash * 0x100000001b3;
         }

src/librustc/util/ppaux.rs

@@ -494,11 +494,11 @@ pub fn parameterized<'tcx>(cx: &ctxt<'tcx>,
         0
     };
 
-    for t in tps[..tps.len() - num_defaults].iter() {
+    for t in &tps[..tps.len() - num_defaults] {
         strs.push(ty_to_string(cx, *t))
     }
 
-    for projection in projections.iter() {
+    for projection in projections {
         strs.push(format!("{}={}",
                           projection.projection_ty.item_name.user_string(cx),
                           projection.ty.user_string(cx)));
@@ -665,7 +665,7 @@ impl<'tcx> UserString<'tcx> for ty::TyTrait<'tcx> {
         components.push(tap.user_string(tcx));
 
         // Builtin bounds.
-        for bound in bounds.builtin_bounds.iter() {
+        for bound in &bounds.builtin_bounds {
             components.push(bound.user_string(tcx));
         }
 
@@ -748,7 +748,7 @@ impl<'tcx> Repr<'tcx> for subst::RegionSubsts {
 impl<'tcx> Repr<'tcx> for ty::BuiltinBounds {
     fn repr(&self, _tcx: &ctxt) -> String {
         let mut res = Vec::new();
-        for b in self.iter() {
+        for b in self {
             res.push(match b {
                 ty::BoundSend => "Send".to_string(),
                 ty::BoundSized => "Sized".to_string(),
@@ -764,7 +764,7 @@ impl<'tcx> Repr<'tcx> for ty::ParamBounds<'tcx> {
     fn repr(&self, tcx: &ctxt<'tcx>) -> String {
         let mut res = Vec::new();
         res.push(self.builtin_bounds.repr(tcx));
-        for t in self.trait_bounds.iter() {
+        for t in &self.trait_bounds {
             res.push(t.repr(tcx));
         }
         res.connect("+")
@@ -1157,7 +1157,7 @@ impl<'tcx> UserString<'tcx> for ty::ParamBounds<'tcx> {
         if !s.is_empty() {
             result.push(s);
         }
-        for n in self.trait_bounds.iter() {
+        for n in &self.trait_bounds {
             result.push(n.user_string(tcx));
         }
         result.connect(" + ")
@@ -1173,11 +1173,11 @@ impl<'tcx> Repr<'tcx> for ty::ExistentialBounds<'tcx> {
             res.push(region_str);
         }
 
-        for bound in self.builtin_bounds.iter() {
+        for bound in &self.builtin_bounds {
             res.push(bound.user_string(tcx));
         }
 
-        for projection_bound in self.projection_bounds.iter() {
+        for projection_bound in &self.projection_bounds {
             res.push(projection_bound.user_string(tcx));
         }
 

src/librustc_back/archive.rs

@@ -99,7 +99,7 @@ pub fn find_library(name: &str, osprefix: &str, ossuffix: &str,
     let oslibname = format!("{}{}{}", osprefix, name, ossuffix);
     let unixlibname = format!("lib{}.a", name);
 
-    for path in search_paths.iter() {
+    for path in search_paths {
         debug!("looking for {} inside {:?}", name, path.display());
         let test = path.join(&oslibname[]);
         if test.exists() { return test }
@@ -244,7 +244,7 @@ impl<'a> ArchiveBuilder<'a> {
         // 32,768, and we leave a bit of extra space for the program name.
         static ARG_LENGTH_LIMIT: uint = 32000;
 
-        for member_name in self.members.iter() {
+        for member_name in &self.members {
             let len = member_name.as_vec().len();
 
             // `len + 1` to account for the space that's inserted before each
@@ -297,7 +297,7 @@ impl<'a> ArchiveBuilder<'a> {
         // all SYMDEF files as these are just magical placeholders which get
         // re-created when we make a new archive anyway.
         let files = try!(fs::readdir(loc.path()));
-        for file in files.iter() {
+        for file in &files {
             let filename = file.filename_str().unwrap();
             if skip(filename) { continue }
             if filename.contains(".SYMDEF") { continue }

src/librustc_back/rpath.rs

@@ -51,7 +51,7 @@ pub fn get_rpath_flags<F, G>(config: RPathConfig<F, G>) -> Vec<String> where
 
 fn rpaths_to_flags(rpaths: &[String]) -> Vec<String> {
     let mut ret = Vec::new();
-    for rpath in rpaths.iter() {
+    for rpath in rpaths {
         ret.push(format!("-Wl,-rpath,{}", &(*rpath)[]));
     }
     return ret;
@@ -63,7 +63,7 @@ fn get_rpaths<F, G>(mut config: RPathConfig<F, G>, libs: &[Path]) -> Vec<String>
 {
     debug!("output: {:?}", config.out_filename.display());
     debug!("libs:");
-    for libpath in libs.iter() {
+    for libpath in libs {
         debug!("    {:?}", libpath.display());
     }
 
@@ -77,7 +77,7 @@ fn get_rpaths<F, G>(mut config: RPathConfig<F, G>, libs: &[Path]) -> Vec<String>
 
     fn log_rpaths(desc: &str, rpaths: &[String]) {
         debug!("{} rpaths:", desc);
-        for rpath in rpaths.iter() {
+        for rpath in rpaths {
             debug!("    {}", *rpath);
         }
     }
@@ -139,7 +139,7 @@ fn get_install_prefix_rpath<F, G>(config: RPathConfig<F, G>) -> String where
 fn minimize_rpaths(rpaths: &[String]) -> Vec<String> {
     let mut set = HashSet::new();
     let mut minimized = Vec::new();
-    for rpath in rpaths.iter() {
+    for rpath in rpaths {
         if set.insert(&rpath[]) {
             minimized.push(rpath.clone());
         }

src/librustc_back/sha2.rs

@@ -557,7 +557,7 @@ mod tests {
 
     fn test_hash<D: Digest>(sh: &mut D, tests: &[Test]) {
         // Test that it works when accepting the message all at once
-        for t in tests.iter() {
+        for t in tests {
             sh.reset();
             sh.input_str(t.input.as_slice());
             let out_str = sh.result_str();
@@ -565,7 +565,7 @@ mod tests {
         }
 
         // Test that it works when accepting the message in pieces
-        for t in tests.iter() {
+        for t in tests {
             sh.reset();
             let len = t.input.len();
             let mut left = len;

src/librustc_back/svh.rs

@@ -79,7 +79,7 @@ impl Svh {
         //        avoid collisions.
         let mut state = SipHasher::new();
 
-        for data in metadata.iter() {
+        for data in metadata {
             data.hash(&mut state);
         }
 
@@ -97,7 +97,7 @@ impl Svh {
         //
         // We hash only the MetaItems instead of the entire Attribute
         // to avoid hashing the AttrId
-        for attr in krate.attrs.iter() {
+        for attr in &krate.attrs {
             attr.node.value.hash(&mut state);
         }
 

src/librustc_back/target/mod.rs

@@ -384,7 +384,7 @@ impl Target {
         let paths = os::split_paths(&target_path[]);
         // FIXME 16351: add a sane default search path?
 
-        for dir in paths.iter() {
+        for dir in &paths {
             let p =  dir.join(path.clone());
             if p.is_file() {
                 return load_file(&p);

src/librustc_borrowck/borrowck/check_loans.rs

@@ -279,7 +279,7 @@ impl<'a, 'tcx> CheckLoanCtxt<'a, 'tcx> {
         let loan_path = owned_ptr_base_path(loan_path);
         let cont = self.each_in_scope_loan(scope, |loan| {
             let mut ret = true;
-            for restr_path in loan.restricted_paths.iter() {
+            for restr_path in &loan.restricted_paths {
                 if **restr_path == *loan_path {
                     if !op(loan) {
                         ret = false;
@@ -361,7 +361,7 @@ impl<'a, 'tcx> CheckLoanCtxt<'a, 'tcx> {
         debug!("new_loan_indices = {:?}", new_loan_indices);
 
         self.each_issued_loan(scope, |issued_loan| {
-            for &new_loan_index in new_loan_indices.iter() {
+            for &new_loan_index in &new_loan_indices {
                 let new_loan = &self.all_loans[new_loan_index];
                 self.report_error_if_loans_conflict(issued_loan, new_loan);
             }
@@ -370,7 +370,7 @@ impl<'a, 'tcx> CheckLoanCtxt<'a, 'tcx> {
 
         for (i, &x) in new_loan_indices.iter().enumerate() {
             let old_loan = &self.all_loans[x];
-            for &y in new_loan_indices[(i+1) ..].iter() {
+            for &y in &new_loan_indices[(i+1) ..] {
                 let new_loan = &self.all_loans[y];
                 self.report_error_if_loans_conflict(old_loan, new_loan);
             }
@@ -416,7 +416,7 @@ impl<'a, 'tcx> CheckLoanCtxt<'a, 'tcx> {
         }
 
         let loan2_base_path = owned_ptr_base_path_rc(&loan2.loan_path);
-        for restr_path in loan1.restricted_paths.iter() {
+        for restr_path in &loan1.restricted_paths {
             if *restr_path != loan2_base_path { continue; }
 
             // If new_loan is something like `x.a`, and old_loan is something like `x.b`, we would

src/librustc_borrowck/borrowck/fragments.rs

@@ -204,14 +204,14 @@ pub fn fixup_fragment_sets<'tcx>(this: &MoveData<'tcx>, tcx: &ty::ctxt<'tcx>) {
     debug!("fragments 1 assigned: {:?}", path_lps(&assigned[]));
 
     // Second, build parents from the moved and assigned.
-    for m in moved.iter() {
+    for m in &moved {
         let mut p = this.path_parent(*m);
         while p != InvalidMovePathIndex {
             parents.push(p);
             p = this.path_parent(p);
         }
     }
-    for a in assigned.iter() {
+    for a in &assigned {
         let mut p = this.path_parent(*a);
         while p != InvalidMovePathIndex {
             parents.push(p);
@@ -231,15 +231,15 @@ pub fn fixup_fragment_sets<'tcx>(this: &MoveData<'tcx>, tcx: &ty::ctxt<'tcx>) {
     debug!("fragments 3 assigned: {:?}", path_lps(&assigned[]));
 
     // Fourth, build the leftover from the moved, assigned, and parents.
-    for m in moved.iter() {
+    for m in &moved {
         let lp = this.path_loan_path(*m);
         add_fragment_siblings(this, tcx, &mut unmoved, lp, None);
     }
-    for a in assigned.iter() {
+    for a in &assigned {
         let lp = this.path_loan_path(*a);
         add_fragment_siblings(this, tcx, &mut unmoved, lp, None);
     }
-    for p in parents.iter() {
+    for p in &parents {
         let lp = this.path_loan_path(*p);
         add_fragment_siblings(this, tcx, &mut unmoved, lp, None);
     }
@@ -369,7 +369,7 @@ fn add_fragment_siblings_for_extension<'tcx>(this: &MoveData<'tcx>,
             let fields = ty::lookup_struct_fields(tcx, def_id);
             match *origin_field_name {
                 mc::NamedField(ast_name) => {
-                    for f in fields.iter() {
+                    for f in &fields {
                         if f.name == ast_name {
                             continue;
                         }
@@ -407,7 +407,7 @@ fn add_fragment_siblings_for_extension<'tcx>(this: &MoveData<'tcx>,
             match *origin_field_name {
                 mc::NamedField(ast_name) => {
                     let variant_arg_names = variant_info.arg_names.as_ref().unwrap();
-                    for variant_arg_ident in variant_arg_names.iter() {
+                    for variant_arg_ident in variant_arg_names {
                         if variant_arg_ident.name == ast_name {
                             continue;
                         }

src/librustc_borrowck/borrowck/gather_loans/move_error.rs

@@ -67,10 +67,10 @@ pub struct GroupedMoveErrors<'tcx> {
 fn report_move_errors<'a, 'tcx>(bccx: &BorrowckCtxt<'a, 'tcx>,
                                 errors: &Vec<MoveError<'tcx>>) {
     let grouped_errors = group_errors_with_same_origin(errors);
-    for error in grouped_errors.iter() {
+    for error in &grouped_errors {
         report_cannot_move_out_of(bccx, error.move_from.clone());
         let mut is_first_note = true;
-        for move_to in error.move_to_places.iter() {
+        for move_to in &error.move_to_places {
             note_move_destination(bccx, move_to.span,
                                   &move_to.ident, is_first_note);
             is_first_note = false;
@@ -81,7 +81,7 @@ fn report_move_errors<'a, 'tcx>(bccx: &BorrowckCtxt<'a, 'tcx>,
 fn group_errors_with_same_origin<'tcx>(errors: &Vec<MoveError<'tcx>>)
                                        -> Vec<GroupedMoveErrors<'tcx>> {
     let mut grouped_errors = Vec::new();
-    for error in errors.iter() {
+    for error in errors {
         append_to_grouped_errors(&mut grouped_errors, error)
     }
     return grouped_errors;

src/librustc_borrowck/borrowck/move_data.rs

@@ -475,13 +475,13 @@ impl<'tcx> MoveData<'tcx> {
             self.kill_moves(assignment.path, assignment.id, dfcx_moves);
         }
 
-        for assignment in self.path_assignments.borrow().iter() {
+        for assignment in &*self.path_assignments.borrow() {
             self.kill_moves(assignment.path, assignment.id, dfcx_moves);
         }
 
         // Kill all moves related to a variable `x` when
         // it goes out of scope:
-        for path in self.paths.borrow().iter() {
+        for path in &*self.paths.borrow() {
             match path.loan_path.kind {
                 LpVar(..) | LpUpvar(..) | LpDowncast(..) => {
                     let kill_scope = path.loan_path.kill_scope(tcx);
@@ -633,11 +633,11 @@ impl<'a, 'tcx> FlowedMoveData<'a, 'tcx> {
         //! Returns the kind of a move of `loan_path` by `id`, if one exists.
 
         let mut ret = None;
-        for loan_path_index in self.move_data.path_map.borrow().get(&*loan_path).iter() {
+        if let Some(loan_path_index) = self.move_data.path_map.borrow().get(&*loan_path) {
             self.dfcx_moves.each_gen_bit(id, |move_index| {
                 let the_move = self.move_data.moves.borrow();
                 let the_move = (*the_move)[move_index];
-                if the_move.path == **loan_path_index {
+                if the_move.path == *loan_path_index {
                     ret = Some(the_move.kind);
                     false
                 } else {
@@ -688,7 +688,7 @@ impl<'a, 'tcx> FlowedMoveData<'a, 'tcx> {
                     ret = false;
                 }
             } else {
-                for &loan_path_index in opt_loan_path_index.iter() {
+                if let Some(loan_path_index) = opt_loan_path_index {
                     let cont = self.move_data.each_base_path(moved_path, |p| {
                         if p == loan_path_index {
                             // Scenario 3: some extension of `loan_path`
@@ -699,7 +699,7 @@ impl<'a, 'tcx> FlowedMoveData<'a, 'tcx> {
                             true
                         }
                     });
-                    if !cont { ret = false; break }
+                    if !cont { ret = false; }
                 }
             }
             ret

src/librustc_borrowck/graphviz.rs

@@ -56,7 +56,7 @@ impl<'a, 'tcx> DataflowLabeller<'a, 'tcx> {
         debug!("dataflow_for({:?}, id={}) {:?}", e, id, self.variants);
         let mut sets = "".to_string();
         let mut seen_one = false;
-        for &variant in self.variants.iter() {
+        for &variant in &self.variants {
             if seen_one { sets.push_str(" "); } else { seen_one = true; }
             sets.push_str(variant.short_name());
             sets.push_str(": ");

src/librustc_driver/driver.rs

@@ -760,11 +760,11 @@ fn write_out_deps(sess: &Session,
                   id: &str) {
 
     let mut out_filenames = Vec::new();
-    for output_type in sess.opts.output_types.iter() {
+    for output_type in &sess.opts.output_types {
         let file = outputs.path(*output_type);
         match *output_type {
             config::OutputTypeExe => {
-                for output in sess.crate_types.borrow().iter() {
+                for output in &*sess.crate_types.borrow() {
                     let p = link::filename_for_input(sess, *output,
                                                      id, &file);
                     out_filenames.push(p);
@@ -800,7 +800,7 @@ fn write_out_deps(sess: &Session,
                                    .map(|fmap| escape_dep_filename(&fmap.name[]))
                                    .collect();
         let mut file = try!(old_io::File::create(&deps_filename));
-        for path in out_filenames.iter() {
+        for path in &out_filenames {
             try!(write!(&mut file as &mut Writer,
                           "{}: {}\n\n", path.display(), files.connect(" ")));
         }

src/librustc_driver/lib.rs

@@ -435,7 +435,7 @@ Available lint options:
 
 fn describe_debug_flags() {
     println!("\nAvailable debug options:\n");
-    for &(name, _, opt_type_desc, desc) in config::DB_OPTIONS.iter() {
+    for &(name, _, opt_type_desc, desc) in config::DB_OPTIONS {
         let (width, extra) = match opt_type_desc {
             Some(..) => (21, "=val"),
             None => (25, "")
@@ -447,7 +447,7 @@ fn describe_debug_flags() {
 
 fn describe_codegen_flags() {
     println!("\nAvailable codegen options:\n");
-    for &(name, _, opt_type_desc, desc) in config::CG_OPTIONS.iter() {
+    for &(name, _, opt_type_desc, desc) in config::CG_OPTIONS {
         let (width, extra) = match opt_type_desc {
             Some(..) => (21, "=val"),
             None => (25, "")
@@ -542,7 +542,7 @@ fn print_crate_info(sess: &Session,
     if sess.opts.prints.len() == 0 { return false }
 
     let attrs = input.map(|input| parse_crate_attrs(sess, input));
-    for req in sess.opts.prints.iter() {
+    for req in &sess.opts.prints {
         match *req {
             PrintRequest::Sysroot => println!("{}", sess.sysroot().display()),
             PrintRequest::FileNames |
@@ -566,7 +566,7 @@ fn print_crate_info(sess: &Session,
                 let crate_types = driver::collect_crate_types(sess, attrs);
                 let metadata = driver::collect_crate_metadata(sess, attrs);
                 *sess.crate_metadata.borrow_mut() = metadata;
-                for &style in crate_types.iter() {
+                for &style in &crate_types {
                     let fname = link::filename_for_input(sess, style,
                                                          id.as_slice(),
                                                          &t_outputs.with_extension(""));
@@ -645,7 +645,7 @@ pub fn monitor<F:FnOnce()+Send>(f: F) {
                             BUG_REPORT_URL),
                     "run with `RUST_BACKTRACE=1` for a backtrace".to_string(),
                 ];
-                for note in xs.iter() {
+                for note in &xs {
                     emitter.emit(None, &note[], None, diagnostic::Note)
                 }
 

src/librustc_driver/test.rs

@@ -147,7 +147,7 @@ impl<'a, 'tcx> Env<'a, 'tcx> {
     }
 
     pub fn create_region_hierarchy(&self, rh: &RH) {
-        for child_rh in rh.sub.iter() {
+        for child_rh in rh.sub {
             self.create_region_hierarchy(child_rh);
             self.infcx.tcx.region_maps.record_encl_scope(
                 CodeExtent::from_node_id(child_rh.id),
@@ -181,7 +181,7 @@ impl<'a, 'tcx> Env<'a, 'tcx> {
                       names: &[String])
                       -> Option<ast::NodeId> {
             assert!(idx < names.len());
-            for item in m.items.iter() {
+            for item in &m.items {
                 if item.ident.user_string(this.infcx.tcx) == names[idx] {
                     return search(this, &**item, idx+1, names);
                 }

src/librustc_llvm/lib.rs

@@ -261,13 +261,13 @@ impl AttrBuilder {
     }
 
     pub fn apply_llfn(&self, llfn: ValueRef) {
-        for &(idx, ref attr) in self.attrs.iter() {
+        for &(idx, ref attr) in &self.attrs {
             attr.apply_llfn(idx as c_uint, llfn);
         }
     }
 
     pub fn apply_callsite(&self, callsite: ValueRef) {
-        for &(idx, ref attr) in self.attrs.iter() {
+        for &(idx, ref attr) in &self.attrs {
             attr.apply_callsite(idx as c_uint, callsite);
         }
     }

src/librustc_privacy/lib.rs

@@ -79,7 +79,7 @@ impl<'v> Visitor<'v> for ParentVisitor {
             // Enum variants are parented to the enum definition itself because
             // they inherit privacy
             ast::ItemEnum(ref def, _) => {
-                for variant in def.variants.iter() {
+                for variant in &def.variants {
                     // The parent is considered the enclosing enum because the
                     // enum will dictate the privacy visibility of this variant
                     // instead.
@@ -93,7 +93,7 @@ impl<'v> Visitor<'v> for ParentVisitor {
             // parent all the methods to the trait to indicate that they're
             // private.
             ast::ItemTrait(_, _, _, ref methods) if item.vis != ast::Public => {
-                for m in methods.iter() {
+                for m in methods {
                     match *m {
                         ast::ProvidedMethod(ref m) => {
                             self.parents.insert(m.id, item.id);
@@ -139,7 +139,7 @@ impl<'v> Visitor<'v> for ParentVisitor {
 
         // While we have the id of the struct definition, go ahead and parent
         // all the fields.
-        for field in s.fields.iter() {
+        for field in &s.fields {
             self.parents.insert(field.node.id, self.curparent);
         }
         visit::walk_struct_def(self, s)
@@ -233,7 +233,7 @@ impl<'a, 'tcx, 'v> Visitor<'v> for EmbargoVisitor<'a, 'tcx> {
             // Enum variants inherit from their parent, so if the enum is
             // public all variants are public unless they're explicitly priv
             ast::ItemEnum(ref def, _) if public_first => {
-                for variant in def.variants.iter() {
+                for variant in &def.variants {
                     self.exported_items.insert(variant.node.id);
                 }
             }
@@ -278,7 +278,7 @@ impl<'a, 'tcx, 'v> Visitor<'v> for EmbargoVisitor<'a, 'tcx> {
                 });
 
                 if public_ty || public_trait {
-                    for impl_item in impl_items.iter() {
+                    for impl_item in impl_items {
                         match *impl_item {
                             ast::MethodImplItem(ref method) => {
                                 let meth_public =
@@ -299,7 +299,7 @@ impl<'a, 'tcx, 'v> Visitor<'v> for EmbargoVisitor<'a, 'tcx> {
             // Default methods on traits are all public so long as the trait
             // is public
             ast::ItemTrait(_, _, _, ref methods) if public_first => {
-                for method in methods.iter() {
+                for method in methods {
                     match *method {
                         ast::ProvidedMethod(ref m) => {
                             debug!("provided {}", m.id);
@@ -359,7 +359,7 @@ impl<'a, 'tcx, 'v> Visitor<'v> for EmbargoVisitor<'a, 'tcx> {
         // crate module gets processed as well.
         if self.prev_exported {
             assert!(self.export_map.contains_key(&id), "wut {}", id);
-            for export in self.export_map[id].iter() {
+            for export in &self.export_map[id] {
                 if is_local(export.def_id) {
                     self.reexports.insert(export.def_id.node);
                 }
@@ -837,7 +837,7 @@ impl<'a, 'tcx, 'v> Visitor<'v> for PrivacyVisitor<'a, 'tcx> {
                 match vpath.node {
                     ast::ViewPathSimple(..) | ast::ViewPathGlob(..) => {}
                     ast::ViewPathList(ref prefix, ref list) => {
-                        for pid in list.iter() {
+                        for pid in list {
                             match pid.node {
                                 ast::PathListIdent { id, name } => {
                                     debug!("privacy - ident item {}", id);
@@ -898,7 +898,7 @@ impl<'a, 'tcx, 'v> Visitor<'v> for PrivacyVisitor<'a, 'tcx> {
             ast::ExprStruct(_, ref fields, _) => {
                 match ty::expr_ty(self.tcx, expr).sty {
                     ty::ty_struct(id, _) => {
-                        for field in (*fields).iter() {
+                        for field in &(*fields) {
                             self.check_field(expr.span, id,
                                              NamedField(field.ident.node));
                         }
@@ -906,7 +906,7 @@ impl<'a, 'tcx, 'v> Visitor<'v> for PrivacyVisitor<'a, 'tcx> {
                     ty::ty_enum(_, _) => {
                         match self.tcx.def_map.borrow()[expr.id].clone() {
                             def::DefVariant(_, variant_id, _) => {
-                                for field in fields.iter() {
+                                for field in fields {
                                     self.check_field(expr.span, variant_id,
                                                      NamedField(field.ident.node));
                                 }
@@ -971,7 +971,7 @@ impl<'a, 'tcx, 'v> Visitor<'v> for PrivacyVisitor<'a, 'tcx> {
             ast::PatStruct(_, ref fields, _) => {
                 match ty::pat_ty(self.tcx, pattern).sty {
                     ty::ty_struct(id, _) => {
-                        for field in fields.iter() {
+                        for field in fields {
                             self.check_field(pattern.span, id,
                                              NamedField(field.node.ident));
                         }
@@ -979,7 +979,7 @@ impl<'a, 'tcx, 'v> Visitor<'v> for PrivacyVisitor<'a, 'tcx> {
                     ty::ty_enum(_, _) => {
                         match self.tcx.def_map.borrow().get(&pattern.id) {
                             Some(&def::DefVariant(_, variant_id, _)) => {
-                                for field in fields.iter() {
+                                for field in fields {
                                     self.check_field(pattern.span, variant_id,
                                                      NamedField(field.node.ident));
                                 }
@@ -1091,7 +1091,7 @@ impl<'a, 'tcx> SanePrivacyVisitor<'a, 'tcx> {
                 check_inherited(item.span, item.vis,
                                 "visibility qualifiers have no effect on trait \
                                  impls");
-                for impl_item in impl_items.iter() {
+                for impl_item in impl_items {
                     match *impl_item {
                         ast::MethodImplItem(ref m) => {
                             check_inherited(m.span, m.pe_vis(), "");
@@ -1112,7 +1112,7 @@ impl<'a, 'tcx> SanePrivacyVisitor<'a, 'tcx> {
             }
 
             ast::ItemEnum(ref def, _) => {
-                for v in def.variants.iter() {
+                for v in &def.variants {
                     match v.node.vis {
                         ast::Public => {
                             if item.vis == ast::Public {
@@ -1126,7 +1126,7 @@ impl<'a, 'tcx> SanePrivacyVisitor<'a, 'tcx> {
             }
 
             ast::ItemTrait(_, _, _, ref methods) => {
-                for m in methods.iter() {
+                for m in methods {
                     match *m {
                         ast::ProvidedMethod(ref m) => {
                             check_inherited(m.span, m.pe_vis(),
@@ -1157,7 +1157,7 @@ impl<'a, 'tcx> SanePrivacyVisitor<'a, 'tcx> {
             }
         }
         let check_struct = |&: def: &ast::StructDef| {
-            for f in def.fields.iter() {
+            for f in &def.fields {
                match f.node.kind {
                     ast::NamedField(_, p) => check_inherited(tcx, f.span, p),
                     ast::UnnamedField(..) => {}
@@ -1167,7 +1167,7 @@ impl<'a, 'tcx> SanePrivacyVisitor<'a, 'tcx> {
         check_inherited(tcx, item.span, item.vis);
         match item.node {
             ast::ItemImpl(_, _, _, _, _, ref impl_items) => {
-                for impl_item in impl_items.iter() {
+                for impl_item in impl_items {
                     match *impl_item {
                         ast::MethodImplItem(ref m) => {
                             check_inherited(tcx, m.span, m.pe_vis());
@@ -1177,12 +1177,12 @@ impl<'a, 'tcx> SanePrivacyVisitor<'a, 'tcx> {
                 }
             }
             ast::ItemForeignMod(ref fm) => {
-                for i in fm.items.iter() {
+                for i in &fm.items {
                     check_inherited(tcx, i.span, i.vis);
                 }
             }
             ast::ItemEnum(ref def, _) => {
-                for v in def.variants.iter() {
+                for v in &def.variants {
                     check_inherited(tcx, v.span, v.node.vis);
                 }
             }
@@ -1190,7 +1190,7 @@ impl<'a, 'tcx> SanePrivacyVisitor<'a, 'tcx> {
             ast::ItemStruct(ref def, _) => check_struct(&**def),
 
             ast::ItemTrait(_, _, _, ref methods) => {
-                for m in methods.iter() {
+                for m in methods {
                     match *m {
                         ast::RequiredMethod(..) => {}
                         ast::ProvidedMethod(ref m) => check_inherited(tcx, m.span,
@@ -1302,7 +1302,7 @@ impl<'a, 'tcx, 'v> Visitor<'v> for VisiblePrivateTypesVisitor<'a, 'tcx> {
                     return
                 }
 
-                for bound in bounds.iter() {
+                for bound in &**bounds {
                     self.check_ty_param_bound(bound)
                 }
             }
@@ -1371,7 +1371,7 @@ impl<'a, 'tcx, 'v> Visitor<'v> for VisiblePrivateTypesVisitor<'a, 'tcx> {
 
                     match *trait_ref {
                         None => {
-                            for impl_item in impl_items.iter() {
+                            for impl_item in impl_items {
                                 match *impl_item {
                                     ast::MethodImplItem(ref method) => {
                                         visit::walk_method_helper(self, &**method)
@@ -1400,7 +1400,7 @@ impl<'a, 'tcx, 'v> Visitor<'v> for VisiblePrivateTypesVisitor<'a, 'tcx> {
                     // impl Public<Private> { ... }. Any public static
                     // methods will be visible as `Public::foo`.
                     let mut found_pub_static = false;
-                    for impl_item in impl_items.iter() {
+                    for impl_item in impl_items {
                         match *impl_item {
                             ast::MethodImplItem(ref method) => {
                                 if method.pe_explicit_self().node ==
@@ -1439,15 +1439,15 @@ impl<'a, 'tcx, 'v> Visitor<'v> for VisiblePrivateTypesVisitor<'a, 'tcx> {
     }
 
     fn visit_generics(&mut self, generics: &ast::Generics) {
-        for ty_param in generics.ty_params.iter() {
-            for bound in ty_param.bounds.iter() {
+        for ty_param in &*generics.ty_params {
+            for bound in &*ty_param.bounds {
                 self.check_ty_param_bound(bound)
             }
         }
-        for predicate in generics.where_clause.predicates.iter() {
+        for predicate in &generics.where_clause.predicates {
             match predicate {
                 &ast::WherePredicate::BoundPredicate(ref bound_pred) => {
-                    for bound in bound_pred.bounds.iter() {
+                    for bound in &*bound_pred.bounds {
                         self.check_ty_param_bound(bound)
                     }
                 }

src/librustc_resolve/build_reduced_graph.rs

@@ -223,8 +223,8 @@ impl<'a, 'b:'a, 'tcx:'b> GraphBuilder<'a, 'b, 'tcx> {
                              token::get_name(name))[]);
                     {
                         let r = child.span_for_namespace(ns);
-                        for sp in r.iter() {
-                            self.session.span_note(*sp,
+                        if let Some(sp) = r {
+                            self.session.span_note(sp,
                                  &format!("first definition of {} `{}` here",
                                       namespace_error_to_string(duplicate_type),
                                       token::get_name(name))[]);
@@ -238,7 +238,7 @@ impl<'a, 'b:'a, 'tcx:'b> GraphBuilder<'a, 'b, 'tcx> {
 
     fn block_needs_anonymous_module(&mut self, block: &Block) -> bool {
         // Check each statement.
-        for statement in block.stmts.iter() {
+        for statement in &block.stmts {
             match statement.node {
                 StmtDecl(ref declaration, _) => {
                     match declaration.node {
@@ -338,7 +338,7 @@ impl<'a, 'b:'a, 'tcx:'b> GraphBuilder<'a, 'b, 'tcx> {
                             }
                         }
 
-                        for source_item in source_items.iter() {
+                        for source_item in source_items {
                             let (module_path, name) = match source_item.node {
                                 PathListIdent { name, .. } =>
                                     (module_path.clone(), name.name),
@@ -477,7 +477,7 @@ impl<'a, 'b:'a, 'tcx:'b> GraphBuilder<'a, 'b, 'tcx> {
 
                 let module = name_bindings.get_module();
 
-                for variant in (*enum_definition).variants.iter() {
+                for variant in &(*enum_definition).variants {
                     self.build_reduced_graph_for_variant(
                         &**variant,
                         local_def(item.id),
@@ -591,7 +591,7 @@ impl<'a, 'b:'a, 'tcx:'b> GraphBuilder<'a, 'b, 'tcx> {
                 };
 
                 // For each implementation item...
-                for impl_item in impl_items.iter() {
+                for impl_item in impl_items {
                     match *impl_item {
                         MethodImplItem(ref method) => {
                             // Add the method to the module.
@@ -675,7 +675,7 @@ impl<'a, 'b:'a, 'tcx:'b> GraphBuilder<'a, 'b, 'tcx> {
                 let def_id = local_def(item.id);
 
                 // Add the names of all the items to the trait info.
-                for trait_item in items.iter() {
+                for trait_item in items {
                     let (name, kind) = match *trait_item {
                         ast::RequiredMethod(_) |
                         ast::ProvidedMethod(_) => {
@@ -926,7 +926,7 @@ impl<'a, 'b:'a, 'tcx:'b> GraphBuilder<'a, 'b, 'tcx> {
 
               let trait_item_def_ids =
                 csearch::get_trait_item_def_ids(&self.session.cstore, def_id);
-              for trait_item_def_id in trait_item_def_ids.iter() {
+              for trait_item_def_id in &trait_item_def_ids {
                   let (trait_item_name, trait_item_kind) =
                       csearch::get_trait_item_name_and_kind(
                           &self.session.cstore,
@@ -1082,7 +1082,7 @@ impl<'a, 'b:'a, 'tcx:'b> GraphBuilder<'a, 'b, 'tcx> {
 
                                 // Add each static method to the module.
                                 let new_parent = type_module;
-                                for method_info in methods.iter() {
+                                for method_info in methods {
                                     let name = method_info.name;
                                     debug!("(building reduced graph for \
                                              external crate) creating \

src/librustc_resolve/check_unused.rs

@@ -136,7 +136,7 @@ impl<'a, 'b, 'v, 'tcx> Visitor<'v> for UnusedImportCheckVisitor<'a, 'b, 'tcx> {
                     }
 
                     ViewPathList(_, ref list) => {
-                        for i in list.iter() {
+                        for i in list {
                             self.finalize_import(i.node.id(), i.span);
                         }
                     }

src/librustc_resolve/lib.rs

@@ -1031,7 +1031,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
         self.current_module = orig_module;
 
         build_reduced_graph::populate_module_if_necessary(self, &module_);
-        for (_, child_node) in module_.children.borrow().iter() {
+        for (_, child_node) in &*module_.children.borrow() {
             match child_node.get_module_if_available() {
                 None => {
                     // Nothing to do.
@@ -1042,7 +1042,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
             }
         }
 
-        for (_, child_module) in module_.anonymous_children.borrow().iter() {
+        for (_, child_module) in &*module_.anonymous_children.borrow() {
             self.resolve_imports_for_module_subtree(child_module.clone());
         }
     }
@@ -1087,7 +1087,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
     fn names_to_string(&self, names: &[Name]) -> String {
         let mut first = true;
         let mut result = String::new();
-        for name in names.iter() {
+        for name in names {
             if first {
                 first = false
             } else {
@@ -1596,7 +1596,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
 
         // Add all resolved imports from the containing module.
         let import_resolutions = containing_module.import_resolutions.borrow();
-        for (ident, target_import_resolution) in import_resolutions.iter() {
+        for (ident, target_import_resolution) in &*import_resolutions {
             debug!("(resolving glob import) writing module resolution \
                     {} into `{}`",
                    token::get_name(*ident),
@@ -1657,7 +1657,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
         // Add all children from the containing module.
         build_reduced_graph::populate_module_if_necessary(self, &containing_module);
 
-        for (&name, name_bindings) in containing_module.children.borrow().iter() {
+        for (&name, name_bindings) in &*containing_module.children.borrow() {
             self.merge_import_resolution(module_,
                                          containing_module.clone(),
                                          import_directive,
@@ -1667,7 +1667,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
         }
 
         // Add external module children from the containing module.
-        for (&name, module) in containing_module.external_module_children.borrow().iter() {
+        for (&name, module) in &*containing_module.external_module_children.borrow() {
             let name_bindings =
                 Rc::new(Resolver::create_name_bindings_from_module(module.clone()));
             self.merge_import_resolution(module_,
@@ -2519,7 +2519,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
         // Descend into children and anonymous children.
         build_reduced_graph::populate_module_if_necessary(self, &module_);
 
-        for (_, child_node) in module_.children.borrow().iter() {
+        for (_, child_node) in &*module_.children.borrow() {
             match child_node.get_module_if_available() {
                 None => {
                     // Continue.
@@ -2530,7 +2530,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
             }
         }
 
-        for (_, module_) in module_.anonymous_children.borrow().iter() {
+        for (_, module_) in &*module_.anonymous_children.borrow() {
             self.report_unresolved_imports(module_.clone());
         }
     }
@@ -2609,7 +2609,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
             DlDef(d @ DefLocal(_)) => {
                 let node_id = d.def_id().node;
                 let mut def = d;
-                for rib in ribs.iter() {
+                for rib in ribs {
                     match rib.kind {
                         NormalRibKind => {
                             // Nothing to do. Continue.
@@ -2680,7 +2680,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
             }
             DlDef(def @ DefTyParam(..)) |
             DlDef(def @ DefSelfTy(..)) => {
-                for rib in ribs.iter() {
+                for rib in ribs {
                     match rib.kind {
                         NormalRibKind | ClosureRibKind(..) => {
                             // Nothing to do. Continue.
@@ -2795,8 +2795,8 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
             // enum item: resolve all the variants' discrs,
             // then resolve the ty params
             ItemEnum(ref enum_def, ref generics) => {
-                for variant in (*enum_def).variants.iter() {
-                    for dis_expr in variant.node.disr_expr.iter() {
+                for variant in &(*enum_def).variants {
+                    if let Some(ref dis_expr) = variant.node.disr_expr {
                         // resolve the discriminator expr
                         // as a constant
                         self.with_constant_rib(|this| {
@@ -2863,7 +2863,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
                     this.resolve_type_parameter_bounds(item.id, bounds,
                                                        TraitDerivation);
 
-                    for trait_item in (*trait_items).iter() {
+                    for trait_item in &(*trait_items) {
                         // Create a new rib for the trait_item-specific type
                         // parameters.
                         //
@@ -2885,7 +2885,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
                                 this.resolve_where_clause(&ty_m.generics
                                                                .where_clause);
 
-                                for argument in ty_m.decl.inputs.iter() {
+                                for argument in &ty_m.decl.inputs {
                                     this.resolve_type(&*argument.ty);
                                 }
 
@@ -2929,7 +2929,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
 
             ItemForeignMod(ref foreign_module) => {
                 self.with_scope(Some(name), |this| {
-                    for foreign_item in foreign_module.items.iter() {
+                    for foreign_item in &foreign_module.items {
                         match foreign_item.node {
                             ForeignItemFn(_, ref generics) => {
                                 this.with_type_parameter_rib(
@@ -3075,7 +3075,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
                 }
                 Some(declaration) => {
                     let mut bindings_list = HashMap::new();
-                    for argument in declaration.inputs.iter() {
+                    for argument in &declaration.inputs {
                         this.resolve_pattern(&*argument.pat,
                                              ArgumentIrrefutableMode,
                                              &mut bindings_list);
@@ -3103,14 +3103,14 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
 
     fn resolve_type_parameters(&mut self,
                                type_parameters: &OwnedSlice<TyParam>) {
-        for type_parameter in type_parameters.iter() {
+        for type_parameter in &**type_parameters {
             self.resolve_type_parameter(type_parameter);
         }
     }
 
     fn resolve_type_parameter(&mut self,
                               type_parameter: &TyParam) {
-        for bound in type_parameter.bounds.iter() {
+        for bound in &*type_parameter.bounds {
             self.resolve_type_parameter_bound(type_parameter.id, bound,
                                               TraitBoundingTypeParameter);
         }
@@ -3124,7 +3124,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
                                      id: NodeId,
                                      type_parameter_bounds: &OwnedSlice<TyParamBound>,
                                      reference_type: TraitReferenceType) {
-        for type_parameter_bound in type_parameter_bounds.iter() {
+        for type_parameter_bound in &**type_parameter_bounds {
             self.resolve_type_parameter_bound(id, type_parameter_bound,
                                               reference_type);
         }
@@ -3193,12 +3193,12 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
     }
 
     fn resolve_where_clause(&mut self, where_clause: &ast::WhereClause) {
-        for predicate in where_clause.predicates.iter() {
+        for predicate in &where_clause.predicates {
             match predicate {
                 &ast::WherePredicate::BoundPredicate(ref bound_pred) => {
                     self.resolve_type(&*bound_pred.bounded_ty);
 
-                    for bound in bound_pred.bounds.iter() {
+                    for bound in &*bound_pred.bounds {
                         self.resolve_type_parameter_bound(bound_pred.bounded_ty.id, bound,
                                                           TraitBoundingTypeParameter);
                     }
@@ -3236,7 +3236,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
             this.resolve_where_clause(&generics.where_clause);
 
             // Resolve fields.
-            for field in fields.iter() {
+            for field in fields {
                 this.resolve_type(&*field.node.ty);
             }
         });
@@ -3320,7 +3320,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
                 this.resolve_type(self_type);
 
                 this.with_current_self_type(self_type, |this| {
-                    for impl_item in impl_items.iter() {
+                    for impl_item in impl_items {
                         match *impl_item {
                             MethodImplItem(ref method) => {
                                 // If this is a trait impl, ensure the method
@@ -3375,7 +3375,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
 
     fn check_trait_item(&self, name: Name, span: Span) {
         // If there is a TraitRef in scope for an impl, then the method must be in the trait.
-        for &(did, ref trait_ref) in self.current_trait_ref.iter() {
+        if let Some((did, ref trait_ref)) = self.current_trait_ref {
             if self.trait_item_map.get(&(name, did)).is_none() {
                 let path_str = self.path_names_to_string(&trait_ref.path);
                 self.resolve_error(span,
@@ -3442,7 +3442,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
         for (i, p) in arm.pats.iter().enumerate() {
             let map_i = self.binding_mode_map(&**p);
 
-            for (&key, &binding_0) in map_0.iter() {
+            for (&key, &binding_0) in &map_0 {
                 match map_i.get(&key) {
                   None => {
                     self.resolve_error(
@@ -3465,7 +3465,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
                 }
             }
 
-            for (&key, &binding) in map_i.iter() {
+            for (&key, &binding) in &map_i {
                 if !map_0.contains_key(&key) {
                     self.resolve_error(
                         binding.span,
@@ -3482,7 +3482,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
         self.value_ribs.push(Rib::new(NormalRibKind));
 
         let mut bindings_list = HashMap::new();
-        for pattern in arm.pats.iter() {
+        for pattern in &arm.pats {
             self.resolve_pattern(&**pattern, RefutableMode, &mut bindings_list);
         }
 
@@ -3513,7 +3513,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
 
         // Check for imports appearing after non-item statements.
         let mut found_non_item = false;
-        for statement in block.stmts.iter() {
+        for statement in &block.stmts {
             if let ast::StmtDecl(ref declaration, _) = statement.node {
                 if let ast::DeclItem(ref i) = declaration.node {
                     match i.node {
@@ -4365,7 +4365,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
         let mut values: Vec<uint> = Vec::new();
 
         for rib in this.value_ribs.iter().rev() {
-            for (&k, _) in rib.bindings.iter() {
+            for (&k, _) in &rib.bindings {
                 maybes.push(token::get_name(k));
                 values.push(uint::MAX);
             }
@@ -4640,7 +4640,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
             build_reduced_graph::populate_module_if_necessary(self, &search_module);
 
             {
-                for (_, child_names) in search_module.children.borrow().iter() {
+                for (_, child_names) in &*search_module.children.borrow() {
                     let def = match child_names.def_for_namespace(TypeNS) {
                         Some(def) => def,
                         None => continue
@@ -4656,7 +4656,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
             }
 
             // Look for imports.
-            for (_, import) in search_module.import_resolutions.borrow().iter() {
+            for (_, import) in &*search_module.import_resolutions.borrow() {
                 let target = match import.target_for_namespace(TypeNS) {
                     None => continue,
                     Some(target) => target,
@@ -4766,13 +4766,13 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
 
         debug!("Children:");
         build_reduced_graph::populate_module_if_necessary(self, &module_);
-        for (&name, _) in module_.children.borrow().iter() {
+        for (&name, _) in &*module_.children.borrow() {
             debug!("* {}", token::get_name(name));
         }
 
         debug!("Import resolutions:");
         let import_resolutions = module_.import_resolutions.borrow();
-        for (&name, import_resolution) in import_resolutions.iter() {
+        for (&name, import_resolution) in &*import_resolutions {
             let value_repr;
             match import_resolution.target_for_namespace(ValueNS) {
                 None => { value_repr = "".to_string(); }

src/librustc_resolve/record_exports.rs

@@ -80,7 +80,7 @@ impl<'a, 'b, 'tcx> ExportRecorder<'a, 'b, 'tcx> {
         self.record_exports_for_module(&*module_);
         build_reduced_graph::populate_module_if_necessary(self.resolver, &module_);
 
-        for (_, child_name_bindings) in module_.children.borrow().iter() {
+        for (_, child_name_bindings) in &*module_.children.borrow() {
             match child_name_bindings.get_module_if_available() {
                 None => {
                     // Nothing to do.
@@ -91,7 +91,7 @@ impl<'a, 'b, 'tcx> ExportRecorder<'a, 'b, 'tcx> {
             }
         }
 
-        for (_, child_module) in module_.anonymous_children.borrow().iter() {
+        for (_, child_module) in &*module_.anonymous_children.borrow() {
             self.record_exports_for_module_subtree(child_module.clone());
         }
     }
@@ -133,12 +133,12 @@ impl<'a, 'b, 'tcx> ExportRecorder<'a, 'b, 'tcx> {
     fn add_exports_for_module(&mut self,
                               exports: &mut Vec<Export>,
                               module_: &Module) {
-        for (name, importresolution) in module_.import_resolutions.borrow().iter() {
+        for (name, importresolution) in &*module_.import_resolutions.borrow() {
             if !importresolution.is_public {
                 continue
             }
             let xs = [TypeNS, ValueNS];
-            for &ns in xs.iter() {
+            for &ns in &xs {
                 match importresolution.target_for_namespace(ns) {
                     Some(target) => {
                         debug!("(computing exports) maybe export '{}'",

src/librustc_trans/back/link.rs

@@ -194,7 +194,7 @@ fn symbol_hash<'tcx>(tcx: &ty::ctxt<'tcx>,
     symbol_hasher.input_str(&link_meta.crate_name[]);
     symbol_hasher.input_str("-");
     symbol_hasher.input_str(link_meta.crate_hash.as_str());
-    for meta in tcx.sess.crate_metadata.borrow().iter() {
+    for meta in &*tcx.sess.crate_metadata.borrow() {
         symbol_hasher.input_str(&meta[]);
     }
     symbol_hasher.input_str("-");
@@ -370,7 +370,7 @@ pub fn link_binary(sess: &Session,
                    outputs: &OutputFilenames,
                    crate_name: &str) -> Vec<Path> {
     let mut out_filenames = Vec::new();
-    for &crate_type in sess.crate_types.borrow().iter() {
+    for &crate_type in &*sess.crate_types.borrow() {
         if invalid_output_for_target(sess, crate_type) {
             sess.bug(&format!("invalid output type `{:?}` for target os `{}`",
                              crate_type, sess.opts.target_triple)[]);
@@ -535,7 +535,7 @@ fn link_rlib<'a>(sess: &'a Session,
     let mut ab = ArchiveBuilder::create(config);
     ab.add_file(obj_filename).unwrap();
 
-    for &(ref l, kind) in sess.cstore.get_used_libraries().borrow().iter() {
+    for &(ref l, kind) in &*sess.cstore.get_used_libraries().borrow() {
         match kind {
             cstore::NativeStatic => {
                 ab.add_native_library(&l[]).unwrap();
@@ -721,7 +721,7 @@ fn link_staticlib(sess: &Session, obj_filename: &Path, out_filename: &Path) {
     let crates = sess.cstore.get_used_crates(cstore::RequireStatic);
     let mut all_native_libs = vec![];
 
-    for &(cnum, ref path) in crates.iter() {
+    for &(cnum, ref path) in &crates {
         let ref name = sess.cstore.get_crate_data(cnum).name;
         let p = match *path {
             Some(ref p) => p.clone(), None => {
@@ -746,7 +746,7 @@ fn link_staticlib(sess: &Session, obj_filename: &Path, out_filename: &Path) {
                   and so may need to be preserved");
     }
 
-    for &(kind, ref lib) in all_native_libs.iter() {
+    for &(kind, ref lib) in &all_native_libs {
         let name = match kind {
             cstore::NativeStatic => "static library",
             cstore::NativeUnknown => "library",
@@ -1133,7 +1133,7 @@ fn add_upstream_rust_crates(cmd: &mut Command, sess: &Session,
     // crates.
     let deps = sess.cstore.get_used_crates(cstore::RequireDynamic);
 
-    for &(cnum, _) in deps.iter() {
+    for &(cnum, _) in &deps {
         // We may not pass all crates through to the linker. Some crates may
         // appear statically in an existing dylib, meaning we'll pick up all the
         // symbols from the dylib.
@@ -1277,7 +1277,7 @@ fn add_upstream_native_libraries(cmd: &mut Command, sess: &Session) {
     let crates = sess.cstore.get_used_crates(cstore::RequireStatic);
     for (cnum, _) in crates.into_iter() {
         let libs = csearch::get_native_libraries(&sess.cstore, cnum);
-        for &(kind, ref lib) in libs.iter() {
+        for &(kind, ref lib) in &libs {
             match kind {
                 cstore::NativeUnknown => {
                     cmd.arg(format!("-l{}", *lib));