collections: Enable IndexMut for some collections

This commit enables implementations of IndexMut for a number of collections,
including Vec, RingBuf, SmallIntMap, TrieMap, TreeMap, and HashMap. At the same
time this deprecates the `get_mut` methods on vectors in favor of using the
indexing notation.

cc #18424

3 files changed, 7 insertions, 9 deletions

diff --git a/src/libsyntax/ext/base.rs b/src/libsyntax/ext/base.rs
index a8326e79ef3..e641abbfeee 100644
--- a/src/libsyntax/ext/base.rs
+++ b/src/libsyntax/ext/base.rs
@@ -785,6 +785,6 @@ impl SyntaxEnv {
 
     pub fn info<'a>(&'a mut self) -> &'a mut BlockInfo {
         let last_chain_index = self.chain.len() - 1;
-        &mut self.chain.get_mut(last_chain_index).info
+        &mut self.chain[last_chain_index].info
     }
 }
diff --git a/src/libsyntax/ext/format.rs b/src/libsyntax/ext/format.rs
index 1b12ae67ee5..fa9a844233a 100644
--- a/src/libsyntax/ext/format.rs
+++ b/src/libsyntax/ext/format.rs
@@ -247,7 +247,7 @@ impl<'a, 'b> Context<'a, 'b> {
                     self.verify_same(self.args[arg].span, &ty, arg_type);
                 }
                 if self.arg_types[arg].is_none() {
-                    *self.arg_types.get_mut(arg) = Some(ty);
+                    self.arg_types[arg] = Some(ty);
                 }
             }
 
@@ -567,7 +567,7 @@ impl<'a, 'b> Context<'a, 'b> {
             let lname = self.ecx.ident_of(format!("__arg{}",
                                                   *name).as_slice());
             pats.push(self.ecx.pat_ident(e.span, lname));
-            *names.get_mut(self.name_positions[*name]) =
+            names[self.name_positions[*name]] =
                 Some(Context::format_arg(self.ecx, e.span, arg_ty,
                                          self.ecx.expr_ident(e.span, lname)));
             heads.push(self.ecx.expr_addr_of(e.span, e));
diff --git a/src/libsyntax/ext/tt/macro_parser.rs b/src/libsyntax/ext/tt/macro_parser.rs
index 9260a45adb9..4de20420148 100644
--- a/src/libsyntax/ext/tt/macro_parser.rs
+++ b/src/libsyntax/ext/tt/macro_parser.rs
@@ -288,8 +288,7 @@ pub fn parse(sess: &ParseSess,
                         // Only touch the binders we have actually bound
                         for idx in range(ei.match_lo, ei.match_hi) {
                             let sub = (ei.matches[idx]).clone();
-                            new_pos.matches
-                                   .get_mut(idx)
+                            new_pos.matches[idx]
                                    .push(Rc::new(MatchedSeq(sub, mk_sp(ei.sp_lo,
                                                                        sp.hi))));
                         }
@@ -331,8 +330,7 @@ pub fn parse(sess: &ParseSess,
                         new_ei.idx += 1u;
                         //we specifically matched zero repeats.
                         for idx in range(match_idx_lo, match_idx_hi) {
-                            new_ei.matches
-                                  .get_mut(idx)
+                            new_ei.matches[idx]
                                   .push(Rc::new(MatchedSeq(Vec::new(), sp)));
                         }
 
@@ -376,7 +374,7 @@ pub fn parse(sess: &ParseSess,
         if token_name_eq(&tok, &token::Eof) {
             if eof_eis.len() == 1u {
                 let mut v = Vec::new();
-                for dv in eof_eis.get_mut(0).matches.iter_mut() {
+                for dv in eof_eis[0].matches.iter_mut() {
                     v.push(dv.pop().unwrap());
                 }
                 return Success(nameize(sess, ms, v.as_slice()));
@@ -417,7 +415,7 @@ pub fn parse(sess: &ParseSess,
                 match ei.elts[ei.idx].node {
                   MatchNonterminal(_, name, idx) => {
                     let name_string = token::get_ident(name);
-                    ei.matches.get_mut(idx).push(Rc::new(MatchedNonterminal(
+                    ei.matches[idx].push(Rc::new(MatchedNonterminal(
                         parse_nt(&mut rust_parser, name_string.get()))));
                     ei.idx += 1u;
                   }