auto merge of #20163 : bfops/rust/master, r=Gankro

TODOs:
  - ~~Entry is still `<'a, K, V>` instead of `<'a, O, V>`~~
  - ~~BTreeMap is still outstanding~~.
  - ~~Transform appropriate things into `.entry(...).get().or_else(|e| ...)`~~

Things that make me frowny face:
  - I'm not happy about the fact that this `clone`s the key even when it's already owned.
  - With small keys (e.g. `int`s), taking a reference seems wasteful.

r? @Gankro
cc: @cgaebel

2 files changed, 8 insertions, 11 deletions

diff --git a/src/libsyntax/ext/mtwt.rs b/src/libsyntax/ext/mtwt.rs
index bac82494f28..4075b208f78 100644
--- a/src/libsyntax/ext/mtwt.rs
+++ b/src/libsyntax/ext/mtwt.rs
@@ -21,7 +21,6 @@ use ast::{Ident, Mrk, Name, SyntaxContext};
 
 use std::cell::RefCell;
 use std::collections::HashMap;
-use std::collections::hash_map::Entry::{Occupied, Vacant};
 
 /// The SCTable contains a table of SyntaxContext_'s. It
 /// represents a flattened tree structure, to avoid having
@@ -67,10 +66,9 @@ pub fn apply_mark(m: Mrk, ctxt: SyntaxContext) -> SyntaxContext {
 /// Extend a syntax context with a given mark and sctable (explicit memoization)
 fn apply_mark_internal(m: Mrk, ctxt: SyntaxContext, table: &SCTable) -> SyntaxContext {
     let key = (ctxt, m);
-    * match table.mark_memo.borrow_mut().entry(key) {
-        Vacant(entry) => entry.set(idx_push(&mut *table.table.borrow_mut(), Mark(m, ctxt))),
-        Occupied(entry) => entry.into_mut(),
-    }
+    * table.mark_memo.borrow_mut().entry(&key).get().unwrap_or_else(
+          |vacant_entry|
+              vacant_entry.insert(idx_push(&mut *table.table.borrow_mut(), Mark(m, ctxt))))
 }
 
 /// Extend a syntax context with a given rename
@@ -86,10 +84,9 @@ fn apply_rename_internal(id: Ident,
                        table: &SCTable) -> SyntaxContext {
     let key = (ctxt, id, to);
 
-    * match table.rename_memo.borrow_mut().entry(key) {
-        Vacant(entry) => entry.set(idx_push(&mut *table.table.borrow_mut(), Rename(id, to, ctxt))),
-        Occupied(entry) => entry.into_mut(),
-    }
+    * table.rename_memo.borrow_mut().entry(&key).get().unwrap_or_else(
+          |vacant_entry|
+              vacant_entry.insert(idx_push(&mut *table.table.borrow_mut(), Rename(id, to, ctxt))))
 }
 
 /// Apply a list of renamings to a context
diff --git a/src/libsyntax/ext/tt/macro_parser.rs b/src/libsyntax/ext/tt/macro_parser.rs
index 69e473055e8..1438d152554 100644
--- a/src/libsyntax/ext/tt/macro_parser.rs
+++ b/src/libsyntax/ext/tt/macro_parser.rs
@@ -219,9 +219,9 @@ pub fn nameize(p_s: &ParseSess, ms: &[TokenTree], res: &[Rc<NamedMatch>])
                 }
             }
             &TtToken(sp, MatchNt(bind_name, _, _, _)) => {
-                match ret_val.entry(bind_name) {
+                match ret_val.entry(&bind_name) {
                     Vacant(spot) => {
-                        spot.set(res[*idx].clone());
+                        spot.insert(res[*idx].clone());
                         *idx += 1;
                     }
                     Occupied(..) => {