auto merge of #8294 : erickt/rust/map-move, r=bblum

According to #7887, we've decided to use the syntax of `fn map<U>(f: &fn(&T) -> U) -> U`, which passes a reference to the closure, and to `fn map_move<U>(f: &fn(T) -> U) -> U` which moves the value into the closure. This PR adds these `.map_move()` functions to `Option` and `Result`.

In addition, it has these other minor features:
 
* Replaces a couple uses of `option.get()`, `result.get()`, and `result.get_err()` with `option.unwrap()`, `result.unwrap()`, and `result.unwrap_err()`. (See #8268 and #8288 for a more thorough adaptation of this functionality.
* Removes `option.take_map()` and `option.take_map_default()`. These two functions can be easily written as `.take().map_move(...)`.
* Adds a better error message to `result.unwrap()` and `result.unwrap_err()`.

2 files changed, 2 insertions, 2 deletions

diff --git a/src/libsyntax/ext/base.rs b/src/libsyntax/ext/base.rs
index 6ed5ca3e402..efaf6b8e001 100644
--- a/src/libsyntax/ext/base.rs
+++ b/src/libsyntax/ext/base.rs
@@ -479,7 +479,7 @@ impl <K: Eq + Hash + IterBytes + 'static, V: 'static> MapChain<K,V>{
             ConsMapChain(ref map,_) => map
         };
         // strip one layer of indirection off the pointer.
-        map.find(key).map(|r| {**r})
+        map.find(key).map_move(|r| {*r})
     }
 
     // insert the binding into the top-level map
diff --git a/src/libsyntax/ext/build.rs b/src/libsyntax/ext/build.rs
index c373a389488..d81dca005b0 100644
--- a/src/libsyntax/ext/build.rs
+++ b/src/libsyntax/ext/build.rs
@@ -591,7 +591,7 @@ impl AstBuilder for @ExtCtxt {
 
     fn expr_if(&self, span: span,
                cond: @ast::expr, then: @ast::expr, els: Option<@ast::expr>) -> @ast::expr {
-        let els = els.map(|x| self.expr_block(self.block_expr(*x)));
+        let els = els.map_move(|x| self.expr_block(self.block_expr(x)));
         self.expr(span, ast::expr_if(cond, self.block_expr(then), els))
     }