auto merge of #6286 : nikomatsakis/rust/issue-5910-dyna-freeze, r=nikomatsakis

This rather sprawling branch refactors the borrow checker and much of the region code, addressing a number of outstanding issues. I will close them manually after validating that there are test cases for each one, but here is a (probably partial) list:

  - #4903: Flow sensitivity
  - #3387: Moves in overloaded operators
  - #3850: Region granularity
  - #4666: Odd loaning errors
  - #6021: borrow check errors with hashmaps
  - #5910: @mut broken

cc #5047

(take 5)

Author: bors

Makefile.in

@@ -110,6 +110,9 @@ endif
 ifdef SAVE_TEMPS
   CFG_RUSTC_FLAGS += --save-temps
 endif
+ifdef ASM_COMMENTS
+  CFG_RUSTC_FLAGS += -z asm-comments
+endif
 ifdef TIME_PASSES
   CFG_RUSTC_FLAGS += -Z time-passes
 endif

src/libcore/cell.rs

@@ -42,7 +42,7 @@ pub fn empty_cell<T>() -> Cell<T> {
 pub impl<T> Cell<T> {
     /// Yields the value, failing if the cell is empty.
     fn take(&self) -> T {
-        let mut self = unsafe { transmute_mut(self) };
+        let self = unsafe { transmute_mut(self) };
         if self.is_empty() {
             fail!(~"attempt to take an empty cell");
         }
@@ -54,7 +54,7 @@ pub impl<T> Cell<T> {
 
     /// Returns the value, failing if the cell is full.
     fn put_back(&self, value: T) {
-        let mut self = unsafe { transmute_mut(self) };
+        let self = unsafe { transmute_mut(self) };
         if !self.is_empty() {
             fail!(~"attempt to put a value back into a full cell");
         }