librustc: Make the compiler ignore purity.

For bootstrapping purposes, this commit does not remove all uses of
the keyword "pure" -- doing so would cause the compiler to no longer
bootstrap due to some syntax extensions ("deriving" in particular).
Instead, it makes the compiler ignore "pure". Post-snapshot, we can
remove "pure" from the language.

There are quite a few (~100) borrow check errors that were essentially
all the result of mutable fields or partial borrows of `@mut`. Per
discussions with Niko I think we want to allow partial borrows of
`@mut` but detect obvious footguns. We should also improve the error
message when `@mut` is erroneously reborrowed.

1 files changed, 2 insertions, 4 deletions

diff --git a/src/libcore/mutable.rs b/src/libcore/mutable.rs
index 875d378b645..d0aa6e050f5 100644
--- a/src/libcore/mutable.rs
+++ b/src/libcore/mutable.rs
@@ -46,8 +46,7 @@ pub fn unwrap<T>(m: Mut<T>) -> T {
 pub impl<T> Data<T> {
     fn borrow_mut<R>(&self, op: &fn(t: &mut T) -> R) -> R {
         match self.mode {
-            Immutable => fail!(fmt!("%? currently immutable",
-                                   self.value)),
+            Immutable => fail!(~"currently immutable"),
             ReadOnly | Mutable => {}
         }
 
@@ -62,8 +61,7 @@ pub impl<T> Data<T> {
 
     fn borrow_imm<R>(&self, op: &fn(t: &T) -> R) -> R {
         match self.mode {
-          Mutable => fail!(fmt!("%? currently mutable",
-                               self.value)),
+          Mutable => fail!(~"currently mutable"),
           ReadOnly | Immutable => {}
         }