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, 4 insertions, 4 deletions

diff --git a/src/libcore/trie.rs b/src/libcore/trie.rs
index 26532c1a4ff..6b2f2bb6a7d 100644
--- a/src/libcore/trie.rs
+++ b/src/libcore/trie.rs
@@ -50,11 +50,11 @@ impl<T> ReverseIter<(uint, &'self T)> for TrieMap<T> {
 impl<T> Container for TrieMap<T> {
     /// Return the number of elements in the map
     #[inline(always)]
-    pure fn len(&self) -> uint { self.length }
+    pure fn len(&const self) -> uint { self.length }
 
     /// Return true if the map contains no elements
     #[inline(always)]
-    pure fn is_empty(&self) -> bool { self.len() == 0 }
+    pure fn is_empty(&const self) -> bool { self.len() == 0 }
 }
 
 impl<T> Mutable for TrieMap<T> {
@@ -178,11 +178,11 @@ impl ReverseIter<uint> for TrieSet {
 impl Container for TrieSet {
     /// Return the number of elements in the set
     #[inline(always)]
-    pure fn len(&self) -> uint { self.map.len() }
+    pure fn len(&const self) -> uint { self.map.len() }
 
     /// Return true if the set contains no elements
     #[inline(always)]
-    pure fn is_empty(&self) -> bool { self.map.is_empty() }
+    pure fn is_empty(&const self) -> bool { self.map.is_empty() }
 }
 
 impl Mutable for TrieSet {