auto merge of #5213 : erickt/rust/vec-ref, r=graydon

This patch series changes a handful of vec functions to return references instead of copies. The one downside with making this change is that these functions aren't usable in a couple cases now due to some purity complaints. For example, this [change](https://github.com/erickt/rust/commit/c31e81a532fc07e89be33cadb5109d167aa725f4#L1R87). I couldn't figure out a way to get `last` to work on a `@mut ~[...]` type, so I ended up having to use `*crate_cache[crate_cache.len() - 1].metas`.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/libstd/workcache.rs b/src/libstd/workcache.rs
index 1dd7bfd75db..c46c2d17ed0 100644
--- a/src/libstd/workcache.rs
+++ b/src/libstd/workcache.rs
@@ -174,7 +174,7 @@ pub impl Database {
         let k = json_encode(&(fn_name, declared_inputs));
         match self.db_cache.find(&k) {
             None => None,
-            Some(&v) => Some(json_decode(copy v))
+            Some(v) => Some(json_decode(*v))
         }
     }