auto merge of #12812 : sfackler/rust/attr-arm, r=alexcrichton

This is really only useful for #[cfg()]. For example:

```rust
enum Foo {
    Bar,
    Baz,
    #[cfg(blob)]
    Blob
}

fn match_foos(f: &Foo) {
    match *f {
        Bar => {}
        Baz => {}
        #[cfg(blob)]
        Blob => {}
    }
}
```

This is a kind of weird place to allow attributes, so it should probably
be discussed before merging.

1 files changed, 7 insertions, 1 deletions

diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs
index 8808312bed7..f30d756d854 100644
--- a/src/libsyntax/parse/parser.rs
+++ b/src/libsyntax/parse/parser.rs
@@ -2539,6 +2539,7 @@ impl<'a> Parser<'a> {
         self.commit_expr_expecting(discriminant, token::LBRACE);
         let mut arms: Vec<Arm> = Vec::new();
         while self.token != token::RBRACE {
+            let attrs = self.parse_outer_attributes();
             let pats = self.parse_pats();
             let mut guard = None;
             if self.eat_keyword(keywords::If) {
@@ -2557,7 +2558,12 @@ impl<'a> Parser<'a> {
                 self.eat(&token::COMMA);
             }
 
-            arms.push(ast::Arm { pats: pats, guard: guard, body: expr });
+            arms.push(ast::Arm {
+                attrs: attrs,
+                pats: pats,
+                guard: guard,
+                body: expr
+            });
         }
         let hi = self.span.hi;
         self.bump();