syntax: make match arms store the expr directly.

Previously `ast::Arm` was always storing a single `ast::Expr` wrapped in an
`ast::Block` (for historical reasons, AIUI), so we might as just store
that expr directly.

Closes #3085.

2 files changed, 3 insertions, 3 deletions

diff --git a/src/libsyntax/ext/build.rs b/src/libsyntax/ext/build.rs
index 34625923ea1..8296ee34c54 100644
--- a/src/libsyntax/ext/build.rs
+++ b/src/libsyntax/ext/build.rs
@@ -679,7 +679,7 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
         ast::Arm {
             pats: pats,
             guard: None,
-            body: self.block_expr(expr)
+            body: expr
         }
     }
 
diff --git a/src/libsyntax/ext/deriving/primitive.rs b/src/libsyntax/ext/deriving/primitive.rs
index ecd042eb172..190f009103f 100644
--- a/src/libsyntax/ext/deriving/primitive.rs
+++ b/src/libsyntax/ext/deriving/primitive.rs
@@ -110,7 +110,7 @@ fn cs_from(name: &str, cx: &mut ExtCtxt, trait_span: Span, substr: &Substructure
                         let arm = ast::Arm {
                             pats: vec!(cx.pat_wild(span)),
                             guard: Some(guard),
-                            body: cx.block_expr(body),
+                            body: body,
                         };
 
                         arms.push(arm);
@@ -129,7 +129,7 @@ fn cs_from(name: &str, cx: &mut ExtCtxt, trait_span: Span, substr: &Substructure
             let arm = ast::Arm {
                 pats: vec!(cx.pat_wild(trait_span)),
                 guard: None,
-                body: cx.block_expr(cx.expr_none(trait_span)),
+                body: cx.expr_none(trait_span),
             };
             arms.push(arm);