auto merge of #19113 : nikomatsakis/rust/unboxed-boxed-closure-unification, r=acrichto

Use the expected type to infer the argument/return types of unboxed closures. Also, in `||` expressions, use the expected type to decide if the result should be a boxed or unboxed closure (and if an unboxed closure, what kind).

This supercedes PR #19089, which was already reviewed by @pcwalton.

2 files changed, 6 insertions, 5 deletions

diff --git a/src/libsyntax/ext/build.rs b/src/libsyntax/ext/build.rs
index ffc42b67033..b18a0c8411c 100644
--- a/src/libsyntax/ext/build.rs
+++ b/src/libsyntax/ext/build.rs
@@ -864,14 +864,14 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
 
     fn lambda_fn_decl(&self, span: Span,
                       fn_decl: P<ast::FnDecl>, blk: P<ast::Block>) -> P<ast::Expr> {
-        self.expr(span, ast::ExprFnBlock(ast::CaptureByRef, fn_decl, blk))
+        self.expr(span, ast::ExprClosure(ast::CaptureByRef, None, fn_decl, blk))
     }
     fn lambda(&self, span: Span, ids: Vec<ast::Ident>, blk: P<ast::Block>) -> P<ast::Expr> {
         let fn_decl = self.fn_decl(
             ids.iter().map(|id| self.arg(span, *id, self.ty_infer(span))).collect(),
             self.ty_infer(span));
 
-        self.expr(span, ast::ExprFnBlock(ast::CaptureByRef, fn_decl, blk))
+        self.expr(span, ast::ExprClosure(ast::CaptureByRef, None, fn_decl, blk))
     }
     fn lambda0(&self, span: Span, blk: P<ast::Block>) -> P<ast::Expr> {
         self.lambda(span, Vec::new(), blk)
diff --git a/src/libsyntax/ext/expand.rs b/src/libsyntax/ext/expand.rs
index 081456bebe1..04132679a03 100644
--- a/src/libsyntax/ext/expand.rs
+++ b/src/libsyntax/ext/expand.rs
@@ -207,10 +207,11 @@ pub fn expand_expr(e: P<ast::Expr>, fld: &mut MacroExpander) -> P<ast::Expr> {
             fld.cx.expr(span, ast::ExprForLoop(pat, head, body, opt_ident))
         }
 
-        ast::ExprFnBlock(capture_clause, fn_decl, block) => {
+        ast::ExprClosure(capture_clause, opt_kind, fn_decl, block) => {
             let (rewritten_fn_decl, rewritten_block)
                 = expand_and_rename_fn_decl_and_block(fn_decl, block, fld);
-            let new_node = ast::ExprFnBlock(capture_clause,
+            let new_node = ast::ExprClosure(capture_clause,
+                                            opt_kind,
                                             rewritten_fn_decl,
                                             rewritten_block);
             P(ast::Expr{id:id, node: new_node, span: fld.new_span(span)})
@@ -1555,7 +1556,7 @@ mod test {
             0)
     }
 
-    // closure arg hygiene (ExprFnBlock)
+    // closure arg hygiene (ExprClosure)
     // expands to fn f(){(|x_1 : int| {(x_2 + x_1)})(3);}
     #[test] fn closure_arg_hygiene(){
         run_renaming_test(