auto merge of #16836 : P1start/rust/closure_ret_bang, r=alexcrichton

Fixes #13490.

Author: bors

src/libsyntax/parse/parser.rs

@@ -4143,20 +4143,20 @@ impl<'a> Parser<'a> {
                 (optional_unboxed_closure_kind, args)
             }
         };
-        let output = if self.eat(&token::RARROW) {
-            self.parse_ty(true)
+        let (style, output) = if self.token == token::RARROW {
+            self.parse_ret_ty()
         } else {
-            P(Ty {
+            (Return, P(Ty {
                 id: ast::DUMMY_NODE_ID,
                 node: TyInfer,
                 span: self.span,
-            })
+            }))
         };
 
         (P(FnDecl {
             inputs: inputs_captures,
             output: output,
-            cf: Return,
+            cf: style,
             variadic: false
         }), optional_unboxed_closure_kind)
     }
@@ -4169,20 +4169,20 @@ impl<'a> Parser<'a> {
                                      seq_sep_trailing_allowed(token::COMMA),
                                      |p| p.parse_fn_block_arg());
 
-        let output = if self.eat(&token::RARROW) {
-            self.parse_ty(true)
+        let (style, output) = if self.token == token::RARROW {
+            self.parse_ret_ty()
         } else {
-            P(Ty {
+            (Return, P(Ty {
                 id: ast::DUMMY_NODE_ID,
                 node: TyInfer,
                 span: self.span,
-            })
+            }))
         };
 
         P(FnDecl {
             inputs: inputs,
             output: output,
-            cf: Return,
+            cf: style,
             variadic: false
         })
     }

src/test/compile-fail/closure-that-fails.rs

@@ -13,5 +13,8 @@ fn foo(f: || -> !) {}
 fn main() {
     // Type inference didn't use to be able to handle this:
     foo(|| fail!());
+    foo(|| -> ! fail!());
     foo(|| 22); //~ ERROR mismatched types
+    foo(|| -> ! 22); //~ ERROR mismatched types
+    let x = || -> ! 1; //~ ERROR mismatched types
 }

src/test/compile-fail/dead-code-closure-bang.rs

@@ -0,0 +1,17 @@
+// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#![deny(unreachable_code)]
+
+fn main() {
+    let x: || -> ! = || fail!();
+    x();
+    println!("Foo bar"); //~ ERROR: unreachable statement
+}

src/test/run-pass/closure-return-bang.rs

@@ -0,0 +1,20 @@
+// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#![allow(dead_code)]
+
+fn f(x: || -> !) -> ! {
+    x();
+}
+
+fn main() {
+    let x: || -> ! = || fail!();
+    let _y: || -> ! = || x();
+}

src/test/run-pass/closure-syntax.rs

@@ -78,6 +78,10 @@ fn bar<'b>() {
 
     let a = A;
     a.foo::<<'a>||>();
+
+    // issue #13490
+    let _ = || -> ! loop {};
+    let _ = proc() -> ! loop {};
 }
 
 struct B<T>;