Auto merge of #27432 - sanxiyn:impl-dotdot, r=sfackler

Fix #27255.

Author: bors

src/libsyntax/parse/parser.rs

@@ -4610,7 +4610,7 @@ impl<'a> Parser<'a> {
             None
         };
 
-        if try!(self.eat(&token::DotDot) ){
+        if opt_trait.is_some() && try!(self.eat(&token::DotDot) ){
             if generics.is_parameterized() {
                 self.span_err(impl_span, "default trait implementations are not \
                                           allowed to have generics");

src/test/parse-fail/empty-impl-semicolon.rs

@@ -10,4 +10,4 @@
 
 // compile-flags: -Z parse-only
 
-impl Foo; //~ ERROR expected one of `(`, `+`, `..`, `::`, `<`, `for`, `where`, or `{`, found `;`
+impl Foo; //~ ERROR expected one of `(`, `+`, `::`, `<`, `for`, `where`, or `{`, found `;`

src/test/parse-fail/issue-27255.rs

@@ -0,0 +1,15 @@
+// Copyright 2015 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.
+
+// compile-flags: -Z parse-only
+
+impl A .. {} //~ ERROR
+
+fn main() {}

src/test/parse-fail/multitrait.rs

@@ -15,7 +15,7 @@ struct S {
 }
 
 impl Cmp, ToString for S {
-//~^ ERROR: expected one of `(`, `+`, `..`, `::`, `<`, `for`, `where`, or `{`, found `,`
+//~^ ERROR: expected one of `(`, `+`, `::`, `<`, `for`, `where`, or `{`, found `,`
   fn eq(&&other: S) { false }
   fn to_string(&self) -> String { "hi".to_string() }
 }

src/test/parse-fail/trait-bounds-not-on-impl.rs

@@ -17,7 +17,7 @@ struct Bar;
 
 impl Foo + Owned for Bar {
 //~^ ERROR not a trait
-//~^^ ERROR expected one of `..`, `where`, or `{`, found `Bar`
+//~^^ ERROR expected one of `where` or `{`, found `Bar`
 }
 
 fn main() { }