syntax: Rewrite parsing of impls

Properly parse impls for the never type `!`
Recover from missing `for` in `impl Trait for Type`
Prohibit inherent default impls and default impls of auto traits
Change wording in more diagnostics to use "auto traits"
Some minor code cleanups in the parser

1 files changed, 23 insertions, 0 deletions

diff --git a/src/test/compile-fail/specialization/defaultimpl/validation.rs b/src/test/compile-fail/specialization/defaultimpl/validation.rs
new file mode 100644
index 00000000000..26b8b737f34
--- /dev/null
+++ b/src/test/compile-fail/specialization/defaultimpl/validation.rs
@@ -0,0 +1,23 @@
+// Copyright 2017 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.
+
+#![feature(optin_builtin_traits)]
+#![feature(specialization)]
+
+struct S;
+struct Z;
+
+default impl S {} //~ ERROR inherent impls cannot be default
+
+default unsafe impl Send for S {} //~ ERROR impls of auto traits cannot be default
+default impl !Send for Z {} //~ ERROR impls of auto traits cannot be default
+
+trait Tr {}
+default impl !Tr for S {} //~ ERROR negative impls are only allowed for auto traits