Make `+` in `impl/dyn Trait` non-associative

1 files changed, 59 insertions, 0 deletions

diff --git a/src/test/ui/impl-trait/impl-trait-plus-priority.rs b/src/test/ui/impl-trait/impl-trait-plus-priority.rs
new file mode 100644
index 00000000000..f451123ca27
--- /dev/null
+++ b/src/test/ui/impl-trait/impl-trait-plus-priority.rs
@@ -0,0 +1,59 @@
+// 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.
+
+// compile-flags: -Z parse-only -Z continue-parse-after-error
+
+fn f() -> impl A + {} // OK
+fn f() -> impl A + B {} // OK
+fn f() -> dyn A + B {} // OK
+fn f() -> A + B {} // OK
+
+impl S {
+    fn f(self) -> impl A + { // OK
+        let _ = |a, b| -> impl A + {}; // OK
+    }
+    fn f(self) -> impl A + B { // OK
+        let _ = |a, b| -> impl A + B {}; // OK
+    }
+    fn f(self) -> dyn A + B { // OK
+        let _ = |a, b| -> dyn A + B {}; // OK
+    }
+    fn f(self) -> A + B { // OK
+        let _ = |a, b| -> A + B {}; // OK
+    }
+}
+
+type A = fn() -> impl A +;
+//~^ ERROR ambiguous `+` in a type
+type A = fn() -> impl A + B;
+//~^ ERROR ambiguous `+` in a type
+type A = fn() -> dyn A + B;
+//~^ ERROR ambiguous `+` in a type
+type A = fn() -> A + B;
+//~^ ERROR expected a path on the left-hand side of `+`, not `fn() -> A`
+
+type A = Fn() -> impl A +;
+//~^ ERROR ambiguous `+` in a type
+type A = Fn() -> impl A + B;
+//~^ ERROR ambiguous `+` in a type
+type A = Fn() -> dyn A + B;
+//~^ ERROR ambiguous `+` in a type
+type A = Fn() -> A + B; // OK, interpreted as `(Fn() -> A) + B` for compatibility
+
+type A = &impl A +;
+//~^ ERROR ambiguous `+` in a type
+type A = &impl A + B;
+//~^ ERROR ambiguous `+` in a type
+type A = &dyn A + B;
+//~^ ERROR ambiguous `+` in a type
+type A = &A + B;
+//~^ ERROR expected a path on the left-hand side of `+`, not `&A`
+
+fn main() {}