--- /dev/null
+// 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(universal_impl_trait)]
+
+use std::fmt::Debug;
+
+fn foo(x: impl Debug, y: impl Debug) -> String {
+ let mut a = x;
+ a = y;
+ format!("{:?}", a)
+}
+
+fn main() { }
--- /dev/null
+error[E0308]: mismatched types
+ --> $DIR/universal-two-impl-traits.rs:17:9
+ |
+17 | a = y;
+ | ^ expected type parameter, found a different type parameter
+ |
+ = note: expected type `impl Debug` (type parameter)
+ found type `impl Debug` (type parameter)
+
+error: aborting due to previous error
+