Regression test for complex case of rust-lang#9197

Closes rust-lang#9197.

src/test/compile-fail/redundant-trait-bounds.rs

@@ -0,0 +1,20 @@
+// Copyright 2013-2015 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.
+
+trait Foo {
+  fn noop(&self) {}
+}
+
+trait Bar: Foo {}
+
+#[allow(dead_code)]
+fn bar<T: Foo + Bar>() {}
+
+fn main() {}