Add test for #17746

Closes #17746

src/test/run-pass/issue-17746.rs

@@ -0,0 +1,33 @@
+// 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.
+
+// Regression test for #17746
+
+fn main() {}
+
+struct A;
+
+impl A {
+    fn b(&mut self) {
+        self.a()
+    }
+}
+
+trait Foo {
+    fn dummy(&self) {}
+}
+trait Bar {
+    fn a(&self);
+}
+
+impl Foo for A {}
+impl<T> Bar for T where T: Foo {
+    fn a(&self) {}
+}