Add regression test for #19109

Closes #19109.

Author: jooert

src/test/compile-fail/issue-19109.rs

@@ -0,0 +1,22 @@
+// 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.
+
+trait Trait { }
+
+fn function(t: &mut Trait) {
+    t as *mut Trait
+ //~^ ERROR: mismatched types:
+ //~| expected `()`,
+ //~|    found `*mut Trait`
+ //~| (expected (),
+ //~|    found *-ptr) [E0308]
+}
+
+fn main() { }