Add regression test for #19380

Closes #19380.

Author: jooert

src/test/compile-fail/issue-19380.rs

@@ -0,0 +1,28 @@
+// 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 Qiz {
+  fn qiz();
+}
+
+struct Foo;
+impl Qiz for Foo {
+  fn qiz() {}
+}
+
+struct Bar {
+  foos: &'static [&'static (Qiz + 'static)]
+}
+
+const FOO : Foo = Foo;
+const BAR : Bar = Bar { foos: &[&FOO]};
+//~^ ERROR: cannot convert to a trait object because trait `Qiz` is not object-safe [E0038]
+
+fn main() { }