Rollup merge of #44464 - Dushistov:master, r=alexcrichton

add test for #41229

Closes #41229

src/test/compile-fail/issue-41229-ref-str.rs

@@ -0,0 +1,16 @@
+// 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.
+
+pub fn example(ref s: str) {}
+//~^ ERROR the trait bound `str: std::marker::Sized` is not satisfied
+//~| `str` does not have a constant size known at compile-time
+//~| the trait `std::marker::Sized` is not implemented for `str`
+
+fn main() {}