Add regression test for issue #17734

Author: bkoropoff

src/test/run-pass/issue-17734.rs

@@ -0,0 +1,23 @@
+// Copyright 2014 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.
+
+// Test that generating drop glue for Box<str> doesn't ICE
+
+fn f(s: Box<str>) -> Box<str> {
+    s
+}
+
+fn main() {
+    // There is currently no safe way to construct a `Box<str>`, so improvise
+    let box_arr: Box<[u8]> = box ['h' as u8, 'e' as u8, 'l' as u8, 'l' as u8, 'o' as u8];
+    let box_str: Box<str> = unsafe { std::mem::transmute(box_arr) };
+    assert_eq!(box_str.as_slice(), "hello");
+    f(box_str);
+}