rollup merge of #19041: japaric/clone

Closes #19037
cc #16918

r? @aturon

src/test/run-pass/issue-19037.rs

@@ -0,0 +1,26 @@
+// 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.
+
+struct Str([u8]);
+
+#[deriving(Clone)]
+struct CharSplits<'a, Sep> {
+    string: &'a Str,
+    sep: Sep,
+    allow_trailing_empty: bool,
+    only_ascii: bool,
+    finished: bool,
+}
+
+fn clone(s: &Str) -> &Str {
+    Clone::clone(&s)
+}
+
+fn main() {}