Ensure that borrows wind up unactivated.

src/test/run-fail/issue-51345.rs

@@ -0,0 +1,18 @@
+// Copyright 2012 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.
+
+// error-pattern: thread 'main' panicked at 'explicit panic'
+
+#![feature(nll)]
+
+fn main() {
+    let mut vec = vec![];
+    vec.push((vec.len(), panic!()));
+}