Add regression test for #29723

fixes #29723

Author: Manishearth

src/test/ui/issue-29723.rs

@@ -0,0 +1,25 @@
+// 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.
+
+#![feature(nll)]
+
+// test for https://github.com/rust-lang/rust/issues/29723
+
+fn foo() {
+    let s = String::new();
+    let _s = match 0 {
+        0 if { drop(s); false } => String::from("oops"),
+        _ => {
+            // This should trigger an error,
+            // s could have been moved from.
+            s
+        }
+    };
+}

src/test/ui/issue-29723.stderr

@@ -0,0 +1,13 @@
+error[E0382]: use of moved value: `s`
+  --> $DIR/issue-29723.rs:22:13
+   |
+18 |         0 if { drop(s); false } => String::from("oops"),
+   |                     - value moved here
+...
+22 |             s
+   |             ^ value used here after move
+   |
+   = note: move occurs because `s` has type `std::string::String`, which does not implement the `Copy` trait
+
+error: aborting due to previous error
+