Add a test case for conditional drop

src/test/run-pass/generator/conditional-drop.rs

@@ -0,0 +1,65 @@
+// 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(generators, generator_trait)]
+
+use std::ops::Generator;
+use std::sync::atomic::{AtomicUsize, ATOMIC_USIZE_INIT, Ordering};
+
+static A: AtomicUsize = ATOMIC_USIZE_INIT;
+
+struct B;
+
+impl Drop for B {
+    fn drop(&mut self) {
+        A.fetch_add(1, Ordering::SeqCst);
+    }
+}
+
+
+fn test() -> bool { true }
+fn test2() -> bool { false }
+
+fn main() {
+    t1();
+    t2();
+}
+
+fn t1() {
+    let mut a = || {
+        let b = B;
+        if test() {
+            drop(b);
+        }
+        yield;
+    };
+
+    let n = A.load(Ordering::SeqCst);
+    a.resume();
+    assert_eq!(A.load(Ordering::SeqCst), n + 1);
+    a.resume();
+    assert_eq!(A.load(Ordering::SeqCst), n + 1);
+}
+
+fn t2() {
+    let mut a = || {
+        let b = B;
+        if test2() {
+            drop(b);
+        }
+        yield;
+    };
+
+    let n = A.load(Ordering::SeqCst);
+    a.resume();
+    assert_eq!(A.load(Ordering::SeqCst), n);
+    a.resume();
+    assert_eq!(A.load(Ordering::SeqCst), n + 1);
+}