Regression test for Issue 21486.

Fix #21486

src/test/run-pass/issue-21486.rs

@@ -0,0 +1,86 @@
+// Copyright 2015 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.
+
+// Issue #21486: Make sure that all structures are dropped, even when
+// created via FRU and control-flow breaks in the middle of
+// construction.
+
+
+use std::sync::atomic::{Ordering, AtomicUsize, ATOMIC_USIZE_INIT};
+
+#[derive(Debug)]
+struct Noisy(u8);
+impl Drop for Noisy {
+    fn drop(&mut self) {
+        // println!("splat #{}", self.0);
+        event(self.0);
+    }
+}
+
+#[allow(dead_code)]
+#[derive(Debug)]
+struct Foo { n0: Noisy, n1: Noisy }
+impl Foo {
+    fn vals(&self) -> (u8, u8) { (self.n0.0, self.n1.0) }
+}
+
+fn leak_1_ret() -> Foo {
+    let _old_foo = Foo { n0: Noisy(1), n1: Noisy(2) };
+    Foo { n0: { return Foo { n0: Noisy(3), n1: Noisy(4) } },
+          .._old_foo
+    };
+}
+
+fn leak_2_ret() -> Foo {
+    let _old_foo = Foo { n0: Noisy(1), n1: Noisy(2) };
+    Foo { n1: { return Foo { n0: Noisy(3), n1: Noisy(4) } },
+          .._old_foo
+    };
+}
+
+// In this case, the control flow break happens *before* we construct
+// `Foo(Noisy(1),Noisy(2))`, so there should be no record of it in the
+// event log.
+fn leak_3_ret() -> Foo {
+    let _old_foo = || Foo { n0: Noisy(1), n1: Noisy(2) };
+    Foo { n1: { return Foo { n0: Noisy(3), n1: Noisy(4) } },
+          .._old_foo()
+    };
+}
+
+pub fn main() {
+    reset_log();
+    assert_eq!(leak_1_ret().vals(), (3,4));
+    assert_eq!(0x01_02_03_04, event_log());
+
+    reset_log();
+    assert_eq!(leak_2_ret().vals(), (3,4));
+    assert_eq!(0x01_02_03_04, event_log());
+
+    reset_log();
+    assert_eq!(leak_3_ret().vals(), (3,4));
+    assert_eq!(0x03_04, event_log());
+}
+
+static LOG: AtomicUsize = ATOMIC_USIZE_INIT;
+
+fn reset_log() {
+    LOG.store(0, Ordering::SeqCst);
+}
+
+fn event_log() -> usize {
+    LOG.load(Ordering::SeqCst)
+}
+
+fn event(tag: u8) {
+    let old_log = LOG.load(Ordering::SeqCst);
+    let new_log = (old_log << 8) + tag as usize;
+    LOG.store(new_log, Ordering::SeqCst);
+}