Safely handle partial drops

We previously weren't tracking partial re-inits while being too
aggressive around partial drops. With this change, we simply ignore
partial drops, which is the safer, more conservative choice.

1 files changed, 29 insertions, 0 deletions

diff --git a/src/test/ui/async-await/partial-drop-partial-reinit.rs b/src/test/ui/async-await/partial-drop-partial-reinit.rs
new file mode 100644
index 00000000000..73f0ca8153c
--- /dev/null
+++ b/src/test/ui/async-await/partial-drop-partial-reinit.rs
@@ -0,0 +1,29 @@
+// edition:2021
+#![feature(negative_impls)]
+#![allow(unused)]
+
+fn main() {
+    gimme_send(foo());
+    //~^ ERROR cannot be sent between threads safely
+}
+
+fn gimme_send<T: Send>(t: T) {
+    drop(t);
+}
+
+struct NotSend {}
+
+impl Drop for NotSend {
+    fn drop(&mut self) {}
+}
+
+impl !Send for NotSend {}
+
+async fn foo() {
+    let mut x = (NotSend {},);
+    drop(x.0);
+    x.0 = NotSend {};
+    bar().await;
+}
+
+async fn bar() {}