Rollup merge of rust-lang#141031 - azhogin:azhogin/async-drop-dependency-fix, r=oli-obk

Async drop fix for dropee from another crate (rust-lang#140858)

Fixes rust-lang#140858.

For `AsyncDestructor` impl def id was wrongly kept as a LocalDefId, which causes crash when dropee is declared in another crate.

Also, potential problem found:
when user crate drops type with async drop in dependency crate, and user crate doesn't enable `feature(async_drop)`, then sync drop version will be used.

Is it a problem? Do we need some notification about such situations?

Author: matthiaskrgr

compiler/rustc_middle/src/ty/mod.rs

@@ -1185,7 +1185,7 @@ pub struct Destructor {
 #[derive(Copy, Clone, Debug, HashStable, Encodable, Decodable)]
 pub struct AsyncDestructor {
     /// The `DefId` of the `impl AsyncDrop`
-    pub impl_did: LocalDefId,
+    pub impl_did: DefId,
 }
 
 #[derive(Clone, Copy, PartialEq, Eq, HashStable, TyEncodable, TyDecodable)]

compiler/rustc_middle/src/ty/util.rs

@@ -465,7 +465,7 @@ impl<'tcx> TyCtxt<'tcx> {
             dtor_candidate = Some(impl_did);
         }
 
-        Some(ty::AsyncDestructor { impl_did: dtor_candidate? })
+        Some(ty::AsyncDestructor { impl_did: dtor_candidate?.into() })
     }
 
     /// Returns the set of types that are required to be alive in

tests/ui/async-await/async-drop/auxiliary/async-drop-dep.rs

@@ -0,0 +1,28 @@
+//@ edition:2021
+
+#![feature(async_drop)]
+#![allow(incomplete_features)]
+
+pub struct HasDrop;
+impl Drop for HasDrop{
+    fn drop(&mut self) {
+        println!("Sync drop");
+    }
+}
+
+pub struct MongoDrop;
+impl MongoDrop {
+    pub async fn new() -> Result<Self, HasDrop> {
+        Ok(Self)
+    }
+}
+impl Drop for MongoDrop{
+    fn drop(&mut self) {
+        println!("Sync drop");
+    }
+}
+impl std::future::AsyncDrop for MongoDrop {
+    async fn drop(self: std::pin::Pin<&mut Self>) {
+        println!("Async drop");
+    }
+}

tests/ui/async-await/async-drop/dependency-dropped.rs

@@ -0,0 +1,34 @@
+//@ run-pass
+//@ check-run-results
+//@ aux-build:async-drop-dep.rs
+//@ edition:2021
+
+#![feature(async_drop)]
+#![allow(incomplete_features)]
+
+extern crate async_drop_dep;
+
+use async_drop_dep::MongoDrop;
+use std::pin::pin;
+use std::task::{Context, Poll, Waker};
+use std::future::Future;
+
+async fn asyncdrop() {
+    let _ = MongoDrop::new().await;
+}
+
+pub fn block_on<T>(fut: impl Future<Output = T>) -> T {
+    let mut fut = pin!(fut);
+    let ctx = &mut Context::from_waker(Waker::noop());
+
+    loop {
+        match fut.as_mut().poll(ctx) {
+            Poll::Pending => {}
+            Poll::Ready(t) => break t,
+        }
+    }
+}
+
+fn main() {
+    let _ = block_on(asyncdrop());
+}

tests/ui/async-await/async-drop/dependency-dropped.run.stdout

@@ -0,0 +1 @@
+Async drop