In ConstructCoroutineInClosureShim, pass receiver by ref, not pointer

compiler/rustc_mir_transform/src/shim.rs

@@ -1015,8 +1015,8 @@ fn build_construct_coroutine_by_move_shim<'tcx>(
  bug!();
  };
 
- // We use `*mut Self` here because we only need to emit an ABI-compatible shim body,
- // rather than match the signature exactly.
+ // We use `&mut Self` here because we only need to emit an ABI-compatible shim body,
+ // rather than match the signature exactly (which might take `&self` instead).
  //
  // The self type here is a coroutine-closure, not a coroutine, and we never read from
  // it because it never has any captures, because this is only true in the Fn/FnMut
@@ -1025,7 +1025,7 @@ fn build_construct_coroutine_by_move_shim<'tcx>(
  if receiver_by_ref {
  // Triple-check that there's no captures here.
  assert_eq!(args.as_coroutine_closure().tupled_upvars_ty(), tcx.types.unit);
- self_ty = Ty::new_mut_ptr(tcx, self_ty);
+ self_ty = Ty::new_mut_ref(tcx, tcx.lifetimes.re_erased, self_ty);
  }
 
  let poly_sig = args.as_coroutine_closure().coroutine_closure_sig().map_bound(|sig| {

compiler/rustc_ty_utils/src/abi.rs

@@ -125,8 +125,12 @@ fn fn_sig_for_fn_abi<'tcx>(
  coroutine_kind = ty::ClosureKind::FnOnce;
 
  // Implementations of `FnMut` and `Fn` for coroutine-closures
- // still take their receiver by ref.
- if receiver_by_ref { Ty::new_mut_ptr(tcx, coroutine_ty) } else { coroutine_ty }
+ // still take their receiver by (mut) ref.
+ if receiver_by_ref {
+ Ty::new_mut_ref(tcx, tcx.lifetimes.re_erased, coroutine_ty)
+ } else {
+ coroutine_ty
+ }
  } else {
  tcx.closure_env_ty(coroutine_ty, coroutine_kind, env_region)
  };

src/tools/miri/tests/pass/async-closure-drop.rs

@@ -0,0 +1,40 @@
+#![feature(async_closure, noop_waker, async_fn_traits)]
+
+use std::future::Future;
+use std::pin::pin;
+use std::task::*;
+
+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,
+ }
+ }
+}
+
+async fn call_once(f: impl async FnOnce(DropMe)) {
+ f(DropMe("world")).await;
+}
+
+#[derive(Debug)]
+struct DropMe(&'static str);
+
+impl Drop for DropMe {
+ fn drop(&mut self) {
+ println!("{}", self.0);
+ }
+}
+
+pub fn main() {
+ block_on(async {
+ let b = DropMe("hello");
+ let async_closure = async move |a: DropMe| {
+ println!("{a:?} {b:?}");
+ };
+ call_once(async_closure).await;
+ });
+}

src/tools/miri/tests/pass/async-closure-drop.stdout

@@ -0,0 +1,3 @@
+DropMe("world") DropMe("hello")
+world
+hello

src/tools/miri/tests/pass/async-closure.rs

@@ -1,6 +1,7 @@
 #![feature(async_closure, noop_waker, async_fn_traits)]
 
 use std::future::Future;
+use std::ops::{AsyncFnMut, AsyncFnOnce};
 use std::pin::pin;
 use std::task::*;
 
@@ -16,25 +17,36 @@ pub fn block_on<T>(fut: impl Future<Output = T>) -> T {
  }
 }
 
-async fn call_once(f: impl async FnOnce(DropMe)) {
- f(DropMe("world")).await;
+async fn call_mut(f: &mut impl AsyncFnMut(i32)) {
+ f(0).await;
 }
 
-#[derive(Debug)]
-struct DropMe(&'static str);
+async fn call_once(f: impl AsyncFnOnce(i32)) {
+ f(1).await;
+}
 
-impl Drop for DropMe {
- fn drop(&mut self) {
- println!("{}", self.0);
- }
+async fn call_normal<F: Future<Output = ()>>(f: &impl Fn(i32) -> F) {
+ f(0).await;
+}
+
+async fn call_normal_once<F: Future<Output = ()>>(f: impl FnOnce(i32) -> F) {
+ f(1).await;
 }
 
 pub fn main() {
  block_on(async {
- let b = DropMe("hello");
- let async_closure = async move |a: DropMe| {
- println!("{a:?} {b:?}");
+ let b = 2i32;
+ let mut async_closure = async move |a: i32| {
+ println!("{a} {b}");
  };
+ call_mut(&mut async_closure).await;
  call_once(async_closure).await;
+
+ // No-capture closures implement `Fn`.
+ let async_closure = async move |a: i32| {
+ println!("{a}");
+ };
+ call_normal(&async_closure).await;
+ call_normal_once(async_closure).await;
  });
 }

src/tools/miri/tests/pass/async-closure.stdout

@@ -1,3 +1,4 @@
-DropMe("world") DropMe("hello")
-world
-hello
+0 2
+1 2
+0
+1

tests/mir-opt/async_closure_shims.main-{closure#0}-{closure#1}.coroutine_closure_by_ref.0.panic-abort.mir

@@ -1,6 +1,6 @@
 // MIR for `main::{closure#0}::{closure#1}` 0 coroutine_closure_by_ref
 
-fn main::{closure#0}::{closure#1}(_1: *mut {async closure@$DIR/async_closure_shims.rs:49:29: 49:48}, _2: i32) -> {async closure body@$DIR/async_closure_shims.rs:49:49: 51:10} {
+fn main::{closure#0}::{closure#1}(_1: &mut {async closure@$DIR/async_closure_shims.rs:49:29: 49:48}, _2: i32) -> {async closure body@$DIR/async_closure_shims.rs:49:49: 51:10} {
  let mut _0: {async closure body@$DIR/async_closure_shims.rs:49:49: 51:10};
 
  bb0: {

tests/mir-opt/async_closure_shims.main-{closure#0}-{closure#1}.coroutine_closure_by_ref.0.panic-unwind.mir

@@ -1,6 +1,6 @@
 // MIR for `main::{closure#0}::{closure#1}` 0 coroutine_closure_by_ref
 
-fn main::{closure#0}::{closure#1}(_1: *mut {async closure@$DIR/async_closure_shims.rs:49:29: 49:48}, _2: i32) -> {async closure body@$DIR/async_closure_shims.rs:49:49: 51:10} {
+fn main::{closure#0}::{closure#1}(_1: &mut {async closure@$DIR/async_closure_shims.rs:49:29: 49:48}, _2: i32) -> {async closure body@$DIR/async_closure_shims.rs:49:49: 51:10} {
  let mut _0: {async closure body@$DIR/async_closure_shims.rs:49:49: 51:10};
 
  bb0: {