Rollup merge of #123049 - compiler-errors:coroutine-closure-rcvr, r=oli-obk

In `ConstructCoroutineInClosureShim`, pass receiver by mut ref, not mut pointer

The receivers were compatible at codegen time, but did not necessarily have the same layouts due to niches, which was caught by miri.

Fixes rust-lang/miri#3400

r? oli-obk

1 files changed, 3 insertions, 3 deletions

diff --git a/compiler/rustc_mir_transform/src/shim.rs b/compiler/rustc_mir_transform/src/shim.rs
index 94a95428ab0..b60ee7649b2 100644
--- a/compiler/rustc_mir_transform/src/shim.rs
+++ b/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| {