Auto merge of #115215 - ouz-a:mir_issue, r=lcnr

Remove assert that checks type equality

https://github.com/rust-lang/rust/pull/112307 although this prevented `unsound` issues it also seems to introduce regressions https://github.com/rust-lang/rust/issues/114858 is example of this regression. I locally tested this https://github.com/rust-lang/rust/issues/114858#issuecomment-1686502262 issue and failing assert is [this](https://www.diffchecker.com/cjb7jSQm/).

This is also related to https://github.com/rust-lang/rust/pull/115025

3 files changed, 53 insertions, 4 deletions

diff --git a/compiler/rustc_codegen_ssa/src/mir/locals.rs b/compiler/rustc_codegen_ssa/src/mir/locals.rs
index da8bf5e7916..378c5401322 100644
--- a/compiler/rustc_codegen_ssa/src/mir/locals.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/locals.rs
@@ -7,7 +7,6 @@ use rustc_index::IndexVec;
 use rustc_middle::mir;
 use rustc_middle::ty::print::with_no_trimmed_paths;
 use std::ops::{Index, IndexMut};
-
 pub(super) struct Locals<'tcx, V> {
     values: IndexVec<mir::Local, LocalRef<'tcx, V>>,
 }
@@ -36,17 +35,18 @@ impl<'tcx, V> Locals<'tcx, V> {
 impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
     pub(super) fn initialize_locals(&mut self, values: Vec<LocalRef<'tcx, Bx::Value>>) {
         assert!(self.locals.values.is_empty());
-
+        // FIXME(#115215): After #115025 get's merged this might not be necessary
         for (local, value) in values.into_iter().enumerate() {
             match value {
                 LocalRef::Place(_) | LocalRef::UnsizedPlace(_) | LocalRef::PendingOperand => (),
                 LocalRef::Operand(op) => {
                     let local = mir::Local::from_usize(local);
                     let expected_ty = self.monomorphize(self.mir.local_decls[local].ty);
-                    assert_eq!(expected_ty, op.layout.ty, "unexpected initial operand type");
+                    if expected_ty != op.layout.ty {
+                        warn!("Unexpected initial operand type. See the issues/114858");
+                    }
                 }
             }
-
             self.locals.values.push(value);
         }
     }
diff --git a/tests/ui/codegen/subtyping-enforces-type-equality.rs b/tests/ui/codegen/subtyping-enforces-type-equality.rs
new file mode 100644
index 00000000000..a5ffcb3f854
--- /dev/null
+++ b/tests/ui/codegen/subtyping-enforces-type-equality.rs
@@ -0,0 +1,48 @@
+// ignore-pass
+// build-pass
+// edition:2021
+use std::future::Future;
+use std::pin::Pin;
+
+type BoxFuture<T> = Pin<Box<dyn Future<Output = T>>>;
+
+fn main() {
+    let _ = wrapper_call(handler);
+}
+
+async fn wrapper_call(handler: impl Handler) {
+    handler.call().await;
+}
+async fn handler() {
+    f(&()).await;
+}
+async fn f<'a>(db: impl Acquire<'a>) {
+    db.acquire().await;
+}
+
+trait Handler {
+    type Future: Future;
+    fn call(self) -> Self::Future;
+}
+
+impl<Fut, F> Handler for F
+where
+    F: Fn() -> Fut,
+    Fut: Future,
+{
+    type Future = Fut;
+    fn call(self) -> Self::Future {
+        loop {}
+    }
+}
+
+trait Acquire<'a> {
+    type Connection;
+    fn acquire(self) -> BoxFuture<Self::Connection>;
+}
+impl<'a> Acquire<'a> for &'a () {
+    type Connection = Self;
+    fn acquire(self) -> BoxFuture<Self> {
+        loop {}
+    }
+}
diff --git a/tests/ui/codegen/subtyping-enforces-type-equality.stderr b/tests/ui/codegen/subtyping-enforces-type-equality.stderr
new file mode 100644
index 00000000000..870ca0f839f
--- /dev/null
+++ b/tests/ui/codegen/subtyping-enforces-type-equality.stderr
@@ -0,0 +1 @@
+WARN rustc_codegen_ssa::mir::locals Unexpected initial operand type. See the issues/114858