revert behaviour to warn!

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>>,
 }
@@ -37,7 +36,17 @@ 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 (_, value) in values.into_iter().enumerate() {
+        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);
+                    if expected_ty != op.layout.ty {
+                        warn!("Unexpected initial operand type. See the issues/114858");
+                    }
+                }
+            }
             self.locals.values.push(value);
         }
     }

tests/ui/codegen/subtyping-enforces-type-equality.rs

@@ -1,5 +1,6 @@
-// run-pass
+// build-pass
 // edition:2021
+#![allow(warnings)]
 use std::future::Future;
 use std::pin::Pin;
 

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