Don't ICE when encountering error regions when confirming object method candidate

compiler/rustc_hir_typeck/src/method/confirm.rs

@@ -16,7 +16,8 @@ use rustc_middle::ty::adjustment::{Adjust, Adjustment, PointerCoercion};
 use rustc_middle::ty::adjustment::{AllowTwoPhase, AutoBorrow, AutoBorrowMutability};
 use rustc_middle::ty::fold::TypeFoldable;
 use rustc_middle::ty::{
- self, GenericArgs, GenericArgsRef, GenericParamDefKind, Ty, TyCtxt, UserArgs, UserType,
+ self, GenericArgs, GenericArgsRef, GenericParamDefKind, Ty, TyCtxt, TypeVisitableExt, UserArgs,
+ UserType,
 };
 use rustc_middle::{bug, span_bug};
 use rustc_span::{Span, DUMMY_SP};
@@ -268,6 +269,17 @@ impl<'a, 'tcx> ConfirmContext<'a, 'tcx> {
 
  probe::ObjectPick => {
  let trait_def_id = pick.item.container_id(self.tcx);
+
+ // This shouldn't happen for non-region error kinds, but may occur
+ // when we have error regions. Specifically, since we canonicalize
+ // during method steps, we may successfully deref when we assemble
+ // the pick, but fail to deref when we try to extract the object
+ // type from the pick during confirmation. This is fine, we're basically
+ // already doomed by this point.
+ if self_ty.references_error() {
+ return ty::GenericArgs::extend_with_error(self.tcx, trait_def_id, &[]);
+ }
+
  self.extract_existential_trait_ref(self_ty, |this, object_ty, principal| {
  // The object data has no entry for the Self
  // Type. For the purposes of this method call, we

tests/ui/methods/dont-ice-on-object-lookup-w-error-region.rs

@@ -0,0 +1,11 @@
+// Fix for issue: #122914
+
+use std::future::Future;
+use std::pin::Pin;
+
+fn project(x: Pin<&'missing mut dyn Future<Output = ()>>) {
+ //~^ ERROR use of undeclared lifetime name `'missing`
+ let _ = x.poll(todo!());
+}
+
+fn main() {}

tests/ui/methods/dont-ice-on-object-lookup-w-error-region.stderr

@@ -0,0 +1,11 @@
+error[E0261]: use of undeclared lifetime name `'missing`
+ --> $DIR/dont-ice-on-object-lookup-w-error-region.rs:6:20
+ |
+LL | fn project(x: Pin<&'missing mut dyn Future<Output = ()>>) {
+ | - ^^^^^^^^ undeclared lifetime
+ | |
+ | help: consider introducing lifetime `'missing` here: `<'missing>`
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0261`.