Normalize in infcx instead of globally for `Option::as_deref` suggestion

The projection may contain inference variables. These inference
variables are local to the local inference context. Using
`tcx.normalize_erasing_regions` doesn't work here because this method is
global and does not have access to the inference context. It's therefore
unable to deal with the inference variables. We normalize in the local
inference context instead, which knowns about the inference variables.

1 files changed, 2 insertions, 1 deletions

diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
index 4ca83904f47..80d0faca670 100644
--- a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
+++ b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
@@ -3592,7 +3592,8 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
             // Extract `<U as Deref>::Target` assoc type and check that it is `T`
             && let Some(deref_target_did) = tcx.lang_items().deref_target()
             && let projection = tcx.mk_projection(deref_target_did, tcx.mk_substs(&[ty::GenericArg::from(found_ty)]))
-            && let Ok(deref_target) = tcx.try_normalize_erasing_regions(param_env, projection)
+            && let InferOk { value: deref_target, obligations } = infcx.at(&ObligationCause::dummy(), param_env).normalize(projection)
+            && obligations.iter().all(|obligation| infcx.predicate_must_hold_modulo_regions(obligation))
             && infcx.can_eq(param_env, deref_target, target_ty)
         {
             let help = if let hir::Mutability::Mut = needs_mut