Normalize opaques with escaping bound vars in AssocTypeNormalizer

Author: compiler-errors

compiler/rustc_trait_selection/src/traits/project.rs

@@ -494,15 +494,15 @@ impl<'a, 'b, 'tcx> TypeFolder<'tcx> for AssocTypeNormalizer<'a, 'b, 'tcx> {
         // to make sure we don't forget to fold the substs regardless.
 
         match *ty.kind() {
-            // This is really important. While we *can* handle this, this has
-            // severe performance implications for large opaque types with
-            // late-bound regions. See `issue-88862` benchmark.
-            ty::Opaque(def_id, substs) if !substs.has_escaping_bound_vars() => {
+            ty::Opaque(def_id, substs) => {
                 // Only normalize `impl Trait` outside of type inference, usually in codegen.
                 match self.param_env.reveal() {
                     Reveal::UserFacing => ty.super_fold_with(self),
 
                     Reveal::All => {
+                        // N.b. there is an assumption here all this code can handle
+                        // escaping bound vars.
+
                         let recursion_limit = self.tcx().recursion_limit();
                         if !recursion_limit.value_within_limit(self.depth) {
                             let obligation = Obligation::with_depth(