Account for flags in const folders

Author: compiler-errors

compiler/rustc_middle/src/ty/abstract_const.rs

@@ -63,7 +63,12 @@ impl<'tcx> TyCtxt<'tcx> {
                     },
                     _ => c,
                 };
-                ct.super_fold_with(self)
+
+                if ct.has_type_flags(ty::TypeFlags::HAS_CT_PROJECTION) {
+                    ct.super_fold_with(self)
+                } else {
+                    ct
+                }
             }
         }
         ac.fold_with(&mut Expander { tcx: self })

compiler/rustc_trait_selection/src/traits/mod.rs

@@ -376,6 +376,22 @@ pub fn normalize_param_env_or_error<'tcx>(
 
                     c
                 }
+
+                fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> {
+                    if t.has_type_flags(ty::TypeFlags::HAS_CT_PROJECTION) {
+                        t.super_fold_with(self)
+                    } else {
+                        t
+                    }
+                }
+
+                fn fold_predicate(&mut self, p: ty::Predicate<'tcx>) -> ty::Predicate<'tcx> {
+                    if p.has_type_flags(ty::TypeFlags::HAS_CT_PROJECTION) {
+                        p.super_fold_with(self)
+                    } else {
+                        p
+                    }
+                }
             }
 
             // This whole normalization step is a hack to work around the fact that