Add needs_normalization

Author: jackh726

Diff for: compiler/rustc_trait_selection/src/traits/project.rs

@@ -293,6 +293,18 @@ where
     result
 }
 
+pub(crate) fn needs_normalization<'tcx, T: TypeFoldable<'tcx>>(value: &T, reveal: Reveal) -> bool {
+    match reveal {
+        Reveal::UserFacing => value
+            .has_type_flags(ty::TypeFlags::HAS_TY_PROJECTION | ty::TypeFlags::HAS_CT_PROJECTION),
+        Reveal::All => value.has_type_flags(
+            ty::TypeFlags::HAS_TY_PROJECTION
+                | ty::TypeFlags::HAS_TY_OPAQUE
+                | ty::TypeFlags::HAS_CT_PROJECTION,
+        ),
+    }
+}
+
 struct AssocTypeNormalizer<'a, 'b, 'tcx> {
     selcx: &'a mut SelectionContext<'b, 'tcx>,
     param_env: ty::ParamEnv<'tcx>,
@@ -323,7 +335,11 @@ impl<'a, 'b, 'tcx> AssocTypeNormalizer<'a, 'b, 'tcx> {
             value
         );
 
-        if !value.has_projections() { value } else { value.fold_with(self) }
+        if !needs_normalization(&value, self.param_env.reveal()) {
+            value
+        } else {
+            value.fold_with(self)
+        }
     }
 }
 
@@ -343,7 +359,7 @@ impl<'a, 'b, 'tcx> TypeFolder<'tcx> for AssocTypeNormalizer<'a, 'b, 'tcx> {
     }
 
     fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> {
-        if !ty.has_projections() {
+        if !needs_normalization(&ty, self.param_env.reveal()) {
             return ty;
         }
         // We don't want to normalize associated types that occur inside of region

Diff for: compiler/rustc_trait_selection/src/traits/query/normalize.rs

@@ -6,6 +6,7 @@ use crate::infer::at::At;
 use crate::infer::canonical::OriginalQueryValues;
 use crate::infer::{InferCtxt, InferOk};
 use crate::traits::error_reporting::InferCtxtExt;
+use crate::traits::project::needs_normalization;
 use crate::traits::{Obligation, ObligationCause, PredicateObligation, Reveal};
 use rustc_data_structures::sso::SsoHashMap;
 use rustc_data_structures::stack::ensure_sufficient_stack;
@@ -49,7 +50,7 @@ impl<'cx, 'tcx> AtExt<'tcx> for At<'cx, 'tcx> {
             value,
             self.param_env,
         );
-        if !value.has_projections() {
+        if !needs_normalization(&value, self.param_env.reveal()) {
             return Ok(Normalized { value, obligations: vec![] });
         }
 
@@ -112,7 +113,7 @@ impl<'cx, 'tcx> TypeFolder<'tcx> for QueryNormalizer<'cx, 'tcx> {
 
     #[instrument(level = "debug", skip(self))]
     fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> {
-        if !ty.has_projections() {
+        if !needs_normalization(&ty, self.param_env.reveal()) {
             return ty;
         }