some type system cleanup

4 files changed, 62 insertions, 63 deletions

diff --git a/compiler/rustc_trait_selection/src/solve/normalize.rs b/compiler/rustc_trait_selection/src/solve/normalize.rs
index b07702e8421..91312c9fdd6 100644
--- a/compiler/rustc_trait_selection/src/solve/normalize.rs
+++ b/compiler/rustc_trait_selection/src/solve/normalize.rs
@@ -85,25 +85,16 @@ impl<'tcx> NormalizationFolder<'_, 'tcx> {
             ),
         );
 
-        // Do not emit an error if normalization is known to fail but instead
-        // keep the projection unnormalized. This is the case for projections
-        // with a `T: Trait` where-clause and opaque types outside of the defining
-        // scope.
-        let result = if infcx.predicate_may_hold(&obligation) {
-            self.fulfill_cx.register_predicate_obligation(infcx, obligation);
-            let errors = self.fulfill_cx.select_all_or_error(infcx);
-            if !errors.is_empty() {
-                return Err(errors);
-            }
-            let ty = infcx.resolve_vars_if_possible(new_infer_ty);
-
-            // Alias is guaranteed to be fully structurally resolved,
-            // so we can super fold here.
-            ty.try_super_fold_with(self)?
-        } else {
-            alias_ty.try_super_fold_with(self)?
-        };
+        self.fulfill_cx.register_predicate_obligation(infcx, obligation);
+        let errors = self.fulfill_cx.select_all_or_error(infcx);
+        if !errors.is_empty() {
+            return Err(errors);
+        }
 
+        // Alias is guaranteed to be fully structurally resolved,
+        // so we can super fold here.
+        let ty = infcx.resolve_vars_if_possible(new_infer_ty);
+        let result = ty.try_super_fold_with(self)?;
         self.depth -= 1;
         Ok(result)
     }
@@ -178,6 +169,7 @@ impl<'tcx> FallibleTypeFolder<TyCtxt<'tcx>> for NormalizationFolder<'_, 'tcx> {
         Ok(t)
     }
 
+    #[instrument(level = "debug", skip(self), ret)]
     fn try_fold_ty(&mut self, ty: Ty<'tcx>) -> Result<Ty<'tcx>, Self::Error> {
         let infcx = self.at.infcx;
         debug_assert_eq!(ty, infcx.shallow_resolve(ty));
@@ -204,6 +196,7 @@ impl<'tcx> FallibleTypeFolder<TyCtxt<'tcx>> for NormalizationFolder<'_, 'tcx> {
         }
     }
 
+    #[instrument(level = "debug", skip(self), ret)]
     fn try_fold_const(&mut self, ct: ty::Const<'tcx>) -> Result<ty::Const<'tcx>, Self::Error> {
         let infcx = self.at.infcx;
         debug_assert_eq!(ct, infcx.shallow_resolve(ct));
diff --git a/compiler/rustc_trait_selection/src/solve/normalizes_to/anon_const.rs b/compiler/rustc_trait_selection/src/solve/normalizes_to/anon_const.rs
new file mode 100644
index 00000000000..911462f4b9a
--- /dev/null
+++ b/compiler/rustc_trait_selection/src/solve/normalizes_to/anon_const.rs
@@ -0,0 +1,25 @@
+use crate::solve::EvalCtxt;
+use rustc_middle::traits::solve::{Certainty, Goal, QueryResult};
+use rustc_middle::ty;
+
+impl<'tcx> EvalCtxt<'_, 'tcx> {
+    #[instrument(level = "debug", skip(self), ret)]
+    pub(super) fn normalize_anon_const(
+        &mut self,
+        goal: Goal<'tcx, ty::NormalizesTo<'tcx>>,
+    ) -> QueryResult<'tcx> {
+        if let Some(normalized_const) = self.try_const_eval_resolve(
+            goal.param_env,
+            ty::UnevaluatedConst::new(goal.predicate.alias.def_id, goal.predicate.alias.args),
+            self.tcx()
+                .type_of(goal.predicate.alias.def_id)
+                .no_bound_vars()
+                .expect("const ty should not rely on other generics"),
+        ) {
+            self.eq(goal.param_env, normalized_const, goal.predicate.term.ct().unwrap())?;
+            self.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
+        } else {
+            self.evaluate_added_goals_and_make_canonical_response(Certainty::AMBIGUOUS)
+        }
+    }
+}
diff --git a/compiler/rustc_trait_selection/src/solve/normalizes_to/mod.rs b/compiler/rustc_trait_selection/src/solve/normalizes_to/mod.rs
index d177109c420..5f625831156 100644
--- a/compiler/rustc_trait_selection/src/solve/normalizes_to/mod.rs
+++ b/compiler/rustc_trait_selection/src/solve/normalizes_to/mod.rs
@@ -18,8 +18,9 @@ use rustc_middle::ty::{self, Ty, TyCtxt};
 use rustc_middle::ty::{ToPredicate, TypeVisitableExt};
 use rustc_span::{sym, ErrorGuaranteed, DUMMY_SP};
 
+mod anon_const;
 mod inherent;
-mod opaques;
+mod opaque_types;
 mod weak_types;
 
 impl<'tcx> EvalCtxt<'_, 'tcx> {
@@ -31,34 +32,34 @@ impl<'tcx> EvalCtxt<'_, 'tcx> {
         let def_id = goal.predicate.def_id();
         match self.tcx().def_kind(def_id) {
             DefKind::AssocTy | DefKind::AssocConst => {
-                // To only compute normalization once for each projection we only
-                // assemble normalization candidates if the expected term is an
-                // unconstrained inference variable.
-                //
-                // Why: For better cache hits, since if we have an unconstrained RHS then
-                // there are only as many cache keys as there are (canonicalized) alias
-                // types in each normalizes-to goal. This also weakens inference in a
-                // forwards-compatible way so we don't use the value of the RHS term to
-                // affect candidate assembly for projections.
-                //
-                // E.g. for `<T as Trait>::Assoc == u32` we recursively compute the goal
-                // `exists<U> <T as Trait>::Assoc == U` and then take the resulting type for
-                // `U` and equate it with `u32`. This means that we don't need a separate
-                // projection cache in the solver, since we're piggybacking off of regular
-                // goal caching.
-                if self.term_is_fully_unconstrained(goal) {
-                    match self.tcx().associated_item(def_id).container {
-                        ty::AssocItemContainer::TraitContainer => {
+                match self.tcx().associated_item(def_id).container {
+                    ty::AssocItemContainer::TraitContainer => {
+                        // To only compute normalization once for each projection we only
+                        // assemble normalization candidates if the expected term is an
+                        // unconstrained inference variable.
+                        //
+                        // Why: For better cache hits, since if we have an unconstrained RHS then
+                        // there are only as many cache keys as there are (canonicalized) alias
+                        // types in each normalizes-to goal. This also weakens inference in a
+                        // forwards-compatible way so we don't use the value of the RHS term to
+                        // affect candidate assembly for projections.
+                        //
+                        // E.g. for `<T as Trait>::Assoc == u32` we recursively compute the goal
+                        // `exists<U> <T as Trait>::Assoc == U` and then take the resulting type for
+                        // `U` and equate it with `u32`. This means that we don't need a separate
+                        // projection cache in the solver, since we're piggybacking off of regular
+                        // goal caching.
+                        if self.term_is_fully_unconstrained(goal) {
                             let candidates = self.assemble_and_evaluate_candidates(goal);
                             self.merge_candidates(candidates)
+                        } else {
+                            self.set_normalizes_to_hack_goal(goal);
+                            self.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
                         }
-                        ty::AssocItemContainer::ImplContainer => {
-                            self.normalize_inherent_associated_type(goal)
-                        }
                     }
-                } else {
-                    self.set_normalizes_to_hack_goal(goal);
-                    self.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
+                    ty::AssocItemContainer::ImplContainer => {
+                        self.normalize_inherent_associated_type(goal)
+                    }
                 }
             }
             DefKind::AnonConst => self.normalize_anon_const(goal),
@@ -67,26 +68,6 @@ impl<'tcx> EvalCtxt<'_, 'tcx> {
             kind => bug!("unknown DefKind {} in projection goal: {goal:#?}", kind.descr(def_id)),
         }
     }
-
-    #[instrument(level = "debug", skip(self), ret)]
-    fn normalize_anon_const(
-        &mut self,
-        goal: Goal<'tcx, ty::NormalizesTo<'tcx>>,
-    ) -> QueryResult<'tcx> {
-        if let Some(normalized_const) = self.try_const_eval_resolve(
-            goal.param_env,
-            ty::UnevaluatedConst::new(goal.predicate.alias.def_id, goal.predicate.alias.args),
-            self.tcx()
-                .type_of(goal.predicate.alias.def_id)
-                .no_bound_vars()
-                .expect("const ty should not rely on other generics"),
-        ) {
-            self.eq(goal.param_env, normalized_const, goal.predicate.term.ct().unwrap())?;
-            self.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
-        } else {
-            self.evaluate_added_goals_and_make_canonical_response(Certainty::AMBIGUOUS)
-        }
-    }
 }
 
 impl<'tcx> assembly::GoalKind<'tcx> for NormalizesTo<'tcx> {
diff --git a/compiler/rustc_trait_selection/src/solve/normalizes_to/opaques.rs b/compiler/rustc_trait_selection/src/solve/normalizes_to/opaque_types.rs
index 356c3776c04..356c3776c04 100644
--- a/compiler/rustc_trait_selection/src/solve/normalizes_to/opaques.rs
+++ b/compiler/rustc_trait_selection/src/solve/normalizes_to/opaque_types.rs