1 files changed, 35 insertions, 42 deletions

diff --git a/compiler/rustc_hir_analysis/src/autoderef.rs b/compiler/rustc_hir_analysis/src/autoderef.rs
index f2ceb470264..2bf14a2461f 100644
--- a/compiler/rustc_hir_analysis/src/autoderef.rs
+++ b/compiler/rustc_hir_analysis/src/autoderef.rs
@@ -1,6 +1,6 @@
 use crate::errors::AutoDerefReachedRecursionLimit;
+use crate::traits;
 use crate::traits::query::evaluate_obligation::InferCtxtExt;
-use crate::traits::{self, TraitEngine, TraitEngineExt};
 use rustc_infer::infer::InferCtxt;
 use rustc_middle::ty::TypeVisitableExt;
 use rustc_middle::ty::{self, Ty, TyCtxt};
@@ -8,7 +8,7 @@ use rustc_session::Limit;
 use rustc_span::def_id::LocalDefId;
 use rustc_span::def_id::LOCAL_CRATE;
 use rustc_span::Span;
-use rustc_trait_selection::traits::StructurallyNormalizeExt;
+use rustc_trait_selection::traits::ObligationCtxt;
 
 #[derive(Copy, Clone, Debug)]
 pub enum AutoderefKind {
@@ -68,28 +68,27 @@ impl<'a, 'tcx> Iterator for Autoderef<'a, 'tcx> {
         }
 
         // Otherwise, deref if type is derefable:
-        let (kind, new_ty) = if let Some(ty::TypeAndMut { ty, .. }) =
-            self.state.cur_ty.builtin_deref(self.include_raw_pointers)
-        {
-            debug_assert_eq!(ty, self.infcx.resolve_vars_if_possible(ty));
-            // NOTE: we may still need to normalize the built-in deref in case
-            // we have some type like `&<Ty as Trait>::Assoc`, since users of
-            // autoderef expect this type to have been structurally normalized.
-            if self.infcx.next_trait_solver()
-                && let ty::Alias(..) = ty.kind()
-            {
-                let (normalized_ty, obligations) = self.structurally_normalize(ty)?;
-                self.state.obligations.extend(obligations);
-                (AutoderefKind::Builtin, normalized_ty)
+        let (kind, new_ty) =
+            if let Some(ty) = self.state.cur_ty.builtin_deref(self.include_raw_pointers) {
+                debug_assert_eq!(ty, self.infcx.resolve_vars_if_possible(ty));
+                // NOTE: we may still need to normalize the built-in deref in case
+                // we have some type like `&<Ty as Trait>::Assoc`, since users of
+                // autoderef expect this type to have been structurally normalized.
+                if self.infcx.next_trait_solver()
+                    && let ty::Alias(..) = ty.kind()
+                {
+                    let (normalized_ty, obligations) = self.structurally_normalize(ty)?;
+                    self.state.obligations.extend(obligations);
+                    (AutoderefKind::Builtin, normalized_ty)
+                } else {
+                    (AutoderefKind::Builtin, ty)
+                }
+            } else if let Some(ty) = self.overloaded_deref_ty(self.state.cur_ty) {
+                // The overloaded deref check already normalizes the pointee type.
+                (AutoderefKind::Overloaded, ty)
             } else {
-                (AutoderefKind::Builtin, ty)
-            }
-        } else if let Some(ty) = self.overloaded_deref_ty(self.state.cur_ty) {
-            // The overloaded deref check already normalizes the pointee type.
-            (AutoderefKind::Overloaded, ty)
-        } else {
-            return None;
-        };
+                return None;
+            };
 
         self.state.steps.push((self.state.cur_ty, kind));
         debug!(
@@ -167,25 +166,19 @@ impl<'a, 'tcx> Autoderef<'a, 'tcx> {
         &self,
         ty: Ty<'tcx>,
     ) -> Option<(Ty<'tcx>, Vec<traits::PredicateObligation<'tcx>>)> {
-        let mut fulfill_cx = <dyn TraitEngine<'tcx>>::new(self.infcx);
-
-        let cause = traits::ObligationCause::misc(self.span, self.body_id);
-        let normalized_ty = match self
-            .infcx
-            .at(&cause, self.param_env)
-            .structurally_normalize(ty, &mut *fulfill_cx)
-        {
-            Ok(normalized_ty) => normalized_ty,
-            Err(errors) => {
-                // This shouldn't happen, except for evaluate/fulfill mismatches,
-                // but that's not a reason for an ICE (`predicate_may_hold` is conservative
-                // by design).
-                debug!(?errors, "encountered errors while fulfilling");
-                return None;
-            }
+        let ocx = ObligationCtxt::new(self.infcx);
+        let Ok(normalized_ty) = ocx.structurally_normalize(
+            &traits::ObligationCause::misc(self.span, self.body_id),
+            self.param_env,
+            ty,
+        ) else {
+            // We shouldn't have errors here, except for evaluate/fulfill mismatches,
+            // but that's not a reason for an ICE (`predicate_may_hold` is conservative
+            // by design).
+            // FIXME(-Znext-solver): This *actually* shouldn't happen then.
+            return None;
         };
-
-        let errors = fulfill_cx.select_where_possible(self.infcx);
+        let errors = ocx.select_where_possible();
         if !errors.is_empty() {
             // This shouldn't happen, except for evaluate/fulfill mismatches,
             // but that's not a reason for an ICE (`predicate_may_hold` is conservative
@@ -194,7 +187,7 @@ impl<'a, 'tcx> Autoderef<'a, 'tcx> {
             return None;
         }
 
-        Some((normalized_ty, fulfill_cx.pending_obligations()))
+        Some((normalized_ty, ocx.into_pending_obligations()))
     }
 
     /// Returns the final type we ended up with, which may be an inference