Split SelectionContext::select into fns that take a binder and don't

compiler/rustc_const_eval/src/transform/check_consts/check.rs

@@ -10,7 +10,7 @@ use rustc_middle::mir::visit::{MutatingUseContext, NonMutatingUseContext, PlaceC
 use rustc_middle::mir::*;
 use rustc_middle::ty::subst::{GenericArgKind, InternalSubsts};
 use rustc_middle::ty::{self, adjustment::PointerCast, Instance, InstanceDef, Ty, TyCtxt};
-use rustc_middle::ty::{Binder, TraitRef, TypeVisitableExt};
+use rustc_middle::ty::{TraitRef, TypeVisitableExt};
 use rustc_mir_dataflow::{self, Analysis};
 use rustc_span::{sym, Span, Symbol};
 use rustc_trait_selection::traits::error_reporting::TypeErrCtxtExt as _;
@@ -755,10 +755,9 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
                     }
 
                     let trait_ref = TraitRef::from_method(tcx, trait_id, substs);
-                    let poly_trait_pred =
-                        Binder::dummy(trait_ref).with_constness(ty::BoundConstness::ConstIfConst);
+                    let trait_ref = trait_ref.with_constness(ty::BoundConstness::ConstIfConst);
                     let obligation =
-                        Obligation::new(tcx, ObligationCause::dummy(), param_env, poly_trait_pred);
+                        Obligation::new(tcx, ObligationCause::dummy(), param_env, trait_ref);
 
                     let implsrc = {
                         let infcx = tcx.infer_ctxt().build();
@@ -776,11 +775,11 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
                         }
                         // Closure: Fn{Once|Mut}
                         Ok(Some(ImplSource::Builtin(_)))
-                            if poly_trait_pred.self_ty().skip_binder().is_closure()
+                            if trait_ref.self_ty().is_closure()
                                 && tcx.fn_trait_kind_from_def_id(trait_id).is_some() =>
                         {
                             let ty::Closure(closure_def_id, substs) =
-                                *poly_trait_pred.self_ty().no_bound_vars().unwrap().kind()
+                                *trait_ref.self_ty().kind()
                             else {
                                 unreachable!()
                             };
@@ -840,7 +839,7 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
                                     tcx,
                                     ObligationCause::dummy_with_span(*fn_span),
                                     param_env,
-                                    poly_trait_pred,
+                                    trait_ref,
                                 );
 
                                 // improve diagnostics by showing what failed. Our requirements are stricter this time

compiler/rustc_const_eval/src/transform/check_consts/ops.rs

@@ -10,8 +10,8 @@ use rustc_infer::traits::{ImplSource, Obligation, ObligationCause};
 use rustc_middle::mir::{self, CallSource};
 use rustc_middle::ty::print::with_no_trimmed_paths;
 use rustc_middle::ty::subst::{GenericArgKind, SubstsRef};
+use rustc_middle::ty::TraitRef;
 use rustc_middle::ty::{suggest_constraining_type_param, Adt, Closure, FnDef, FnPtr, Param, Ty};
-use rustc_middle::ty::{Binder, TraitRef};
 use rustc_middle::util::{call_kind, CallDesugaringKind, CallKind};
 use rustc_session::parse::feature_err;
 use rustc_span::symbol::sym;
@@ -137,12 +137,8 @@ impl<'tcx> NonConstOp<'tcx> for FnCallNonConst<'tcx> {
                     }
                 }
                 Adt(..) => {
-                    let obligation = Obligation::new(
-                        tcx,
-                        ObligationCause::dummy(),
-                        param_env,
-                        Binder::dummy(trait_ref),
-                    );
+                    let obligation =
+                        Obligation::new(tcx, ObligationCause::dummy(), param_env, trait_ref);
 
                     let infcx = tcx.infer_ctxt().build();
                     let mut selcx = SelectionContext::new(&infcx);

compiler/rustc_hir_typeck/src/coercion.rs

@@ -632,9 +632,8 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
         while !queue.is_empty() {
             let obligation = queue.remove(0);
             debug!("coerce_unsized resolve step: {:?}", obligation);
-            let bound_predicate = obligation.predicate.kind();
-            let trait_pred = match bound_predicate.skip_binder() {
-                ty::PredicateKind::Clause(ty::ClauseKind::Trait(trait_pred))
+            let trait_pred = match obligation.predicate.kind().no_bound_vars() {
+                Some(ty::PredicateKind::Clause(ty::ClauseKind::Trait(trait_pred)))
                     if traits.contains(&trait_pred.def_id()) =>
                 {
                     if unsize_did == trait_pred.def_id() {
@@ -652,7 +651,7 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
                             has_unsized_tuple_coercion = true;
                         }
                     }
-                    bound_predicate.rebind(trait_pred)
+                    trait_pred
                 }
                 _ => {
                     coercion.obligations.push(obligation);
@@ -664,8 +663,8 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
                 Ok(None) => {
                     if trait_pred.def_id() == unsize_did {
                         let trait_pred = self.resolve_vars_if_possible(trait_pred);
-                        let self_ty = trait_pred.skip_binder().self_ty();
-                        let unsize_ty = trait_pred.skip_binder().trait_ref.substs[1].expect_ty();
+                        let self_ty = trait_pred.self_ty();
+                        let unsize_ty = trait_pred.trait_ref.substs[1].expect_ty();
                         debug!("coerce_unsized: ambiguous unsize case for {:?}", trait_pred);
                         match (self_ty.kind(), unsize_ty.kind()) {
                             (&ty::Infer(ty::TyVar(v)), ty::Dynamic(..))

compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs

@@ -1982,7 +1982,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                             self.tcx,
                             traits::ObligationCause::dummy(),
                             self.param_env,
-                            ty::Binder::dummy(trait_ref),
+                            trait_ref,
                         );
                         match SelectionContext::new(&self).select(&obligation) {
                             Ok(Some(traits::ImplSource::UserDefined(impl_source))) => {

compiler/rustc_hir_typeck/src/method/probe.rs

@@ -1441,8 +1441,7 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
         trait_ref: ty::TraitRef<'tcx>,
     ) -> traits::SelectionResult<'tcx, traits::Selection<'tcx>> {
         let cause = traits::ObligationCause::misc(self.span, self.body_id);
-        let predicate = ty::Binder::dummy(trait_ref);
-        let obligation = traits::Obligation::new(self.tcx, cause, self.param_env, predicate);
+        let obligation = traits::Obligation::new(self.tcx, cause, self.param_env, trait_ref);
         traits::SelectionContext::new(self).select(&obligation)
     }
 

compiler/rustc_infer/src/traits/mod.rs

@@ -62,7 +62,8 @@ impl<'tcx, P> From<Obligation<'tcx, P>> for solve::Goal<'tcx, P> {
 }
 
 pub type PredicateObligation<'tcx> = Obligation<'tcx, ty::Predicate<'tcx>>;
-pub type TraitObligation<'tcx> = Obligation<'tcx, ty::PolyTraitPredicate<'tcx>>;
+pub type TraitObligation<'tcx> = Obligation<'tcx, ty::TraitPredicate<'tcx>>;
+pub type PolyTraitObligation<'tcx> = Obligation<'tcx, ty::PolyTraitPredicate<'tcx>>;
 
 impl<'tcx> PredicateObligation<'tcx> {
     /// Flips the polarity of the inner predicate.
@@ -86,7 +87,7 @@ impl<'tcx> PredicateObligation<'tcx> {
     }
 }
 
-impl<'tcx> TraitObligation<'tcx> {
+impl<'tcx> PolyTraitObligation<'tcx> {
     /// Returns `true` if the trait predicate is considered `const` in its ParamEnv.
     pub fn is_const(&self) -> bool {
         matches!(
@@ -193,7 +194,7 @@ impl<'tcx> FulfillmentError<'tcx> {
     }
 }
 
-impl<'tcx> TraitObligation<'tcx> {
+impl<'tcx> PolyTraitObligation<'tcx> {
     pub fn polarity(&self) -> ty::ImplPolarity {
         self.predicate.skip_binder().polarity
     }

compiler/rustc_middle/src/query/keys.rs

@@ -318,11 +318,11 @@ impl<'tcx> Key for (LocalDefId, DefId, SubstsRef<'tcx>) {
     }
 }
 
-impl<'tcx> Key for (ty::ParamEnv<'tcx>, ty::PolyTraitRef<'tcx>) {
+impl<'tcx> Key for (ty::ParamEnv<'tcx>, ty::TraitRef<'tcx>) {
     type CacheSelector = DefaultCacheSelector<Self>;
 
     fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
-        tcx.def_span(self.1.def_id())
+        tcx.def_span(self.1.def_id)
     }
 }
 

compiler/rustc_middle/src/query/mod.rs

@@ -1278,7 +1278,7 @@ rustc_queries! {
     }
 
     query codegen_select_candidate(
-        key: (ty::ParamEnv<'tcx>, ty::PolyTraitRef<'tcx>)
+        key: (ty::ParamEnv<'tcx>, ty::TraitRef<'tcx>)
     ) -> Result<&'tcx ImplSource<'tcx, ()>, CodegenObligationError> {
         cache_on_disk_if { true }
         desc { |tcx| "computing candidate for `{}`", key.1 }

compiler/rustc_middle/src/ty/mod.rs

@@ -1306,6 +1306,13 @@ impl<'tcx> ToPredicate<'tcx> for TraitRef<'tcx> {
     }
 }
 
+impl<'tcx> ToPredicate<'tcx, TraitPredicate<'tcx>> for TraitRef<'tcx> {
+    #[inline(always)]
+    fn to_predicate(self, _tcx: TyCtxt<'tcx>) -> TraitPredicate<'tcx> {
+        self.without_const()
+    }
+}
+
 impl<'tcx> ToPredicate<'tcx, Clause<'tcx>> for TraitRef<'tcx> {
     #[inline(always)]
     fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Clause<'tcx> {

compiler/rustc_monomorphize/src/lib.rs

@@ -31,12 +31,12 @@ fn custom_coerce_unsize_info<'tcx>(
     source_ty: Ty<'tcx>,
     target_ty: Ty<'tcx>,
 ) -> CustomCoerceUnsized {
-    let trait_ref = ty::Binder::dummy(ty::TraitRef::from_lang_item(
+    let trait_ref = ty::TraitRef::from_lang_item(
         tcx.tcx,
         LangItem::CoerceUnsized,
         tcx.span,
         [source_ty, target_ty],
-    ));
+    );
 
     match tcx.codegen_select_candidate((ty::ParamEnv::reveal_all(), trait_ref)) {
         Ok(traits::ImplSource::UserDefined(traits::ImplSourceUserDefinedData {

compiler/rustc_trait_selection/src/solve/eval_ctxt/select.rs

@@ -4,7 +4,7 @@ use rustc_hir::def_id::DefId;
 use rustc_infer::infer::{DefineOpaqueTypes, InferCtxt, InferOk};
 use rustc_infer::traits::util::supertraits;
 use rustc_infer::traits::{
-    Obligation, PredicateObligation, Selection, SelectionResult, TraitObligation,
+    Obligation, PolyTraitObligation, PredicateObligation, Selection, SelectionResult,
 };
 use rustc_middle::traits::solve::{CanonicalInput, Certainty, Goal};
 use rustc_middle::traits::{
@@ -23,14 +23,14 @@ use crate::traits::vtable::{count_own_vtable_entries, prepare_vtable_segments, V
 pub trait InferCtxtSelectExt<'tcx> {
     fn select_in_new_trait_solver(
         &self,
-        obligation: &TraitObligation<'tcx>,
+        obligation: &PolyTraitObligation<'tcx>,
     ) -> SelectionResult<'tcx, Selection<'tcx>>;
 }
 
 impl<'tcx> InferCtxtSelectExt<'tcx> for InferCtxt<'tcx> {
     fn select_in_new_trait_solver(
         &self,
-        obligation: &TraitObligation<'tcx>,
+        obligation: &PolyTraitObligation<'tcx>,
     ) -> SelectionResult<'tcx, Selection<'tcx>> {
         assert!(self.next_trait_solver());
 

compiler/rustc_trait_selection/src/traits/auto_trait.rs

@@ -95,15 +95,15 @@ impl<'tcx> AutoTraitFinder<'tcx> {
                 tcx,
                 ObligationCause::dummy(),
                 orig_env,
-                ty::Binder::dummy(ty::TraitPredicate {
+                ty::TraitPredicate {
                     trait_ref,
                     constness: ty::BoundConstness::NotConst,
                     polarity: if polarity {
                         ImplPolarity::Positive
                     } else {
                         ImplPolarity::Negative
                     },
-                }),
+                },
             ));
             if let Ok(Some(ImplSource::UserDefined(_))) = result {
                 debug!(
@@ -292,7 +292,7 @@ impl<'tcx> AutoTraitFinder<'tcx> {
                 new_env,
                 pred,
             ));
-            let result = select.select(&obligation);
+            let result = select.poly_select(&obligation);
 
             match result {
                 Ok(Some(ref impl_source)) => {

compiler/rustc_trait_selection/src/traits/error_reporting/ambiguity.rs

@@ -1,7 +1,7 @@
 use rustc_hir::def_id::DefId;
 use rustc_infer::infer::{InferCtxt, LateBoundRegionConversionTime};
 use rustc_infer::traits::util::elaborate;
-use rustc_infer::traits::{Obligation, ObligationCause, TraitObligation};
+use rustc_infer::traits::{Obligation, ObligationCause, PolyTraitObligation};
 use rustc_middle::ty;
 use rustc_span::{Span, DUMMY_SP};
 
@@ -14,7 +14,7 @@ pub enum Ambiguity {
 
 pub fn recompute_applicable_impls<'tcx>(
     infcx: &InferCtxt<'tcx>,
-    obligation: &TraitObligation<'tcx>,
+    obligation: &PolyTraitObligation<'tcx>,
 ) -> Vec<Ambiguity> {
     let tcx = infcx.tcx;
     let param_env = obligation.param_env;

compiler/rustc_trait_selection/src/traits/fulfill.rs

@@ -4,7 +4,7 @@ use rustc_data_structures::obligation_forest::{Error, ForestObligation, Outcome}
 use rustc_data_structures::obligation_forest::{ObligationForest, ObligationProcessor};
 use rustc_infer::infer::DefineOpaqueTypes;
 use rustc_infer::traits::ProjectionCacheKey;
-use rustc_infer::traits::{SelectionError, TraitEngine, TraitObligation};
+use rustc_infer::traits::{PolyTraitObligation, SelectionError, TraitEngine};
 use rustc_middle::mir::interpret::ErrorHandled;
 use rustc_middle::ty::abstract_const::NotConstEvaluatable;
 use rustc_middle::ty::error::{ExpectedFound, TypeError};
@@ -667,7 +667,7 @@ impl<'a, 'tcx> FulfillProcessor<'a, 'tcx> {
     fn process_trait_obligation(
         &mut self,
         obligation: &PredicateObligation<'tcx>,
-        trait_obligation: TraitObligation<'tcx>,
+        trait_obligation: PolyTraitObligation<'tcx>,
         stalled_on: &mut Vec<TyOrConstInferVar<'tcx>>,
     ) -> ProcessResult<PendingPredicateObligation<'tcx>, FulfillmentErrorCode<'tcx>> {
         let infcx = self.selcx.infcx;
@@ -683,7 +683,7 @@ impl<'a, 'tcx> FulfillProcessor<'a, 'tcx> {
             }
         }
 
-        match self.selcx.select(&trait_obligation) {
+        match self.selcx.poly_select(&trait_obligation) {
             Ok(Some(impl_source)) => {
                 debug!("selecting trait at depth {} yielded Ok(Some)", obligation.recursion_depth);
                 ProcessResult::Changed(mk_pending(impl_source.nested_obligations()))

compiler/rustc_trait_selection/src/traits/project.rs

@@ -1545,7 +1545,6 @@ fn assemble_candidate_for_impl_trait_in_trait<'cx, 'tcx>(
         let trait_def_id = tcx.parent(trait_fn_def_id);
         let trait_substs =
             obligation.predicate.substs.truncate_to(tcx, tcx.generics_of(trait_def_id));
-        // FIXME(named-returns): Binders
         let trait_predicate = ty::TraitRef::new(tcx, trait_def_id, trait_substs);
 
         let _ = selcx.infcx.commit_if_ok(|_| {
@@ -1747,8 +1746,8 @@ fn assemble_candidates_from_impls<'cx, 'tcx>(
 
     // If we are resolving `<T as TraitRef<...>>::Item == Type`,
     // start out by selecting the predicate `T as TraitRef<...>`:
-    let poly_trait_ref = ty::Binder::dummy(obligation.predicate.trait_ref(selcx.tcx()));
-    let trait_obligation = obligation.with(selcx.tcx(), poly_trait_ref);
+    let trait_ref = obligation.predicate.trait_ref(selcx.tcx());
+    let trait_obligation = obligation.with(selcx.tcx(), trait_ref);
     let _ = selcx.infcx.commit_if_ok(|_| {
         let impl_source = match selcx.select(&trait_obligation) {
             Ok(Some(impl_source)) => impl_source,
@@ -1802,7 +1801,7 @@ fn assemble_candidates_from_impls<'cx, 'tcx>(
                     if obligation.param_env.reveal() == Reveal::All {
                         // NOTE(eddyb) inference variables can resolve to parameters, so
                         // assume `poly_trait_ref` isn't monomorphic, if it contains any.
-                        let poly_trait_ref = selcx.infcx.resolve_vars_if_possible(poly_trait_ref);
+                        let poly_trait_ref = selcx.infcx.resolve_vars_if_possible(trait_ref);
                         !poly_trait_ref.still_further_specializable()
                     } else {
                         debug!(
@@ -1821,11 +1820,11 @@ fn assemble_candidates_from_impls<'cx, 'tcx>(
                 let self_ty = selcx.infcx.shallow_resolve(obligation.predicate.self_ty());
 
                 let lang_items = selcx.tcx().lang_items();
-                if [lang_items.gen_trait(), lang_items.future_trait()].contains(&Some(poly_trait_ref.def_id()))
-                    || selcx.tcx().fn_trait_kind_from_def_id(poly_trait_ref.def_id()).is_some()
+                if [lang_items.gen_trait(), lang_items.future_trait()].contains(&Some(trait_ref.def_id))
+                    || selcx.tcx().fn_trait_kind_from_def_id(trait_ref.def_id).is_some()
                 {
                     true
-                } else if lang_items.discriminant_kind_trait() == Some(poly_trait_ref.def_id()) {
+                } else if lang_items.discriminant_kind_trait() == Some(trait_ref.def_id) {
                     match self_ty.kind() {
                         ty::Bool
                         | ty::Char
@@ -1860,7 +1859,7 @@ fn assemble_candidates_from_impls<'cx, 'tcx>(
                         | ty::Infer(..)
                         | ty::Error(_) => false,
                     }
-                } else if lang_items.pointee_trait() == Some(poly_trait_ref.def_id()) {
+                } else if lang_items.pointee_trait() == Some(trait_ref.def_id) {
                     let tail = selcx.tcx().struct_tail_with_normalize(
                         self_ty,
                         |ty| {
@@ -1935,7 +1934,7 @@ fn assemble_candidates_from_impls<'cx, 'tcx>(
                         }
                     }
                 } else {
-                    bug!("unexpected builtin trait with associated type: {poly_trait_ref:?}")
+                    bug!("unexpected builtin trait with associated type: {trait_ref:?}")
                 }
             }
             super::ImplSource::Param(..) => {

compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs

@@ -10,7 +10,7 @@ use hir::def_id::DefId;
 use hir::LangItem;
 use rustc_hir as hir;
 use rustc_infer::traits::ObligationCause;
-use rustc_infer::traits::{Obligation, SelectionError, TraitObligation};
+use rustc_infer::traits::{Obligation, PolyTraitObligation, SelectionError};
 use rustc_middle::ty::fast_reject::{DeepRejectCtxt, TreatParams};
 use rustc_middle::ty::{self, Ty, TypeVisitableExt};
 
@@ -137,7 +137,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
     #[instrument(level = "debug", skip(self, candidates))]
     fn assemble_candidates_from_projected_tys(
         &mut self,
-        obligation: &TraitObligation<'tcx>,
+        obligation: &PolyTraitObligation<'tcx>,
         candidates: &mut SelectionCandidateSet<'tcx>,
     ) {
         // Before we go into the whole placeholder thing, just
@@ -206,7 +206,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
 
     fn assemble_generator_candidates(
         &mut self,
-        obligation: &TraitObligation<'tcx>,
+        obligation: &PolyTraitObligation<'tcx>,
         candidates: &mut SelectionCandidateSet<'tcx>,
     ) {
         // Okay to skip binder because the substs on generator types never
@@ -231,7 +231,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
 
     fn assemble_future_candidates(
         &mut self,
-        obligation: &TraitObligation<'tcx>,
+        obligation: &PolyTraitObligation<'tcx>,
         candidates: &mut SelectionCandidateSet<'tcx>,
     ) {
         let self_ty = obligation.self_ty().skip_binder();
@@ -254,7 +254,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
     /// unified during the confirmation step.
     fn assemble_closure_candidates(
         &mut self,
-        obligation: &TraitObligation<'tcx>,
+        obligation: &PolyTraitObligation<'tcx>,
         candidates: &mut SelectionCandidateSet<'tcx>,
     ) {
         let Some(kind) = self.tcx().fn_trait_kind_from_def_id(obligation.predicate.def_id()) else {
@@ -292,7 +292,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
     /// Implements one of the `Fn()` family for a fn pointer.
     fn assemble_fn_pointer_candidates(
         &mut self,
-        obligation: &TraitObligation<'tcx>,
+        obligation: &PolyTraitObligation<'tcx>,
         candidates: &mut SelectionCandidateSet<'tcx>,
     ) {
         // We provide impl of all fn traits for fn pointers.
@@ -334,7 +334,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
     #[instrument(level = "debug", skip(self, candidates))]
     fn assemble_candidates_from_impls(
         &mut self,
-        obligation: &TraitObligation<'tcx>,
+        obligation: &PolyTraitObligation<'tcx>,
         candidates: &mut SelectionCandidateSet<'tcx>,
     ) {
         // Essentially any user-written impl will match with an error type,
@@ -390,7 +390,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
     fn reject_fn_ptr_impls(
         &mut self,
         impl_def_id: DefId,
-        obligation: &TraitObligation<'tcx>,
+        obligation: &PolyTraitObligation<'tcx>,
         impl_self_ty: Ty<'tcx>,
     ) -> bool {
         // Let `impl<T: FnPtr> Trait for Vec<T>` go through the normal rejection path.
@@ -475,7 +475,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
 
     fn assemble_candidates_from_auto_impls(
         &mut self,
-        obligation: &TraitObligation<'tcx>,
+        obligation: &PolyTraitObligation<'tcx>,
         candidates: &mut SelectionCandidateSet<'tcx>,
     ) {
         // Okay to skip binder here because the tests we do below do not involve bound regions.
@@ -544,7 +544,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
     /// Searches for impls that might apply to `obligation`.
     fn assemble_candidates_from_object_ty(
         &mut self,
-        obligation: &TraitObligation<'tcx>,
+        obligation: &PolyTraitObligation<'tcx>,
         candidates: &mut SelectionCandidateSet<'tcx>,
     ) {
         debug!(
@@ -668,7 +668,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
     /// Searches for unsizing that might apply to `obligation`.
     fn assemble_candidates_for_unsizing(
         &mut self,
-        obligation: &TraitObligation<'tcx>,
+        obligation: &PolyTraitObligation<'tcx>,
         candidates: &mut SelectionCandidateSet<'tcx>,
     ) {
         // We currently never consider higher-ranked obligations e.g.
@@ -782,7 +782,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
     #[instrument(level = "debug", skip(self, obligation, candidates))]
     fn assemble_candidates_for_transmutability(
         &mut self,
-        obligation: &TraitObligation<'tcx>,
+        obligation: &PolyTraitObligation<'tcx>,
         candidates: &mut SelectionCandidateSet<'tcx>,
     ) {
         if obligation.predicate.has_non_region_param() {
@@ -800,7 +800,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
     #[instrument(level = "debug", skip(self, obligation, candidates))]
     fn assemble_candidates_for_trait_alias(
         &mut self,
-        obligation: &TraitObligation<'tcx>,
+        obligation: &PolyTraitObligation<'tcx>,
         candidates: &mut SelectionCandidateSet<'tcx>,
     ) {
         // Okay to skip binder here because the tests we do below do not involve bound regions.
@@ -837,7 +837,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
 
     fn assemble_const_destruct_candidates(
         &mut self,
-        obligation: &TraitObligation<'tcx>,
+        obligation: &PolyTraitObligation<'tcx>,
         candidates: &mut SelectionCandidateSet<'tcx>,
     ) {
         // If the predicate is `~const Destruct` in a non-const environment, we don't actually need
@@ -924,7 +924,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
 
     fn assemble_candidate_for_tuple(
         &mut self,
-        obligation: &TraitObligation<'tcx>,
+        obligation: &PolyTraitObligation<'tcx>,
         candidates: &mut SelectionCandidateSet<'tcx>,
     ) {
         let self_ty = self.infcx.shallow_resolve(obligation.self_ty().skip_binder());
@@ -966,7 +966,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
 
     fn assemble_candidate_for_pointer_like(
         &mut self,
-        obligation: &TraitObligation<'tcx>,
+        obligation: &PolyTraitObligation<'tcx>,
         candidates: &mut SelectionCandidateSet<'tcx>,
     ) {
         // The regions of a type don't affect the size of the type
@@ -991,7 +991,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
 
     fn assemble_candidates_for_fn_ptr_trait(
         &mut self,
-        obligation: &TraitObligation<'tcx>,
+        obligation: &PolyTraitObligation<'tcx>,
         candidates: &mut SelectionCandidateSet<'tcx>,
     ) {
         let self_ty = self.infcx.shallow_resolve(obligation.self_ty());

compiler/rustc_trait_selection/src/traits/select/confirmation.rs

@@ -27,8 +27,8 @@ use crate::traits::vtable::{
 use crate::traits::{
     BuiltinDerivedObligation, ImplDerivedObligation, ImplDerivedObligationCause, ImplSource,
     ImplSourceObjectData, ImplSourceTraitUpcastingData, ImplSourceUserDefinedData, Normalized,
-    Obligation, ObligationCause, OutputTypeParameterMismatch, PredicateObligation, Selection,
-    SelectionError, TraitNotObjectSafe, TraitObligation, Unimplemented,
+    Obligation, ObligationCause, OutputTypeParameterMismatch, PolyTraitObligation,
+    PredicateObligation, Selection, SelectionError, TraitNotObjectSafe, Unimplemented,
 };
 
 use super::BuiltinImplConditions;
@@ -42,7 +42,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
     #[instrument(level = "debug", skip(self))]
     pub(super) fn confirm_candidate(
         &mut self,
-        obligation: &TraitObligation<'tcx>,
+        obligation: &PolyTraitObligation<'tcx>,
         candidate: SelectionCandidate<'tcx>,
     ) -> Result<Selection<'tcx>, SelectionError<'tcx>> {
         let mut impl_src = match candidate {
@@ -148,7 +148,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
 
     fn confirm_projection_candidate(
         &mut self,
-        obligation: &TraitObligation<'tcx>,
+        obligation: &PolyTraitObligation<'tcx>,
         idx: usize,
     ) -> Result<Vec<PredicateObligation<'tcx>>, SelectionError<'tcx>> {
         let tcx = self.tcx();
@@ -215,7 +215,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
 
     fn confirm_param_candidate(
         &mut self,
-        obligation: &TraitObligation<'tcx>,
+        obligation: &PolyTraitObligation<'tcx>,
         param: ty::PolyTraitRef<'tcx>,
     ) -> Vec<PredicateObligation<'tcx>> {
         debug!(?obligation, ?param, "confirm_param_candidate");
@@ -238,7 +238,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
 
     fn confirm_builtin_candidate(
         &mut self,
-        obligation: &TraitObligation<'tcx>,
+        obligation: &PolyTraitObligation<'tcx>,
         has_nested: bool,
     ) -> Vec<PredicateObligation<'tcx>> {
         debug!(?obligation, ?has_nested, "confirm_builtin_candidate");
@@ -279,13 +279,13 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
     #[instrument(level = "debug", skip(self))]
     fn confirm_transmutability_candidate(
         &mut self,
-        obligation: &TraitObligation<'tcx>,
+        obligation: &PolyTraitObligation<'tcx>,
     ) -> Result<Vec<PredicateObligation<'tcx>>, SelectionError<'tcx>> {
         use rustc_transmute::{Answer, Condition};
         #[instrument(level = "debug", skip(tcx, obligation, predicate))]
         fn flatten_answer_tree<'tcx>(
             tcx: TyCtxt<'tcx>,
-            obligation: &TraitObligation<'tcx>,
+            obligation: &PolyTraitObligation<'tcx>,
             predicate: TraitPredicate<'tcx>,
             cond: Condition<rustc_transmute::layout::rustc::Ref<'tcx>>,
         ) -> Vec<PredicateObligation<'tcx>> {
@@ -375,7 +375,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
     /// 2. For each where-clause `C` declared on `Foo`, `[Self => X] C` holds.
     fn confirm_auto_impl_candidate(
         &mut self,
-        obligation: &TraitObligation<'tcx>,
+        obligation: &PolyTraitObligation<'tcx>,
     ) -> Result<Vec<PredicateObligation<'tcx>>, SelectionError<'tcx>> {
         debug!(?obligation, "confirm_auto_impl_candidate");
 
@@ -387,7 +387,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
     /// See `confirm_auto_impl_candidate`.
     fn vtable_auto_impl(
         &mut self,
-        obligation: &TraitObligation<'tcx>,
+        obligation: &PolyTraitObligation<'tcx>,
         trait_def_id: DefId,
         nested: ty::Binder<'tcx, Vec<Ty<'tcx>>>,
     ) -> Vec<PredicateObligation<'tcx>> {
@@ -426,7 +426,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
 
     fn confirm_impl_candidate(
         &mut self,
-        obligation: &TraitObligation<'tcx>,
+        obligation: &PolyTraitObligation<'tcx>,
         impl_def_id: DefId,
     ) -> ImplSourceUserDefinedData<'tcx, PredicateObligation<'tcx>> {
         debug!(?obligation, ?impl_def_id, "confirm_impl_candidate");
@@ -481,7 +481,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
 
     fn confirm_object_candidate(
         &mut self,
-        obligation: &TraitObligation<'tcx>,
+        obligation: &PolyTraitObligation<'tcx>,
         index: usize,
     ) -> Result<ImplSourceObjectData<PredicateObligation<'tcx>>, SelectionError<'tcx>> {
         let tcx = self.tcx();
@@ -655,7 +655,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
 
     fn confirm_fn_pointer_candidate(
         &mut self,
-        obligation: &TraitObligation<'tcx>,
+        obligation: &PolyTraitObligation<'tcx>,
         is_const: bool,
     ) -> Result<Vec<PredicateObligation<'tcx>>, SelectionError<'tcx>> {
         debug!(?obligation, "confirm_fn_pointer_candidate");
@@ -714,7 +714,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
 
     fn confirm_trait_alias_candidate(
         &mut self,
-        obligation: &TraitObligation<'tcx>,
+        obligation: &PolyTraitObligation<'tcx>,
     ) -> Vec<PredicateObligation<'tcx>> {
         debug!(?obligation, "confirm_trait_alias_candidate");
 
@@ -739,7 +739,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
 
     fn confirm_generator_candidate(
         &mut self,
-        obligation: &TraitObligation<'tcx>,
+        obligation: &PolyTraitObligation<'tcx>,
     ) -> Result<Vec<PredicateObligation<'tcx>>, SelectionError<'tcx>> {
         // Okay to skip binder because the substs on generator types never
         // touch bound regions, they just capture the in-scope
@@ -778,7 +778,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
 
     fn confirm_future_candidate(
         &mut self,
-        obligation: &TraitObligation<'tcx>,
+        obligation: &PolyTraitObligation<'tcx>,
     ) -> Result<Vec<PredicateObligation<'tcx>>, SelectionError<'tcx>> {
         // Okay to skip binder because the substs on generator types never
         // touch bound regions, they just capture the in-scope
@@ -809,7 +809,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
     #[instrument(skip(self), level = "debug")]
     fn confirm_closure_candidate(
         &mut self,
-        obligation: &TraitObligation<'tcx>,
+        obligation: &PolyTraitObligation<'tcx>,
     ) -> Result<Vec<PredicateObligation<'tcx>>, SelectionError<'tcx>> {
         let kind = self
             .tcx()
@@ -865,7 +865,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
     #[instrument(skip(self), level = "trace")]
     fn confirm_poly_trait_refs(
         &mut self,
-        obligation: &TraitObligation<'tcx>,
+        obligation: &PolyTraitObligation<'tcx>,
         self_ty_trait_ref: ty::PolyTraitRef<'tcx>,
     ) -> Result<Vec<PredicateObligation<'tcx>>, SelectionError<'tcx>> {
         let obligation_trait_ref = obligation.predicate.to_poly_trait_ref();
@@ -900,7 +900,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
 
     fn confirm_trait_upcasting_unsize_candidate(
         &mut self,
-        obligation: &TraitObligation<'tcx>,
+        obligation: &PolyTraitObligation<'tcx>,
         idx: usize,
     ) -> Result<ImplSourceTraitUpcastingData<PredicateObligation<'tcx>>, SelectionError<'tcx>> {
         let tcx = self.tcx();
@@ -1004,7 +1004,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
 
     fn confirm_builtin_unsize_candidate(
         &mut self,
-        obligation: &TraitObligation<'tcx>,
+        obligation: &PolyTraitObligation<'tcx>,
     ) -> Result<Vec<PredicateObligation<'tcx>>, SelectionError<'tcx>> {
         let tcx = self.tcx();
 
@@ -1213,7 +1213,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
 
     fn confirm_const_destruct_candidate(
         &mut self,
-        obligation: &TraitObligation<'tcx>,
+        obligation: &PolyTraitObligation<'tcx>,
         impl_def_id: Option<DefId>,
     ) -> Result<Vec<PredicateObligation<'tcx>>, SelectionError<'tcx>> {
         // `~const Destruct` in a non-const environment is always trivially true, since our type is `Drop`

compiler/rustc_trait_selection/src/traits/select/mod.rs

@@ -15,8 +15,8 @@ use super::util::closure_trait_ref_and_return_type;
 use super::wf;
 use super::{
     ErrorReporting, ImplDerivedObligation, ImplDerivedObligationCause, Normalized, Obligation,
-    ObligationCause, ObligationCauseCode, Overflow, PredicateObligation, Selection, SelectionError,
-    SelectionResult, TraitObligation, TraitQueryMode,
+    ObligationCause, ObligationCauseCode, Overflow, PolyTraitObligation, PredicateObligation,
+    Selection, SelectionError, SelectionResult, TraitQueryMode,
 };
 
 use crate::infer::{InferCtxt, InferOk, TypeFreshener};
@@ -34,6 +34,7 @@ use rustc_hir as hir;
 use rustc_hir::def_id::DefId;
 use rustc_infer::infer::DefineOpaqueTypes;
 use rustc_infer::infer::LateBoundRegionConversionTime;
+use rustc_infer::traits::TraitObligation;
 use rustc_middle::dep_graph::{DepKind, DepNodeIndex};
 use rustc_middle::mir::interpret::ErrorHandled;
 use rustc_middle::ty::abstract_const::NotConstEvaluatable;
@@ -122,7 +123,7 @@ pub struct SelectionContext<'cx, 'tcx> {
 
 // A stack that walks back up the stack frame.
 struct TraitObligationStack<'prev, 'tcx> {
-    obligation: &'prev TraitObligation<'tcx>,
+    obligation: &'prev PolyTraitObligation<'tcx>,
 
     /// The trait predicate from `obligation` but "freshened" with the
     /// selection-context's freshener. Used to check for recursion.
@@ -259,9 +260,9 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
     /// Attempts to satisfy the obligation. If successful, this will affect the surrounding
     /// type environment by performing unification.
     #[instrument(level = "debug", skip(self), ret)]
-    pub fn select(
+    pub fn poly_select(
         &mut self,
-        obligation: &TraitObligation<'tcx>,
+        obligation: &PolyTraitObligation<'tcx>,
     ) -> SelectionResult<'tcx, Selection<'tcx>> {
         if self.infcx.next_trait_solver() {
             return self.infcx.select_in_new_trait_solver(obligation);
@@ -293,9 +294,21 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         }
     }
 
-    fn select_from_obligation(
+    pub fn select(
         &mut self,
         obligation: &TraitObligation<'tcx>,
+    ) -> SelectionResult<'tcx, Selection<'tcx>> {
+        self.poly_select(&Obligation {
+            cause: obligation.cause.clone(),
+            param_env: obligation.param_env,
+            predicate: ty::Binder::dummy(obligation.predicate),
+            recursion_depth: obligation.recursion_depth,
+        })
+    }
+
+    fn select_from_obligation(
+        &mut self,
+        obligation: &PolyTraitObligation<'tcx>,
     ) -> SelectionResult<'tcx, SelectionCandidate<'tcx>> {
         debug_assert!(!obligation.predicate.has_escaping_bound_vars());
 
@@ -612,7 +625,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         obligation: PredicateObligation<'tcx>,
     ) -> Result<EvaluationResult, OverflowError> {
         debug_assert!(!self.infcx.next_trait_solver());
-        // `previous_stack` stores a `TraitObligation`, while `obligation` is
+        // `previous_stack` stores a `PolyTraitObligation`, while `obligation` is
         // a `PredicateObligation`. These are distinct types, so we can't
         // use any `Option` combinator method that would force them to be
         // the same.
@@ -973,7 +986,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
     fn evaluate_trait_predicate_recursively<'o>(
         &mut self,
         previous_stack: TraitObligationStackList<'o, 'tcx>,
-        mut obligation: TraitObligation<'tcx>,
+        mut obligation: PolyTraitObligation<'tcx>,
     ) -> Result<EvaluationResult, OverflowError> {
         if !self.is_intercrate()
             && obligation.is_global()
@@ -1379,7 +1392,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
     fn filter_impls(
         &mut self,
         candidates: Vec<SelectionCandidate<'tcx>>,
-        obligation: &TraitObligation<'tcx>,
+        obligation: &PolyTraitObligation<'tcx>,
     ) -> Vec<SelectionCandidate<'tcx>> {
         trace!("{candidates:#?}");
         let tcx = self.tcx();
@@ -1442,7 +1455,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
     fn filter_reservation_impls(
         &mut self,
         candidate: SelectionCandidate<'tcx>,
-        obligation: &TraitObligation<'tcx>,
+        obligation: &PolyTraitObligation<'tcx>,
     ) -> SelectionResult<'tcx, SelectionCandidate<'tcx>> {
         let tcx = self.tcx();
         // Treat reservation impls as ambiguity.
@@ -1614,7 +1627,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
     #[instrument(level = "debug", skip(self), ret)]
     fn match_projection_obligation_against_definition_bounds(
         &mut self,
-        obligation: &TraitObligation<'tcx>,
+        obligation: &PolyTraitObligation<'tcx>,
     ) -> smallvec::SmallVec<[(usize, ty::BoundConstness); 2]> {
         let poly_trait_predicate = self.infcx.resolve_vars_if_possible(obligation.predicate);
         let placeholder_trait_predicate =
@@ -1677,7 +1690,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
     /// variables or placeholders, the normalized bound is returned.
     fn match_normalize_trait_ref(
         &mut self,
-        obligation: &TraitObligation<'tcx>,
+        obligation: &PolyTraitObligation<'tcx>,
         trait_bound: ty::PolyTraitRef<'tcx>,
         placeholder_trait_ref: ty::TraitRef<'tcx>,
     ) -> Result<Option<ty::PolyTraitRef<'tcx>>, ()> {
@@ -2078,7 +2091,7 @@ impl<'tcx> SelectionContext<'_, 'tcx> {
 impl<'tcx> SelectionContext<'_, 'tcx> {
     fn sized_conditions(
         &mut self,
-        obligation: &TraitObligation<'tcx>,
+        obligation: &PolyTraitObligation<'tcx>,
     ) -> BuiltinImplConditions<'tcx> {
         use self::BuiltinImplConditions::{Ambiguous, None, Where};
 
@@ -2138,7 +2151,7 @@ impl<'tcx> SelectionContext<'_, 'tcx> {
 
     fn copy_clone_conditions(
         &mut self,
-        obligation: &TraitObligation<'tcx>,
+        obligation: &PolyTraitObligation<'tcx>,
     ) -> BuiltinImplConditions<'tcx> {
         // NOTE: binder moved to (*)
         let self_ty = self.infcx.shallow_resolve(obligation.predicate.skip_binder().self_ty());
@@ -2414,7 +2427,7 @@ impl<'tcx> SelectionContext<'_, 'tcx> {
     fn rematch_impl(
         &mut self,
         impl_def_id: DefId,
-        obligation: &TraitObligation<'tcx>,
+        obligation: &PolyTraitObligation<'tcx>,
     ) -> Normalized<'tcx, SubstsRef<'tcx>> {
         let impl_trait_ref = self.tcx().impl_trait_ref(impl_def_id).unwrap();
         match self.match_impl(impl_def_id, impl_trait_ref, obligation) {
@@ -2452,7 +2465,7 @@ impl<'tcx> SelectionContext<'_, 'tcx> {
         &mut self,
         impl_def_id: DefId,
         impl_trait_ref: EarlyBinder<ty::TraitRef<'tcx>>,
-        obligation: &TraitObligation<'tcx>,
+        obligation: &PolyTraitObligation<'tcx>,
     ) -> Result<Normalized<'tcx, SubstsRef<'tcx>>, ()> {
         let placeholder_obligation =
             self.infcx.instantiate_binder_with_placeholders(obligation.predicate);
@@ -2510,7 +2523,7 @@ impl<'tcx> SelectionContext<'_, 'tcx> {
     /// result from the normalization.
     fn match_where_clause_trait_ref(
         &mut self,
-        obligation: &TraitObligation<'tcx>,
+        obligation: &PolyTraitObligation<'tcx>,
         where_clause_trait_ref: ty::PolyTraitRef<'tcx>,
     ) -> Result<Vec<PredicateObligation<'tcx>>, ()> {
         self.match_poly_trait_ref(obligation, where_clause_trait_ref)
@@ -2521,7 +2534,7 @@ impl<'tcx> SelectionContext<'_, 'tcx> {
     #[instrument(skip(self), level = "debug")]
     fn match_poly_trait_ref(
         &mut self,
-        obligation: &TraitObligation<'tcx>,
+        obligation: &PolyTraitObligation<'tcx>,
         poly_trait_ref: ty::PolyTraitRef<'tcx>,
     ) -> Result<Vec<PredicateObligation<'tcx>>, ()> {
         self.infcx
@@ -2547,7 +2560,7 @@ impl<'tcx> SelectionContext<'_, 'tcx> {
     fn push_stack<'o>(
         &mut self,
         previous_stack: TraitObligationStackList<'o, 'tcx>,
-        obligation: &'o TraitObligation<'tcx>,
+        obligation: &'o PolyTraitObligation<'tcx>,
     ) -> TraitObligationStack<'o, 'tcx> {
         let fresh_trait_pred = obligation.predicate.fold_with(&mut self.freshener);
 
@@ -2566,7 +2579,7 @@ impl<'tcx> SelectionContext<'_, 'tcx> {
     #[instrument(skip(self), level = "debug")]
     fn closure_trait_ref_unnormalized(
         &mut self,
-        obligation: &TraitObligation<'tcx>,
+        obligation: &PolyTraitObligation<'tcx>,
         substs: SubstsRef<'tcx>,
     ) -> ty::PolyTraitRef<'tcx> {
         let closure_sig = substs.as_closure().sig();

compiler/rustc_trait_selection/src/traits/vtable.rs

@@ -362,7 +362,7 @@ pub(crate) fn vtable_trait_upcasting_coercion_new_vptr_slot<'tcx>(
 
     let trait_ref = ty::TraitRef::new(tcx, unsize_trait_did, [source, target]);
 
-    match tcx.codegen_select_candidate((ty::ParamEnv::reveal_all(), ty::Binder::dummy(trait_ref))) {
+    match tcx.codegen_select_candidate((ty::ParamEnv::reveal_all(), trait_ref)) {
         Ok(ImplSource::TraitUpcasting(implsrc_traitcasting)) => {
             implsrc_traitcasting.vtable_vptr_slot
         }

compiler/rustc_traits/src/codegen.rs

@@ -22,7 +22,7 @@ use rustc_trait_selection::traits::{
 /// This also expects that `trait_ref` is fully normalized.
 pub fn codegen_select_candidate<'tcx>(
     tcx: TyCtxt<'tcx>,
-    (param_env, trait_ref): (ty::ParamEnv<'tcx>, ty::PolyTraitRef<'tcx>),
+    (param_env, trait_ref): (ty::ParamEnv<'tcx>, ty::TraitRef<'tcx>),
 ) -> Result<&'tcx ImplSource<'tcx, ()>, CodegenObligationError> {
     // We expect the input to be fully normalized.
     debug_assert_eq!(trait_ref, tcx.normalize_erasing_regions(param_env, trait_ref));

compiler/rustc_ty_utils/src/instance.rs

@@ -80,7 +80,7 @@ fn resolve_associated_item<'tcx>(
 
     let trait_ref = ty::TraitRef::from_method(tcx, trait_id, rcvr_substs);
 
-    let vtbl = match tcx.codegen_select_candidate((param_env, ty::Binder::dummy(trait_ref))) {
+    let vtbl = match tcx.codegen_select_candidate((param_env, trait_ref)) {
         Ok(vtbl) => vtbl,
         Err(CodegenObligationError::Ambiguity) => {
             let reported = tcx.sess.delay_span_bug(