dedup assembly

compiler/rustc_trait_selection/src/solve/assembly.rs

@@ -0,0 +1,150 @@
+//! Code shared by trait and projection goals for candidate assembly.
+
+use super::infcx_ext::InferCtxtExt;
+use super::{
+    fixme_instantiate_canonical_query_response, CanonicalGoal, CanonicalResponse, Certainty,
+    EvalCtxt, Goal,
+};
+use rustc_hir::def_id::DefId;
+use rustc_infer::infer::TyCtxtInferExt;
+use rustc_infer::infer::{
+    canonical::{CanonicalVarValues, OriginalQueryValues},
+    InferCtxt,
+};
+use rustc_infer::traits::query::NoSolution;
+use rustc_middle::ty::TypeFoldable;
+use rustc_middle::ty::{self, Ty, TyCtxt};
+use rustc_span::DUMMY_SP;
+use std::fmt::Debug;
+
+/// A candidate is a possible way to prove a goal.
+///
+/// It consists of both the `source`, which describes how that goal would be proven,
+/// and the `result` when using the given `source`.
+///
+/// For the list of possible candidates, please look at the documentation of
+/// [super::trait_goals::CandidateSource] and [super::project_goals::CandidateSource].
+#[derive(Debug, Clone)]
+pub(super) struct Candidate<'tcx, G: GoalKind<'tcx>> {
+    pub(super) source: G::CandidateSource,
+    pub(super) result: CanonicalResponse<'tcx>,
+}
+
+pub(super) trait GoalKind<'tcx>: TypeFoldable<'tcx> + Copy {
+    type CandidateSource: Debug + Copy;
+
+    fn self_ty(self) -> Ty<'tcx>;
+
+    fn with_self_ty(self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> Self;
+
+    fn trait_def_id(self, tcx: TyCtxt<'tcx>) -> DefId;
+
+    fn consider_impl_candidate(
+        acx: &mut AssemblyCtxt<'_, 'tcx, Self>,
+        goal: Goal<'tcx, Self>,
+        impl_def_id: DefId,
+    );
+}
+
+/// An abstraction which correctly deals with the canonical results for candidates.
+///
+/// It also deduplicates the behavior between trait and projection predicates.
+pub(super) struct AssemblyCtxt<'a, 'tcx, G: GoalKind<'tcx>> {
+    pub(super) cx: &'a mut EvalCtxt<'tcx>,
+    pub(super) infcx: &'a InferCtxt<'tcx>,
+    var_values: CanonicalVarValues<'tcx>,
+    candidates: Vec<Candidate<'tcx, G>>,
+}
+
+impl<'a, 'tcx, G: GoalKind<'tcx>> AssemblyCtxt<'a, 'tcx, G> {
+    pub(super) fn assemble_and_evaluate_candidates(
+        cx: &'a mut EvalCtxt<'tcx>,
+        goal: CanonicalGoal<'tcx, G>,
+    ) -> Vec<Candidate<'tcx, G>> {
+        let (ref infcx, goal, var_values) =
+            cx.tcx.infer_ctxt().build_with_canonical(DUMMY_SP, &goal);
+        let mut acx = AssemblyCtxt { cx, infcx, var_values, candidates: Vec::new() };
+
+        acx.assemble_candidates_after_normalizing_self_ty(goal);
+
+        acx.assemble_impl_candidates(goal);
+
+        acx.candidates
+    }
+
+    pub(super) fn try_insert_candidate(
+        &mut self,
+        source: G::CandidateSource,
+        certainty: Certainty,
+    ) {
+        match self.infcx.make_canonical_response(self.var_values.clone(), certainty) {
+            Ok(result) => self.candidates.push(Candidate { source, result }),
+            Err(NoSolution) => debug!(?source, ?certainty, "failed leakcheck"),
+        }
+    }
+
+    /// If the self type of a goal is a projection, computing the relevant candidates is difficult.
+    ///
+    /// To deal with this, we first try to normalize the self type and add the candidates for the normalized
+    /// self type to the list of candidates in case that succeeds. Note that we can't just eagerly return in
+    /// this case as projections as self types add `
+    fn assemble_candidates_after_normalizing_self_ty(&mut self, goal: Goal<'tcx, G>) {
+        let tcx = self.cx.tcx;
+        // FIXME: We also have to normalize opaque types, not sure where to best fit that in.
+        let &ty::Alias(ty::Projection, projection_ty) = goal.predicate.self_ty().kind() else {
+            return
+        };
+        self.infcx.probe(|_| {
+            let normalized_ty = self.infcx.next_ty_infer();
+            let normalizes_to_goal = goal.with(
+                tcx,
+                ty::Binder::dummy(ty::ProjectionPredicate {
+                    projection_ty,
+                    term: normalized_ty.into(),
+                }),
+            );
+            let normalization_certainty =
+                match self.cx.evaluate_goal(&self.infcx, normalizes_to_goal) {
+                    Ok((_, certainty)) => certainty,
+                    Err(NoSolution) => return,
+                };
+
+            // NOTE: Alternatively we could call `evaluate_goal` here and only have a `Normalized` candidate.
+            // This doesn't work as long as we use `CandidateSource` in both winnowing and to resolve associated items.
+            let goal = goal.with(tcx, goal.predicate.with_self_ty(tcx, normalized_ty));
+            let mut orig_values = OriginalQueryValues::default();
+            let goal = self.infcx.canonicalize_query(goal, &mut orig_values);
+            let normalized_candidates =
+                AssemblyCtxt::assemble_and_evaluate_candidates(self.cx, goal);
+
+            // Map each candidate from being canonical wrt the current inference context to being
+            // canonical wrt the caller.
+            for Candidate { source, result } in normalized_candidates {
+                self.infcx.probe(|_| {
+                    let candidate_certainty = fixme_instantiate_canonical_query_response(
+                        &self.infcx,
+                        &orig_values,
+                        result,
+                    );
+
+                    // FIXME: This is a bit scary if the `normalizes_to_goal` overflows.
+                    //
+                    // If we have an ambiguous candidate it hides that normalization
+                    // caused an overflow which may cause issues.
+                    self.try_insert_candidate(
+                        source,
+                        normalization_certainty.unify_and(candidate_certainty),
+                    )
+                })
+            }
+        })
+    }
+
+    fn assemble_impl_candidates(&mut self, goal: Goal<'tcx, G>) {
+        self.cx.tcx.for_each_relevant_impl(
+            goal.predicate.trait_def_id(self.cx.tcx),
+            goal.predicate.self_ty(),
+            |impl_def_id| G::consider_impl_candidate(self, goal, impl_def_id),
+        );
+    }
+}

compiler/rustc_trait_selection/src/solve/mod.rs

@@ -30,6 +30,7 @@ use rustc_span::DUMMY_SP;
 
 use self::infcx_ext::InferCtxtExt;
 
+mod assembly;
 mod cache;
 mod fulfill;
 mod infcx_ext;

compiler/rustc_trait_selection/src/solve/project_goals.rs

@@ -1,64 +1,40 @@
 use crate::traits::{specialization_graph, translate_substs};
 
-use super::infcx_ext::InferCtxtExt;
+use super::assembly::{self, AssemblyCtxt};
-use super::{
+use super::{CanonicalGoal, EvalCtxt, Goal, QueryResult};
-    fixme_instantiate_canonical_query_response, CanonicalGoal, CanonicalResponse, Certainty,
-    EvalCtxt, Goal, QueryResult,
-};
 use rustc_errors::ErrorGuaranteed;
 use rustc_hir::def::DefKind;
 use rustc_hir::def_id::DefId;
-use rustc_infer::infer::canonical::{CanonicalVarValues, OriginalQueryValues};
+use rustc_infer::infer::{InferCtxt, InferOk};
-use rustc_infer::infer::{InferCtxt, InferOk, TyCtxtInferExt};
 use rustc_infer::traits::query::NoSolution;
 use rustc_infer::traits::specialization_graph::LeafDef;
 use rustc_infer::traits::{ObligationCause, Reveal};
-use rustc_middle::ty;
 use rustc_middle::ty::fast_reject::{DeepRejectCtxt, TreatParams};
 use rustc_middle::ty::ProjectionPredicate;
 use rustc_middle::ty::TypeVisitable;
+use rustc_middle::ty::{self, Ty, TyCtxt};
 use rustc_span::DUMMY_SP;
 use std::iter;
 
-// FIXME: Deduplicate the candidate code between projection and trait goal.
-
-/// Similar to [super::trait_goals::Candidate] but for `Projection` goals.
-#[derive(Debug, Clone)]
-struct Candidate<'tcx> {
-    source: CandidateSource,
-    result: CanonicalResponse<'tcx>,
-}
-
 #[allow(dead_code)] // FIXME: implement and use all variants.
 #[derive(Debug, Clone, Copy)]
-enum CandidateSource {
+pub(super) enum CandidateSource {
     Impl(DefId),
     ParamEnv(usize),
     Builtin,
 }
 
+type Candidate<'tcx> = assembly::Candidate<'tcx, ProjectionPredicate<'tcx>>;
+
 impl<'tcx> EvalCtxt<'tcx> {
     pub(super) fn compute_projection_goal(
         &mut self,
         goal: CanonicalGoal<'tcx, ProjectionPredicate<'tcx>>,
     ) -> QueryResult<'tcx> {
-        let candidates = self.assemble_and_evaluate_project_candidates(goal);
+        let candidates = AssemblyCtxt::assemble_and_evaluate_candidates(self, goal);
         self.merge_project_candidates(candidates)
     }
 
-    fn assemble_and_evaluate_project_candidates(
-        &mut self,
-        goal: CanonicalGoal<'tcx, ProjectionPredicate<'tcx>>,
-    ) -> Vec<Candidate<'tcx>> {
-        let (ref infcx, goal, var_values) =
-            self.tcx.infer_ctxt().build_with_canonical(DUMMY_SP, &goal);
-        let mut acx = AssemblyCtxt { cx: self, infcx, var_values, candidates: Vec::new() };
-
-        acx.assemble_candidates_after_normalizing_self_ty(goal);
-        acx.assemble_impl_candidates(goal);
-        acx.candidates
-    }
-
     fn merge_project_candidates(
         &mut self,
         mut candidates: Vec<Candidate<'tcx>>,
@@ -112,83 +88,27 @@ impl<'tcx> EvalCtxt<'tcx> {
     }
 }
 
-/// Similar to [super::trait_goals::AssemblyCtxt] but for `Projection` goals.
+impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> {
-struct AssemblyCtxt<'a, 'tcx> {
+    type CandidateSource = CandidateSource;
-    cx: &'a mut EvalCtxt<'tcx>,
-    infcx: &'a InferCtxt<'tcx>,
-    var_values: CanonicalVarValues<'tcx>,
-    candidates: Vec<Candidate<'tcx>>,
-}
 
-impl<'tcx> AssemblyCtxt<'_, 'tcx> {
+    fn self_ty(self) -> Ty<'tcx> {
-    fn try_insert_candidate(&mut self, source: CandidateSource, certainty: Certainty) {
+        self.self_ty()
-        match self.infcx.make_canonical_response(self.var_values.clone(), certainty) {
-            Ok(result) => self.candidates.push(Candidate { source, result }),
-            Err(NoSolution) => debug!(?source, ?certainty, "failed leakcheck"),
-        }
     }
 
-    fn assemble_candidates_after_normalizing_self_ty(
+    fn with_self_ty(self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> Self {
-        &mut self,
+        self.with_self_ty(tcx, self_ty)
-        goal: Goal<'tcx, ProjectionPredicate<'tcx>>,
-    ) {
-        let tcx = self.cx.tcx;
-        let &ty::Alias(ty::Projection, projection_ty) = goal.predicate.projection_ty.self_ty().kind() else {
-            return
-        };
-        self.infcx.probe(|_| {
-            let normalized_ty = self.infcx.next_ty_infer();
-            let normalizes_to_goal = goal.with(
-                tcx,
-                ty::Binder::dummy(ty::ProjectionPredicate {
-                    projection_ty,
-                    term: normalized_ty.into(),
-                }),
-            );
-            let normalization_certainty =
-                match self.cx.evaluate_goal(&self.infcx, normalizes_to_goal) {
-                    Ok((_, certainty)) => certainty,
-                    Err(NoSolution) => return,
-                };
-
-            // NOTE: Alternatively we could call `evaluate_goal` here and only have a `Normalized` candidate.
-            // This doesn't work as long as we use `CandidateSource` in both winnowing and to resolve associated items.
-            let goal = goal.with(tcx, goal.predicate.with_self_ty(tcx, normalized_ty));
-            let mut orig_values = OriginalQueryValues::default();
-            let goal = self.infcx.canonicalize_query(goal, &mut orig_values);
-            let normalized_candidates = self.cx.assemble_and_evaluate_project_candidates(goal);
-            // Map each candidate from being canonical wrt the current inference context to being
-            // canonical wrt the caller.
-            for Candidate { source, result } in normalized_candidates {
-                self.infcx.probe(|_| {
-                    let candidate_certainty = fixme_instantiate_canonical_query_response(
-                        self.infcx,
-                        &orig_values,
-                        result,
-                    );
-                    self.try_insert_candidate(
-                        source,
-                        normalization_certainty.unify_and(candidate_certainty),
-                    )
-                })
-            }
-        })
     }
 
-    fn assemble_impl_candidates(&mut self, goal: Goal<'tcx, ProjectionPredicate<'tcx>>) {
+    fn trait_def_id(self, tcx: TyCtxt<'tcx>) -> DefId {
-        self.cx.tcx.for_each_relevant_impl(
+        self.trait_def_id(tcx)
-            goal.predicate.trait_def_id(self.cx.tcx),
-            goal.predicate.self_ty(),
-            |impl_def_id| self.consider_impl_candidate(goal, impl_def_id),
-        );
     }
 
     fn consider_impl_candidate(
-        &mut self,
+        acx: &mut AssemblyCtxt<'_, 'tcx, ProjectionPredicate<'tcx>>,
         goal: Goal<'tcx, ProjectionPredicate<'tcx>>,
         impl_def_id: DefId,
     ) {
-        let tcx = self.cx.tcx;
+        let tcx = acx.cx.tcx;
         let goal_trait_ref = goal.predicate.projection_ty.trait_ref(tcx);
         let impl_trait_ref = tcx.bound_impl_trait_ref(impl_def_id).unwrap();
         let drcx = DeepRejectCtxt { treat_obligation_params: TreatParams::AsPlaceholder };
@@ -198,11 +118,11 @@ impl<'tcx> AssemblyCtxt<'_, 'tcx> {
             return;
         }
 
-        self.infcx.probe(|_| {
+        acx.infcx.probe(|_| {
-            let impl_substs = self.infcx.fresh_substs_for_item(DUMMY_SP, impl_def_id);
+            let impl_substs = acx.infcx.fresh_substs_for_item(DUMMY_SP, impl_def_id);
             let impl_trait_ref = impl_trait_ref.subst(tcx, impl_substs);
 
-            let Ok(InferOk { obligations, .. }) = self
+            let Ok(InferOk { obligations, .. }) = acx
                 .infcx
                 .at(&ObligationCause::dummy(), goal.param_env)
                 .define_opaque_types(false)
@@ -213,9 +133,10 @@ impl<'tcx> AssemblyCtxt<'_, 'tcx> {
             };
 
             let nested_goals = obligations.into_iter().map(|o| o.into()).collect();
-            let Ok(trait_ref_certainty) = self.cx.evaluate_all(self.infcx, nested_goals) else { return };
+            let Ok(trait_ref_certainty) = acx.cx.evaluate_all(acx.infcx, nested_goals) else { return };
 
-            let Some(assoc_def) = self.fetch_eligible_assoc_item_def(
+            let Some(assoc_def) = fetch_eligible_assoc_item_def(
+                acx.infcx,
                 goal.param_env,
                 goal_trait_ref,
                 goal.predicate.def_id(),
@@ -247,7 +168,7 @@ impl<'tcx> AssemblyCtxt<'_, 'tcx> {
                 impl_trait_ref.substs,
             );
             let substs = translate_substs(
-                self.infcx,
+                acx.infcx,
                 goal.param_env,
                 impl_def_id,
                 impl_substs_with_gat,
@@ -267,7 +188,7 @@ impl<'tcx> AssemblyCtxt<'_, 'tcx> {
                 ty.map_bound(|ty| ty.into())
             };
 
-            let Ok(InferOk { obligations, .. }) = self
+            let Ok(InferOk { obligations, .. }) = acx
                 .infcx
                 .at(&ObligationCause::dummy(), goal.param_env)
                 .define_opaque_types(false)
@@ -278,27 +199,27 @@ impl<'tcx> AssemblyCtxt<'_, 'tcx> {
             };
 
             let nested_goals = obligations.into_iter().map(|o| o.into()).collect();
-            let Ok(rhs_certainty) = self.cx.evaluate_all(self.infcx, nested_goals) else { return };
+            let Ok(rhs_certainty) = acx.cx.evaluate_all(acx.infcx, nested_goals) else { return };
 
             let certainty = trait_ref_certainty.unify_and(rhs_certainty);
-            self.try_insert_candidate(CandidateSource::Impl(impl_def_id), certainty);
+            acx.try_insert_candidate(CandidateSource::Impl(impl_def_id), certainty);
         })
     }
+}
 
-    /// This behavior is also implemented in `rustc_ty_utils` and in the old `project` code.
+/// This behavior is also implemented in `rustc_ty_utils` and in the old `project` code.
-    ///
+///
-    /// FIXME: We should merge these 3 implementations as it's likely that they otherwise
+/// FIXME: We should merge these 3 implementations as it's likely that they otherwise
-    /// diverge.
+/// diverge.
-    #[instrument(level = "debug", skip(self, param_env), ret)]
+#[instrument(level = "debug", skip(infcx, param_env), ret)]
-    fn fetch_eligible_assoc_item_def(
+fn fetch_eligible_assoc_item_def<'tcx>(
-        &self,
+    infcx: &InferCtxt<'tcx>,
     param_env: ty::ParamEnv<'tcx>,
     goal_trait_ref: ty::TraitRef<'tcx>,
     trait_assoc_def_id: DefId,
     impl_def_id: DefId,
-    ) -> Option<LeafDef> {
+) -> Option<LeafDef> {
-        let node_item =
+    let node_item = specialization_graph::assoc_def(infcx.tcx, impl_def_id, trait_assoc_def_id)
-            specialization_graph::assoc_def(self.cx.tcx, impl_def_id, trait_assoc_def_id)
         .map_err(|ErrorGuaranteed { .. }| ())
         .ok()?;
 
@@ -311,7 +232,7 @@ impl<'tcx> AssemblyCtxt<'_, 'tcx> {
         // transmute checking and polymorphic MIR optimizations could
         // get a result which isn't correct for all monomorphizations.
         if param_env.reveal() == Reveal::All {
-                let poly_trait_ref = self.infcx.resolve_vars_if_possible(goal_trait_ref);
+            let poly_trait_ref = infcx.resolve_vars_if_possible(goal_trait_ref);
             !poly_trait_ref.still_further_specializable()
         } else {
             debug!(?node_item.item.def_id, "not eligible due to default");
@@ -320,5 +241,4 @@ impl<'tcx> AssemblyCtxt<'_, 'tcx> {
     };
 
     if eligible { Some(node_item) } else { None }
-    }
 }

compiler/rustc_trait_selection/src/solve/trait_goals.rs

@@ -2,35 +2,17 @@
 
 use std::iter;
 
-use super::infcx_ext::InferCtxtExt;
+use super::assembly::{self, AssemblyCtxt};
-use super::{
+use super::{CanonicalGoal, EvalCtxt, Goal, QueryResult};
-    fixme_instantiate_canonical_query_response, CanonicalGoal, CanonicalResponse, Certainty,
-    EvalCtxt, Goal, QueryResult,
-};
 use rustc_hir::def_id::DefId;
-use rustc_infer::infer::canonical::{CanonicalVarValues, OriginalQueryValues};
+use rustc_infer::infer::InferOk;
-use rustc_infer::infer::TyCtxtInferExt;
-use rustc_infer::infer::{InferCtxt, InferOk};
 use rustc_infer::traits::query::NoSolution;
 use rustc_infer::traits::ObligationCause;
-use rustc_middle::ty;
 use rustc_middle::ty::fast_reject::{DeepRejectCtxt, TreatParams};
 use rustc_middle::ty::TraitPredicate;
+use rustc_middle::ty::{self, Ty, TyCtxt};
 use rustc_span::DUMMY_SP;
 
-/// A candidate is a possible way to prove a goal.
-///
-/// It consists of both the `source`, which describes how that goal
-/// would be proven, and the `result` when using the given `source`.
-///
-/// For the list of possible candidates, please look at the documentation
-/// of [CandidateSource].
-#[derive(Debug, Clone)]
-pub(super) struct Candidate<'tcx> {
-    source: CandidateSource,
-    result: CanonicalResponse<'tcx>,
-}
-
 #[allow(dead_code)] // FIXME: implement and use all variants.
 #[derive(Debug, Clone, Copy)]
 pub(super) enum CandidateSource {
@@ -67,11 +49,56 @@ pub(super) enum CandidateSource {
     AutoImpl,
 }
 
-struct AssemblyCtxt<'a, 'tcx> {
+type Candidate<'tcx> = assembly::Candidate<'tcx, TraitPredicate<'tcx>>;
-    cx: &'a mut EvalCtxt<'tcx>,
+
-    infcx: &'a InferCtxt<'tcx>,
+impl<'tcx> assembly::GoalKind<'tcx> for TraitPredicate<'tcx> {
-    var_values: CanonicalVarValues<'tcx>,
+    type CandidateSource = CandidateSource;
-    candidates: Vec<Candidate<'tcx>>,
+
+    fn self_ty(self) -> Ty<'tcx> {
+        self.self_ty()
+    }
+
+    fn with_self_ty(self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> Self {
+        self.with_self_ty(tcx, self_ty)
+    }
+
+    fn trait_def_id(self, _: TyCtxt<'tcx>) -> DefId {
+        self.def_id()
+    }
+
+    fn consider_impl_candidate(
+        acx: &mut AssemblyCtxt<'_, 'tcx, Self>,
+        goal: Goal<'tcx, TraitPredicate<'tcx>>,
+        impl_def_id: DefId,
+    ) {
+        let impl_trait_ref = acx.cx.tcx.bound_impl_trait_ref(impl_def_id).unwrap();
+        let drcx = DeepRejectCtxt { treat_obligation_params: TreatParams::AsPlaceholder };
+        if iter::zip(goal.predicate.trait_ref.substs, impl_trait_ref.skip_binder().substs)
+            .any(|(goal, imp)| !drcx.generic_args_may_unify(goal, imp))
+        {
+            return;
+        }
+
+        acx.infcx.probe(|_| {
+            let impl_substs = acx.infcx.fresh_substs_for_item(DUMMY_SP, impl_def_id);
+            let impl_trait_ref = impl_trait_ref.subst(acx.cx.tcx, impl_substs);
+
+            let Ok(InferOk { obligations, .. }) = acx
+                .infcx
+                .at(&ObligationCause::dummy(), goal.param_env)
+                .define_opaque_types(false)
+                .eq(goal.predicate.trait_ref, impl_trait_ref)
+                .map_err(|e| debug!("failed to equate trait refs: {e:?}"))
+            else {
+                return
+            };
+
+            let nested_goals = obligations.into_iter().map(|o| o.into()).collect();
+
+            let Ok(certainty) = acx.cx.evaluate_all(acx.infcx, nested_goals) else { return };
+            acx.try_insert_candidate(CandidateSource::Impl(impl_def_id), certainty);
+        })
+    }
 }
 
 impl<'tcx> EvalCtxt<'tcx> {
@@ -79,25 +106,10 @@ impl<'tcx> EvalCtxt<'tcx> {
         &mut self,
         goal: CanonicalGoal<'tcx, TraitPredicate<'tcx>>,
     ) -> QueryResult<'tcx> {
-        let candidates = self.assemble_and_evaluate_trait_candidates(goal);
+        let candidates = AssemblyCtxt::assemble_and_evaluate_candidates(self, goal);
         self.merge_trait_candidates_discard_reservation_impls(candidates)
     }
 
-    pub(super) fn assemble_and_evaluate_trait_candidates(
-        &mut self,
-        goal: CanonicalGoal<'tcx, TraitPredicate<'tcx>>,
-    ) -> Vec<Candidate<'tcx>> {
-        let (ref infcx, goal, var_values) =
-            self.tcx.infer_ctxt().build_with_canonical(DUMMY_SP, &goal);
-        let mut acx = AssemblyCtxt { cx: self, infcx, var_values, candidates: Vec::new() };
-
-        acx.assemble_candidates_after_normalizing_self_ty(goal);
-        acx.assemble_impl_candidates(goal);
-
-        // FIXME: Remaining candidates
-        acx.candidates
-    }
-
     #[instrument(level = "debug", skip(self), ret)]
     pub(super) fn merge_trait_candidates_discard_reservation_impls(
         &mut self,
@@ -166,117 +178,3 @@ impl<'tcx> EvalCtxt<'tcx> {
         candidate
     }
 }
-
-impl<'tcx> AssemblyCtxt<'_, 'tcx> {
-    /// Adds a new candidate using the current state of the inference context.
-    ///
-    /// This does require each assembly method to correctly use `probe` to not taint
-    /// the results of other candidates.
-    fn try_insert_candidate(&mut self, source: CandidateSource, certainty: Certainty) {
-        match self.infcx.make_canonical_response(self.var_values.clone(), certainty) {
-            Ok(result) => self.candidates.push(Candidate { source, result }),
-            Err(NoSolution) => debug!(?source, ?certainty, "failed leakcheck"),
-        }
-    }
-
-    /// If the self type of a trait goal is a projection, computing the relevant candidates is difficult.
-    ///
-    /// To deal with this, we first try to normalize the self type and add the candidates for the normalized
-    /// self type to the list of candidates in case that succeeds. Note that we can't just eagerly return in
-    /// this case as projections as self types add `
-    fn assemble_candidates_after_normalizing_self_ty(
-        &mut self,
-        goal: Goal<'tcx, TraitPredicate<'tcx>>,
-    ) {
-        let tcx = self.cx.tcx;
-        // FIXME: We also have to normalize opaque types, not sure where to best fit that in.
-        let &ty::Alias(ty::Projection, projection_ty) = goal.predicate.self_ty().kind() else {
-            return
-        };
-        self.infcx.probe(|_| {
-            let normalized_ty = self.infcx.next_ty_infer();
-            let normalizes_to_goal = goal.with(
-                tcx,
-                ty::Binder::dummy(ty::ProjectionPredicate {
-                    projection_ty,
-                    term: normalized_ty.into(),
-                }),
-            );
-            let normalization_certainty =
-                match self.cx.evaluate_goal(&self.infcx, normalizes_to_goal) {
-                    Ok((_, certainty)) => certainty,
-                    Err(NoSolution) => return,
-                };
-
-            // NOTE: Alternatively we could call `evaluate_goal` here and only have a `Normalized` candidate.
-            // This doesn't work as long as we use `CandidateSource` in both winnowing and to resolve associated items.
-            let goal = goal.with(tcx, goal.predicate.with_self_type(tcx, normalized_ty));
-            let mut orig_values = OriginalQueryValues::default();
-            let goal = self.infcx.canonicalize_query(goal, &mut orig_values);
-            let normalized_candidates = self.cx.assemble_and_evaluate_trait_candidates(goal);
-
-            // Map each candidate from being canonical wrt the current inference context to being
-            // canonical wrt the caller.
-            for Candidate { source, result } in normalized_candidates {
-                self.infcx.probe(|_| {
-                    let candidate_certainty = fixme_instantiate_canonical_query_response(
-                        self.infcx,
-                        &orig_values,
-                        result,
-                    );
-
-                    // FIXME: This is a bit scary if the `normalizes_to_goal` overflows.
-                    //
-                    // If we have an ambiguous candidate it hides that normalization
-                    // caused an overflow which may cause issues.
-                    self.try_insert_candidate(
-                        source,
-                        normalization_certainty.unify_and(candidate_certainty),
-                    )
-                })
-            }
-        })
-    }
-
-    fn assemble_impl_candidates(&mut self, goal: Goal<'tcx, TraitPredicate<'tcx>>) {
-        self.cx.tcx.for_each_relevant_impl(
-            goal.predicate.def_id(),
-            goal.predicate.self_ty(),
-            |impl_def_id| self.consider_impl_candidate(goal, impl_def_id),
-        );
-    }
-
-    fn consider_impl_candidate(
-        &mut self,
-        goal: Goal<'tcx, TraitPredicate<'tcx>>,
-        impl_def_id: DefId,
-    ) {
-        let impl_trait_ref = self.cx.tcx.bound_impl_trait_ref(impl_def_id).unwrap();
-        let drcx = DeepRejectCtxt { treat_obligation_params: TreatParams::AsPlaceholder };
-        if iter::zip(goal.predicate.trait_ref.substs, impl_trait_ref.skip_binder().substs)
-            .any(|(goal, imp)| !drcx.generic_args_may_unify(goal, imp))
-        {
-            return;
-        }
-
-        self.infcx.probe(|_| {
-            let impl_substs = self.infcx.fresh_substs_for_item(DUMMY_SP, impl_def_id);
-            let impl_trait_ref = impl_trait_ref.subst(self.cx.tcx, impl_substs);
-
-            let Ok(InferOk { obligations, .. }) = self
-                .infcx
-                .at(&ObligationCause::dummy(), goal.param_env)
-                .define_opaque_types(false)
-                .eq(goal.predicate.trait_ref, impl_trait_ref)
-                .map_err(|e| debug!("failed to equate trait refs: {e:?}"))
-            else {
-                return
-            };
-
-            let nested_goals = obligations.into_iter().map(|o| o.into()).collect();
-
-            let Ok(certainty) = self.cx.evaluate_all(self.infcx, nested_goals) else { return };
-            self.try_insert_candidate(CandidateSource::Impl(impl_def_id), certainty);
-        })
-    }
-}