Merge pull request #2358 from rust-lang/rustc-pull

Rustc pull update

9 files changed, 206 insertions, 171 deletions

diff --git a/compiler/rustc_next_trait_solver/src/delegate.rs b/compiler/rustc_next_trait_solver/src/delegate.rs
index c4b6b18c45d..25493970a0c 100644
--- a/compiler/rustc_next_trait_solver/src/delegate.rs
+++ b/compiler/rustc_next_trait_solver/src/delegate.rs
@@ -36,7 +36,7 @@ pub trait SolverDelegate: Deref<Target = Self::Infcx> + Sized {
     fn well_formed_goals(
         &self,
         param_env: <Self::Interner as Interner>::ParamEnv,
-        arg: <Self::Interner as Interner>::GenericArg,
+        term: <Self::Interner as Interner>::Term,
     ) -> Option<Vec<Goal<Self::Interner, <Self::Interner as Interner>::Predicate>>>;
 
     fn clone_opaque_types_for_query_response(
diff --git a/compiler/rustc_next_trait_solver/src/solve/alias_relate.rs b/compiler/rustc_next_trait_solver/src/solve/alias_relate.rs
index 0fc313e33b3..f7bd4600943 100644
--- a/compiler/rustc_next_trait_solver/src/solve/alias_relate.rs
+++ b/compiler/rustc_next_trait_solver/src/solve/alias_relate.rs
@@ -16,6 +16,7 @@
 //! relate them structurally.
 
 use rustc_type_ir::inherent::*;
+use rustc_type_ir::solve::GoalSource;
 use rustc_type_ir::{self as ty, Interner};
 use tracing::{instrument, trace};
 
@@ -49,7 +50,10 @@ where
         // Structurally normalize the lhs.
         let lhs = if let Some(alias) = lhs.to_alias_term() {
             let term = self.next_term_infer_of_kind(lhs);
-            self.add_normalizes_to_goal(goal.with(cx, ty::NormalizesTo { alias, term }));
+            self.add_goal(
+                GoalSource::TypeRelating,
+                goal.with(cx, ty::NormalizesTo { alias, term }),
+            );
             term
         } else {
             lhs
@@ -58,7 +62,10 @@ where
         // Structurally normalize the rhs.
         let rhs = if let Some(alias) = rhs.to_alias_term() {
             let term = self.next_term_infer_of_kind(rhs);
-            self.add_normalizes_to_goal(goal.with(cx, ty::NormalizesTo { alias, term }));
+            self.add_goal(
+                GoalSource::TypeRelating,
+                goal.with(cx, ty::NormalizesTo { alias, term }),
+            );
             term
         } else {
             rhs
diff --git a/compiler/rustc_next_trait_solver/src/solve/assembly/mod.rs b/compiler/rustc_next_trait_solver/src/solve/assembly/mod.rs
index ecb57cc0ad7..381a732b8de 100644
--- a/compiler/rustc_next_trait_solver/src/solve/assembly/mod.rs
+++ b/compiler/rustc_next_trait_solver/src/solve/assembly/mod.rs
@@ -10,6 +10,7 @@ use rustc_type_ir::{
 };
 use tracing::{debug, instrument};
 
+use super::has_only_region_constraints;
 use super::trait_goals::TraitGoalProvenVia;
 use crate::delegate::SolverDelegate;
 use crate::solve::inspect::ProbeKind;
@@ -771,6 +772,69 @@ where
             }
         })
     }
+}
+
+pub(super) enum AllowInferenceConstraints {
+    Yes,
+    No,
+}
+
+impl<D, I> EvalCtxt<'_, D>
+where
+    D: SolverDelegate<Interner = I>,
+    I: Interner,
+{
+    /// Check whether we can ignore impl candidates due to specialization.
+    ///
+    /// This is only necessary for `feature(specialization)` and seems quite ugly.
+    pub(super) fn filter_specialized_impls(
+        &mut self,
+        allow_inference_constraints: AllowInferenceConstraints,
+        candidates: &mut Vec<Candidate<I>>,
+    ) {
+        match self.typing_mode() {
+            TypingMode::Coherence => return,
+            TypingMode::Analysis { .. }
+            | TypingMode::Borrowck { .. }
+            | TypingMode::PostBorrowckAnalysis { .. }
+            | TypingMode::PostAnalysis => {}
+        }
+
+        let mut i = 0;
+        'outer: while i < candidates.len() {
+            let CandidateSource::Impl(victim_def_id) = candidates[i].source else {
+                i += 1;
+                continue;
+            };
+
+            for (j, c) in candidates.iter().enumerate() {
+                if i == j {
+                    continue;
+                }
+
+                let CandidateSource::Impl(other_def_id) = c.source else {
+                    continue;
+                };
+
+                // See if we can toss out `victim` based on specialization.
+                //
+                // While this requires us to know *for sure* that the `lhs` impl applies
+                // we still use modulo regions here. This is fine as specialization currently
+                // assumes that specializing impls have to be always applicable, meaning that
+                // the only allowed region constraints may be constraints also present on the default impl.
+                if matches!(allow_inference_constraints, AllowInferenceConstraints::Yes)
+                    || has_only_region_constraints(c.result)
+                {
+                    if self.cx().impl_specializes(other_def_id, victim_def_id) {
+                        candidates.remove(i);
+                        continue 'outer;
+                    }
+                }
+            }
+
+            i += 1;
+        }
+    }
 
     /// Assemble and merge candidates for goals which are related to an underlying trait
     /// goal. Right now, this is normalizes-to and host effect goals.
@@ -857,7 +921,7 @@ where
                 }
             }
             TraitGoalProvenVia::Misc => {
-                let candidates =
+                let mut candidates =
                     self.assemble_and_evaluate_candidates(goal, AssembleCandidatesFrom::All);
 
                 // Prefer "orphaned" param-env normalization predicates, which are used
@@ -871,6 +935,13 @@ where
                     return Ok(response);
                 }
 
+                // We drop specialized impls to allow normalization via a final impl here. In case
+                // the specializing impl has different inference constraints from the specialized
+                // impl, proving the trait goal is already ambiguous, so we never get here. This
+                // means we can just ignore inference constraints and don't have to special-case
+                // constraining the normalized-to `term`.
+                self.filter_specialized_impls(AllowInferenceConstraints::Yes, &mut candidates);
+
                 let responses: Vec<_> = candidates.iter().map(|c| c.result).collect();
                 if let Some(response) = self.try_merge_responses(&responses) {
                     Ok(response)
diff --git a/compiler/rustc_next_trait_solver/src/solve/eval_ctxt/canonical.rs b/compiler/rustc_next_trait_solver/src/solve/eval_ctxt/canonical.rs
index d56b0e5847e..04f80a056f9 100644
--- a/compiler/rustc_next_trait_solver/src/solve/eval_ctxt/canonical.rs
+++ b/compiler/rustc_next_trait_solver/src/solve/eval_ctxt/canonical.rs
@@ -22,7 +22,7 @@ use tracing::{debug, instrument, trace};
 use crate::canonicalizer::Canonicalizer;
 use crate::delegate::SolverDelegate;
 use crate::resolve::EagerResolver;
-use crate::solve::eval_ctxt::{CurrentGoalKind, NestedGoals};
+use crate::solve::eval_ctxt::CurrentGoalKind;
 use crate::solve::{
     CanonicalInput, CanonicalResponse, Certainty, EvalCtxt, ExternalConstraintsData, Goal,
     MaybeCause, NestedNormalizationGoals, NoSolution, PredefinedOpaquesData, QueryInput,
@@ -112,13 +112,9 @@ where
         // by `try_evaluate_added_goals()`.
         let (certainty, normalization_nested_goals) = match self.current_goal_kind {
             CurrentGoalKind::NormalizesTo => {
-                let NestedGoals { normalizes_to_goals, goals } =
-                    std::mem::take(&mut self.nested_goals);
-                if cfg!(debug_assertions) {
-                    assert!(normalizes_to_goals.is_empty());
-                    if goals.is_empty() {
-                        assert!(matches!(goals_certainty, Certainty::Yes));
-                    }
+                let goals = std::mem::take(&mut self.nested_goals);
+                if goals.is_empty() {
+                    assert!(matches!(goals_certainty, Certainty::Yes));
                 }
                 (certainty, NestedNormalizationGoals(goals))
             }
diff --git a/compiler/rustc_next_trait_solver/src/solve/eval_ctxt/mod.rs b/compiler/rustc_next_trait_solver/src/solve/eval_ctxt/mod.rs
index 9994c85d0d0..6dd554299a6 100644
--- a/compiler/rustc_next_trait_solver/src/solve/eval_ctxt/mod.rs
+++ b/compiler/rustc_next_trait_solver/src/solve/eval_ctxt/mod.rs
@@ -1,8 +1,8 @@
+use std::mem;
 use std::ops::ControlFlow;
 
-use derive_where::derive_where;
 #[cfg(feature = "nightly")]
-use rustc_macros::{Decodable_NoContext, Encodable_NoContext, HashStable_NoContext};
+use rustc_macros::HashStable_NoContext;
 use rustc_type_ir::data_structures::{HashMap, HashSet, ensure_sufficient_stack};
 use rustc_type_ir::fast_reject::DeepRejectCtxt;
 use rustc_type_ir::inherent::*;
@@ -14,9 +14,9 @@ use rustc_type_ir::{
     TypeSuperFoldable, TypeSuperVisitable, TypeVisitable, TypeVisitableExt, TypeVisitor,
     TypingMode,
 };
-use rustc_type_ir_macros::{Lift_Generic, TypeFoldable_Generic, TypeVisitable_Generic};
 use tracing::{instrument, trace};
 
+use super::has_only_region_constraints;
 use crate::coherence;
 use crate::delegate::SolverDelegate;
 use crate::solve::inspect::{self, ProofTreeBuilder};
@@ -114,7 +114,7 @@ where
 
     pub(super) search_graph: &'a mut SearchGraph<D>,
 
-    nested_goals: NestedGoals<I>,
+    nested_goals: Vec<(GoalSource, Goal<I, I::Predicate>)>,
 
     pub(super) origin_span: I::Span,
 
@@ -129,38 +129,6 @@ where
     pub(super) inspect: ProofTreeBuilder<D>,
 }
 
-#[derive_where(Clone, Debug, Default; I: Interner)]
-#[derive(TypeVisitable_Generic, TypeFoldable_Generic, Lift_Generic)]
-#[cfg_attr(
-    feature = "nightly",
-    derive(Decodable_NoContext, Encodable_NoContext, HashStable_NoContext)
-)]
-struct NestedGoals<I: Interner> {
-    /// These normalizes-to goals are treated specially during the evaluation
-    /// loop. In each iteration we take the RHS of the projection, replace it with
-    /// a fresh inference variable, and only after evaluating that goal do we
-    /// equate the fresh inference variable with the actual RHS of the predicate.
-    ///
-    /// This is both to improve caching, and to avoid using the RHS of the
-    /// projection predicate to influence the normalizes-to candidate we select.
-    ///
-    /// Forgetting to replace the RHS with a fresh inference variable when we evaluate
-    /// this goal results in an ICE..
-    pub normalizes_to_goals: Vec<Goal<I, ty::NormalizesTo<I>>>,
-    /// The rest of the goals which have not yet processed or remain ambiguous.
-    pub goals: Vec<(GoalSource, Goal<I, I::Predicate>)>,
-}
-
-impl<I: Interner> NestedGoals<I> {
-    fn new() -> Self {
-        Self { normalizes_to_goals: Vec::new(), goals: Vec::new() }
-    }
-
-    fn is_empty(&self) -> bool {
-        self.normalizes_to_goals.is_empty() && self.goals.is_empty()
-    }
-}
-
 #[derive(PartialEq, Eq, Debug, Hash, Clone, Copy)]
 #[cfg_attr(feature = "nightly", derive(HashStable_NoContext))]
 pub enum GenerateProofTree {
@@ -332,7 +300,7 @@ where
         let mut ecx = EvalCtxt {
             delegate,
             search_graph: &mut search_graph,
-            nested_goals: NestedGoals::new(),
+            nested_goals: Default::default(),
             inspect: ProofTreeBuilder::new_maybe_root(generate_proof_tree),
 
             // Only relevant when canonicalizing the response,
@@ -385,7 +353,7 @@ where
             predefined_opaques_in_body: input.predefined_opaques_in_body,
             max_input_universe: canonical_input.canonical.max_universe,
             search_graph,
-            nested_goals: NestedGoals::new(),
+            nested_goals: Default::default(),
             origin_span: I::Span::dummy(),
             tainted: Ok(()),
             inspect: canonical_goal_evaluation.new_goal_evaluation_step(var_values),
@@ -509,13 +477,8 @@ where
             Ok(response) => response,
         };
 
-        let has_changed = if !response.value.var_values.is_identity_modulo_regions()
-            || !response.value.external_constraints.opaque_types.is_empty()
-        {
-            HasChanged::Yes
-        } else {
-            HasChanged::No
-        };
+        let has_changed =
+            if !has_only_region_constraints(response) { HasChanged::Yes } else { HasChanged::No };
 
         let (normalization_nested_goals, certainty) =
             self.instantiate_and_apply_query_response(goal.param_env, orig_values, response);
@@ -566,8 +529,8 @@ where
                 ty::PredicateKind::DynCompatible(trait_def_id) => {
                     self.compute_dyn_compatible_goal(trait_def_id)
                 }
-                ty::PredicateKind::Clause(ty::ClauseKind::WellFormed(arg)) => {
-                    self.compute_well_formed_goal(Goal { param_env, predicate: arg })
+                ty::PredicateKind::Clause(ty::ClauseKind::WellFormed(term)) => {
+                    self.compute_well_formed_goal(Goal { param_env, predicate: term })
                 }
                 ty::PredicateKind::Clause(ty::ClauseKind::ConstEvaluatable(ct)) => {
                     self.compute_const_evaluatable_goal(Goal { param_env, predicate: ct })
@@ -629,78 +592,83 @@ where
     /// Goals for the next step get directly added to the nested goals of the `EvalCtxt`.
     fn evaluate_added_goals_step(&mut self) -> Result<Option<Certainty>, NoSolution> {
         let cx = self.cx();
-        let mut goals = core::mem::take(&mut self.nested_goals);
-
         // If this loop did not result in any progress, what's our final certainty.
         let mut unchanged_certainty = Some(Certainty::Yes);
-        for goal in goals.normalizes_to_goals {
-            // Replace the goal with an unconstrained infer var, so the
-            // RHS does not affect projection candidate assembly.
-            let unconstrained_rhs = self.next_term_infer_of_kind(goal.predicate.term);
-            let unconstrained_goal = goal.with(
-                cx,
-                ty::NormalizesTo { alias: goal.predicate.alias, term: unconstrained_rhs },
-            );
-
-            let (NestedNormalizationGoals(nested_goals), _, certainty) = self.evaluate_goal_raw(
-                GoalEvaluationKind::Nested,
-                GoalSource::TypeRelating,
-                unconstrained_goal,
-            )?;
-            // Add the nested goals from normalization to our own nested goals.
-            trace!(?nested_goals);
-            goals.goals.extend(nested_goals);
-
-            // Finally, equate the goal's RHS with the unconstrained var.
-            //
-            // SUBTLE:
-            // We structurally relate aliases here. This is necessary
-            // as we otherwise emit a nested `AliasRelate` goal in case the
-            // returned term is a rigid alias, resulting in overflow.
+        for (source, goal) in mem::take(&mut self.nested_goals) {
+            // We treat normalizes-to goals specially here. In each iteration we take the
+            // RHS of the projection, replace it with a fresh inference variable, and only
+            // after evaluating that goal do we equate the fresh inference variable with the
+            // actual RHS of the predicate.
             //
-            // It is correct as both `goal.predicate.term` and `unconstrained_rhs`
-            // start out as an unconstrained inference variable so any aliases get
-            // fully normalized when instantiating it.
+            // This is both to improve caching, and to avoid using the RHS of the
+            // projection predicate to influence the normalizes-to candidate we select.
             //
-            // FIXME: Strictly speaking this may be incomplete if the normalized-to
-            // type contains an ambiguous alias referencing bound regions. We should
-            // consider changing this to only use "shallow structural equality".
-            self.eq_structurally_relating_aliases(
-                goal.param_env,
-                goal.predicate.term,
-                unconstrained_rhs,
-            )?;
-
-            // We only look at the `projection_ty` part here rather than
-            // looking at the "has changed" return from evaluate_goal,
-            // because we expect the `unconstrained_rhs` part of the predicate
-            // to have changed -- that means we actually normalized successfully!
-            let with_resolved_vars = self.resolve_vars_if_possible(goal);
-            if goal.predicate.alias != with_resolved_vars.predicate.alias {
-                unchanged_certainty = None;
-            }
-
-            match certainty {
-                Certainty::Yes => {}
-                Certainty::Maybe(_) => {
-                    self.nested_goals.normalizes_to_goals.push(with_resolved_vars);
-                    unchanged_certainty = unchanged_certainty.map(|c| c.unify_with(certainty));
+            // Forgetting to replace the RHS with a fresh inference variable when we evaluate
+            // this goal results in an ICE.
+            if let Some(pred) = goal.predicate.as_normalizes_to() {
+                // We should never encounter higher-ranked normalizes-to goals.
+                let pred = pred.no_bound_vars().unwrap();
+                // Replace the goal with an unconstrained infer var, so the
+                // RHS does not affect projection candidate assembly.
+                let unconstrained_rhs = self.next_term_infer_of_kind(pred.term);
+                let unconstrained_goal =
+                    goal.with(cx, ty::NormalizesTo { alias: pred.alias, term: unconstrained_rhs });
+
+                let (NestedNormalizationGoals(nested_goals), _, certainty) =
+                    self.evaluate_goal_raw(GoalEvaluationKind::Nested, source, unconstrained_goal)?;
+                // Add the nested goals from normalization to our own nested goals.
+                trace!(?nested_goals);
+                self.nested_goals.extend(nested_goals);
+
+                // Finally, equate the goal's RHS with the unconstrained var.
+                //
+                // SUBTLE:
+                // We structurally relate aliases here. This is necessary
+                // as we otherwise emit a nested `AliasRelate` goal in case the
+                // returned term is a rigid alias, resulting in overflow.
+                //
+                // It is correct as both `goal.predicate.term` and `unconstrained_rhs`
+                // start out as an unconstrained inference variable so any aliases get
+                // fully normalized when instantiating it.
+                //
+                // FIXME: Strictly speaking this may be incomplete if the normalized-to
+                // type contains an ambiguous alias referencing bound regions. We should
+                // consider changing this to only use "shallow structural equality".
+                self.eq_structurally_relating_aliases(
+                    goal.param_env,
+                    pred.term,
+                    unconstrained_rhs,
+                )?;
+
+                // We only look at the `projection_ty` part here rather than
+                // looking at the "has changed" return from evaluate_goal,
+                // because we expect the `unconstrained_rhs` part of the predicate
+                // to have changed -- that means we actually normalized successfully!
+                let with_resolved_vars = self.resolve_vars_if_possible(goal);
+                if pred.alias != goal.predicate.as_normalizes_to().unwrap().skip_binder().alias {
+                    unchanged_certainty = None;
                 }
-            }
-        }
 
-        for (source, goal) in goals.goals {
-            let (has_changed, certainty) =
-                self.evaluate_goal(GoalEvaluationKind::Nested, source, goal)?;
-            if has_changed == HasChanged::Yes {
-                unchanged_certainty = None;
-            }
+                match certainty {
+                    Certainty::Yes => {}
+                    Certainty::Maybe(_) => {
+                        self.nested_goals.push((source, with_resolved_vars));
+                        unchanged_certainty = unchanged_certainty.map(|c| c.unify_with(certainty));
+                    }
+                }
+            } else {
+                let (has_changed, certainty) =
+                    self.evaluate_goal(GoalEvaluationKind::Nested, source, goal)?;
+                if has_changed == HasChanged::Yes {
+                    unchanged_certainty = None;
+                }
 
-            match certainty {
-                Certainty::Yes => {}
-                Certainty::Maybe(_) => {
-                    self.nested_goals.goals.push((source, goal));
-                    unchanged_certainty = unchanged_certainty.map(|c| c.unify_with(certainty));
+                match certainty {
+                    Certainty::Yes => {}
+                    Certainty::Maybe(_) => {
+                        self.nested_goals.push((source, goal));
+                        unchanged_certainty = unchanged_certainty.map(|c| c.unify_with(certainty));
+                    }
                 }
             }
         }
@@ -717,23 +685,12 @@ where
         self.delegate.cx()
     }
 
-    #[instrument(level = "trace", skip(self))]
-    pub(super) fn add_normalizes_to_goal(&mut self, mut goal: Goal<I, ty::NormalizesTo<I>>) {
-        goal.predicate = goal.predicate.fold_with(&mut ReplaceAliasWithInfer::new(
-            self,
-            GoalSource::TypeRelating,
-            goal.param_env,
-        ));
-        self.inspect.add_normalizes_to_goal(self.delegate, self.max_input_universe, goal);
-        self.nested_goals.normalizes_to_goals.push(goal);
-    }
-
     #[instrument(level = "debug", skip(self))]
     pub(super) fn add_goal(&mut self, source: GoalSource, mut goal: Goal<I, I::Predicate>) {
         goal.predicate =
             goal.predicate.fold_with(&mut ReplaceAliasWithInfer::new(self, source, goal.param_env));
         self.inspect.add_goal(self.delegate, self.max_input_universe, source, goal);
-        self.nested_goals.goals.push((source, goal));
+        self.nested_goals.push((source, goal));
     }
 
     #[instrument(level = "trace", skip(self, goals))]
@@ -1051,9 +1008,9 @@ where
     pub(super) fn well_formed_goals(
         &self,
         param_env: I::ParamEnv,
-        arg: I::GenericArg,
+        term: I::Term,
     ) -> Option<Vec<Goal<I, I::Predicate>>> {
-        self.delegate.well_formed_goals(param_env, arg)
+        self.delegate.well_formed_goals(param_env, term)
     }
 
     pub(super) fn trait_ref_is_knowable(
diff --git a/compiler/rustc_next_trait_solver/src/solve/inspect/build.rs b/compiler/rustc_next_trait_solver/src/solve/inspect/build.rs
index 6a8e0790f7c..f22b275bc44 100644
--- a/compiler/rustc_next_trait_solver/src/solve/inspect/build.rs
+++ b/compiler/rustc_next_trait_solver/src/solve/inspect/build.rs
@@ -412,20 +412,6 @@ impl<D: SolverDelegate<Interner = I>, I: Interner> ProofTreeBuilder<D> {
         }
     }
 
-    pub(crate) fn add_normalizes_to_goal(
-        &mut self,
-        delegate: &D,
-        max_input_universe: ty::UniverseIndex,
-        goal: Goal<I, ty::NormalizesTo<I>>,
-    ) {
-        self.add_goal(
-            delegate,
-            max_input_universe,
-            GoalSource::TypeRelating,
-            goal.with(delegate.cx(), goal.predicate),
-        );
-    }
-
     pub(crate) fn add_goal(
         &mut self,
         delegate: &D,
diff --git a/compiler/rustc_next_trait_solver/src/solve/mod.rs b/compiler/rustc_next_trait_solver/src/solve/mod.rs
index 0695c5acdca..c9f4fc649b5 100644
--- a/compiler/rustc_next_trait_solver/src/solve/mod.rs
+++ b/compiler/rustc_next_trait_solver/src/solve/mod.rs
@@ -70,6 +70,17 @@ fn has_no_inference_or_external_constraints<I: Interner>(
         && normalization_nested_goals.is_empty()
 }
 
+fn has_only_region_constraints<I: Interner>(response: ty::Canonical<I, Response<I>>) -> bool {
+    let ExternalConstraintsData {
+        region_constraints: _,
+        ref opaque_types,
+        ref normalization_nested_goals,
+    } = *response.value.external_constraints;
+    response.value.var_values.is_identity_modulo_regions()
+        && opaque_types.is_empty()
+        && normalization_nested_goals.is_empty()
+}
+
 impl<'a, D, I> EvalCtxt<'a, D>
 where
     D: SolverDelegate<Interner = I>,
@@ -126,7 +137,7 @@ where
     }
 
     #[instrument(level = "trace", skip(self))]
-    fn compute_well_formed_goal(&mut self, goal: Goal<I, I::GenericArg>) -> QueryResult<I> {
+    fn compute_well_formed_goal(&mut self, goal: Goal<I, I::Term>) -> QueryResult<I> {
         match self.well_formed_goals(goal.param_env, goal.predicate) {
             Some(goals) => {
                 self.add_goals(GoalSource::Misc, goals);
diff --git a/compiler/rustc_next_trait_solver/src/solve/normalizes_to/mod.rs b/compiler/rustc_next_trait_solver/src/solve/normalizes_to/mod.rs
index 9466901683e..119d197de13 100644
--- a/compiler/rustc_next_trait_solver/src/solve/normalizes_to/mod.rs
+++ b/compiler/rustc_next_trait_solver/src/solve/normalizes_to/mod.rs
@@ -213,9 +213,6 @@ where
                 ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
             };
 
-            // In case the associated item is hidden due to specialization, we have to
-            // return ambiguity this would otherwise be incomplete, resulting in
-            // unsoundness during coherence (#105782).
             let target_item_def_id = match ecx.fetch_eligible_assoc_item(
                 goal_trait_ref,
                 goal.predicate.def_id(),
@@ -223,8 +220,28 @@ where
             ) {
                 Ok(Some(target_item_def_id)) => target_item_def_id,
                 Ok(None) => {
-                    return ecx
-                        .evaluate_added_goals_and_make_canonical_response(Certainty::AMBIGUOUS);
+                    match ecx.typing_mode() {
+                        // In case the associated item is hidden due to specialization, we have to
+                        // return ambiguity this would otherwise be incomplete, resulting in
+                        // unsoundness during coherence (#105782).
+                        ty::TypingMode::Coherence => {
+                            return ecx.evaluate_added_goals_and_make_canonical_response(
+                                Certainty::AMBIGUOUS,
+                            );
+                        }
+                        // Outside of coherence, we treat the associated item as rigid instead.
+                        ty::TypingMode::Analysis { .. }
+                        | ty::TypingMode::Borrowck { .. }
+                        | ty::TypingMode::PostBorrowckAnalysis { .. }
+                        | ty::TypingMode::PostAnalysis => {
+                            ecx.structurally_instantiate_normalizes_to_term(
+                                goal,
+                                goal.predicate.alias,
+                            );
+                            return ecx
+                                .evaluate_added_goals_and_make_canonical_response(Certainty::Yes);
+                        }
+                    };
                 }
                 Err(guar) => return error_response(ecx, guar),
             };
diff --git a/compiler/rustc_next_trait_solver/src/solve/trait_goals.rs b/compiler/rustc_next_trait_solver/src/solve/trait_goals.rs
index 827853be280..24657496df6 100644
--- a/compiler/rustc_next_trait_solver/src/solve/trait_goals.rs
+++ b/compiler/rustc_next_trait_solver/src/solve/trait_goals.rs
@@ -13,7 +13,7 @@ use tracing::{instrument, trace};
 
 use crate::delegate::SolverDelegate;
 use crate::solve::assembly::structural_traits::{self, AsyncCallableRelevantTypes};
-use crate::solve::assembly::{self, AssembleCandidatesFrom, Candidate};
+use crate::solve::assembly::{self, AllowInferenceConstraints, AssembleCandidatesFrom, Candidate};
 use crate::solve::inspect::ProbeKind;
 use crate::solve::{
     BuiltinImplSource, CandidateSource, Certainty, EvalCtxt, Goal, GoalSource, MaybeCause,
@@ -1308,18 +1308,6 @@ where
                     return true;
                 }
 
-                // We don't consider a trait-bound global if it has a projection bound.
-                //
-                // See ui/traits/next-solver/normalization-shadowing/global-trait-with-project.rs
-                // for an example where this is necessary.
-                for p in goal.param_env.caller_bounds().iter() {
-                    if let ty::ClauseKind::Projection(proj) = p.kind().skip_binder() {
-                        if proj.projection_term.trait_ref(self.cx()) == trait_pred.trait_ref {
-                            return true;
-                        }
-                    }
-                }
-
                 false
             }
             _ => false,
@@ -1350,6 +1338,8 @@ where
             };
         }
 
+        self.filter_specialized_impls(AllowInferenceConstraints::No, &mut candidates);
+
         // If there are *only* global where bounds, then make sure to return that this
         // is still reported as being proven-via the param-env so that rigid projections
         // operate correctly. Otherwise, drop all global where-bounds before merging the