Rollup merge of rust-lang#131599 - compiler-errors:storage, r=lcnr

Shallowly match opaque key in storage

Using a full eq on the key *and* the hidden type means that in cases where we first ambiguously register a `?t` hidden type then constrain that `?t` to be a type that doesn't actually satisfy its bounds, we end up with bogus entries in the opaque type storage. We should commit to the type in the storage if it's registered.

r? lcnr

Author: matthiaskrgr

compiler/rustc_next_trait_solver/src/solve/eval_ctxt/mod.rs

@@ -4,6 +4,7 @@ use derive_where::derive_where;
 #[cfg(feature = "nightly")]
 use rustc_macros::{HashStable_NoContext, TyDecodable, TyEncodable};
 use rustc_type_ir::data_structures::{HashMap, HashSet, ensure_sufficient_stack};
+use rustc_type_ir::fast_reject::DeepRejectCtxt;
 use rustc_type_ir::fold::{TypeFoldable, TypeFolder, TypeSuperFoldable};
 use rustc_type_ir::inherent::*;
 use rustc_type_ir::relate::Relate;
@@ -18,9 +19,9 @@ use crate::delegate::SolverDelegate;
 use crate::solve::inspect::{self, ProofTreeBuilder};
 use crate::solve::search_graph::SearchGraph;
 use crate::solve::{
-    CanonicalInput, CanonicalResponse, Certainty, FIXPOINT_STEP_LIMIT, Goal, GoalEvaluationKind,
-    GoalSource, HasChanged, NestedNormalizationGoals, NoSolution, PredefinedOpaquesData,
-    QueryResult, SolverMode,
+    CanonicalInput, Certainty, FIXPOINT_STEP_LIMIT, Goal, GoalEvaluationKind, GoalSource,
+    HasChanged, NestedNormalizationGoals, NoSolution, PredefinedOpaquesData, QueryResult,
+    SolverMode,
 };
 
 pub(super) mod canonical;
@@ -987,40 +988,22 @@ where
 
     // Do something for each opaque/hidden pair defined with `def_id` in the
     // current inference context.
-    pub(super) fn unify_existing_opaque_tys(
+    pub(super) fn probe_existing_opaque_ty(
         &mut self,
-        param_env: I::ParamEnv,
         key: ty::OpaqueTypeKey<I>,
-        ty: I::Ty,
-    ) -> Vec<CanonicalResponse<I>> {
-        // FIXME: Super inefficient to be cloning this...
-        let opaques = self.delegate.clone_opaque_types_for_query_response();
-
-        let mut values = vec![];
-        for (candidate_key, candidate_ty) in opaques {
-            if candidate_key.def_id != key.def_id {
-                continue;
-            }
-            values.extend(
-                self.probe(|result| inspect::ProbeKind::OpaqueTypeStorageLookup {
-                    result: *result,
-                })
-                .enter(|ecx| {
-                    for (a, b) in std::iter::zip(candidate_key.args.iter(), key.args.iter()) {
-                        ecx.eq(param_env, a, b)?;
-                    }
-                    ecx.eq(param_env, candidate_ty, ty)?;
-                    ecx.add_item_bounds_for_hidden_type(
-                        candidate_key.def_id.into(),
-                        candidate_key.args,
-                        param_env,
-                        candidate_ty,
-                    );
-                    ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
-                }),
+    ) -> Option<(ty::OpaqueTypeKey<I>, I::Ty)> {
+        let mut matching =
+            self.delegate.clone_opaque_types_for_query_response().into_iter().filter(
+                |(candidate_key, _)| {
+                    candidate_key.def_id == key.def_id
+                        && DeepRejectCtxt::relate_rigid_rigid(self.cx())
+                            .args_may_unify(candidate_key.args, key.args)
+                },
             );
-        }
-        values
+        let first = matching.next();
+        let second = matching.next();
+        assert_eq!(second, None);
+        first
     }
 
     // Try to evaluate a const, or return `None` if the const is too generic.

compiler/rustc_next_trait_solver/src/solve/normalizes_to/opaque_types.rs

@@ -7,7 +7,9 @@ use rustc_type_ir::inherent::*;
 use rustc_type_ir::{self as ty, Interner};
 
 use crate::delegate::SolverDelegate;
-use crate::solve::{Certainty, EvalCtxt, Goal, NoSolution, QueryResult, Reveal, SolverMode};
+use crate::solve::{
+    Certainty, EvalCtxt, Goal, NoSolution, QueryResult, Reveal, SolverMode, inspect,
+};
 
 impl<D, I> EvalCtxt<'_, D>
 where
@@ -52,14 +54,28 @@ where
                 //
                 // If that fails, we insert `expected` as a new hidden type instead of
                 // eagerly emitting an error.
-                let matches =
-                    self.unify_existing_opaque_tys(goal.param_env, opaque_type_key, expected);
-                if !matches.is_empty() {
-                    if let Some(response) = self.try_merge_responses(&matches) {
-                        return Ok(response);
-                    } else {
-                        return self.flounder(&matches);
-                    }
+                let existing = self.probe_existing_opaque_ty(opaque_type_key);
+                if let Some((candidate_key, candidate_ty)) = existing {
+                    return self
+                        .probe(|result| inspect::ProbeKind::OpaqueTypeStorageLookup {
+                            result: *result,
+                        })
+                        .enter(|ecx| {
+                            for (a, b) in std::iter::zip(
+                                candidate_key.args.iter(),
+                                opaque_type_key.args.iter(),
+                            ) {
+                                ecx.eq(goal.param_env, a, b)?;
+                            }
+                            ecx.eq(goal.param_env, candidate_ty, expected)?;
+                            ecx.add_item_bounds_for_hidden_type(
+                                candidate_key.def_id.into(),
+                                candidate_key.args,
+                                goal.param_env,
+                                candidate_ty,
+                            );
+                            ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
+                        });
                 }
 
                 // Otherwise, define a new opaque type