Auto merge of #142774 - lcnr:search_graph-2, r=<try>

rust-bors[bot] · web-flow · commit 9101c8e8c9b6 · 2025-06-23T09:50:57.000Z
`evaluate_goal` avoid unnecessary step based on #142617. This does not mess with the debug logging for the trait solver and is a very nice cleanup for #142735. E.g. for ```rust #[derive(Clone)] struct Wrapper<T>(T); #[derive(Clone)] struct Nested; // using a separate type to avoid the fast paths fn is_clone<T: Clone>() {} fn main() { is_clone::<Wrapper<Nested>>(); } ``` We get the following proof tree with `RUSTC_LOG=rustc_type_ir::search_graph=debug,rustc_next_trait_solver=debug` ``` rustc_next_trait_solver::solve::eval_ctxt::evaluate_root_goal goal=Goal { param_env: ParamEnv { caller_bounds: [] }, predicate: Binder { value: TraitPredicate(<Wrapper<Nested> as std::clone::Clone>, polarity:Positive), bound_vars: [] } }, generate_proof_tree=No, span=src/main.rs:7:5: 7:34 (#0), stalled_on=None rustc_type_ir::search_graph::evaluate_goal input=CanonicalQueryInput { canonical: Canonical { value: QueryInput { goal: Goal { param_env: ParamEnv { caller_bounds: [] }, predicate: Binder { value: TraitPredicate(<Wrapper<Nested> as std::clone::Clone>, polarity:Positive), bound_vars: [] } }, predefined_opaques_in_body: PredefinedOpaques(PredefinedOpaquesData { opaque_types: [] }) }, max_universe: U0, variables: [] }, typing_mode: Analysis { defining_opaque_types_and_generators: [] } }, step_kind_from_parent=Unknown rustc_next_trait_solver::solve::eval_ctxt::probe::enter source=Impl(DefId(0:10 ~ main[21d2]::{impl#0})) rustc_next_trait_solver::solve::eval_ctxt::add_goal source=ImplWhereBound, goal=Goal { param_env: ParamEnv { caller_bounds: [] }, predicate: Binder { value: TraitPredicate(<_ as std::marker::Sized>, polarity:Positive), bound_vars: [] } } rustc_next_trait_solver::solve::eval_ctxt::add_goal source=ImplWhereBound, goal=Goal { param_env: ParamEnv { caller_bounds: [] }, predicate: Binder { value: TraitPredicate(<_ as std::clone::Clone>, polarity:Positive), bound_vars: [] } } rustc_type_ir::search_graph::evaluate_goal input=CanonicalQueryInput { canonical: Canonical { value: QueryInput { goal: Goal { param_env: ParamEnv { caller_bounds: [] }, predicate: Binder { value: TraitPredicate(<Nested as std::clone::Clone>, polarity:Positive), bound_vars: [] } }, predefined_opaques_in_body: PredefinedOpaques(PredefinedOpaquesData { opaque_types: [] }) }, max_universe: U0, variables: [] }, typing_mode: Analysis { defining_opaque_types_and_generators: [] } }, step_kind_from_parent=Unknown 0ms DEBUG rustc_type_ir::search_graph global cache hit, required_depth=0 0ms DEBUG rustc_type_ir::search_graph return=Ok(Canonical { value: Response { certainty: Yes, var_values: CanonicalVarValues { var_values: [] }, external_constraints: ExternalConstraints(ExternalConstraintsData { region_constraints: [], opaque_types: [], normalization_nested_goals: NestedNormalizationGoals([]) }) }, max_universe: U0, variables: [] }) rustc_next_trait_solver::solve::eval_ctxt::probe::enter source=BuiltinImpl(Misc) rustc_next_trait_solver::solve::trait_goals::merge_trait_candidates candidates=[Candidate { source: Impl(DefId(0:10 ~ main[21d2]::{impl#0})), result: Canonical { value: Response { certainty: Yes, var_values: CanonicalVarValues { var_values: [] }, external_constraints: ExternalConstraints(ExternalConstraintsData { region_constraints: [], opaque_types: [], normalization_nested_goals: NestedNormalizationGoals([]) }) }, max_universe: U0, variables: [] } }] 0ms DEBUG rustc_next_trait_solver::solve::trait_goals return=Ok((Canonical { value: Response { certainty: Yes, var_values: CanonicalVarValues { var_values: [] }, external_constraints: ExternalConstraints(ExternalConstraintsData { region_constraints: [], opaque_types: [], normalization_nested_goals: NestedNormalizationGoals([]) }) }, max_universe: U0, variables: [] }, Some(Misc))) 0ms DEBUG rustc_type_ir::search_graph insert global cache, evaluation_result=EvaluationResult { encountered_overflow: false, required_depth: 1, heads: CycleHeads { heads: {} }, nested_goals: NestedGoals { nested_goals: {} }, result: Ok(Canonical { value: Response { certainty: Yes, var_values: CanonicalVarValues { var_values: [] }, external_constraints: ExternalConstraints(ExternalConstraintsData { region_constraints: [], opaque_types: [], normalization_nested_goals: NestedNormalizationGoals([]) }) }, max_universe: U0, variables: [] }) } 0ms DEBUG rustc_type_ir::search_graph return=Ok(Canonical { value: Response { certainty: Yes, var_values: CanonicalVarValues { var_values: [] }, external_constraints: ExternalConstraints(ExternalConstraintsData { region_constraints: [], opaque_types: [], normalization_nested_goals: NestedNormalizationGoals([]) }) }, max_universe: U0, variables: [] }) ```
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
@@ -3,7 +3,7 @@ use std::ops::ControlFlow;
 
 #[cfg(feature = "nightly")]
 use rustc_macros::HashStable_NoContext;
-use rustc_type_ir::data_structures::{HashMap, HashSet, ensure_sufficient_stack};
+use rustc_type_ir::data_structures::{HashMap, HashSet};
 use rustc_type_ir::fast_reject::DeepRejectCtxt;
 use rustc_type_ir::inherent::*;
 use rustc_type_ir::relate::Relate;
@@ -339,13 +339,12 @@ where
 
     /// Creates a nested evaluation context that shares the same search graph as the
     /// one passed in. This is suitable for evaluation, granted that the search graph
-    /// has had the nested goal recorded on its stack ([`SearchGraph::with_new_goal`]),
-    /// but it's preferable to use other methods that call this one rather than this
-    /// method directly.
+    /// has had the nested goal recorded on its stack. This method only be used by
+    /// `search_graph::Delegate::compute_goal`.
     ///
     /// This function takes care of setting up the inference context, setting the anchor,
     /// and registering opaques from the canonicalized input.
-    fn enter_canonical<R>(
+    pub(super) fn enter_canonical<R>(
         cx: I,
         search_graph: &'a mut SearchGraph<D>,
         canonical_input: CanonicalInput<I>,
@@ -401,56 +400,6 @@ where
         result
     }
 
-    /// The entry point of the solver.
-    ///
-    /// This function deals with (coinductive) cycles, overflow, and caching
-    /// and then calls [`EvalCtxt::compute_goal`] which contains the actual
-    /// logic of the solver.
-    ///
-    /// Instead of calling this function directly, use either [EvalCtxt::evaluate_goal]
-    /// if you're inside of the solver or [SolverDelegateEvalExt::evaluate_root_goal] if you're
-    /// outside of it.
-    #[instrument(level = "debug", skip(cx, search_graph, goal_evaluation), ret)]
-    fn evaluate_canonical_goal(
-        cx: I,
-        search_graph: &'a mut SearchGraph<D>,
-        canonical_input: CanonicalInput<I>,
-        step_kind_from_parent: PathKind,
-        goal_evaluation: &mut ProofTreeBuilder<D>,
-    ) -> QueryResult<I> {
-        let mut canonical_goal_evaluation =
-            goal_evaluation.new_canonical_goal_evaluation(canonical_input);
-
-        // Deal with overflow, caching, and coinduction.
-        //
-        // The actual solver logic happens in `ecx.compute_goal`.
-        let result = ensure_sufficient_stack(|| {
-            search_graph.with_new_goal(
-                cx,
-                canonical_input,
-                step_kind_from_parent,
-                &mut canonical_goal_evaluation,
-                |search_graph, cx, canonical_input, canonical_goal_evaluation| {
-                    EvalCtxt::enter_canonical(
-                        cx,
-                        search_graph,
-                        canonical_input,
-                        canonical_goal_evaluation,
-                        |ecx, goal| {
-                            let result = ecx.compute_goal(goal);
-                            ecx.inspect.query_result(result);
-                            result
-                        },
-                    )
-                },
-            )
-        });
-
-        canonical_goal_evaluation.query_result(result);
-        goal_evaluation.canonical_goal_evaluation(canonical_goal_evaluation);
-        result
-    }
-
     /// Recursively evaluates `goal`, returning whether any inference vars have
     /// been constrained and the certainty of the result.
     fn evaluate_goal(
@@ -504,18 +453,16 @@ where
         let (orig_values, canonical_goal) = self.canonicalize_goal(goal);
         let mut goal_evaluation =
             self.inspect.new_goal_evaluation(goal, &orig_values, goal_evaluation_kind);
-        let canonical_response = EvalCtxt::evaluate_canonical_goal(
+        let canonical_result = self.search_graph.evaluate_goal(
             self.cx(),
-            self.search_graph,
             canonical_goal,
             self.step_kind_for_source(source),
             &mut goal_evaluation,
         );
-        let response = match canonical_response {
-            Err(e) => {
-                self.inspect.goal_evaluation(goal_evaluation);
-                return Err(e);
-            }
+        goal_evaluation.query_result(canonical_result);
+        self.inspect.goal_evaluation(goal_evaluation);
+        let response = match canonical_result {
+            Err(e) => return Err(e),
             Ok(response) => response,
         };
 
@@ -524,7 +471,6 @@ where
 
         let (normalization_nested_goals, certainty) =
             self.instantiate_and_apply_query_response(goal.param_env, &orig_values, response);
-        self.inspect.goal_evaluation(goal_evaluation);
 
         // FIXME: We previously had an assert here that checked that recomputing
         // a goal after applying its constraints did not change its response.
@@ -585,7 +531,7 @@ where
         Ok((normalization_nested_goals, GoalEvaluation { certainty, has_changed, stalled_on }))
     }
 
-    fn compute_goal(&mut self, goal: Goal<I, I::Predicate>) -> QueryResult<I> {
+    pub(super) fn compute_goal(&mut self, goal: Goal<I, I::Predicate>) -> QueryResult<I> {
         let Goal { param_env, predicate } = goal;
         let kind = predicate.kind();
         if let Some(kind) = kind.no_bound_vars() {
diff --git a/compiler/rustc_next_trait_solver/src/solve/inspect/build.rs b/compiler/rustc_next_trait_solver/src/solve/inspect/build.rs
@@ -13,8 +13,7 @@ use rustc_type_ir::{self as ty, Interner};
 use crate::delegate::SolverDelegate;
 use crate::solve::eval_ctxt::canonical;
 use crate::solve::{
-    CanonicalInput, Certainty, GenerateProofTree, Goal, GoalEvaluationKind, GoalSource,
-    QueryResult, inspect,
+    Certainty, GenerateProofTree, Goal, GoalEvaluationKind, GoalSource, QueryResult, inspect,
 };
 
 /// The core data structure when building proof trees.
@@ -54,7 +53,6 @@ where
 enum DebugSolver<I: Interner> {
     Root,
     GoalEvaluation(WipGoalEvaluation<I>),
-    CanonicalGoalEvaluation(WipCanonicalGoalEvaluation<I>),
     CanonicalGoalEvaluationStep(WipCanonicalGoalEvaluationStep<I>),
 }
 
@@ -64,12 +62,6 @@ impl<I: Interner> From<WipGoalEvaluation<I>> for DebugSolver<I> {
     }
 }
 
-impl<I: Interner> From<WipCanonicalGoalEvaluation<I>> for DebugSolver<I> {
-    fn from(g: WipCanonicalGoalEvaluation<I>) -> DebugSolver<I> {
-        DebugSolver::CanonicalGoalEvaluation(g)
-    }
-}
-
 impl<I: Interner> From<WipCanonicalGoalEvaluationStep<I>> for DebugSolver<I> {
     fn from(g: WipCanonicalGoalEvaluationStep<I>) -> DebugSolver<I> {
         DebugSolver::CanonicalGoalEvaluationStep(g)
@@ -80,39 +72,23 @@ impl<I: Interner> From<WipCanonicalGoalEvaluationStep<I>> for DebugSolver<I> {
 struct WipGoalEvaluation<I: Interner> {
     pub uncanonicalized_goal: Goal<I, I::Predicate>,
     pub orig_values: Vec<I::GenericArg>,
-    pub evaluation: Option<WipCanonicalGoalEvaluation<I>>,
+    pub encountered_overflow: bool,
+    /// After we finished evaluating this is moved into `kind`.
+    pub final_revision: Option<WipCanonicalGoalEvaluationStep<I>>,
+    pub result: Option<QueryResult<I>>,
 }
 
 impl<I: Interner> WipGoalEvaluation<I> {
     fn finalize(self) -> inspect::GoalEvaluation<I> {
         inspect::GoalEvaluation {
             uncanonicalized_goal: self.uncanonicalized_goal,
             orig_values: self.orig_values,
-            evaluation: self.evaluation.unwrap().finalize(),
-        }
-    }
-}
-
-#[derive_where(PartialEq, Eq, Debug; I: Interner)]
-struct WipCanonicalGoalEvaluation<I: Interner> {
-    goal: CanonicalInput<I>,
-    encountered_overflow: bool,
-    /// Only used for uncached goals. After we finished evaluating
-    /// the goal, this is interned and moved into `kind`.
-    final_revision: Option<WipCanonicalGoalEvaluationStep<I>>,
-    result: Option<QueryResult<I>>,
-}
-
-impl<I: Interner> WipCanonicalGoalEvaluation<I> {
-    fn finalize(self) -> inspect::CanonicalGoalEvaluation<I> {
-        inspect::CanonicalGoalEvaluation {
-            goal: self.goal,
             kind: if self.encountered_overflow {
                 assert!(self.final_revision.is_none());
-                inspect::CanonicalGoalEvaluationKind::Overflow
+                inspect::GoalEvaluationKind::Overflow
             } else {
                 let final_revision = self.final_revision.unwrap().finalize();
-                inspect::CanonicalGoalEvaluationKind::Evaluation { final_revision }
+                inspect::GoalEvaluationKind::Evaluation { final_revision }
             },
             result: self.result.unwrap(),
         }
@@ -256,55 +232,27 @@ impl<D: SolverDelegate<Interner = I>, I: Interner> ProofTreeBuilder<D> {
 
     pub(in crate::solve) fn new_goal_evaluation(
         &mut self,
-        goal: Goal<I, I::Predicate>,
+        uncanonicalized_goal: Goal<I, I::Predicate>,
         orig_values: &[I::GenericArg],
         kind: GoalEvaluationKind,
     ) -> ProofTreeBuilder<D> {
         self.opt_nested(|| match kind {
             GoalEvaluationKind::Root => Some(WipGoalEvaluation {
-                uncanonicalized_goal: goal,
+                uncanonicalized_goal,
                 orig_values: orig_values.to_vec(),
-                evaluation: None,
+                encountered_overflow: false,
+                final_revision: None,
+                result: None,
             }),
             GoalEvaluationKind::Nested => None,
         })
     }
 
-    pub(crate) fn new_canonical_goal_evaluation(
-        &mut self,
-        goal: CanonicalInput<I>,
-    ) -> ProofTreeBuilder<D> {
-        self.nested(|| WipCanonicalGoalEvaluation {
-            goal,
-            encountered_overflow: false,
-            final_revision: None,
-            result: None,
-        })
-    }
-
-    pub(crate) fn canonical_goal_evaluation(
-        &mut self,
-        canonical_goal_evaluation: ProofTreeBuilder<D>,
-    ) {
-        if let Some(this) = self.as_mut() {
-            match (this, *canonical_goal_evaluation.state.unwrap()) {
-                (
-                    DebugSolver::GoalEvaluation(goal_evaluation),
-                    DebugSolver::CanonicalGoalEvaluation(canonical_goal_evaluation),
-                ) => {
-                    let prev = goal_evaluation.evaluation.replace(canonical_goal_evaluation);
-                    assert_eq!(prev, None);
-                }
-                _ => unreachable!(),
-            }
-        }
-    }
-
     pub(crate) fn canonical_goal_evaluation_overflow(&mut self) {
         if let Some(this) = self.as_mut() {
             match this {
-                DebugSolver::CanonicalGoalEvaluation(canonical_goal_evaluation) => {
-                    canonical_goal_evaluation.encountered_overflow = true;
+                DebugSolver::GoalEvaluation(goal_evaluation) => {
+                    goal_evaluation.encountered_overflow = true;
                 }
                 _ => unreachable!(),
             };
@@ -343,10 +291,10 @@ impl<D: SolverDelegate<Interner = I>, I: Interner> ProofTreeBuilder<D> {
         if let Some(this) = self.as_mut() {
             match (this, *goal_evaluation_step.state.unwrap()) {
                 (
-                    DebugSolver::CanonicalGoalEvaluation(canonical_goal_evaluations),
+                    DebugSolver::GoalEvaluation(goal_evaluation),
                     DebugSolver::CanonicalGoalEvaluationStep(goal_evaluation_step),
                 ) => {
-                    canonical_goal_evaluations.final_revision = Some(goal_evaluation_step);
+                    goal_evaluation.final_revision = Some(goal_evaluation_step);
                 }
                 _ => unreachable!(),
             }
@@ -489,8 +437,8 @@ impl<D: SolverDelegate<Interner = I>, I: Interner> ProofTreeBuilder<D> {
     pub(crate) fn query_result(&mut self, result: QueryResult<I>) {
         if let Some(this) = self.as_mut() {
             match this {
-                DebugSolver::CanonicalGoalEvaluation(canonical_goal_evaluation) => {
-                    assert_eq!(canonical_goal_evaluation.result.replace(result), None);
+                DebugSolver::GoalEvaluation(goal_evaluation) => {
+                    assert_eq!(goal_evaluation.result.replace(result), None);
                 }
                 DebugSolver::CanonicalGoalEvaluationStep(evaluation_step) => {
                     assert_eq!(
diff --git a/compiler/rustc_next_trait_solver/src/solve/search_graph.rs b/compiler/rustc_next_trait_solver/src/solve/search_graph.rs
@@ -1,13 +1,14 @@
 use std::convert::Infallible;
 use std::marker::PhantomData;
 
+use rustc_type_ir::data_structures::ensure_sufficient_stack;
 use rustc_type_ir::search_graph::{self, PathKind};
 use rustc_type_ir::solve::{CanonicalInput, Certainty, NoSolution, QueryResult};
 use rustc_type_ir::{Interner, TypingMode};
 
-use super::inspect::ProofTreeBuilder;
-use super::{FIXPOINT_STEP_LIMIT, has_no_inference_or_external_constraints};
 use crate::delegate::SolverDelegate;
+use crate::solve::inspect::ProofTreeBuilder;
+use crate::solve::{EvalCtxt, FIXPOINT_STEP_LIMIT, has_no_inference_or_external_constraints};
 
 /// This type is never constructed. We only use it to implement `search_graph::Delegate`
 /// for all types which impl `SolverDelegate` and doing it directly fails in coherence.
@@ -80,8 +81,8 @@ where
 
     fn on_stack_overflow(
         cx: I,
-        inspect: &mut ProofTreeBuilder<D>,
         input: CanonicalInput<I>,
+        inspect: &mut ProofTreeBuilder<D>,
     ) -> QueryResult<I> {
         inspect.canonical_goal_evaluation_overflow();
         response_no_constraints(cx, input, Certainty::overflow(true))
@@ -106,6 +107,21 @@ where
         let certainty = from_result.unwrap().value.certainty;
         response_no_constraints(cx, for_input, certainty)
     }
+
+    fn compute_goal(
+        search_graph: &mut SearchGraph<D>,
+        cx: I,
+        input: CanonicalInput<I>,
+        inspect: &mut Self::ProofTreeBuilder,
+    ) -> QueryResult<I> {
+        ensure_sufficient_stack(|| {
+            EvalCtxt::enter_canonical(cx, search_graph, input, inspect, |ecx, goal| {
+                let result = ecx.compute_goal(goal);
+                ecx.inspect.query_result(result);
+                result
+            })
+        })
+    }
 }
 
 fn response_no_constraints<I: Interner>(
diff --git a/compiler/rustc_trait_selection/src/solve/inspect/analyse.rs b/compiler/rustc_trait_selection/src/solve/inspect/analyse.rs
@@ -37,7 +37,7 @@ pub struct InspectGoal<'a, 'tcx> {
     orig_values: Vec<ty::GenericArg<'tcx>>,
     goal: Goal<'tcx, ty::Predicate<'tcx>>,
     result: Result<Certainty, NoSolution>,
-    evaluation_kind: inspect::CanonicalGoalEvaluationKind<TyCtxt<'tcx>>,
+    evaluation_kind: inspect::GoalEvaluationKind<TyCtxt<'tcx>>,
     normalizes_to_term_hack: Option<NormalizesToTermHack<'tcx>>,
     source: GoalSource,
 }
@@ -396,8 +396,8 @@ impl<'a, 'tcx> InspectGoal<'a, 'tcx> {
         let mut candidates = vec![];
         let last_eval_step = match &self.evaluation_kind {
             // An annoying edge case in case the recursion limit is 0.
-            inspect::CanonicalGoalEvaluationKind::Overflow => return vec![],
-            inspect::CanonicalGoalEvaluationKind::Evaluation { final_revision } => final_revision,
+            inspect::GoalEvaluationKind::Overflow => return vec![],
+            inspect::GoalEvaluationKind::Evaluation { final_revision } => final_revision,
         };
 
         let mut nested_goals = vec![];
@@ -429,10 +429,10 @@ impl<'a, 'tcx> InspectGoal<'a, 'tcx> {
     ) -> Self {
         let infcx = <&SolverDelegate<'tcx>>::from(infcx);
 
-        let inspect::GoalEvaluation { uncanonicalized_goal, orig_values, evaluation } = root;
+        let inspect::GoalEvaluation { uncanonicalized_goal, orig_values, kind, result } = root;
         // If there's a normalizes-to goal, AND the evaluation result with the result of
         // constraining the normalizes-to RHS and computing the nested goals.
-        let result = evaluation.result.and_then(|ok| {
+        let result = result.and_then(|ok| {
             let nested_goals_certainty =
                 term_hack_and_nested_certainty.map_or(Ok(Certainty::Yes), |(_, c)| c)?;
             Ok(ok.value.certainty.and(nested_goals_certainty))
@@ -444,7 +444,7 @@ impl<'a, 'tcx> InspectGoal<'a, 'tcx> {
             orig_values,
             goal: eager_resolve_vars(infcx, uncanonicalized_goal),
             result,
-            evaluation_kind: evaluation.kind,
+            evaluation_kind: kind,
             normalizes_to_term_hack: term_hack_and_nested_certainty.map(|(n, _)| n),
             source,
         }
diff --git a/compiler/rustc_type_ir/src/search_graph/mod.rs b/compiler/rustc_type_ir/src/search_graph/mod.rs
diff --git a/compiler/rustc_type_ir/src/solve/inspect.rs b/compiler/rustc_type_ir/src/solve/inspect.rs
