From 207b4b8e88d3fad105e3fe892c64cdf8d1ace252 Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Mon, 6 May 2024 11:24:40 -0400
Subject: [PATCH 1/2] Record impl args in the InsepctCandiate rather than
rematching during select
---
.../rustc_middle/src/traits/solve/inspect.rs | 2 +
.../src/traits/solve/inspect/format.rs | 3 +
.../src/solve/eval_ctxt/mod.rs | 5 ++
.../src/solve/eval_ctxt/select.rs | 81 +++++--------------
.../src/solve/inspect/analyse.rs | 42 ++++++++--
.../src/solve/inspect/build.rs | 30 ++++++-
.../src/solve/trait_goals.rs | 1 +
7 files changed, 99 insertions(+), 65 deletions(-)
diff --git a/compiler/rustc_middle/src/traits/solve/inspect.rs b/compiler/rustc_middle/src/traits/solve/inspect.rs
index cddf9d5f874a3..2ddcb8aab2530 100644
--- a/compiler/rustc_middle/src/traits/solve/inspect.rs
+++ b/compiler/rustc_middle/src/traits/solve/inspect.rs
@@ -123,6 +123,8 @@ pub enum ProbeStep<'tcx> {
/// used whenever there are multiple candidates to prove the
/// current goalby .
NestedProbe(Probe<'tcx>),
+ /// A trait goal was satisfied by an impl candidate.
+ RecordImplArgs { impl_args: CanonicalState<'tcx, ty::GenericArgsRef<'tcx>> },
/// A call to `EvalCtxt::evaluate_added_goals_make_canonical_response` with
/// `Certainty` was made. This is the certainty passed in, so it's not unified
/// with the certainty of the `try_evaluate_added_goals` that is done within;
diff --git a/compiler/rustc_middle/src/traits/solve/inspect/format.rs b/compiler/rustc_middle/src/traits/solve/inspect/format.rs
index 11aa0e10931cb..e652f0586c4ea 100644
--- a/compiler/rustc_middle/src/traits/solve/inspect/format.rs
+++ b/compiler/rustc_middle/src/traits/solve/inspect/format.rs
@@ -136,6 +136,9 @@ impl<'a, 'b> ProofTreeFormatter<'a, 'b> {
ProbeStep::MakeCanonicalResponse { shallow_certainty } => {
writeln!(this.f, "EVALUATE GOALS AND MAKE RESPONSE: {shallow_certainty:?}")?
}
+ ProbeStep::RecordImplArgs { impl_args } => {
+ writeln!(this.f, "RECORDED IMPL ARGS: {impl_args:?}")?
+ }
}
}
Ok(())
diff --git a/compiler/rustc_trait_selection/src/solve/eval_ctxt/mod.rs b/compiler/rustc_trait_selection/src/solve/eval_ctxt/mod.rs
index 773babde0d7b3..b103cbe9d480d 100644
--- a/compiler/rustc_trait_selection/src/solve/eval_ctxt/mod.rs
+++ b/compiler/rustc_trait_selection/src/solve/eval_ctxt/mod.rs
@@ -587,6 +587,11 @@ impl<'a, 'tcx> EvalCtxt<'a, 'tcx> {
Ok(unchanged_certainty)
}
+
+ /// Record impl args in the proof tree for later access by `InspectCandidate`.
+ pub(crate) fn record_impl_args(&mut self, impl_args: ty::GenericArgsRef<'tcx>) {
+ self.inspect.record_impl_args(self.infcx, self.max_input_universe, impl_args)
+ }
}
impl<'tcx> EvalCtxt<'_, 'tcx> {
diff --git a/compiler/rustc_trait_selection/src/solve/eval_ctxt/select.rs b/compiler/rustc_trait_selection/src/solve/eval_ctxt/select.rs
index 16fe045b82de7..3700ddf7ef5d1 100644
--- a/compiler/rustc_trait_selection/src/solve/eval_ctxt/select.rs
+++ b/compiler/rustc_trait_selection/src/solve/eval_ctxt/select.rs
@@ -1,12 +1,11 @@
use std::ops::ControlFlow;
-use rustc_hir::def_id::DefId;
-use rustc_infer::infer::{DefineOpaqueTypes, InferCtxt, InferOk};
+use rustc_infer::infer::InferCtxt;
use rustc_infer::traits::solve::inspect::ProbeKind;
use rustc_infer::traits::solve::{CandidateSource, Certainty, Goal};
use rustc_infer::traits::{
BuiltinImplSource, ImplSource, ImplSourceUserDefinedData, Obligation, ObligationCause,
- PolyTraitObligation, PredicateObligation, Selection, SelectionError, SelectionResult,
+ PolyTraitObligation, Selection, SelectionError, SelectionResult,
};
use rustc_macros::extension;
use rustc_span::Span;
@@ -133,32 +132,33 @@ fn to_selection<'tcx>(
return None;
}
- let make_nested = || {
- cand.instantiate_nested_goals(span)
- .into_iter()
- .map(|nested| {
- Obligation::new(
- nested.infcx().tcx,
- ObligationCause::dummy_with_span(span),
- nested.goal().param_env,
- nested.goal().predicate,
- )
- })
- .collect()
- };
+ let (nested, impl_args) = cand.instantiate_nested_goals_and_opt_impl_args(span);
+ let nested = nested
+ .into_iter()
+ .map(|nested| {
+ Obligation::new(
+ nested.infcx().tcx,
+ ObligationCause::dummy_with_span(span),
+ nested.goal().param_env,
+ nested.goal().predicate,
+ )
+ })
+ .collect();
Some(match cand.kind() {
ProbeKind::TraitCandidate { source, result: _ } => match source {
CandidateSource::Impl(impl_def_id) => {
// FIXME: Remove this in favor of storing this in the tree
// For impl candidates, we do the rematch manually to compute the args.
- ImplSource::UserDefined(rematch_impl(cand.goal(), impl_def_id, span))
- }
- CandidateSource::BuiltinImpl(builtin) => ImplSource::Builtin(builtin, make_nested()),
- CandidateSource::ParamEnv(_) => ImplSource::Param(make_nested()),
- CandidateSource::AliasBound => {
- ImplSource::Builtin(BuiltinImplSource::Misc, make_nested())
+ ImplSource::UserDefined(ImplSourceUserDefinedData {
+ impl_def_id,
+ args: impl_args.expect("expected recorded impl args for impl candidate"),
+ nested,
+ })
}
+ CandidateSource::BuiltinImpl(builtin) => ImplSource::Builtin(builtin, nested),
+ CandidateSource::ParamEnv(_) => ImplSource::Param(nested),
+ CandidateSource::AliasBound => ImplSource::Builtin(BuiltinImplSource::Misc, nested),
CandidateSource::CoherenceUnknowable => {
span_bug!(span, "didn't expect to select an unknowable candidate")
}
@@ -173,40 +173,3 @@ fn to_selection<'tcx>(
}
})
}
-
-fn rematch_impl<'tcx>(
- goal: &inspect::InspectGoal<'_, 'tcx>,
- impl_def_id: DefId,
- span: Span,
-) -> ImplSourceUserDefinedData<'tcx, PredicateObligation<'tcx>> {
- let infcx = goal.infcx();
- let goal_trait_ref = infcx
- .enter_forall_and_leak_universe(goal.goal().predicate.to_opt_poly_trait_pred().unwrap())
- .trait_ref;
-
- let args = infcx.fresh_args_for_item(span, impl_def_id);
- let impl_trait_ref =
- infcx.tcx.impl_trait_ref(impl_def_id).unwrap().instantiate(infcx.tcx, args);
-
- let InferOk { value: (), obligations: mut nested } = infcx
- .at(&ObligationCause::dummy_with_span(span), goal.goal().param_env)
- .eq(DefineOpaqueTypes::Yes, goal_trait_ref, impl_trait_ref)
- .expect("rematching impl failed");
-
- // FIXME(-Znext-solver=coinductive): We need to add supertraits here eventually.
-
- nested.extend(
- infcx.tcx.predicates_of(impl_def_id).instantiate(infcx.tcx, args).into_iter().map(
- |(clause, _)| {
- Obligation::new(
- infcx.tcx,
- ObligationCause::dummy_with_span(span),
- goal.goal().param_env,
- clause,
- )
- },
- ),
- );
-
- ImplSourceUserDefinedData { impl_def_id, nested, args }
-}
diff --git a/compiler/rustc_trait_selection/src/solve/inspect/analyse.rs b/compiler/rustc_trait_selection/src/solve/inspect/analyse.rs
index 4f79f1b2aafe0..fa4323a3a944d 100644
--- a/compiler/rustc_trait_selection/src/solve/inspect/analyse.rs
+++ b/compiler/rustc_trait_selection/src/solve/inspect/analyse.rs
@@ -93,6 +93,7 @@ pub struct InspectCandidate<'a, 'tcx> {
kind: inspect::ProbeKind<'tcx>,
nested_goals: Vec<(GoalSource, inspect::CanonicalState<'tcx, Goal<'tcx, ty::Predicate<'tcx>>>)>,
final_state: inspect::CanonicalState<'tcx, ()>,
+ impl_args: Option<inspect::CanonicalState<'tcx, ty::GenericArgsRef<'tcx>>>,
result: QueryResult<'tcx>,
shallow_certainty: Certainty,
}
@@ -135,7 +136,20 @@ impl<'a, 'tcx> InspectCandidate<'a, 'tcx> {
/// Instantiate the nested goals for the candidate without rolling back their
/// inference constraints. This function modifies the state of the `infcx`.
+ ///
+ /// See [`Self::instantiate_nested_goals_and_opt_impl_args`] if you need the impl args too.
pub fn instantiate_nested_goals(&self, span: Span) -> Vec<InspectGoal<'a, 'tcx>> {
+ self.instantiate_nested_goals_and_opt_impl_args(span).0
+ }
+
+ /// Instantiate the nested goals for the candidate without rolling back their
+ /// inference constraints, and optionally the args of an impl if this candidate
+ /// came from a `CandidateSource::Impl`. This function modifies the state of the
+ /// `infcx`.
+ pub fn instantiate_nested_goals_and_opt_impl_args(
+ &self,
+ span: Span,
+ ) -> (Vec<InspectGoal<'a, 'tcx>>, Option<ty::GenericArgsRef<'tcx>>) {
let infcx = self.goal.infcx;
let param_env = self.goal.goal.param_env;
let mut orig_values = self.goal.orig_values.to_vec();
@@ -164,6 +178,17 @@ impl<'a, 'tcx> InspectCandidate<'a, 'tcx> {
self.final_state,
);
+ let impl_args = self.impl_args.map(|impl_args| {
+ canonical::instantiate_canonical_state(
+ infcx,
+ span,
+ param_env,
+ &mut orig_values,
+ impl_args,
+ )
+ .fold_with(&mut EagerResolver::new(infcx))
+ });
+
if let Some(term_hack) = self.goal.normalizes_to_term_hack {
// FIXME: We ignore the expected term of `NormalizesTo` goals
// when computing the result of its candidates. This is
@@ -171,7 +196,7 @@ impl<'a, 'tcx> InspectCandidate<'a, 'tcx> {
let _ = term_hack.constrain(infcx, span, param_env);
}
- instantiated_goals
+ let goals = instantiated_goals
.into_iter()
.map(|(source, goal)| match goal.predicate.kind().no_bound_vars() {
Some(ty::PredicateKind::NormalizesTo(ty::NormalizesTo { alias, term })) => {
@@ -208,7 +233,9 @@ impl<'a, 'tcx> InspectCandidate<'a, 'tcx> {
source,
),
})
- .collect()
+ .collect();
+
+ (goals, impl_args)
}
/// Visit all nested goals of this candidate, rolling back
@@ -245,9 +272,10 @@ impl<'a, 'tcx> InspectGoal<'a, 'tcx> {
probe: &inspect::Probe<'tcx>,
) {
let mut shallow_certainty = None;
+ let mut impl_args = None;
for step in &probe.steps {
- match step {
- &inspect::ProbeStep::AddGoal(source, goal) => nested_goals.push((source, goal)),
+ match *step {
+ inspect::ProbeStep::AddGoal(source, goal) => nested_goals.push((source, goal)),
inspect::ProbeStep::NestedProbe(ref probe) => {
// Nested probes have to prove goals added in their parent
// but do not leak them, so we truncate the added goals
@@ -257,7 +285,10 @@ impl<'a, 'tcx> InspectGoal<'a, 'tcx> {
nested_goals.truncate(num_goals);
}
inspect::ProbeStep::MakeCanonicalResponse { shallow_certainty: c } => {
- assert_eq!(shallow_certainty.replace(*c), None);
+ assert_eq!(shallow_certainty.replace(c), None);
+ }
+ inspect::ProbeStep::RecordImplArgs { impl_args: i } => {
+ assert_eq!(impl_args.replace(i), None);
}
inspect::ProbeStep::EvaluateGoals(_) => (),
}
@@ -284,6 +315,7 @@ impl<'a, 'tcx> InspectGoal<'a, 'tcx> {
final_state: probe.final_state,
result,
shallow_certainty,
+ impl_args,
});
}
}
diff --git a/compiler/rustc_trait_selection/src/solve/inspect/build.rs b/compiler/rustc_trait_selection/src/solve/inspect/build.rs
index 466d0d8006018..79d8901a260b4 100644
--- a/compiler/rustc_trait_selection/src/solve/inspect/build.rs
+++ b/compiler/rustc_trait_selection/src/solve/inspect/build.rs
@@ -242,6 +242,7 @@ enum WipProbeStep<'tcx> {
EvaluateGoals(WipAddedGoalsEvaluation<'tcx>),
NestedProbe(WipProbe<'tcx>),
MakeCanonicalResponse { shallow_certainty: Certainty },
+ RecordImplArgs { impl_args: inspect::CanonicalState<'tcx, ty::GenericArgsRef<'tcx>> },
}
impl<'tcx> WipProbeStep<'tcx> {
@@ -250,6 +251,9 @@ impl<'tcx> WipProbeStep<'tcx> {
WipProbeStep::AddGoal(source, goal) => inspect::ProbeStep::AddGoal(source, goal),
WipProbeStep::EvaluateGoals(eval) => inspect::ProbeStep::EvaluateGoals(eval.finalize()),
WipProbeStep::NestedProbe(probe) => inspect::ProbeStep::NestedProbe(probe.finalize()),
+ WipProbeStep::RecordImplArgs { impl_args } => {
+ inspect::ProbeStep::RecordImplArgs { impl_args }
+ }
WipProbeStep::MakeCanonicalResponse { shallow_certainty } => {
inspect::ProbeStep::MakeCanonicalResponse { shallow_certainty }
}
@@ -534,6 +538,30 @@ impl<'tcx> ProofTreeBuilder<'tcx> {
}
}
+ pub(crate) fn record_impl_args(
+ &mut self,
+ infcx: &InferCtxt<'tcx>,
+ max_input_universe: ty::UniverseIndex,
+ impl_args: ty::GenericArgsRef<'tcx>,
+ ) {
+ match self.as_mut() {
+ Some(DebugSolver::GoalEvaluationStep(state)) => {
+ let impl_args = canonical::make_canonical_state(
+ infcx,
+ &state.var_values,
+ max_input_universe,
+ impl_args,
+ );
+ state
+ .current_evaluation_scope()
+ .steps
+ .push(WipProbeStep::RecordImplArgs { impl_args });
+ }
+ None => {}
+ _ => bug!(),
+ }
+ }
+
pub fn make_canonical_response(&mut self, shallow_certainty: Certainty) {
match self.as_mut() {
Some(DebugSolver::GoalEvaluationStep(state)) => {
@@ -543,7 +571,7 @@ impl<'tcx> ProofTreeBuilder<'tcx> {
.push(WipProbeStep::MakeCanonicalResponse { shallow_certainty });
}
None => {}
- _ => {}
+ _ => bug!(),
}
}
diff --git a/compiler/rustc_trait_selection/src/solve/trait_goals.rs b/compiler/rustc_trait_selection/src/solve/trait_goals.rs
index d2b893d6383bd..0fde9dd4cd680 100644
--- a/compiler/rustc_trait_selection/src/solve/trait_goals.rs
+++ b/compiler/rustc_trait_selection/src/solve/trait_goals.rs
@@ -75,6 +75,7 @@ impl<'tcx> assembly::GoalKind<'tcx> for TraitPredicate<'tcx> {
ecx.probe_trait_candidate(CandidateSource::Impl(impl_def_id)).enter(|ecx| {
let impl_args = ecx.fresh_args_for_item(impl_def_id);
+ ecx.record_impl_args(impl_args);
let impl_trait_ref = impl_trait_header.trait_ref.instantiate(tcx, impl_args);
ecx.eq(goal.param_env, goal.predicate.trait_ref, impl_trait_ref)?;
From e34723997ae8e44538cea5f9f68085d828771e54 Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Mon, 6 May 2024 14:11:21 -0400
Subject: [PATCH 2/2] Use correct ImplSource for alias bounds
---
.../src/solve/eval_ctxt/select.rs | 3 +--
.../next-solver/select-alias-bound-as-param.rs | 13 +++++++++++++
2 files changed, 14 insertions(+), 2 deletions(-)
create mode 100644 tests/ui/traits/next-solver/select-alias-bound-as-param.rs
diff --git a/compiler/rustc_trait_selection/src/solve/eval_ctxt/select.rs b/compiler/rustc_trait_selection/src/solve/eval_ctxt/select.rs
index 3700ddf7ef5d1..f586a74258d7e 100644
--- a/compiler/rustc_trait_selection/src/solve/eval_ctxt/select.rs
+++ b/compiler/rustc_trait_selection/src/solve/eval_ctxt/select.rs
@@ -157,8 +157,7 @@ fn to_selection<'tcx>(
})
}
CandidateSource::BuiltinImpl(builtin) => ImplSource::Builtin(builtin, nested),
- CandidateSource::ParamEnv(_) => ImplSource::Param(nested),
- CandidateSource::AliasBound => ImplSource::Builtin(BuiltinImplSource::Misc, nested),
+ CandidateSource::ParamEnv(_) | CandidateSource::AliasBound => ImplSource::Param(nested),
CandidateSource::CoherenceUnknowable => {
span_bug!(span, "didn't expect to select an unknowable candidate")
}
diff --git a/tests/ui/traits/next-solver/select-alias-bound-as-param.rs b/tests/ui/traits/next-solver/select-alias-bound-as-param.rs
new file mode 100644
index 0000000000000..fd40ef1f872f3
--- /dev/null
+++ b/tests/ui/traits/next-solver/select-alias-bound-as-param.rs
@@ -0,0 +1,13 @@
+//@ check-pass
+//@ compile-flags: -Znext-solver
+
+pub(crate) fn y() -> impl FnMut() {
+ || {}
+}
+
+pub(crate) fn x(a: (), b: ()) {
+ let x = ();
+ y()()
+}
+
+fn main() {}