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Manually walk into WF obligations in BestObligation proof tree visitor

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This commit is contained in:
Michael Goulet 2025-01-22 20:13:36 +00:00
parent d8b176f683
commit 304b3cfcb2
18 changed files with 164 additions and 104 deletions
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9
compiler/rustc_trait_selection/src/solve/delegate.rs
View file

@ -1,7 +1,7 @@
use std::ops::Deref;
use rustc_data_structures::fx::FxHashSet;
use rustc_hir::def_id::DefId;
use rustc_hir::def_id::{CRATE_DEF_ID, DefId};
use rustc_infer::infer::canonical::query_response::make_query_region_constraints;
use rustc_infer::infer::canonical::{
Canonical, CanonicalExt as _, CanonicalQueryInput, CanonicalVarInfo, CanonicalVarValues,
@ -98,9 +98,10 @@ impl<'tcx> rustc_next_trait_solver::delegate::SolverDelegate for SolverDelegate<
param_env: ty::ParamEnv<'tcx>,
arg: ty::GenericArg<'tcx>,
) -> Option<Vec<Goal<'tcx, ty::Predicate<'tcx>>>> {
crate::traits::wf::unnormalized_obligations(&self.0, param_env, arg).map(|obligations| {
obligations.into_iter().map(|obligation| obligation.into()).collect()
})
crate::traits::wf::unnormalized_obligations(&self.0, param_env, arg, DUMMY_SP, CRATE_DEF_ID)
.map(|obligations| {
obligations.into_iter().map(|obligation| obligation.into()).collect()
})
}
fn clone_opaque_types_for_query_response(&self) -> Vec<(ty::OpaqueTypeKey<'tcx>, Ty<'tcx>)> {

60
compiler/rustc_trait_selection/src/solve/fulfill/derive_errors.rs
View file

@ -10,13 +10,13 @@ use rustc_middle::ty::error::{ExpectedFound, TypeError};
use rustc_middle::ty::{self, TyCtxt};
use rustc_middle::{bug, span_bug};
use rustc_next_trait_solver::solve::{GenerateProofTree, SolverDelegateEvalExt as _};
use rustc_type_ir::solve::NoSolution;
use rustc_type_ir::solve::{Goal, NoSolution};
use tracing::{instrument, trace};
use crate::solve::Certainty;
use crate::solve::delegate::SolverDelegate;
use crate::solve::inspect::{self, ProofTreeInferCtxtExt, ProofTreeVisitor};
use crate::traits::{FulfillmentError, FulfillmentErrorCode};
use crate::traits::{FulfillmentError, FulfillmentErrorCode, wf};
pub(super) fn fulfillment_error_for_no_solution<'tcx>(
infcx: &InferCtxt<'tcx>,
@ -207,14 +207,10 @@ impl<'tcx> BestObligation<'tcx> {
| GoalSource::AliasBoundConstCondition
| GoalSource::InstantiateHigherRanked
| GoalSource::AliasWellFormed
) && match self.consider_ambiguities {
true => {
matches!(
nested_goal.result(),
Ok(Certainty::Maybe(MaybeCause::Ambiguity))
)
}
false => matches!(nested_goal.result(), Err(_)),
) && match (self.consider_ambiguities, nested_goal.result()) {
(true, Ok(Certainty::Maybe(MaybeCause::Ambiguity)))
| (false, Err(_)) => true,
_ => false,
}
},
)
@ -233,6 +229,39 @@ impl<'tcx> BestObligation<'tcx> {
candidates
}
/// HACK: We walk the nested obligations for a well-formed arg manually,
/// since there's nontrivial logic in `wf.rs` to set up an obligation cause.
/// Ideally we'd be able to track this better.
fn visit_well_formed_goal(
&mut self,
candidate: &inspect::InspectCandidate<'_, 'tcx>,
arg: ty::GenericArg<'tcx>,
) -> ControlFlow<PredicateObligation<'tcx>> {
let infcx = candidate.goal().infcx();
let param_env = candidate.goal().goal().param_env;
let body_id = self.obligation.cause.body_id;
for obligation in wf::unnormalized_obligations(infcx, param_env, arg, self.span(), body_id)
.into_iter()
.flatten()
{
let nested_goal = candidate.instantiate_proof_tree_for_nested_goal(
GoalSource::Misc,
Goal::new(infcx.tcx, obligation.param_env, obligation.predicate),
self.span(),
);
// Skip nested goals that aren't the *reason* for our goal's failure.
match (self.consider_ambiguities, nested_goal.result()) {
(true, Ok(Certainty::Maybe(MaybeCause::Ambiguity))) | (false, Err(_)) => {}
_ => continue,
}
self.with_derived_obligation(obligation, |this| nested_goal.visit_with(this))?;
}
ControlFlow::Break(self.obligation.clone())
}
}
impl<'tcx> ProofTreeVisitor<'tcx> for BestObligation<'tcx> {
@ -283,6 +312,9 @@ impl<'tcx> ProofTreeVisitor<'tcx> for BestObligation<'tcx> {
polarity: ty::PredicatePolarity::Positive,
}))
}
ty::PredicateKind::Clause(ty::ClauseKind::WellFormed(arg)) => {
return self.visit_well_formed_goal(candidate, arg);
}
_ => ChildMode::PassThrough,
};
@ -355,12 +387,8 @@ impl<'tcx> ProofTreeVisitor<'tcx> for BestObligation<'tcx> {
}
// Skip nested goals that aren't the *reason* for our goal's failure.
match self.consider_ambiguities {
true if matches!(
nested_goal.result(),
Ok(Certainty::Maybe(MaybeCause::Ambiguity))
) => {}
false if matches!(nested_goal.result(), Err(_)) => {}
match (self.consider_ambiguities, nested_goal.result()) {
(true, Ok(Certainty::Maybe(MaybeCause::Ambiguity))) | (false, Err(_)) => {}
_ => continue,
}

82
compiler/rustc_trait_selection/src/solve/inspect/analyse.rs
View file

@ -194,47 +194,57 @@ impl<'a, 'tcx> InspectCandidate<'a, 'tcx> {
let goals = instantiated_goals
.into_iter()
.map(|(source, goal)| match goal.predicate.kind().no_bound_vars() {
Some(ty::PredicateKind::NormalizesTo(ty::NormalizesTo { alias, term })) => {
let unconstrained_term = match term.unpack() {
ty::TermKind::Ty(_) => infcx.next_ty_var(span).into(),
ty::TermKind::Const(_) => infcx.next_const_var(span).into(),
};
let goal =
goal.with(infcx.tcx, ty::NormalizesTo { alias, term: unconstrained_term });
// We have to use a `probe` here as evaluating a `NormalizesTo` can constrain the
// expected term. This means that candidates which only fail due to nested goals
// and which normalize to a different term then the final result could ICE: when
// building their proof tree, the expected term was unconstrained, but when
// instantiating the candidate it is already constrained to the result of another
// candidate.
let proof_tree = infcx
.probe(|_| infcx.evaluate_root_goal_raw(goal, GenerateProofTree::Yes).1);
InspectGoal::new(
infcx,
self.goal.depth + 1,
proof_tree.unwrap(),
Some(NormalizesToTermHack { term, unconstrained_term }),
source,
)
}
_ => {
// We're using a probe here as evaluating a goal could constrain
// inference variables by choosing one candidate. If we then recurse
// into another candidate who ends up with different inference
// constraints, we get an ICE if we already applied the constraints
// from the chosen candidate.
let proof_tree = infcx
.probe(|_| infcx.evaluate_root_goal(goal, GenerateProofTree::Yes).1)
.unwrap();
InspectGoal::new(infcx, self.goal.depth + 1, proof_tree, None, source)
}
})
.map(|(source, goal)| self.instantiate_proof_tree_for_nested_goal(source, goal, span))
.collect();
(goals, opt_impl_args)
}
pub fn instantiate_proof_tree_for_nested_goal(
&self,
source: GoalSource,
goal: Goal<'tcx, ty::Predicate<'tcx>>,
span: Span,
) -> InspectGoal<'a, 'tcx> {
let infcx = self.goal.infcx;
match goal.predicate.kind().no_bound_vars() {
Some(ty::PredicateKind::NormalizesTo(ty::NormalizesTo { alias, term })) => {
let unconstrained_term = match term.unpack() {
ty::TermKind::Ty(_) => infcx.next_ty_var(span).into(),
ty::TermKind::Const(_) => infcx.next_const_var(span).into(),
};
let goal =
goal.with(infcx.tcx, ty::NormalizesTo { alias, term: unconstrained_term });
// We have to use a `probe` here as evaluating a `NormalizesTo` can constrain the
// expected term. This means that candidates which only fail due to nested goals
// and which normalize to a different term then the final result could ICE: when
// building their proof tree, the expected term was unconstrained, but when
// instantiating the candidate it is already constrained to the result of another
// candidate.
let proof_tree =
infcx.probe(|_| infcx.evaluate_root_goal_raw(goal, GenerateProofTree::Yes).1);
InspectGoal::new(
infcx,
self.goal.depth + 1,
proof_tree.unwrap(),
Some(NormalizesToTermHack { term, unconstrained_term }),
source,
)
}
_ => {
// We're using a probe here as evaluating a goal could constrain
// inference variables by choosing one candidate. If we then recurse
// into another candidate who ends up with different inference
// constraints, we get an ICE if we already applied the constraints
// from the chosen candidate.
let proof_tree = infcx
.probe(|_| infcx.evaluate_root_goal(goal, GenerateProofTree::Yes).1)
.unwrap();
InspectGoal::new(infcx, self.goal.depth + 1, proof_tree, None, source)
}
}
}
/// Visit all nested goals of this candidate, rolling back
/// all inference constraints.
pub fn visit_nested_in_probe<V: ProofTreeVisitor<'tcx>>(&self, visitor: &mut V) -> V::Result {

6
compiler/rustc_trait_selection/src/traits/query/type_op/implied_outlives_bounds.rs
View file

@ -5,8 +5,8 @@ use rustc_infer::traits::query::type_op::ImpliedOutlivesBounds;
use rustc_middle::infer::canonical::CanonicalQueryResponse;
use rustc_middle::traits::ObligationCause;
use rustc_middle::ty::{self, ParamEnvAnd, Ty, TyCtxt, TypeFolder, TypeVisitableExt};
use rustc_span::Span;
use rustc_span::def_id::CRATE_DEF_ID;
use rustc_span::{DUMMY_SP, Span};
use rustc_type_ir::outlives::{Component, push_outlives_components};
use smallvec::{SmallVec, smallvec};
use tracing::debug;
@ -92,7 +92,9 @@ pub fn compute_implied_outlives_bounds_inner<'tcx>(
// From the full set of obligations, just filter down to the region relationships.
for obligation in
wf::unnormalized_obligations(ocx.infcx, param_env, arg).into_iter().flatten()
wf::unnormalized_obligations(ocx.infcx, param_env, arg, DUMMY_SP, CRATE_DEF_ID)
.into_iter()
.flatten()
{
assert!(!obligation.has_escaping_bound_vars());
let Some(pred) = obligation.predicate.kind().no_bound_vars() else {

10
compiler/rustc_trait_selection/src/traits/wf.rs
View file

@ -8,8 +8,8 @@ use rustc_middle::ty::{
self, GenericArg, GenericArgKind, GenericArgsRef, Ty, TyCtxt, TypeSuperVisitable,
TypeVisitable, TypeVisitableExt, TypeVisitor,
};
use rustc_span::def_id::{CRATE_DEF_ID, DefId, LocalDefId};
use rustc_span::{DUMMY_SP, Span};
use rustc_span::Span;
use rustc_span::def_id::{DefId, LocalDefId};
use tracing::{debug, instrument, trace};
use crate::infer::InferCtxt;
@ -89,6 +89,8 @@ pub fn unnormalized_obligations<'tcx>(
infcx: &InferCtxt<'tcx>,
param_env: ty::ParamEnv<'tcx>,
arg: GenericArg<'tcx>,
span: Span,
body_id: LocalDefId,
) -> Option<PredicateObligations<'tcx>> {
debug_assert_eq!(arg, infcx.resolve_vars_if_possible(arg));
@ -106,8 +108,8 @@ pub fn unnormalized_obligations<'tcx>(
let mut wf = WfPredicates {
infcx,
param_env,
body_id: CRATE_DEF_ID,
span: DUMMY_SP,
body_id,
span,
out: PredicateObligations::new(),
recursion_depth: 0,
item: None,