bjoernager/rust
bjoernager/rust
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new solver cleanup + coherence

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This commit is contained in:
lcnr 2023-03-21 16:26:23 +01:00
parent a01b4cc9f3
commit 47f24a881b
18 changed files with 203 additions and 52 deletions
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27
compiler/rustc_trait_selection/src/solve/trait_goals.rs
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@ -2,7 +2,7 @@
use std::iter;
use super::{assembly, EvalCtxt};
use super::{assembly, EvalCtxt, SolverMode};
use rustc_hir::def_id::DefId;
use rustc_hir::LangItem;
use rustc_infer::traits::query::NoSolution;
@ -20,6 +20,10 @@ impl<'tcx> assembly::GoalKind<'tcx> for TraitPredicate<'tcx> {
self.self_ty()
}
fn trait_ref(self, _: TyCtxt<'tcx>) -> ty::TraitRef<'tcx> {
self.trait_ref
}
fn with_self_ty(self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> Self {
self.with_self_ty(tcx, self_ty)
}
@ -43,6 +47,22 @@ impl<'tcx> assembly::GoalKind<'tcx> for TraitPredicate<'tcx> {
return Err(NoSolution);
}
let impl_polarity = tcx.impl_polarity(impl_def_id);
// An upper bound of the certainty of this goal, used to lower the certainty
// of reservation impl to ambiguous during coherence.
let maximal_certainty = match impl_polarity {
ty::ImplPolarity::Positive | ty::ImplPolarity::Negative => {
match impl_polarity == goal.predicate.polarity {
true => Certainty::Yes,
false => return Err(NoSolution),
}
}
ty::ImplPolarity::Reservation => match ecx.solver_mode() {
SolverMode::Normal => return Err(NoSolution),
SolverMode::Coherence => Certainty::AMBIGUOUS,
},
};
ecx.probe(|ecx| {
let impl_substs = ecx.fresh_substs_for_item(impl_def_id);
let impl_trait_ref = impl_trait_ref.subst(tcx, impl_substs);
@ -55,7 +75,8 @@ impl<'tcx> assembly::GoalKind<'tcx> for TraitPredicate<'tcx> {
.into_iter()
.map(|pred| goal.with(tcx, pred));
ecx.add_goals(where_clause_bounds);
ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
ecx.evaluate_added_goals_and_make_canonical_response(maximal_certainty)
})
}
@ -547,6 +568,6 @@ impl<'tcx> EvalCtxt<'_, 'tcx> {
goal: Goal<'tcx, TraitPredicate<'tcx>>,
) -> QueryResult<'tcx> {
let candidates = self.assemble_and_evaluate_candidates(goal);
self.merge_candidates_and_discard_reservation_impls(candidates)
self.merge_candidates(candidates)
}
}