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lcnr 2024-05-01 15:03:15 +00:00
parent da969d41a3
commit f323f9dedb
1 changed files with 15 additions and 13 deletions
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28
compiler/rustc_trait_selection/src/solve/inspect/analyse.rs
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@ -41,19 +41,18 @@ pub struct InspectGoal<'a, 'tcx> {
goal: Goal<'tcx, ty::Predicate<'tcx>>,
result: Result<Certainty, NoSolution>,
evaluation_kind: inspect::CanonicalGoalEvaluationKind<'tcx>,
/// The expected term of a `NormalizesTo` goal. It gets
/// replaced with an unconstrained inference variable when
/// computing `NormalizesTo` goals and we return the nested
/// goals to the caller, who also equates the actual term
/// with the expected.
///
/// This is an implementation detail of the trait solver and
/// not something we want to leak to users. We therefore
/// treat `NormalizesTo` goals as if they apply the expected
/// type at the end of each candidate.
normalizes_to_term_hack: Option<NormalizesToTermHack<'tcx>>,
}
/// The expected term of a `NormalizesTo` goal gets replaced
/// with an unconstrained inference variable when computing
/// `NormalizesTo` goals and we return the nested goals to the
/// caller, who also equates the actual term with the expected.
///
/// This is an implementation detail of the trait solver and
/// not something we want to leak to users. We therefore
/// treat `NormalizesTo` goals as if they apply the expected
/// type at the end of each candidate.
#[derive(Copy, Clone)]
struct NormalizesToTermHack<'tcx> {
term: ty::Term<'tcx>,
@ -61,7 +60,10 @@ struct NormalizesToTermHack<'tcx> {
}
impl<'tcx> NormalizesToTermHack<'tcx> {
fn relate(
/// Relate the `term` with the new `unconstrained_term` created
/// when computing the proof tree for this `NormalizesTo` goals.
/// This handles nested obligations.
fn constrain(
self,
infcx: &InferCtxt<'tcx>,
span: Span,
@ -166,7 +168,7 @@ impl<'a, 'tcx> InspectCandidate<'a, 'tcx> {
// FIXME: We ignore the expected term of `NormalizesTo` goals
// when computing the result of its candidates. This is
// scuffed.
let _ = term_hack.relate(infcx, span, param_env);
let _ = term_hack.constrain(infcx, span, param_env);
}
instantiated_goals
@ -326,7 +328,7 @@ impl<'a, 'tcx> InspectGoal<'a, 'tcx> {
let result = evaluation.result.and_then(|ok| {
if let Some(term_hack) = normalizes_to_term_hack {
infcx
.probe(|_| term_hack.relate(infcx, DUMMY_SP, uncanonicalized_goal.param_env))
.probe(|_| term_hack.constrain(infcx, DUMMY_SP, uncanonicalized_goal.param_env))
.map(|certainty| ok.value.certainty.unify_with(certainty))
} else {
Ok(ok.value.certainty)