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HACK: self ty ambiguity hack

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This commit is contained in:
Michael Goulet 2023-01-19 03:26:54 +00:00
parent 280f69d858
commit c9c8e294d2
1 changed files with 11 additions and 1 deletions
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12
compiler/rustc_trait_selection/src/solve/assembly.rs
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@ -1,7 +1,7 @@
//! Code shared by trait and projection goals for candidate assembly.
use super::infcx_ext::InferCtxtExt;
use super::{CanonicalResponse, EvalCtxt, Goal, QueryResult};
use super::{CanonicalResponse, Certainty, EvalCtxt, Goal, MaybeCause, QueryResult};
use rustc_hir::def_id::DefId;
use rustc_infer::traits::query::NoSolution;
use rustc_infer::traits::util::elaborate_predicates;
@ -124,6 +124,16 @@ pub(super) fn assemble_and_evaluate_candidates<G: GoalKind<'tcx>>(
&mut self,
goal: Goal<'tcx, G>,
) -> Vec<Candidate<'tcx>> {
// HACK: `_: Trait` is ambiguous, because it may be satisfied via a builtin rule,
// object bound, alias bound, etc. We are unable to determine this until we can at
// least structually resolve the type one layer.
if goal.predicate.self_ty().is_ty_var() {
return vec![Candidate {
source: CandidateSource::BuiltinImpl,
result: self.make_canonical_response(Certainty::Maybe(MaybeCause::Ambiguity)).unwrap(),
}];
}
let mut candidates = Vec::new();
self.assemble_candidates_after_normalizing_self_ty(goal, &mut candidates);