bjoernager/rust
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Multiple candidates with same response is not ambiguous

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This commit is contained in:
Michael Goulet 2023-02-09 18:14:13 +00:00
parent 8996ea93b6
commit 3c4e1f85cb
5 changed files with 8 additions and 15 deletions
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8
compiler/rustc_trait_selection/src/solve/assembly.rs
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@ -4,6 +4,7 @@ use super::infcx_ext::InferCtxtExt;
#[cfg(doc)]
use super::trait_goals::structural_traits::*;
use super::{CanonicalResponse, Certainty, EvalCtxt, Goal, MaybeCause, QueryResult};
use itertools::Itertools;
use rustc_hir::def_id::DefId;
use rustc_infer::traits::query::NoSolution;
use rustc_infer::traits::util::elaborate_predicates;
@ -489,9 +490,9 @@ impl<'tcx> EvalCtxt<'_, 'tcx> {
i += 1;
}
// If there are *STILL* multiple candidates, give up
// and report ambiguity.
if candidates.len() > 1 {
// If there are *STILL* multiple candidates that have *different* response
// results, give up and report ambiguity.
if candidates.len() > 1 && !candidates.iter().map(|cand| cand.result).all_equal() {
let certainty = if candidates.iter().all(|x| {
matches!(x.result.value.certainty, Certainty::Maybe(MaybeCause::Overflow))
}) {
@ -503,6 +504,7 @@ impl<'tcx> EvalCtxt<'_, 'tcx> {
}
}
// FIXME: What if there are >1 candidates left with the same response, and one is a reservation impl?
Ok(self.discard_reservation_impl(candidates.pop().unwrap()).result)
}