diff options
Diffstat (limited to 'compiler')
| -rw-r--r-- | compiler/rustc_next_trait_solver/src/solve/assembly/mod.rs | 29 |
1 files changed, 14 insertions, 15 deletions
diff --git a/compiler/rustc_next_trait_solver/src/solve/assembly/mod.rs b/compiler/rustc_next_trait_solver/src/solve/assembly/mod.rs index 579be70fccf..542e212e1bf 100644 --- a/compiler/rustc_next_trait_solver/src/solve/assembly/mod.rs +++ b/compiler/rustc_next_trait_solver/src/solve/assembly/mod.rs @@ -2,6 +2,7 @@ pub(super) mod structural_traits; +use std::cell::Cell; use std::ops::ControlFlow; use derive_where::derive_where; @@ -118,25 +119,23 @@ where Self::fast_reject_assumption(ecx, goal, assumption)?; // Dealing with `ParamEnv` candidates is a bit of a mess as we need to lazily - // check whether the candidate is global. - ecx.probe(|candidate: &Result<Candidate<I>, NoSolution>| match candidate { - Ok(candidate) => inspect::ProbeKind::TraitCandidate { - source: candidate.source, - result: Ok(candidate.result), - }, - Err(NoSolution) => inspect::ProbeKind::TraitCandidate { - source: CandidateSource::ParamEnv(ParamEnvSource::Global), - result: Err(NoSolution), - }, + // check whether the candidate is global while considering normalization. + // + // We need to write into `source` inside of `match_assumption`, but need to access it + // in `probe` even if the candidate does not apply before we get there. We handle this + // by using a `Cell` here. We only ever write into it inside of `match_assumption`. + let source = Cell::new(CandidateSource::ParamEnv(ParamEnvSource::Global)); + ecx.probe(|result: &QueryResult<I>| inspect::ProbeKind::TraitCandidate { + source: source.get(), + result: *result, }) .enter(|ecx| { - let mut source = CandidateSource::ParamEnv(ParamEnvSource::Global); - let result = Self::match_assumption(ecx, goal, assumption, |ecx| { - source = ecx.characterize_param_env_assumption(goal.param_env, assumption)?; + Self::match_assumption(ecx, goal, assumption, |ecx| { + source.set(ecx.characterize_param_env_assumption(goal.param_env, assumption)?); ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes) - })?; - Ok(Candidate { source, result }) + }) }) + .map(|result| Candidate { source: source.get(), result }) } /// Try equating an assumption predicate against a goal's predicate. If it |