1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
|
use rustc_infer::infer::TyCtxtInferExt;
use rustc_middle::query::Providers;
use rustc_middle::traits::query::NoSolution;
use rustc_middle::ty::{self, ParamEnvAnd, TyCtxt, TypeFoldable, TypeVisitableExt};
use rustc_trait_selection::traits::query::normalize::QueryNormalizeExt;
use rustc_trait_selection::traits::{Normalized, ObligationCause};
pub(crate) fn provide(p: &mut Providers) {
*p = Providers {
try_normalize_generic_arg_after_erasing_regions: |tcx, goal| {
debug!("try_normalize_generic_arg_after_erasing_regions(goal={:#?}", goal);
try_normalize_after_erasing_regions(tcx, goal)
},
..*p
};
}
fn try_normalize_after_erasing_regions<'tcx, T: TypeFoldable<TyCtxt<'tcx>> + PartialEq + Copy>(
tcx: TyCtxt<'tcx>,
goal: ParamEnvAnd<'tcx, T>,
) -> Result<T, NoSolution> {
let ParamEnvAnd { param_env, value } = goal;
let infcx = tcx.infer_ctxt().build();
let cause = ObligationCause::dummy();
match infcx.at(&cause, param_env).query_normalize(value) {
Ok(Normalized { value: normalized_value, obligations: normalized_obligations }) => {
// We don't care about the `obligations`; they are
// always only region relations, and we are about to
// erase those anyway:
// This has been seen to fail in RL, so making it a non-debug assertion to better catch
// those cases.
assert_eq!(
normalized_obligations.iter().find(|p| not_outlives_predicate(p.predicate)),
None,
);
let resolved_value = infcx.resolve_vars_if_possible(normalized_value);
// It's unclear when `resolve_vars` would have an effect in a
// fresh `InferCtxt`. If this assert does trigger, it will give
// us a test case.
debug_assert_eq!(normalized_value, resolved_value);
let erased = infcx.tcx.erase_regions(resolved_value);
debug_assert!(!erased.has_infer(), "{erased:?}");
Ok(erased)
}
Err(NoSolution) => Err(NoSolution),
}
}
fn not_outlives_predicate(p: ty::Predicate<'_>) -> bool {
match p.kind().skip_binder() {
ty::PredicateKind::Clause(ty::ClauseKind::RegionOutlives(..))
| ty::PredicateKind::Clause(ty::ClauseKind::TypeOutlives(..)) => false,
ty::PredicateKind::Clause(ty::ClauseKind::Trait(..))
| ty::PredicateKind::Clause(ty::ClauseKind::Projection(..))
| ty::PredicateKind::Clause(ty::ClauseKind::ConstArgHasType(..))
| ty::PredicateKind::NormalizesTo(..)
| ty::PredicateKind::AliasRelate(..)
| ty::PredicateKind::Clause(ty::ClauseKind::WellFormed(..))
| ty::PredicateKind::ObjectSafe(..)
| ty::PredicateKind::Subtype(..)
| ty::PredicateKind::Coerce(..)
| ty::PredicateKind::Clause(ty::ClauseKind::ConstEvaluatable(..))
| ty::PredicateKind::ConstEquate(..)
| ty::PredicateKind::Ambiguous => true,
}
}
|
