bjoernager/rust
bjoernager/rust
1
Fork 0
Code Issues Pull requests Activity

implement version of normalize_erasing_regions that doesn't assume value is normalizable

Browse source
This commit is contained in:
b-naber 2021-11-26 17:41:22 +01:00
parent 2446a21595
commit ff448cfcee
6 changed files with 203 additions and 3 deletions
Download patch file Download diff file Expand all files Collapse all files

40
compiler/rustc_traits/src/normalize_erasing_regions.rs
View file

@ -20,6 +20,14 @@ crate fn provide(p: &mut Providers) {
normalize_mir_const_after_erasing_regions: |tcx, goal| {
normalize_after_erasing_regions(tcx, goal)
},
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)
},
try_normalize_mir_const_after_erasing_regions: |tcx, goal| {
try_normalize_after_erasing_regions(tcx, goal)
},
..*p
};
}
@ -56,6 +64,38 @@ fn normalize_after_erasing_regions<'tcx, T: TypeFoldable<'tcx> + PartialEq + Cop
})
}
#[instrument(level = "debug", skip(tcx))]
fn try_normalize_after_erasing_regions<'tcx, T: TypeFoldable<'tcx> + PartialEq + Copy>(
tcx: TyCtxt<'tcx>,
goal: ParamEnvAnd<'tcx, T>,
) -> Result<T, NoSolution> {
let ParamEnvAnd { param_env, value } = goal;
tcx.infer_ctxt().enter(|infcx| {
let cause = ObligationCause::dummy();
match infcx.at(&cause, param_env).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:
debug_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.needs_infer(), "{:?}", erased);
Ok(erased)
}
Err(NoSolution) => Err(NoSolution),
}
})
}
fn not_outlives_predicate(p: &ty::Predicate<'tcx>) -> bool {
match p.kind().skip_binder() {
ty::PredicateKind::RegionOutlives(..) | ty::PredicateKind::TypeOutlives(..) => false,