bjoernager/rust
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add a debug assertion that only outlives-oblig. result from norm.

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This commit is contained in:
Niko Matsakis 2018-03-09 16:44:20 -05:00
parent 6288faa3a3
commit fc04c41a40
1 changed files with 32 additions and 7 deletions
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39
src/librustc_traits/normalize_erasing_regions.rs
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@ -10,7 +10,7 @@
use rustc::traits::{Normalized, ObligationCause};
use rustc::traits::query::NoSolution;
use rustc::ty::{ParamEnvAnd, Ty, TyCtxt};
use rustc::ty::{self, ParamEnvAnd, Ty, TyCtxt};
use rustc::util::common::CellUsizeExt;
crate fn normalize_ty_after_erasing_regions<'tcx>(
@ -18,15 +18,27 @@ crate fn normalize_ty_after_erasing_regions<'tcx>(
goal: ParamEnvAnd<'tcx, Ty<'tcx>>,
) -> Ty<'tcx> {
let ParamEnvAnd { param_env, value } = goal;
tcx.sess.perf_stats.normalize_ty_after_erasing_regions.increment();
tcx.sess
.perf_stats
.normalize_ty_after_erasing_regions
.increment();
tcx.infer_ctxt().enter(|infcx| {
let cause = ObligationCause::dummy();
match infcx.at(&cause, param_env).normalize(&value) {
Ok(Normalized { value: normalized_value, obligations: _ }) => {
// ^^^^^^^^^^^
// We don't care about the `obligations`,
// they are always only region relations,
// and we are about to erase those anyway.
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 normalized_value = infcx.resolve_type_vars_if_possible(&normalized_value);
let normalized_value = infcx.tcx.erase_regions(&normalized_value);
tcx.lift_to_global(&normalized_value).unwrap()
@ -35,3 +47,16 @@ crate fn normalize_ty_after_erasing_regions<'tcx>(
}
})
}
fn not_outlives_predicate(p: &ty::Predicate<'_>) -> bool {
match p {
ty::Predicate::RegionOutlives(..) | ty::Predicate::TypeOutlives(..) => false,
ty::Predicate::Trait(..)
| ty::Predicate::Projection(..)
| ty::Predicate::WellFormed(..)
| ty::Predicate::ObjectSafe(..)
| ty::Predicate::ClosureKind(..)
| ty::Predicate::Subtype(..)
| ty::Predicate::ConstEvaluatable(..) => true,
}
}