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Fix incorrect usage of EvaluatedToOk when evaluating TypeOutlives

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A global predicate is not guarnatenteed to outlive all regions.
If the predicate involves late-bound regions, then it may fail
to outlive other regions (e.g. `for<'b> &'b bool: 'static` does not
hold)

We now only produce `EvaluatedToOk` when a global predicate has no
late-bound regions - in that case, the ony region that can be present
in the type is 'static
This commit is contained in:
Aaron Hill 2021-11-28 14:31:22 -05:00
parent e6d2de9483
commit 4910fe6889
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4 changed files with 82 additions and 1 deletions
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6
compiler/rustc_trait_selection/src/traits/select/mod.rs
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@ -558,7 +558,11 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
},
ty::PredicateKind::TypeOutlives(pred) => {
if pred.0.is_known_global() {
// A global type with no late-bound regions can only
// contain the "'static" lifetime (any other lifetime
// would either be late-bound or local), so it is guaranteed
// to outlive any other lifetime
if pred.0.is_global(self.infcx.tcx) && !pred.0.has_late_bound_regions() {
Ok(EvaluatedToOk)
} else {
Ok(EvaluatedToOkModuloRegions)