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Normalize types when applying uninhabited predicate.

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This commit is contained in:
Camille GILLOT 2023-06-27 16:56:58 +00:00
parent e0ba2d038d
commit 6f3f878351
2 changed files with 44 additions and 1 deletions
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13
compiler/rustc_middle/src/ty/inhabitedness/inhabited_predicate.rs
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@ -62,7 +62,18 @@ impl<'tcx> InhabitedPredicate<'tcx> {
Some(1..) => Ok(false),
},
Self::NotInModule(id) => in_module(id).map(|in_mod| !in_mod),
Self::GenericType(_) => Ok(true),
// `t` may be a projection, for which `inhabited_predicate` returns a `GenericType`. As
// we have a param_env available, we can do better.
Self::GenericType(t) => {
let normalized_pred = tcx
.try_normalize_erasing_regions(param_env, t)
.map_or(self, |t| t.inhabited_predicate(tcx));
match normalized_pred {
// We don't have more information than we started with, so consider inhabited.
Self::GenericType(_) => Ok(true),
pred => pred.apply_inner(tcx, param_env, in_module),
}
}
Self::And([a, b]) => try_and(a, b, |x| x.apply_inner(tcx, param_env, in_module)),
Self::Or([a, b]) => try_or(a, b, |x| x.apply_inner(tcx, param_env, in_module)),
}