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Rollup merge of #110195 - compiler-errors:issue-110052, r=aliemjay

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Erase lifetimes above `ty::INNERMOST` when probing ambiguous types

Turns out that `TyCtxt::replace_escaping_bound_vars_uncached` only erases bound vars exactly at `ty::INNERMOST`, and not everything above. This regresses the suggestions for non-lifetime binders, but oh well, I don't really care about those.

Fixes #110052
This commit is contained in:
Matthias Krüger 2023-04-13 11:21:00 +02:00 • committed by GitHub
commit 958413cc08
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4 changed files with 33 additions and 15 deletions
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20
compiler/rustc_hir_analysis/src/astconv/mod.rs
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@ -2520,24 +2520,16 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
tcx,
infcx.fresh_substs_for_item(DUMMY_SP, impl_def_id),
);
// I guess we don't need to make a universe unless we need it,
// but also we're on the error path, so it doesn't matter here.
let universe = infcx.create_next_universe();
let value = tcx.fold_regions(qself_ty, |_, _| tcx.lifetimes.re_erased);
// FIXME: Don't bother dealing with non-lifetime binders here...
if value.has_escaping_bound_vars() {
return false;
}
infcx
.can_eq(
ty::ParamEnv::empty(),
impl_.self_ty(),
tcx.replace_escaping_bound_vars_uncached(qself_ty, ty::fold::FnMutDelegate {
regions: &mut |_| tcx.lifetimes.re_erased,
types: &mut |bv| tcx.mk_placeholder(ty::PlaceholderType {
universe,
bound: bv,
}),
consts: &mut |bv, ty| tcx.mk_const(ty::PlaceholderConst {
universe,
bound: bv,
}, ty),
})
value,
)
})
&& tcx.impl_polarity(impl_def_id) != ty::ImplPolarity::Negative