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Rollup merge of #109423 - fmease:iat-selection-erase-regions-in-self-ty, r=compiler-errors

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Use region-erased self type during IAT selection

Split off from #109410 as discussed.
Fixes #109299.

Re UI test: I use a reproducer of #109299 that contains a name resolution error instead of reproducer [`regionck-2.rs`](fc7ed4af16/tests/ui/associated-inherent-types/regionck-2.rs) (as found in the `AliasKind::Inherent` PR) since it would (incorrectly) pass typeck in this PR due to the lack of regionck and I'd rather not make *that* a regression test (with or without `known-bug`).

``@rustbot`` label F-inherent_associated_types

r? ``@compiler-errors``
This commit is contained in:
Matthias Krüger 2023-03-22 22:44:42 +01:00 • committed by GitHub
commit b22db3fca4
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5 changed files with 101 additions and 31 deletions
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82
compiler/rustc_hir_analysis/src/astconv/mod.rs
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@ -31,6 +31,7 @@ use rustc_infer::infer::{InferCtxt, TyCtxtInferExt};
use rustc_infer::traits::ObligationCause;
use rustc_middle::infer::unify_key::{ConstVariableOrigin, ConstVariableOriginKind};
use rustc_middle::middle::stability::AllowUnstable;
use rustc_middle::ty::fold::FnMutDelegate;
use rustc_middle::ty::subst::{self, GenericArgKind, InternalSubsts, SubstsRef};
use rustc_middle::ty::DynKind;
use rustc_middle::ty::GenericParamDefKind;
@ -2225,47 +2226,66 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
let param_env = tcx.param_env(block.owner.to_def_id());
let cause = ObligationCause::misc(span, block.owner.def_id);
let mut fulfillment_errors = Vec::new();
let mut applicable_candidates: Vec<_> = candidates
.iter()
.filter_map(|&(impl_, (assoc_item, def_scope))| {
infcx.probe(|_| {
let ocx = ObligationCtxt::new_in_snapshot(&infcx);
let mut applicable_candidates: Vec<_> = infcx.probe(|_| {
let universe = infcx.create_next_universe();
let impl_ty = tcx.type_of(impl_);
let impl_substs = infcx.fresh_item_substs(impl_);
let impl_ty = impl_ty.subst(tcx, impl_substs);
let impl_ty = ocx.normalize(&cause, param_env, impl_ty);
// Regions are not considered during selection.
let self_ty = tcx.replace_escaping_bound_vars_uncached(
self_ty,
FnMutDelegate {
regions: &mut |_| tcx.lifetimes.re_erased,
types: &mut |bv| {
tcx.mk_placeholder(ty::PlaceholderType { universe, name: bv.kind })
},
consts: &mut |bv, ty| {
tcx.mk_const(ty::PlaceholderConst { universe, name: bv }, ty)
},
},
);
// Check that the Self-types can be related.
// FIXME(fmease): Should we use `eq` here?
ocx.sup(&ObligationCause::dummy(), param_env, impl_ty, self_ty).ok()?;
candidates
.iter()
.filter_map(|&(impl_, (assoc_item, def_scope))| {
infcx.probe(|_| {
let ocx = ObligationCtxt::new_in_snapshot(&infcx);
// Check whether the impl imposes obligations we have to worry about.
let impl_bounds = tcx.predicates_of(impl_);
let impl_bounds = impl_bounds.instantiate(tcx, impl_substs);
let impl_ty = tcx.type_of(impl_);
let impl_substs = infcx.fresh_item_substs(impl_);
let impl_ty = impl_ty.subst(tcx, impl_substs);
let impl_ty = ocx.normalize(&cause, param_env, impl_ty);
let impl_bounds = ocx.normalize(&cause, param_env, impl_bounds);
// Check that the Self-types can be related.
// FIXME(fmease): Should we use `eq` here?
ocx.sup(&ObligationCause::dummy(), param_env, impl_ty, self_ty).ok()?;
let impl_obligations = traits::predicates_for_generics(
|_, _| cause.clone(),
param_env,
impl_bounds,
);
// Check whether the impl imposes obligations we have to worry about.
let impl_bounds = tcx.predicates_of(impl_);
let impl_bounds = impl_bounds.instantiate(tcx, impl_substs);
ocx.register_obligations(impl_obligations);
let impl_bounds = ocx.normalize(&cause, param_env, impl_bounds);
let mut errors = ocx.select_where_possible();
if !errors.is_empty() {
fulfillment_errors.append(&mut errors);
return None;
}
let impl_obligations = traits::predicates_for_generics(
|_, _| cause.clone(),
param_env,
impl_bounds,
);
// FIXME(fmease): Unsolved vars can escape this InferCtxt snapshot.
Some((assoc_item, def_scope, infcx.resolve_vars_if_possible(impl_substs)))
ocx.register_obligations(impl_obligations);
let mut errors = ocx.select_where_possible();
if !errors.is_empty() {
fulfillment_errors.append(&mut errors);
return None;
}
// FIXME(fmease): Unsolved vars can escape this InferCtxt snapshot.
Some((assoc_item, def_scope, infcx.resolve_vars_if_possible(impl_substs)))
})
})
})
.collect();
.collect()
});
if applicable_candidates.len() > 1 {
return Err(self.complain_about_ambiguous_inherent_assoc_type(