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properly elaborate effects implied bounds for super traits

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This commit is contained in:
Deadbeef
2024-08-24 14:01:00 +08:00
parent 4428a05167
commit 7c2a24b50c
11 changed files with 132 additions and 84 deletions
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44
compiler/rustc_hir_analysis/src/bounds.rs
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@@ -91,12 +91,46 @@ impl<'tcx> Bounds<'tcx> {
}
tcx.consts.true_
}
(DefKind::Trait, ty::BoundConstness::ConstIfConst) => {
// we are in a trait, where `bound_trait_ref` could be:
// (1) a super trait `trait Foo: ~const Bar`.
// - This generates `<Self as Foo>::Effects: TyCompat<<Self as Bar>::Effects>`
//
// (2) a where clause `where for<..> Something: ~const Bar`.
// - This generates `for<..> <Self as Foo>::Effects: TyCompat<<Something as Bar>::Effects>`
let Some(own_fx) = tcx.associated_type_for_effects(defining_def_id) else {
tcx.dcx().span_delayed_bug(span, "should not have allowed `~const` on a trait that doesn't have `#[const_trait]`");
return;
};
let own_fx_ty = Ty::new_projection(
tcx,
own_fx,
ty::GenericArgs::identity_for_item(tcx, own_fx),
);
let Some(their_fx) = tcx.associated_type_for_effects(bound_trait_ref.def_id())
else {
tcx.dcx().span_delayed_bug(span, "`~const` on trait without Effects assoc");
return;
};
let their_fx_ty =
Ty::new_projection(tcx, their_fx, bound_trait_ref.skip_binder().args);
let compat = tcx.require_lang_item(LangItem::EffectsTyCompat, Some(span));
let clause = bound_trait_ref
.map_bound(|_| {
let trait_ref = ty::TraitRef::new(tcx, compat, [own_fx_ty, their_fx_ty]);
ty::ClauseKind::Trait(ty::TraitPredicate {
trait_ref,
polarity: ty::PredicatePolarity::Positive,
})
})
.upcast(tcx);
(
DefKind::Trait | DefKind::Impl { of_trait: true },
ty::BoundConstness::ConstIfConst,
) => {
// this is either a where clause on an impl/trait header or on a trait.
self.clauses.push((clause, span));
return;
}
(DefKind::Impl { of_trait: true }, ty::BoundConstness::ConstIfConst) => {
// this is a where clause on an impl header.
// push `<T as Tr>::Effects` into the set for the `Min` bound.
let Some(assoc) = tcx.associated_type_for_effects(bound_trait_ref.def_id()) else {
tcx.dcx().span_delayed_bug(span, "`~const` on trait without Effects assoc");