bjoernager/rust
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CFI: Encode Virtual calls as calls through the defining trait

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For example, if `trait Foo: Bar`, and we try to call a method from `Bar`
on `dyn Foo`, encode the callsite as passing a `dyn Bar`, not a `dyn
Foo`.
This commit is contained in:
Matthew Maurer 2024-03-24 18:56:15 +00:00
parent d779a7a25f
commit d301f40c84
2 changed files with 87 additions and 10 deletions
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24
compiler/rustc_symbol_mangling/src/typeid/typeid_itanium_cxx_abi.rs
View file

@ -1140,8 +1140,17 @@ pub fn typeid_for_instance<'tcx>(
let predicates = tcx.mk_poly_existential_predicates(&[ty::Binder::dummy(predicate)]);
let self_ty = Ty::new_dynamic(tcx, predicates, tcx.lifetimes.re_erased, ty::Dyn);
instance.args = tcx.mk_args_trait(self_ty, List::empty());
} else if matches!(instance.def, ty::InstanceDef::Virtual(..)) {
instance.args = strip_receiver_auto(tcx, instance.args);
} else if let ty::InstanceDef::Virtual(def_id, _) = instance.def {
let upcast_ty = match tcx.trait_of_item(def_id) {
Some(trait_id) => trait_object_ty(
tcx,
ty::Binder::dummy(ty::TraitRef::from_method(tcx, trait_id, instance.args)),
),
// drop_in_place won't have a defining trait, skip the upcast
None => instance.args.type_at(0),
};
let stripped_ty = strip_receiver_auto(tcx, upcast_ty);
instance.args = tcx.mk_args_trait(stripped_ty, instance.args.into_iter().skip(1));
}
if let Some(impl_id) = tcx.impl_of_method(instance.def_id())
@ -1190,15 +1199,11 @@ pub fn typeid_for_instance<'tcx>(
typeid_for_fnabi(tcx, fn_abi, options)
}
fn strip_receiver_auto<'tcx>(
tcx: TyCtxt<'tcx>,
args: ty::GenericArgsRef<'tcx>,
) -> ty::GenericArgsRef<'tcx> {
let ty = args.type_at(0);
fn strip_receiver_auto<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> Ty<'tcx> {
let ty::Dynamic(preds, lifetime, kind) = ty.kind() else {
bug!("Tried to strip auto traits from non-dynamic type {ty}");
};
let new_rcvr = if preds.principal().is_some() {
if preds.principal().is_some() {
let filtered_preds =
tcx.mk_poly_existential_predicates_from_iter(preds.into_iter().filter(|pred| {
!matches!(pred.skip_binder(), ty::ExistentialPredicate::AutoTrait(..))
@ -1209,8 +1214,7 @@ fn strip_receiver_auto<'tcx>(
// about it. This technically discards the knowledge that it was a type that was made
// into a trait object at some point, but that's not a lot.
tcx.types.unit
};
tcx.mk_args_trait(new_rcvr, args.into_iter().skip(1))
}
}
#[instrument(skip(tcx), ret)]