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Make sure to detect trait upcasting coercion even after normalization

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This commit is contained in:
Michael Goulet 2023-07-16 22:11:03 +00:00
parent 7e66c0b7ed
commit 24eefd08e2
4 changed files with 20 additions and 29 deletions
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35
compiler/rustc_hir_typeck/src/coercion.rs
View File

@ -622,7 +622,6 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
ty::TraitRef::new(self.tcx, coerce_unsized_did, [coerce_source, coerce_target])
)];
let mut has_unsized_tuple_coercion = false;
let mut has_trait_upcasting_coercion = None;
// Keep resolving `CoerceUnsized` and `Unsize` predicates to avoid
@ -636,22 +635,6 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
Some(ty::PredicateKind::Clause(ty::ClauseKind::Trait(trait_pred)))
if traits.contains(&trait_pred.def_id()) =>
{
let trait_pred = self.resolve_vars_if_possible(trait_pred);
if unsize_did == trait_pred.def_id() {
let self_ty = trait_pred.self_ty();
let unsize_ty = trait_pred.trait_ref.args[1].expect_ty();
if let (ty::Dynamic(ref data_a, ..), ty::Dynamic(ref data_b, ..)) =
(self_ty.kind(), unsize_ty.kind())
&& data_a.principal_def_id() != data_b.principal_def_id()
{
debug!("coerce_unsized: found trait upcasting coercion");
has_trait_upcasting_coercion = Some((self_ty, unsize_ty));
}
if let ty::Tuple(..) = unsize_ty.kind() {
debug!("coerce_unsized: found unsized tuple coercion");
has_unsized_tuple_coercion = true;
}
}
trait_pred
}
_ => {
@ -659,6 +642,7 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
continue;
}
};
let trait_pred = self.resolve_vars_if_possible(trait_pred);
match selcx.select(&obligation.with(selcx.tcx(), trait_pred)) {
// Uncertain or unimplemented.
Ok(None) => {
@ -701,18 +685,15 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
// be silent, as it causes a type mismatch later.
}
Ok(Some(impl_source)) => queue.extend(impl_source.nested_obligations()),
}
Ok(Some(impl_source)) => {
if matches!(impl_source, traits::ImplSource::TraitUpcasting(..)) {
has_trait_upcasting_coercion =
Some((trait_pred.self_ty(), trait_pred.trait_ref.args.type_at(1)));
}
if has_unsized_tuple_coercion && !self.tcx.features().unsized_tuple_coercion {
feature_err(
&self.tcx.sess.parse_sess,
sym::unsized_tuple_coercion,
self.cause.span,
"unsized tuple coercion is not stable enough for use and is subject to change",
)
.emit();
queue.extend(impl_source.nested_obligations())
}
}
}
if let Some((sub, sup)) = has_trait_upcasting_coercion

6
compiler/rustc_trait_selection/src/solve/eval_ctxt/select.rs
View File

@ -315,7 +315,13 @@ fn rematch_object<'tcx>(
// If we're upcasting, get the offset of the vtable pointer, otherwise get
// the base of the vtable.
Ok(Some(if is_upcasting {
// If source and target trait def ids are identical,
// then we are simply removing auto traits.
if source_trait_ref.def_id() == target_trait_ref.def_id() {
ImplSource::Builtin(nested)
} else {
ImplSource::TraitUpcasting(ImplSourceTraitUpcastingData { vtable_vptr_slot, nested })
}
} else {
ImplSource::Object(ImplSourceObjectData { vtable_base, nested })
}))

2
tests/ui/traits/new-solver/normalize-unsize-rhs.rs
View File

@ -1,6 +1,8 @@
// compile-flags: -Ztrait-solver=next
// check-pass
#![feature(trait_upcasting)]
trait A {}
trait B: A {}

2
tests/ui/traits/new-solver/trait-upcast-lhs-needs-normalization.rs
View File

@ -1,6 +1,8 @@
// check-pass
// compile-flags: -Ztrait-solver=next
#![feature(trait_upcasting)]
pub trait A {}
pub trait B: A {}