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Instantiate auto trait before computing higher-ranked constituent types

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This commit is contained in:
Michael Goulet
2025-07-06 20:02:45 +00:00
parent 040e2f8b9f
commit 8d2d4eb89a
2 changed files with 23 additions and 16 deletions
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1
compiler/rustc_trait_selection/src/traits/select/confirmation.rs
View File

@@ -403,6 +403,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
let self_ty =
obligation.predicate.self_ty().map_bound(|ty| self.infcx.shallow_resolve(ty));
let self_ty = self.infcx.enter_forall_and_leak_universe(self_ty);
let types = self.constituent_types_for_ty(self_ty)?;
let types = self.infcx.enter_forall_and_leak_universe(types);

38
compiler/rustc_trait_selection/src/traits/select/mod.rs
View File

@@ -2330,9 +2330,9 @@ impl<'tcx> SelectionContext<'_, 'tcx> {
#[instrument(level = "debug", skip(self), ret)]
fn constituent_types_for_ty(
&self,
t: ty::Binder<'tcx, Ty<'tcx>>,
t: Ty<'tcx>,
) -> Result<ty::Binder<'tcx, Vec<Ty<'tcx>>>, SelectionError<'tcx>> {
Ok(match *t.skip_binder().kind() {
Ok(match *t.kind() {
ty::Uint(_)
| ty::Int(_)
| ty::Bool
@@ -2349,8 +2349,7 @@ impl<'tcx> SelectionContext<'_, 'tcx> {
// `assemble_candidates_from_auto_impls`.
ty::Foreign(..) => ty::Binder::dummy(Vec::new()),
// FIXME(unsafe_binders): Squash the double binder for now, I guess.
ty::UnsafeBinder(_) => return Err(SelectionError::Unimplemented),
ty::UnsafeBinder(ty) => ty.map_bound(|ty| vec![ty]),
// Treat this like `struct str([u8]);`
ty::Str => ty::Binder::dummy(vec![Ty::new_slice(self.tcx(), self.tcx().types.u8)]),
@@ -2364,40 +2363,47 @@ impl<'tcx> SelectionContext<'_, 'tcx> {
bug!("asked to assemble constituent types of unexpected type: {:?}", t);
}
ty::RawPtr(element_ty, _) | ty::Ref(_, element_ty, _) => t.rebind(vec![element_ty]),
ty::RawPtr(element_ty, _) | ty::Ref(_, element_ty, _) => {
ty::Binder::dummy(vec![element_ty])
}
ty::Pat(ty, _) | ty::Array(ty, _) | ty::Slice(ty) => t.rebind(vec![ty]),
ty::Pat(ty, _) | ty::Array(ty, _) | ty::Slice(ty) => ty::Binder::dummy(vec![ty]),
ty::Tuple(tys) => {
// (T1, ..., Tn) -- meets any bound that all of T1...Tn meet
t.rebind(tys.iter().collect())
ty::Binder::dummy(tys.iter().collect())
}
ty::Closure(_, args) => {
let ty = self.infcx.shallow_resolve(args.as_closure().tupled_upvars_ty());
t.rebind(vec![ty])
ty::Binder::dummy(vec![ty])
}
ty::CoroutineClosure(_, args) => {
let ty = self.infcx.shallow_resolve(args.as_coroutine_closure().tupled_upvars_ty());
t.rebind(vec![ty])
ty::Binder::dummy(vec![ty])
}
ty::Coroutine(_, args) => {
let ty = self.infcx.shallow_resolve(args.as_coroutine().tupled_upvars_ty());
let witness = args.as_coroutine().witness();
t.rebind([ty].into_iter().chain(iter::once(witness)).collect())
ty::Binder::dummy([ty].into_iter().chain(iter::once(witness)).collect())
}
ty::CoroutineWitness(def_id, args) => {
rebind_coroutine_witness_types(self.infcx.tcx, def_id, args, t.bound_vars())
}
ty::CoroutineWitness(def_id, args) => self
.infcx
.tcx
.coroutine_hidden_types(def_id)
.instantiate(self.infcx.tcx, args)
.map_bound(|witness| witness.types.to_vec()),
// For `PhantomData<T>`, we pass `T`.
ty::Adt(def, args) if def.is_phantom_data() => t.rebind(args.types().collect()),
ty::Adt(def, args) if def.is_phantom_data() => {
ty::Binder::dummy(args.types().collect())
}
ty::Adt(def, args) => {
t.rebind(def.all_fields().map(|f| f.ty(self.tcx(), args)).collect())
ty::Binder::dummy(def.all_fields().map(|f| f.ty(self.tcx(), args)).collect())
}
ty::Alias(ty::Opaque, ty::AliasTy { def_id, args, .. }) => {
@@ -2408,7 +2414,7 @@ impl<'tcx> SelectionContext<'_, 'tcx> {
// which enforces a DAG between the functions requiring
// the auto trait bounds in question.
match self.tcx().type_of_opaque(def_id) {
Ok(ty) => t.rebind(vec![ty.instantiate(self.tcx(), args)]),
Ok(ty) => ty::Binder::dummy(vec![ty.instantiate(self.tcx(), args)]),
Err(_) => {
return Err(SelectionError::OpaqueTypeAutoTraitLeakageUnknown(def_id));
}