bjoernager/rust
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Support weak alias types as self type of inherent impls

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This commit is contained in:
León Orell Valerian Liehr 2024-02-08 12:54:07 +01:00
parent 0a5b998c57
commit 8677d64c72
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GPG key ID: D17A07215F68E713
9 changed files with 193 additions and 1 deletions
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31
compiler/rustc_hir_analysis/src/coherence/inherent_impls.rs
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@ -144,6 +144,7 @@ impl<'tcx> InherentCollect<'tcx> {
let id = id.owner_id.def_id;
let item_span = self.tcx.def_span(id);
let self_ty = self.tcx.type_of(id).instantiate_identity();
let self_ty = peel_off_weak_aliases(self.tcx, self_ty);
match *self_ty.kind() {
ty::Adt(def, _) => self.check_def_id(id, self_ty, def.did()),
ty::Foreign(did) => self.check_def_id(id, self_ty, did),
@ -166,7 +167,7 @@ impl<'tcx> InherentCollect<'tcx> {
| ty::Never
| ty::FnPtr(_)
| ty::Tuple(..) => self.check_primitive_impl(id, self_ty),
ty::Alias(..) | ty::Param(_) => {
ty::Alias(ty::Projection | ty::Inherent | ty::Opaque, _) | ty::Param(_) => {
Err(self.tcx.dcx().emit_err(errors::InherentNominal { span: item_span }))
}
ty::FnDef(..)
@ -174,6 +175,7 @@ impl<'tcx> InherentCollect<'tcx> {
| ty::CoroutineClosure(..)
| ty::Coroutine(..)
| ty::CoroutineWitness(..)
| ty::Alias(ty::Weak, _)
| ty::Bound(..)
| ty::Placeholder(_)
| ty::Infer(_) => {
@ -184,3 +186,30 @@ impl<'tcx> InherentCollect<'tcx> {
}
}
}
/// Peel off all weak alias types in this type until there are none left.
///
/// <div class="warning">
///
/// This assumes that `ty` gets normalized later and that any overflows occurring
/// during said normalization get reported.
///
/// </div>
fn peel_off_weak_aliases<'tcx>(tcx: TyCtxt<'tcx>, mut ty: Ty<'tcx>) -> Ty<'tcx> {
let ty::Alias(ty::Weak, _) = ty.kind() else { return ty };
let limit = tcx.recursion_limit();
let mut depth = 0;
while let ty::Alias(ty::Weak, alias) = ty.kind() {
if !limit.value_within_limit(depth) {
let guar = tcx.dcx().delayed_bug("overflow expanding weak alias type");
return Ty::new_error(tcx, guar);
}
ty = tcx.type_of(alias.def_id).instantiate(tcx, alias.args);
depth += 1;
}
ty
}