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fix structurally relate for weak aliases

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This commit is contained in:
lcnr 2023-06-27 23:09:53 +02:00
parent 8ebb3d49e4
commit bd0d533d23
1 changed files with 15 additions and 11 deletions
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26
compiler/rustc_middle/src/ty/relate.rs
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@ -544,17 +544,8 @@ pub fn structurally_relate_tys<'tcx, R: TypeRelation<'tcx>>(
Ok(tcx.mk_fn_ptr(fty))
}
// these two are already handled downstream in case of lazy normalization
(&ty::Alias(ty::Projection, a_data), &ty::Alias(ty::Projection, b_data)) => {
let projection_ty = relation.relate(a_data, b_data)?;
Ok(tcx.mk_projection(projection_ty.def_id, projection_ty.substs))
}
(&ty::Alias(ty::Inherent, a_data), &ty::Alias(ty::Inherent, b_data)) => {
let alias_ty = relation.relate(a_data, b_data)?;
Ok(tcx.mk_alias(ty::Inherent, tcx.mk_alias_ty(alias_ty.def_id, alias_ty.substs)))
}
// The substs of opaque types may not all be invariant, so we have
// to treat them separately from other aliases.
(
&ty::Alias(ty::Opaque, ty::AliasTy { def_id: a_def_id, substs: a_substs, .. }),
&ty::Alias(ty::Opaque, ty::AliasTy { def_id: b_def_id, substs: b_substs, .. }),
@ -571,6 +562,19 @@ pub fn structurally_relate_tys<'tcx, R: TypeRelation<'tcx>>(
Ok(tcx.mk_opaque(a_def_id, substs))
}
// Alias tend to mostly already be handled downstream due to normalization.
(&ty::Alias(a_kind, a_data), &ty::Alias(b_kind, b_data)) => {
// FIXME(-Zlower-impl-trait-in-trait-to-assoc-ty): This if can be removed
// and the assert uncommented once the new desugaring is stable.
if a_kind == b_kind {
let alias_ty = relation.relate(a_data, b_data)?;
// assert_eq!(a_kind, b_kind);
Ok(tcx.mk_alias(a_kind, alias_ty))
} else {
Err(TypeError::Sorts(expected_found(relation, a, b)))
}
}
_ => Err(TypeError::Sorts(expected_found(relation, a, b))),
}
}