let tcx = self.tcx();
let opt_variances = tcx.variances_of(item_def_id);
- relate_substs_with_variances(self, item_def_id, opt_variances, a_subst, b_subst)
+ relate_substs_with_variances(self, item_def_id, opt_variances, a_subst, b_subst, true)
}
/// Switch variance for the purpose of relating `a` and `b`.
variances: &[ty::Variance],
a_subst: SubstsRef<'tcx>,
b_subst: SubstsRef<'tcx>,
+ fetch_ty_for_diag: bool,
) -> RelateResult<'tcx, SubstsRef<'tcx>> {
let tcx = relation.tcx();
let mut cached_ty = None;
let params = iter::zip(a_subst, b_subst).enumerate().map(|(i, (a, b))| {
let variance = variances[i];
- let variance_info = if variance == ty::Invariant {
+ let variance_info = if variance == ty::Invariant && fetch_ty_for_diag {
let ty =
*cached_ty.get_or_insert_with(|| tcx.bound_type_of(ty_def_id).subst(tcx, a_subst));
ty::VarianceDiagInfo::Invariant { ty, param_index: i.try_into().unwrap() }
tcx.mk_substs(params)
}
-#[instrument(level = "trace", skip(relation), ret)]
-fn relate_opaque_item_substs<'tcx, R: TypeRelation<'tcx>>(
- relation: &mut R,
- def_id: DefId,
- a_subst: SubstsRef<'tcx>,
- b_subst: SubstsRef<'tcx>,
-) -> RelateResult<'tcx, SubstsRef<'tcx>> {
- let tcx = relation.tcx();
- let variances = tcx.variances_of(def_id);
- debug!(?variances);
-
- let params = iter::zip(a_subst, b_subst).enumerate().map(|(i, (a, b))| {
- let variance = variances[i];
- let variance_info = ty::VarianceDiagInfo::default();
- relation.relate_with_variance(variance, variance_info, a, b)
- });
-
- tcx.mk_substs(params)
-}
-
impl<'tcx> Relate<'tcx> for ty::FnSig<'tcx> {
fn relate<R: TypeRelation<'tcx>>(
relation: &mut R,
(&ty::Opaque(a_def_id, a_substs), &ty::Opaque(b_def_id, b_substs))
if a_def_id == b_def_id =>
{
- let substs = relate_opaque_item_substs(relation, a_def_id, a_substs, b_substs)?;
+ let opt_variances = tcx.variances_of(a_def_id);
+ let substs = relate_substs_with_variances(
+ relation,
+ a_def_id,
+ opt_variances,
+ a_substs,
+ b_substs,
+ false, // do not fetch `type_of(a_def_id)`, as it will cause a cycle
+ )?;
Ok(tcx.mk_opaque(a_def_id, substs))
}