Function orphan_check

fn orphan_check<'tcx>(
    tcx: TyCtxt<'tcx>,
    impl_def_id: LocalDefId,
    mode: OrphanCheckMode,
) -> Result<(), OrphanCheckErr<TyCtxt<'tcx>, FxIndexSet<DefId>>>

Checks the coherence orphan rules.

impl_def_id should be the DefId of a trait impl.

To pass, either the trait must be local, or else two conditions must be satisfied:

1. All type parameters in Self must be “covered” by some local type constructor.
2. Some local type must appear in Self.