fn default_struct_substructure(
cx: &ExtCtxt<'_>,
trait_span: Span,
substr: Substructure<'_>,
variant_data: &VariantData,
) -> BlockOrExprfn default_struct_substructure(
cx: &ExtCtxt<'_>,
trait_span: Span,
substr: Substructure<'_>,
variant_data: &VariantData,
) -> BlockOrExpr