fn default_enum_substructure(
cx: &ExtCtxt<'_>,
trait_span: Span,
enum_def: &EnumDef,
item_span: Span,
) -> BlockOrExprfn default_enum_substructure(
cx: &ExtCtxt<'_>,
trait_span: Span,
enum_def: &EnumDef,
item_span: Span,
) -> BlockOrExpr