if ($$->u.unary_expression.type == UNARY_UNSIGNED_CONSTANT) {
$$->u.unary_expression.type = UNARY_SIGNED_CONSTANT;
$$->u.unary_expression.u.signed_constant =
-($$->u.unary_expression.u.unsigned_constant);
if ($$->u.unary_expression.type == UNARY_UNSIGNED_CONSTANT) {
$$->u.unary_expression.type = UNARY_SIGNED_CONSTANT;
$$->u.unary_expression.u.signed_constant =
-($$->u.unary_expression.u.unsigned_constant);