Support for the Ruby 2.4 series has ended. See here for reference.
See also BigDecimal.new
static VALUE
BigDecimal_global_new(int argc, VALUE *argv, VALUE self)
{
ENTER(1);
Real *pv;
VALUE obj;
obj = TypedData_Wrap_Struct(rb_cBigDecimal, &BigDecimal_data_type, 0);
GUARD_OBJ(pv, BigDecimal_new(argc, argv));
if (ToValue(pv)) pv = VpCopy(NULL, pv);
RTYPEDDATA_DATA(obj) = pv;
return pv->obj = obj;
}