In https://stackoverflow.com/a/15483397/368896, the poster indicates - if I'm reading it correctly - that at least one data member must be present in order for a class not to be a POD.
class X {}; // This class is a POD
class Y { int y; } // This class is not, because of the presence of the data member
Why does there need to be at least 1 data member in order for a class to NOT be a POD?