C++ default initialization and value initialization: which is which, which is called when and how to reliably initialize a template-type member

Question

My question somewhat overlaps with this and several other similar ones. Those have some great answers, but I\'ve read them and I\'m still confused, so please don\'t consider

Answer 1

Yes, A inst4 (); is treated as a function declaration. std::string str(); should be the same (i.e. I think you mistakenly thought it worked).

Apparently (from here), C++03 will have inst3._a be 0, but C++98 would have left it uninitialized.