Question

I do realize is_pod is a sufficient condition for a type to be memcpy-able, but is has_trivial_destructor also sufficient for this purpose? If not, why?

Answer 1

No. The requirement is that the type be trivially copyable (§3.9/2) which has a few more requirements, like the lack of a non-trivial copy constructor (§9/6).

A trivially copyable class is a class that:

— has no non-trivial copy constructors (12.8),

— has no non-trivial move constructors (12.8),

— has no non-trivial copy assignment operators (13.5.3, 12.8),

— has no non-trivial move assignment operators (13.5.3, 12.8), and

— has a trivial destructor (12.4).

So you should use is_trivially_copyable instead.