Eljay Love-Jensen <eljay@xxxxxxxxx> writes:
> Hi,
>
> >hm. So if a type is both POD and UDT, what do you do?
>
> I didn't know that was possible, in C++.
struct f{};
struct f2{int i;};
template<class T>
struct cmp{bool operator()(T lhs,T rhs){return lhs < rhs;}};
f foo;
f2 foo2;
cmp<int> c;
foo, foo2, and c are all both POD and UDT. It's not just possible;
it's quite common; any C++ project which relies on 3rd party C
libraries uses types that are both POD and UDT. Most standard C++
libraries (including gcc's libstdc++) contain many types that that
are both POD and UDT.
For reference, see the middle of 9/4:
# [...] A POD-struct is an aggregate class that has no non-static
# data members of type non-POD-struct, non-POD-union (or array of
# such types) or reference, and has no user-defined copy assignment
# operator and no user-defined destructor. [...]
and also 8.5.1/1:
# An aggregate is an array or a class (clause 9) with no
# user-declared constructors (12.1), no private or protected
# non-static data members (clause 11), no base classes (clause 10),
# and no virtual functions (10.3).
