Reputation: 7699
Ok, this one drives me mad. I can't figure out why a constructor is not called.
Here is the code:
template<class T>
struct JV {
JV() {}
JV(const T& t0) : F{{t0}} {
std::cout << __PRETTY_FUNCTION__ << "\n";
}
std::array<T,1> F;
};
template<class T>
struct RS : public JV<T>
{
RS(): JV<T>() {}
RS(const T& rhs) : JV<T>(rhs) {
std::cout << __PRETTY_FUNCTION__ << "\n";
}
};
template<class T>
struct PS : public JV<T>
{
PS(): JV<T>() {}
PS(const T& rhs) : JV<T>(rhs) {
std::cout << __PRETTY_FUNCTION__ << "\n";
}
};
template<class T>
struct WJ
{
WJ() {
std::cout << "WJ::WJ()\n";
}
};
int main() {
PS<RS<WJ<float> > > wj;
std::cout << "go for it\n";
PS<PS<RS<WJ<float> > > > copy(wj);
}
If compiled with GCC g++ 4.7.2 -std=c++0x
and run the output is:
WJ::WJ()
go for it
JV<T>::JV(const T&) [with T = PS<RS<WJ<float> > >]
PS<T>::PS(const T1&) [with T1 = PS<RS<WJ<float> > >; T = PS<RS<WJ<float> > >]
Why does JV<T>::JV(const T&) [with T = PS<RS<WJ<float> > >]
not call the
overloaded constructor of PS<RS<WJ<float> > >::PS<RS<WJ<float> > >(const RS<WJ<float> >&)
?
Edit:
Also, it doesn't call it when restricting the overloaded constructor, see above.
Upvotes: 0
Views: 168
Reputation: 208323
Templated constructors are never copy constructors. The compiler is using the copy constructor to construct PS<RS<WJ<float>>>
inside the std::array
in JV
. You are not tracking in your code copy construcotrs so no other message is shown after JV<T>::JV(T const&)
.
Upvotes: 3