Explicit instantiation of templated constructor for template class

Question

I am uncertain if it is a bug in Clang 3.2 or a violation of C++03, but it appears that explicit instantiation of templated constructors for template classes fails, but expl

Answer 1

It looks like you've found a GCC bug. These both name the implicitly-declared copy constructor:

template Foo<int>::Foo( const Foo<int>& foo );
template Foo<float>::Foo( const Foo<float>& foo );

Per [temp.explicit]p4,

If the declaration of the explicit instantiation names an implicitly-declared special member function (Clause 12), the program is ill-formed.

Therefore Clang is correct to reject this code.