This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21 Core Issues List revision 115d. See http://www.open-std.org/jtc1/sc22/wg21/ for the official list.
2024-10-26
Consider a case like
struct X { template<typename T> void f(T); void f(int); }; template void X::f(int);
or
template<typename T> void f(T) {} void f(int); template void f(int);
Presumably in both these cases the explicit instantiation should refer to the template and not to the non-template; however, 13.7.3 [temp.mem] paragraph 2 says,
A normal (non-template) member function with a given name and type and a member function template of the same name, which could be used to generate a specialization of the same type, can both be declared in a class. When both exist, a use of that name and type refers to the non-template member unless an explicit template argument list is supplied.
This would appear to give the wrong answer for the first example. It's not clearly stated, but consistency would suggest a similar wrong answer for the second. Presumably a statement is needed somewhere that an explicit instantiation directive applies to a template and not a non-template function if both are visible.
Additional note, January, 2014:
A related example has been raised:
template<typename T> class Matrix { public: Matrix(){} Matrix(const Matrix&){} template<typename U> Matrix(const Matrix<U>&); }; template Matrix<int>::Matrix(const Matrix&); Matrix<int> m; Matrix<int> mm(m);
If the explicit instantiation directive applies to the constructor template, there is no way to explicitly instantiate the copy constructor.