static_cast<the_template<int>*>(0) - does this instantiate the_template with type int?
The reason for asking is the following code, which will error at linking time with an undefined reference to check_error<char>(void*, long) with Clang and GCC 4.4.5, indicating that it does not instantiate the template. MSVC and GCC 4.5.1 however compile and link just fine, leading to the believe that it does instantiate the template. However, if you leave out the cast, MSVC and GCC (both 4.4.5 and 4.5.1) will error on check_error<char> only (the wanted behaviour), while Clang will error on both calls. Normally I believe Clang when it comes to conforming stuff, but I wonder:
Which compiler is correct and what does the standard say about it?
#include <type_traits>
template<class T>
void check_error(void*, long);
template<class T>
struct foo{
template<class U>
friend typename std::enable_if<
std::is_same<T,U>::value
>::type check_error(foo<T>*, int){}
};
template struct foo<int>;
int main()
{
check_error<int>(static_cast<foo<int>*>(0), 0);
check_error<char>(static_cast<foo<char>*>(0), 0);
}
