我想通过使用模板别名和模板特化的组合来确定模板参数的基础模板。下面的代码在gcc 4.8,6.2.1上编译得很好，但在clang 3.5,3.8上没有编译。
#include <iostream>
template <typename T> struct First {};
template <typename T> struct Second {};
template <template <typename> class F, typename T> struct Foo {};
template <typename T> struct Foo<First, T>
{
void f() { std::cout << __PRETTY_FUNCTION__ << std::endl; }
};
template <typename T> struct Foo<Second, T>
{
void f() { std::cout << __PRETTY_FUNCTION__ << std::endl; }
};
template <typename F, typename T> struct Resolution {};
template <typename T> struct Resolution<First<T>, T>
{
template <typename P> using type = First<P>;
};
template <typename T> struct Resolution<Second<T>, T>
{
template <typename P> using type = Second<P>;
};
int main()
{
Foo<Resolution<First<int>, int>::type, float> my_foo;
my_foo.f(); // main.cpp:34:12: error: no member named 'f' in 'Foo<Resolution<First<int>, int>::type, float>'
return 0;
}
哪种行为符合标准？