Search code examples
c++c++11recursionvariadic-templates

The type in template specialization will be continue to calculate？

just like these code,In the template specialization defined the type,will be the type(at the label 1),the code test_two<N+1, Max, std::size_t> continue to match the template specialization(struct test_two<N,Max,std::size_t>) and caculate the type of test_two<N+1, Max, std::size_t> and so on?

template<std::size_t N, std::size_t Max, typename T>
struct test_two
{

};

template<std::size_t N, std::size_t Max>
struct test_two<N,Max,std::size_t>
{
    using type = test_two<N+1, Max, std::size_t>  //label:1
};

As above

Solution

  • The declaration using type = test_two<N+1, Max, std::size_t>; does not require the right-hand-side type to be complete, so it will not instantiate the definition of test_two<N+1, Max, std::size_t>, only its declaration. There is therefore no infinite recursion.