Comparing std::minmax against a pair

std::minmax has an initializer_list overload. This returns a non-const non-reference pair:

static_assert(std::minmax({2, 1}) == std::make_pair(1, 2));

Unfortunately this may be less performant, since the complexities respectively are "exactly one comparison" and "at most (3/2) * t.size() applications of the corresponding predicate".

One thing you could do is take advantage of the std::minmax overload that takes a std::initializer_list<T> and returns a std::pair<T,T>. Using that you could have

int main()
{
    const int a = 10, b = 20;
    static_assert(std::minmax({2, 1}) == std::make_pair(1, 2));
    static_assert(std::minmax({a, b}) == std::make_pair(a, b));
}

Which will compile and allows you to get rid of make_cref_pair. It does call std::minmax_element so I am not sure if this decreases the efficiency or not.

One option is to explicitly convert the left-hand side to std::pair<int,int>:

#include <algorithm>
#include <utility>

template <typename T1, typename T2>
constexpr std::pair<T1,T2> myminmax(const T1& t1, const T2& t2)
{
    return std::minmax(t1,t2);
}

int main()
{
    static_assert(myminmax(2, 1) == std::make_pair(1, 2));
}