libcxx/test/std/algorithms/alg.sorting/alg.min.max/minmax_comp.pass.cpp

//===----------------------------------------------------------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is dual licensed under the MIT and the University of Illinois Open
// Source Licenses. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

// <algorithm>

// template<class T, StrictWeakOrder<auto, T> Compare>
//   requires !SameType<T, Compare> && CopyConstructible<Compare>
//   pair<const T&, const T&>
//   minmax(const T& a, const T& b, Compare comp);

#include <algorithm>
#include <functional>
#include <cassert>

template <class T, class C>
void
test(const T& a, const T& b, C c, const T& x, const T& y)
{
    std::pair<const T&, const T&> p = std::minmax(a, b, c);
    assert(&p.first == &x);
    assert(&p.second == &y);
}


int main()
{
    {
    int x = 0;
    int y = 0;
    test(x, y, std::greater<int>(), x, y);
    test(y, x, std::greater<int>(), y, x);
    }
    {
    int x = 0;
    int y = 1;
    test(x, y, std::greater<int>(), y, x);
    test(y, x, std::greater<int>(), y, x);
    }
    {
    int x = 1;
    int y = 0;
    test(x, y, std::greater<int>(), x, y);
    test(y, x, std::greater<int>(), x, y);
    }
#if _LIBCPP_STD_VER > 11
    {
//  Note that you can't take a reference to a local var, since 
//  its address is not a compile-time constant.
    constexpr static int x = 1;
    constexpr static int y = 0;
    constexpr auto p1 = std::minmax(x, y, std::greater<>());
    static_assert(p1.first  == x, "");
    static_assert(p1.second == y, "");
    constexpr auto p2 = std::minmax(y, x, std::greater<>());
    static_assert(p2.first  == x, "");
    static_assert(p2.second == y, "");
    }
#endif
}