CHECK_CXX_SOURCE_COMPILES(
    "
    #include <iostream>
    #include <optional>
    #include <tuple>

    #if __cplusplus < 201703L && !defined(_MSC_VER) && !defined(__INTEL_COMPILER)
    #  error \"insufficient support for C++17\"
    #endif

    //check for some C++17 features that we use in our headers:
    using std::apply;
    using std::optional;

    [[nodiscard]] int test_nodiscard()
    {
      return 1;
    }

    int main()
    {
      const unsigned int n=1;
      switch (n)
      {
        case 1:
          std::cout << n;
          [[fallthrough]];
        case 2:
          std::cout << n;
      }

      [[maybe_unused]] int i = test_nodiscard();

      constexpr bool flag = false;
      if constexpr(flag)
        return 1;
      return 0;
    }
    "
    DEAL_II_HAVE_CXX17_FEATURES)