#pragma clang system_header namespace std { template struct integral_constant { static constexpr T value = v; typedef T value_type; typedef integral_constant type; constexpr operator value_type() const noexcept { return value; } }; template using bool_constant = integral_constant; using true_type = bool_constant; using false_type = bool_constant; template struct is_error_code_enum : false_type {}; template void swap(T &a, T &b); }