forward_like.hpp

Go to the documentation of this file.

#pragma once
 
#include <type_traits>
 
namespace std {
 
#ifndef __cpp_lib_forward_like
  namespace detail {
    template <typename T, typename U>
    using override_ref_t = conditional_t<is_rvalue_reference_v<T>, remove_reference_t<U> &&, U &>;
 
    template <typename T, typename U>
    using copy_const_t = conditional_t<is_const_v<remove_reference_t<T>>, U const, U>;
 
    template <typename T, typename U>
    using forward_like_t = override_ref_t<T &&, copy_const_t<T, remove_reference_t<U>>>;
  }
 
  template <typename T>
    [[nodiscard]] constexpr
    auto forward_like(auto&& x) noexcept -> detail::forward_like_t<T, decltype(x)> {
    return static_cast<detail::forward_like_t<T, decltype(x)>>(x);
  }
#endif
}