experimental/status-code/error.hpp

0001 /* Proposed SG14 status_code
0002 (C) 2018-2024 Niall Douglas <http://www.nedproductions.biz/> (5 commits)
0003 File Created: Feb 2018
0004
0005
0006 Boost Software License - Version 1.0 - August 17th, 2003
0007
0008 Permission is hereby granted, free of charge, to any person or organization
0009 obtaining a copy of the software and accompanying documentation covered by
0010 this license (the "Software") to use, reproduce, display, distribute,
0011 execute, and transmit the Software, and to prepare derivative works of the
0012 Software, and to permit third-parties to whom the Software is furnished to
0013 do so, all subject to the following:
0014
0015 The copyright notices in the Software and this entire statement, including
0016 the above license grant, this restriction and the following disclaimer,
0017 must be included in all copies of the Software, in whole or in part, and
0018 all derivative works of the Software, unless such copies or derivative
0019 works are solely in the form of machine-executable object code generated by
0020 a source language processor.
0021
0022 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
0023 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
0024 FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
0025 SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
0026 FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
0027 ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
0028 DEALINGS IN THE SOFTWARE.
0029 */
0030
0031 #ifndef BOOST_OUTCOME_SYSTEM_ERROR2_ERROR_HPP
0032 #define BOOST_OUTCOME_SYSTEM_ERROR2_ERROR_HPP
0033
0034 #include "errored_status_code.hpp"
0035 #include "system_code.hpp"
0036
0037 BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE_BEGIN
0038
0039 /*! An errored `system_code` which must be a failure upon copy or move or
0040 non-default construction. The closest equivalent to `std::error_code`, except
0041 it cannot be modified.
0042
0043 This refines `system_code` into an `error` object meeting the requirements of
0044 [P0709 Zero-overhead deterministic exceptions](https://wg21.link/P0709).
0045
0046 Differences from `system_code`:
0047
0048 - Almost always a failure (this is checked at copy or move and non-default
0049 construction, and if not the case, the program is terminated as this is a logic
0050 error)
0051 - Is immutable.
0052
0053 As with `system_code`, it remains guaranteed to be two CPU registers in size,
0054 and move bitcopying.
0055 */
0056 using error = erased_errored_status_code<system_code::value_type>;
0057
0058 #ifndef NDEBUG
0059 static_assert(sizeof(error) == 2 * sizeof(void *), "error is not exactly two pointers in size!");
0060 static_assert(traits::is_move_bitcopying<error>::value, "error is not move bitcopying!");
0061 #endif
0062
0063 BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE_END
0064
0065 #endif