ceph/src/boost/boost/outcome/experimental/status-code/error.hpp

   1 /* Proposed SG14 status_code
   2 (C) 2018-2020 Niall Douglas <http://www.nedproductions.biz/> (5 commits)
   3 File Created: Feb 2018
   4
   5
   6 Boost Software License - Version 1.0 - August 17th, 2003
   7
   8 Permission is hereby granted, free of charge, to any person or organization
   9 obtaining a copy of the software and accompanying documentation covered by
  10 this license (the "Software") to use, reproduce, display, distribute,
  11 execute, and transmit the Software, and to prepare derivative works of the
  12 Software, and to permit third-parties to whom the Software is furnished to
  13 do so, all subject to the following:
  14
  15 The copyright notices in the Software and this entire statement, including
  16 the above license grant, this restriction and the following disclaimer,
  17 must be included in all copies of the Software, in whole or in part, and
  18 all derivative works of the Software, unless such copies or derivative
  19 works are solely in the form of machine-executable object code generated by
  20 a source language processor.
  21
  22 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  23 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  24 FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
  25 SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
  26 FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
  27 ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  28 DEALINGS IN THE SOFTWARE.
  29 */
  30
  31 #ifndef BOOST_OUTCOME_SYSTEM_ERROR2_ERROR_HPP
  32 #define BOOST_OUTCOME_SYSTEM_ERROR2_ERROR_HPP
  33
  34 #include "errored_status_code.hpp"
  35 #include "system_code.hpp"
  36
  37 BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE_BEGIN
  38
  39 /*! An erased `system_code` which is always a failure. The closest equivalent to
  40 `std::error_code`, except it cannot be null and cannot be modified.
  41
  42 This refines `system_code` into an `error` object meeting the requirements of
  43 [P0709 Zero-overhead deterministic exceptions](https://wg21.link/P0709).
  44
  45 Differences from `system_code`:
  46
  47 - Always a failure (this is checked at construction, and if not the case,
  48 the program is terminated as this is a logic error)
  49 - No default construction.
  50 - No empty state possible.
  51 - Is immutable.
  52
  53 As with `system_code`, it remains guaranteed to be two CPU registers in size,
  54 and move bitcopying.
  55 */
  56 using error = errored_status_code<erased<system_code::value_type>>;
  57
  58 #ifndef NDEBUG
  59 static_assert(sizeof(error) == 2 * sizeof(void *), "error is not exactly two pointers in size!");
  60 static_assert(traits::is_move_bitcopying<error>::value, "error is not move bitcopying!");
  61 #endif
  62
  63 BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE_END
  64
  65 #endif