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

   1 /* Proposed SG14 status_code
   2 (C) 2018 - 2019 Niall Douglas <http://www.nedproductions.biz/> (5 commits)
   3 File Created: Feb 2018
   4
   5
   6 Licensed under the Apache License, Version 2.0 (the "License");
   7 you may not use this file except in compliance with the License.
   8 You may obtain a copy of the License in the accompanying file
   9 Licence.txt or at
  10
  11 http://www.apache.org/licenses/LICENSE-2.0
  12
  13 Unless required by applicable law or agreed to in writing, software
  14 distributed under the License is distributed on an "AS IS" BASIS,
  15 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  16 See the License for the specific language governing permissions and
  17 limitations under the License.
  18
  19
  20 Distributed under the Boost Software License, Version 1.0.
  21 (See accompanying file Licence.txt or copy at
  22 http://www.boost.org/LICENSE_1_0.txt)
  23 */
  24
  25 #ifndef BOOST_OUTCOME_SYSTEM_ERROR2_CONFIG_HPP
  26 #define BOOST_OUTCOME_SYSTEM_ERROR2_CONFIG_HPP
  27
  28 // < 0.1 each
  29 #include <cassert>
  30 #include <cstddef>  // for size_t
  31 #include <cstdlib>  // for free
  32
  33 // 0.22
  34 #include <type_traits>
  35
  36 // 0.29
  37 #include <atomic>
  38
  39 // 0.28 (0.15 of which is exception_ptr)
  40 #include <exception>  // for std::exception
  41 // <new> includes <exception>, <exception> includes <new>
  42 #include <new>
  43
  44 // 0.01
  45 #include <initializer_list>
  46
  47 #ifndef BOOST_OUTCOME_SYSTEM_ERROR2_CONSTEXPR14
  48 #if defined(BOOST_OUTCOME_STANDARDESE_IS_IN_THE_HOUSE) || __cplusplus >= 201400 || _MSC_VER >= 1910 /* VS2017 */
  49 //! Defined to be `constexpr` when on C++ 14 or better compilers. Usually automatic, can be overriden.
  50 #define BOOST_OUTCOME_SYSTEM_ERROR2_CONSTEXPR14 constexpr
  51 #else
  52 #define BOOST_OUTCOME_SYSTEM_ERROR2_CONSTEXPR14
  53 #endif
  54 #endif
  55
  56 #ifndef BOOST_OUTCOME_SYSTEM_ERROR2_NORETURN
  57 #if defined(BOOST_OUTCOME_STANDARDESE_IS_IN_THE_HOUSE) || (_HAS_CXX17 && _MSC_VER >= 1911 /* VS2017.3 */)
  58 #define BOOST_OUTCOME_SYSTEM_ERROR2_NORETURN [[noreturn]]
  59 #endif
  60 #endif
  61 #if !defined(BOOST_OUTCOME_SYSTEM_ERROR2_NORETURN)
  62 #ifdef __has_cpp_attribute
  63 #if __has_cpp_attribute(noreturn)
  64 #define BOOST_OUTCOME_SYSTEM_ERROR2_NORETURN [[noreturn]]
  65 #endif
  66 #endif
  67 #endif
  68 #if !defined(BOOST_OUTCOME_SYSTEM_ERROR2_NORETURN)
  69 #if defined(_MSC_VER)
  70 #define BOOST_OUTCOME_SYSTEM_ERROR2_NORETURN __declspec(noreturn)
  71 #elif defined(__GNUC__)
  72 #define BOOST_OUTCOME_SYSTEM_ERROR2_NORETURN __attribute__((__noreturn__))
  73 #else
  74 #define BOOST_OUTCOME_SYSTEM_ERROR2_NORETURN
  75 #endif
  76 #endif
  77 // GCCs before 7 don't grok [[noreturn]] virtual functions, and warn annoyingly
  78 #if defined(__GNUC__) && !defined(__clang__) && __GNUC__ < 7
  79 #undef BOOST_OUTCOME_SYSTEM_ERROR2_NORETURN
  80 #define BOOST_OUTCOME_SYSTEM_ERROR2_NORETURN
  81 #endif
  82
  83 #ifndef BOOST_OUTCOME_SYSTEM_ERROR2_NODISCARD
  84 #if defined(BOOST_OUTCOME_STANDARDESE_IS_IN_THE_HOUSE) || (_HAS_CXX17 && _MSC_VER >= 1911 /* VS2017.3 */)
  85 #define BOOST_OUTCOME_SYSTEM_ERROR2_NODISCARD [[nodiscard]]
  86 #endif
  87 #endif
  88 #ifndef BOOST_OUTCOME_SYSTEM_ERROR2_NODISCARD
  89 #ifdef __has_cpp_attribute
  90 #if __has_cpp_attribute(nodiscard)
  91 #define BOOST_OUTCOME_SYSTEM_ERROR2_NODISCARD [[nodiscard]]
  92 #endif
  93 #elif defined(__clang__)
  94 #define BOOST_OUTCOME_SYSTEM_ERROR2_NODISCARD __attribute__((warn_unused_result))
  95 #elif defined(_MSC_VER)
  96 // _Must_inspect_result_ expands into this
  97 #define BOOST_OUTCOME_SYSTEM_ERROR2_NODISCARD                                                                                                                                                                                                                                                                                                \
  98   __declspec("SAL_name"                                                                                                                                                                                                                                                                                                        \
  99              "("                                                                                                                                                                                                                                                                                                               \
 100              "\"_Must_inspect_result_\""                                                                                                                                                                                                                                                                                       \
 101              ","                                                                                                                                                                                                                                                                                                               \
 102              "\"\""                                                                                                                                                                                                                                                                                                            \
 103              ","                                                                                                                                                                                                                                                                                                               \
 104              "\"2\""                                                                                                                                                                                                                                                                                                           \
 105              ")") __declspec("SAL_begin") __declspec("SAL_post") __declspec("SAL_mustInspect") __declspec("SAL_post") __declspec("SAL_checkReturn") __declspec("SAL_end")
 106 #endif
 107 #endif
 108 #ifndef BOOST_OUTCOME_SYSTEM_ERROR2_NODISCARD
 109 #define BOOST_OUTCOME_SYSTEM_ERROR2_NODISCARD
 110 #endif
 111
 112 #ifndef BOOST_OUTCOME_SYSTEM_ERROR2_TRIVIAL_ABI
 113 #if defined(BOOST_OUTCOME_STANDARDESE_IS_IN_THE_HOUSE) || (__clang_major__ >= 7 && !defined(__APPLE__))
 114 //! Defined to be `[[clang::trivial_abi]]` when on a new enough clang compiler. Usually automatic, can be overriden.
 115 #define BOOST_OUTCOME_SYSTEM_ERROR2_TRIVIAL_ABI [[clang::trivial_abi]]
 116 #else
 117 #define BOOST_OUTCOME_SYSTEM_ERROR2_TRIVIAL_ABI
 118 #endif
 119 #endif
 120
 121 #ifndef BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE
 122 //! The system_error2 namespace name.
 123 #define BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE system_error2
 124 //! Begins the system_error2 namespace.
 125 #define BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE_BEGIN                                                                                                                                                                                                                                                                                          \
 126   namespace system_error2                                                                                                                                                                                                                                                                                                      \
 127   {
 128 //! Ends the system_error2 namespace.
 129 #define BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE_END }
 130 #endif
 131
 132 //! Namespace for the library
 133 BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE_BEGIN
 134
 135 //! Namespace for user specialised traits
 136 namespace traits
 137 {
 138   /*! Specialise to true if you guarantee that a type is move relocating (i.e.
 139   its move constructor equals copying bits from old to new, old is left in a
 140   default constructed state, and calling the destructor on a default constructed
 141   instance is trivial). All trivially copyable types are move relocating by
 142   definition, and that is the unspecialised implementation.
 143   */
 144   template <class T> struct is_move_relocating
 145   {
 146     static constexpr bool value = std::is_trivially_copyable<T>::value;
 147   };
 148 }  // namespace traits
 149
 150 namespace detail
 151 {
 152   inline BOOST_OUTCOME_SYSTEM_ERROR2_CONSTEXPR14 size_t cstrlen(const char *str)
 153   {
 154     const char *end = nullptr;
 155     for(end = str; *end != 0; ++end)  // NOLINT
 156       ;
 157     return end - str;
 158   }
 159
 160   /* A partially compliant implementation of C++20's std::bit_cast function contributed
 161   by Jesse Towner. TODO FIXME Replace with C++ 20 bit_cast when available.
 162
 163   Our bit_cast is only guaranteed to be constexpr when both the input and output
 164   arguments are either integrals or enums. However, this covers most use cases
 165   since the vast majority of status_codes have an underlying type that is either
 166   an integral or enum. We still attempt a constexpr union-based type pun for non-array
 167   input types, which some compilers accept. For array inputs, we fall back to
 168   non-constexpr memmove.
 169   */
 170
 171   template <class T> using is_integral_or_enum = std::integral_constant<bool, std::is_integral<T>::value || std::is_enum<T>::value>;
 172
 173   template <class To, class From> using is_static_castable = std::integral_constant<bool, is_integral_or_enum<To>::value && is_integral_or_enum<From>::value>;
 174
 175   template <class To, class From> using is_union_castable = std::integral_constant<bool, !is_static_castable<To, From>::value && !std::is_array<To>::value && !std::is_array<From>::value>;
 176
 177   template <class To, class From> using is_bit_castable = std::integral_constant<bool, sizeof(To) == sizeof(From) && traits::is_move_relocating<To>::value && traits::is_move_relocating<From>::value>;
 178
 179   template <class To, class From> union bit_cast_union {
 180     From source;
 181     To target;
 182   };
 183
 184   template <class To, class From,
 185             typename std::enable_if<                //
 186             is_bit_castable<To, From>::value        //
 187             && is_static_castable<To, From>::value  //
 188             && !is_union_castable<To, From>::value,  //
 189             bool>::type = true>  //
 190   constexpr To bit_cast(const From &from) noexcept
 191   {
 192     return static_cast<To>(from);
 193   }
 194
 195   template <class To, class From,
 196             typename std::enable_if<                 //
 197             is_bit_castable<To, From>::value         //
 198             && !is_static_castable<To, From>::value  //
 199             && is_union_castable<To, From>::value,    //
 200             bool>::type = true>  //
 201   constexpr To bit_cast(const From &from) noexcept
 202   {
 203     return bit_cast_union<To, From>{from}.target;
 204   }
 205
 206   template <class To, class From,
 207             typename std::enable_if<                 //
 208             is_bit_castable<To, From>::value         //
 209             && !is_static_castable<To, From>::value  //
 210             && !is_union_castable<To, From>::value,   //
 211             bool>::type = true>  //
 212   To bit_cast(const From &from) noexcept
 213   {
 214     bit_cast_union<To, From> ret;
 215     memmove(&ret.source, &from, sizeof(ret.source));
 216     return ret.target;
 217   }
 218
 219   /* erasure_cast performs a bit_cast with additional rules to handle types
 220   of differing sizes. For integral & enum types, it may perform a narrowing
 221   or widing conversion with static_cast if necessary, before doing the final
 222   conversion with bit_cast. When casting to or from non-integral, non-enum
 223   types it may insert the value into another object with extra padding bytes
 224   to satisfy bit_cast's preconditions that both types have the same size. */
 225
 226   template <class To, class From> using is_erasure_castable = std::integral_constant<bool, traits::is_move_relocating<To>::value && traits::is_move_relocating<From>::value>;
 227
 228   template <class T, bool = std::is_enum<T>::value> struct identity_or_underlying_type
 229   {
 230     using type = T;
 231   };
 232   template <class T> struct identity_or_underlying_type<T, true>
 233   {
 234     using type = typename std::underlying_type<T>::type;
 235   };
 236
 237   template <class OfSize, class OfSign>
 238   using erasure_integer_type = typename std::conditional<std::is_signed<typename identity_or_underlying_type<OfSign>::type>::value, typename std::make_signed<typename identity_or_underlying_type<OfSize>::type>::type, typename std::make_unsigned<typename identity_or_underlying_type<OfSize>::type>::type>::type;
 239
 240   template <class ErasedType, std::size_t N> struct padded_erasure_object
 241   {
 242     static_assert(traits::is_move_relocating<ErasedType>::value, "ErasedType must be TriviallyCopyable or MoveRelocating");
 243     static_assert(alignof(ErasedType) <= sizeof(ErasedType), "ErasedType must not be over-aligned");
 244     ErasedType value;
 245     char padding[N];
 246     constexpr explicit padded_erasure_object(const ErasedType &v) noexcept
 247         : value(v)
 248         , padding{}
 249     {
 250     }
 251   };
 252
 253   template <class To, class From, typename std::enable_if<is_erasure_castable<To, From>::value && (sizeof(To) == sizeof(From)), bool>::type = true> constexpr To erasure_cast(const From &from) noexcept { return bit_cast<To>(from); }
 254
 255   template <class To, class From, typename std::enable_if<is_erasure_castable<To, From>::value && is_static_castable<To, From>::value && (sizeof(To) < sizeof(From)), bool>::type = true> constexpr To erasure_cast(const From &from) noexcept { return static_cast<To>(bit_cast<erasure_integer_type<From, To>>(from)); }
 256
 257   template <class To, class From, typename std::enable_if<is_erasure_castable<To, From>::value && is_static_castable<To, From>::value && (sizeof(To) > sizeof(From)), bool>::type = true> constexpr To erasure_cast(const From &from) noexcept { return bit_cast<To>(static_cast<erasure_integer_type<To, From>>(from)); }
 258
 259   template <class To, class From, typename std::enable_if<is_erasure_castable<To, From>::value && !is_static_castable<To, From>::value && (sizeof(To) < sizeof(From)), bool>::type = true> constexpr To erasure_cast(const From &from) noexcept
 260   {
 261     return bit_cast<padded_erasure_object<To, sizeof(From) - sizeof(To)>>(from).value;
 262   }
 263
 264   template <class To, class From, typename std::enable_if<is_erasure_castable<To, From>::value && !is_static_castable<To, From>::value && (sizeof(To) > sizeof(From)), bool>::type = true> constexpr To erasure_cast(const From &from) noexcept
 265   {
 266     return bit_cast<To>(padded_erasure_object<From, sizeof(To) - sizeof(From)>{from});
 267   }
 268 }  // namespace detail
 269 BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE_END
 270
 271 #ifndef BOOST_OUTCOME_SYSTEM_ERROR2_FATAL
 272 #include <cstdlib>  // for abort
 273 #ifdef __APPLE__
 274 #include <unistd.h>  // for write
 275 #endif
 276
 277 BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE_BEGIN
 278 namespace detail
 279 {
 280   namespace avoid_stdio_include
 281   {
 282 #ifndef __APPLE__
 283     extern "C" ptrdiff_t write(int, const void *, size_t);
 284 #endif
 285   }  // namespace avoid_stdio_include
 286   inline void do_fatal_exit(const char *msg)
 287   {
 288     using namespace avoid_stdio_include;
 289     write(2 /*stderr*/, msg, cstrlen(msg));
 290     write(2 /*stderr*/, "\n", 1);
 291     abort();
 292   }
 293 }  // namespace detail
 294 BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE_END
 295 //! Prints msg to stderr, and calls `std::terminate()`. Can be overriden via predefinition.
 296 #define BOOST_OUTCOME_SYSTEM_ERROR2_FATAL(msg) ::BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE::detail::do_fatal_exit(msg)
 297 #endif
 298
 299 #endif