libcxx/include/__availability

   1 // -*- C++ -*-
   2 //===----------------------------------------------------------------------===//
   3 //
   4 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   5 // See https://llvm.org/LICENSE.txt for license information.
   6 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   7 //
   8 //===----------------------------------------------------------------------===//
   9
  10 #ifndef _LIBCPP___AVAILABILITY
  11 #define _LIBCPP___AVAILABILITY
  12
  13 #include <__config>
  14
  15 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  16 #   pragma GCC system_header
  17 #endif
  18
  19 // Libc++ is shipped by various vendors. In particular, it is used as a system
  20 // library on macOS, iOS and other Apple platforms. In order for users to be
  21 // able to compile a binary that is intended to be deployed to an older version
  22 // of a platform, Clang provides availability attributes [1]. These attributes
  23 // can be placed on declarations and are used to describe the life cycle of a
  24 // symbol in the library.
  25 //
  26 // The main goal is to ensure a compile-time error if a symbol that hasn't been
  27 // introduced in a previously released library is used in a program that targets
  28 // that previously released library. Normally, this would be a load-time error
  29 // when one tries to launch the program against the older library.
  30 //
  31 // For example, the filesystem library was introduced in the dylib in macOS 10.15.
  32 // If a user compiles on a macOS 10.15 host but targets macOS 10.13 with their
  33 // program, the compiler would normally not complain (because the required
  34 // declarations are in the headers), but the dynamic loader would fail to find
  35 // the symbols when actually trying to launch the program on macOS 10.13. To
  36 // turn this into a compile-time issue instead, declarations are annotated with
  37 // when they were introduced, and the compiler can produce a diagnostic if the
  38 // program references something that isn't available on the deployment target.
  39 //
  40 // This mechanism is general in nature, and any vendor can add their markup to
  41 // the library (see below). Whenever a new feature is added that requires support
  42 // in the shared library, a macro should be added below to mark this feature
  43 // as unavailable. When vendors decide to ship the feature as part of their
  44 // shared library, they can update the markup appropriately.
  45 //
  46 // Furthermore, many features in the standard library have corresponding
  47 // feature-test macros. When a feature is made unavailable on some deployment
  48 // target, a macro should be defined to signal that it is unavailable. That
  49 // macro can then be picked up when feature-test macros are generated (see
  50 // generate_feature_test_macro_components.py) to make sure that feature-test
  51 // macros don't announce a feature as being implemented if it has been marked
  52 // as unavailable.
  53 //
  54 // Note that this mechanism is disabled by default in the "upstream" libc++.
  55 // Availability annotations are only meaningful when shipping libc++ inside
  56 // a platform (i.e. as a system library), and so vendors that want them should
  57 // turn those annotations on at CMake configuration time.
  58 //
  59 // [1]: https://clang.llvm.org/docs/AttributeReference.html#availability
  60
  61
  62 // For backwards compatibility, allow users to define _LIBCPP_DISABLE_AVAILABILITY
  63 // for a while.
  64 #if defined(_LIBCPP_DISABLE_AVAILABILITY)
  65 #   if !defined(_LIBCPP_HAS_NO_VENDOR_AVAILABILITY_ANNOTATIONS)
  66 #       define _LIBCPP_HAS_NO_VENDOR_AVAILABILITY_ANNOTATIONS
  67 #   endif
  68 #endif
  69
  70 // Availability markup is disabled when building the library, or when the compiler
  71 // doesn't support the proper attributes.
  72 #if defined(_LIBCPP_BUILDING_LIBRARY) ||                                        \
  73     defined(_LIBCXXABI_BUILDING_LIBRARY) ||                                     \
  74     !__has_feature(attribute_availability_with_strict) ||                       \
  75     !__has_feature(attribute_availability_in_templates) ||                      \
  76     !__has_extension(pragma_clang_attribute_external_declaration)
  77 #   if !defined(_LIBCPP_HAS_NO_VENDOR_AVAILABILITY_ANNOTATIONS)
  78 #       define _LIBCPP_HAS_NO_VENDOR_AVAILABILITY_ANNOTATIONS
  79 #   endif
  80 #endif
  81
  82 #if defined(_LIBCPP_HAS_NO_VENDOR_AVAILABILITY_ANNOTATIONS)
  83
  84     // This controls the availability of std::shared_mutex and std::shared_timed_mutex,
  85     // which were added to the dylib later.
  86 #   define _LIBCPP_AVAILABILITY_SHARED_MUTEX
  87 // #   define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_shared_mutex
  88 // #   define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_shared_timed_mutex
  89
  90     // These macros control the availability of std::bad_optional_access and
  91     // other exception types. These were put in the shared library to prevent
  92     // code bloat from every user program defining the vtable for these exception
  93     // types.
  94 #   define _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS
  95 #   define _LIBCPP_AVAILABILITY_BAD_VARIANT_ACCESS
  96 #   define _LIBCPP_AVAILABILITY_BAD_ANY_CAST
  97
  98     // This controls the availability of std::uncaught_exceptions().
  99 #   define _LIBCPP_AVAILABILITY_UNCAUGHT_EXCEPTIONS
 100
 101     // This controls the availability of the sized version of ::operator delete,
 102     // which was added to the dylib later.
 103 #   define _LIBCPP_AVAILABILITY_SIZED_NEW_DELETE
 104
 105     // This controls the availability of the std::future_error exception.
 106 #   define _LIBCPP_AVAILABILITY_FUTURE_ERROR
 107
 108     // This controls the availability of std::type_info's vtable.
 109     // I can't imagine how using std::type_info can work at all if
 110     // this isn't supported.
 111 #   define _LIBCPP_AVAILABILITY_TYPEINFO_VTABLE
 112
 113     // This controls the availability of std::locale::category members
 114     // (e.g. std::locale::collate), which are defined in the dylib.
 115 #   define _LIBCPP_AVAILABILITY_LOCALE_CATEGORY
 116
 117     // This controls the availability of atomic operations on std::shared_ptr
 118     // (e.g. `std::atomic_store(std::shared_ptr)`), which require a shared
 119     // lock table located in the dylib.
 120 #   define _LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR
 121
 122     // These macros control the availability of all parts of <filesystem> that
 123     // depend on something in the dylib.
 124 #   define _LIBCPP_AVAILABILITY_FILESYSTEM
 125 #   define _LIBCPP_AVAILABILITY_FILESYSTEM_PUSH
 126 #   define _LIBCPP_AVAILABILITY_FILESYSTEM_POP
 127 // #   define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_filesystem
 128
 129     // This controls the availability of std::to_chars.
 130 #   define _LIBCPP_AVAILABILITY_TO_CHARS
 131
 132     // This controls the availability of floating-point std::to_chars functions.
 133     // These overloads were added later than the integer overloads.
 134 #   define _LIBCPP_AVAILABILITY_TO_CHARS_FLOATING_POINT
 135
 136     // This controls the availability of the C++20 synchronization library,
 137     // which requires shared library support for various operations
 138     // (see libcxx/src/atomic.cpp).
 139 #   define _LIBCPP_AVAILABILITY_SYNC
 140 // #   define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_atomic_wait
 141 // #   define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_barrier
 142 // #   define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_latch
 143 // #   define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_semaphore
 144
 145     // This controls the availability of the C++20 format library.
 146     // The library is in development and not ABI stable yet. P2216 is
 147     // retroactively accepted in C++20. This paper contains ABI breaking
 148     // changes.
 149 #   define _LIBCPP_AVAILABILITY_FORMAT
 150 // #   define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_format
 151
 152 #elif defined(__APPLE__)
 153
 154 #   define _LIBCPP_AVAILABILITY_SHARED_MUTEX                                    \
 155         __attribute__((availability(macosx,strict,introduced=10.12)))           \
 156         __attribute__((availability(ios,strict,introduced=10.0)))               \
 157         __attribute__((availability(tvos,strict,introduced=10.0)))              \
 158         __attribute__((availability(watchos,strict,introduced=3.0)))
 159 #   if (defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 101200) ||    \
 160         (defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__ < 100000) || \
 161         (defined(__ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__ < 100000) ||         \
 162         (defined(__ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__ < 30000)
 163 #       define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_shared_mutex
 164 #       define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_shared_timed_mutex
 165 #   endif
 166
 167 #   define _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS                             \
 168         __attribute__((availability(macosx,strict,introduced=10.13)))           \
 169         __attribute__((availability(ios,strict,introduced=11.0)))               \
 170         __attribute__((availability(tvos,strict,introduced=11.0)))              \
 171         __attribute__((availability(watchos,strict,introduced=4.0)))
 172 #   define _LIBCPP_AVAILABILITY_BAD_VARIANT_ACCESS                              \
 173         _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS
 174 #   define _LIBCPP_AVAILABILITY_BAD_ANY_CAST                                    \
 175         _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS
 176
 177 #   define _LIBCPP_AVAILABILITY_UNCAUGHT_EXCEPTIONS                             \
 178         __attribute__((availability(macosx,strict,introduced=10.12)))           \
 179         __attribute__((availability(ios,strict,introduced=10.0)))               \
 180         __attribute__((availability(tvos,strict,introduced=10.0)))              \
 181         __attribute__((availability(watchos,strict,introduced=3.0)))
 182
 183 #   define _LIBCPP_AVAILABILITY_SIZED_NEW_DELETE                                \
 184         __attribute__((availability(macosx,strict,introduced=10.12)))           \
 185         __attribute__((availability(ios,strict,introduced=10.0)))               \
 186         __attribute__((availability(tvos,strict,introduced=10.0)))              \
 187         __attribute__((availability(watchos,strict,introduced=3.0)))
 188
 189 #   define _LIBCPP_AVAILABILITY_FUTURE_ERROR                                    \
 190         __attribute__((availability(ios,strict,introduced=6.0)))
 191
 192 #   define _LIBCPP_AVAILABILITY_TYPEINFO_VTABLE                                 \
 193         __attribute__((availability(macosx,strict,introduced=10.9)))            \
 194         __attribute__((availability(ios,strict,introduced=7.0)))
 195
 196 #   define _LIBCPP_AVAILABILITY_LOCALE_CATEGORY                                 \
 197         __attribute__((availability(macosx,strict,introduced=10.9)))            \
 198         __attribute__((availability(ios,strict,introduced=7.0)))
 199
 200 #   define _LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR                               \
 201         __attribute__((availability(macosx,strict,introduced=10.9)))            \
 202         __attribute__((availability(ios,strict,introduced=7.0)))
 203
 204 #   define _LIBCPP_AVAILABILITY_FILESYSTEM                                      \
 205         __attribute__((availability(macosx,strict,introduced=10.15)))           \
 206         __attribute__((availability(ios,strict,introduced=13.0)))               \
 207         __attribute__((availability(tvos,strict,introduced=13.0)))              \
 208         __attribute__((availability(watchos,strict,introduced=6.0)))
 209 #   define _LIBCPP_AVAILABILITY_FILESYSTEM_PUSH                                 \
 210         _Pragma("clang attribute push(__attribute__((availability(macosx,strict,introduced=10.15))), apply_to=any(function,record))") \
 211         _Pragma("clang attribute push(__attribute__((availability(ios,strict,introduced=13.0))), apply_to=any(function,record))")     \
 212         _Pragma("clang attribute push(__attribute__((availability(tvos,strict,introduced=13.0))), apply_to=any(function,record))")    \
 213         _Pragma("clang attribute push(__attribute__((availability(watchos,strict,introduced=6.0))), apply_to=any(function,record))")
 214 #   define _LIBCPP_AVAILABILITY_FILESYSTEM_POP                                  \
 215         _Pragma("clang attribute pop")                                          \
 216         _Pragma("clang attribute pop")                                          \
 217         _Pragma("clang attribute pop")                                          \
 218         _Pragma("clang attribute pop")
 219 #   if (defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 101500) ||    \
 220         (defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__ < 130000) || \
 221         (defined(__ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__ < 130000) ||         \
 222         (defined(__ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__ < 60000)
 223 #       define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_filesystem
 224 #   endif
 225
 226 #   define _LIBCPP_AVAILABILITY_TO_CHARS                                        \
 227         _LIBCPP_AVAILABILITY_FILESYSTEM
 228
 229 #   define _LIBCPP_AVAILABILITY_TO_CHARS_FLOATING_POINT                         \
 230         __attribute__((unavailable))
 231
 232 #   define _LIBCPP_AVAILABILITY_SYNC                                            \
 233         __attribute__((availability(macosx,strict,introduced=11.0)))            \
 234         __attribute__((availability(ios,strict,introduced=14.0)))               \
 235         __attribute__((availability(tvos,strict,introduced=14.0)))              \
 236         __attribute__((availability(watchos,strict,introduced=7.0)))
 237 #   if (defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 110000) ||    \
 238         (defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__ < 140000) || \
 239         (defined(__ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__ < 140000) ||         \
 240         (defined(__ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__ < 70000)
 241 #       define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_atomic_wait
 242 #       define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_barrier
 243 #       define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_latch
 244 #       define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_semaphore
 245 #   endif
 246
 247     // This controls the availability of the C++20 format library.
 248     // The library is in development and not ABI stable yet. P2216 is
 249     // retroactively accepted in C++20. This paper contains ABI breaking
 250     // changes.
 251 #   define _LIBCPP_AVAILABILITY_FORMAT                                          \
 252         __attribute__((unavailable))
 253 #   define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_format
 254 #else
 255
 256 // ...New vendors can add availability markup here...
 257
 258 #   error "It looks like you're trying to enable vendor availability markup, but you haven't defined the corresponding macros yet!"
 259
 260 #endif
 261
 262 // Define availability attributes that depend on _LIBCPP_NO_EXCEPTIONS.
 263 // Those are defined in terms of the availability attributes above, and
 264 // should not be vendor-specific.
 265 #if defined(_LIBCPP_NO_EXCEPTIONS)
 266 #   define _LIBCPP_AVAILABILITY_FUTURE
 267 #   define _LIBCPP_AVAILABILITY_THROW_BAD_ANY_CAST
 268 #   define _LIBCPP_AVAILABILITY_THROW_BAD_OPTIONAL_ACCESS
 269 #   define _LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS
 270 #else
 271 #   define _LIBCPP_AVAILABILITY_FUTURE                    _LIBCPP_AVAILABILITY_FUTURE_ERROR
 272 #   define _LIBCPP_AVAILABILITY_THROW_BAD_ANY_CAST        _LIBCPP_AVAILABILITY_BAD_ANY_CAST
 273 #   define _LIBCPP_AVAILABILITY_THROW_BAD_OPTIONAL_ACCESS _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS
 274 #   define _LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS  _LIBCPP_AVAILABILITY_BAD_VARIANT_ACCESS
 275 #endif
 276
 277 #endif // _LIBCPP___AVAILABILITY