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 // 95 // Note that when exceptions are disabled, the methods that normally throw 96 // these exceptions can be used even on older deployment targets, but those 97 // methods will abort instead of throwing. 98# define _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS 99# define _LIBCPP_AVAILABILITY_BAD_VARIANT_ACCESS 100# define _LIBCPP_AVAILABILITY_BAD_ANY_CAST 101 102 // This controls the availability of std::uncaught_exceptions(). 103# define _LIBCPP_AVAILABILITY_UNCAUGHT_EXCEPTIONS 104 105 // This controls the availability of the sized version of ::operator delete, 106 // ::operator delete[], and their align_val_t variants, which were all added 107 // in C++17, and hence not present in early dylibs. 108# define _LIBCPP_AVAILABILITY_SIZED_NEW_DELETE 109 110 // This controls the availability of the std::future_error exception. 111 // 112 // Note that when exceptions are disabled, the methods that normally throw 113 // std::future_error can be used even on older deployment targets, but those 114 // methods will abort instead of throwing. 115# define _LIBCPP_AVAILABILITY_FUTURE_ERROR 116 117 // This controls the availability of std::type_info's vtable. 118 // I can't imagine how using std::type_info can work at all if 119 // this isn't supported. 120# define _LIBCPP_AVAILABILITY_TYPEINFO_VTABLE 121 122 // This controls the availability of std::locale::category members 123 // (e.g. std::locale::collate), which are defined in the dylib. 124# define _LIBCPP_AVAILABILITY_LOCALE_CATEGORY 125 126 // This controls the availability of atomic operations on std::shared_ptr 127 // (e.g. `std::atomic_store(std::shared_ptr)`), which require a shared 128 // lock table located in the dylib. 129# define _LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR 130 131 // These macros control the availability of all parts of <filesystem> that 132 // depend on something in the dylib. 133# define _LIBCPP_AVAILABILITY_FILESYSTEM 134# define _LIBCPP_AVAILABILITY_FILESYSTEM_PUSH 135# define _LIBCPP_AVAILABILITY_FILESYSTEM_POP 136// # define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_filesystem 137 138 // This controls the availability of std::to_chars for integral arguments. 139# define _LIBCPP_AVAILABILITY_TO_CHARS 140 141 // This controls the availability of floating-point std::to_chars functions. 142 // These overloads were added later than the integer overloads. 143# define _LIBCPP_AVAILABILITY_TO_CHARS_FLOATING_POINT 144 145 // This controls the availability of the C++20 synchronization library, 146 // which requires shared library support for various operations 147 // (see libcxx/src/atomic.cpp). This includes <barier>, <latch>, 148 // <semaphore>, and notification functions on std::atomic. 149# define _LIBCPP_AVAILABILITY_SYNC 150// # define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_atomic_wait 151// # define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_barrier 152// # define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_latch 153// # define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_semaphore 154 155 // This controls the availability of the C++20 format library. 156 // The library is in development and not ABI stable yet. P2216 is 157 // retroactively accepted in C++20. This paper contains ABI breaking 158 // changes. 159# define _LIBCPP_AVAILABILITY_FORMAT 160// # define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_format 161 162 // This controls whether the std::__libcpp_assertion_handler default 163 // assertion handler is provided by the library. 164 // 165 // Note that when users provide their own custom assertion handler, 166 // it doesn't matter whether the dylib provides a default handler, 167 // and the availability markup can actually give a false positive 168 // diagnostic (it will think that no handler is provided, when in 169 // reality the user has provided their own). 170 // 171 // Users can pass -D_LIBCPP_AVAILABILITY_CUSTOM_ASSERTION_HANDLER_PROVIDED 172 // to the compiler to tell the library to ignore the fact that the 173 // default handler isn't available on their deployment target. Note that 174 // defining this macro but failing to define a custom assertion handler 175 // will lead to a load-time error on back-deployment targets, so it 176 // should be avoided. 177# define _LIBCPP_AVAILABILITY_DEFAULT_ASSERTION_HANDLER 178 179#elif defined(__APPLE__) 180 181# define _LIBCPP_AVAILABILITY_SHARED_MUTEX \ 182 __attribute__((availability(macos,strict,introduced=10.12))) \ 183 __attribute__((availability(ios,strict,introduced=10.0))) \ 184 __attribute__((availability(tvos,strict,introduced=10.0))) \ 185 __attribute__((availability(watchos,strict,introduced=3.0))) 186# if (defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 101200) || \ 187 (defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__ < 100000) || \ 188 (defined(__ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__ < 100000) || \ 189 (defined(__ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__ < 30000) 190# define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_shared_mutex 191# define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_shared_timed_mutex 192# endif 193 194 // Note: bad_optional_access & friends were not introduced in the matching 195 // macOS and iOS versions, so the version mismatch between macOS and others 196 // is intended. 197# define _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS \ 198 __attribute__((availability(macos,strict,introduced=10.13))) \ 199 __attribute__((availability(ios,strict,introduced=12.0))) \ 200 __attribute__((availability(tvos,strict,introduced=12.0))) \ 201 __attribute__((availability(watchos,strict,introduced=5.0))) 202# define _LIBCPP_AVAILABILITY_BAD_VARIANT_ACCESS \ 203 _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS 204# define _LIBCPP_AVAILABILITY_BAD_ANY_CAST \ 205 _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS 206 207# define _LIBCPP_AVAILABILITY_UNCAUGHT_EXCEPTIONS \ 208 __attribute__((availability(macos,strict,introduced=10.12))) \ 209 __attribute__((availability(ios,strict,introduced=10.0))) \ 210 __attribute__((availability(tvos,strict,introduced=10.0))) \ 211 __attribute__((availability(watchos,strict,introduced=3.0))) 212 213# define _LIBCPP_AVAILABILITY_SIZED_NEW_DELETE \ 214 __attribute__((availability(macos,strict,introduced=10.12))) \ 215 __attribute__((availability(ios,strict,introduced=10.0))) \ 216 __attribute__((availability(tvos,strict,introduced=10.0))) \ 217 __attribute__((availability(watchos,strict,introduced=3.0))) 218 219# define _LIBCPP_AVAILABILITY_FUTURE_ERROR \ 220 __attribute__((availability(ios,strict,introduced=6.0))) 221 222# define _LIBCPP_AVAILABILITY_TYPEINFO_VTABLE \ 223 __attribute__((availability(macos,strict,introduced=10.9))) \ 224 __attribute__((availability(ios,strict,introduced=7.0))) 225 226# define _LIBCPP_AVAILABILITY_LOCALE_CATEGORY \ 227 __attribute__((availability(macos,strict,introduced=10.9))) \ 228 __attribute__((availability(ios,strict,introduced=7.0))) 229 230# define _LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR \ 231 __attribute__((availability(macos,strict,introduced=10.9))) \ 232 __attribute__((availability(ios,strict,introduced=7.0))) 233 234# define _LIBCPP_AVAILABILITY_FILESYSTEM \ 235 __attribute__((availability(macos,strict,introduced=10.15))) \ 236 __attribute__((availability(ios,strict,introduced=13.0))) \ 237 __attribute__((availability(tvos,strict,introduced=13.0))) \ 238 __attribute__((availability(watchos,strict,introduced=6.0))) 239# define _LIBCPP_AVAILABILITY_FILESYSTEM_PUSH \ 240 _Pragma("clang attribute push(__attribute__((availability(macos,strict,introduced=10.15))), apply_to=any(function,record))") \ 241 _Pragma("clang attribute push(__attribute__((availability(ios,strict,introduced=13.0))), apply_to=any(function,record))") \ 242 _Pragma("clang attribute push(__attribute__((availability(tvos,strict,introduced=13.0))), apply_to=any(function,record))") \ 243 _Pragma("clang attribute push(__attribute__((availability(watchos,strict,introduced=6.0))), apply_to=any(function,record))") 244# define _LIBCPP_AVAILABILITY_FILESYSTEM_POP \ 245 _Pragma("clang attribute pop") \ 246 _Pragma("clang attribute pop") \ 247 _Pragma("clang attribute pop") \ 248 _Pragma("clang attribute pop") 249# if (defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 101500) || \ 250 (defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__ < 130000) || \ 251 (defined(__ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__ < 130000) || \ 252 (defined(__ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__ < 60000) 253# define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_filesystem 254# endif 255 256# define _LIBCPP_AVAILABILITY_TO_CHARS \ 257 _LIBCPP_AVAILABILITY_FILESYSTEM 258 259# define _LIBCPP_AVAILABILITY_TO_CHARS_FLOATING_POINT \ 260 __attribute__((unavailable)) 261 262# define _LIBCPP_AVAILABILITY_SYNC \ 263 __attribute__((availability(macos,strict,introduced=11.0))) \ 264 __attribute__((availability(ios,strict,introduced=14.0))) \ 265 __attribute__((availability(tvos,strict,introduced=14.0))) \ 266 __attribute__((availability(watchos,strict,introduced=7.0))) 267# if (defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 110000) || \ 268 (defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__ < 140000) || \ 269 (defined(__ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__ < 140000) || \ 270 (defined(__ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__ < 70000) 271# define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_atomic_wait 272# define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_barrier 273# define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_latch 274# define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_semaphore 275# endif 276 277# define _LIBCPP_AVAILABILITY_FORMAT \ 278 __attribute__((unavailable)) 279# define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_format 280 281# define _LIBCPP_AVAILABILITY_DEFAULT_ASSERTION_HANDLER \ 282 __attribute__((unavailable)) 283#else 284 285// ...New vendors can add availability markup here... 286 287# error "It looks like you're trying to enable vendor availability markup, but you haven't defined the corresponding macros yet!" 288 289#endif 290 291// Define availability attributes that depend on _LIBCPP_NO_EXCEPTIONS. 292// Those are defined in terms of the availability attributes above, and 293// should not be vendor-specific. 294#if defined(_LIBCPP_NO_EXCEPTIONS) 295# define _LIBCPP_AVAILABILITY_FUTURE 296# define _LIBCPP_AVAILABILITY_THROW_BAD_ANY_CAST 297# define _LIBCPP_AVAILABILITY_THROW_BAD_OPTIONAL_ACCESS 298# define _LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS 299#else 300# define _LIBCPP_AVAILABILITY_FUTURE _LIBCPP_AVAILABILITY_FUTURE_ERROR 301# define _LIBCPP_AVAILABILITY_THROW_BAD_ANY_CAST _LIBCPP_AVAILABILITY_BAD_ANY_CAST 302# define _LIBCPP_AVAILABILITY_THROW_BAD_OPTIONAL_ACCESS _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS 303# define _LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS _LIBCPP_AVAILABILITY_BAD_VARIANT_ACCESS 304#endif 305 306// Define the special assertion handler availability attribute, which can be silenced by 307// users if they provide their own custom assertion handler. The rest of the code should 308// not use the *_DEFAULT_* macro directly, since that would make it ignore the fact that 309// the user provided a custom handler. 310#if defined(_LIBCPP_AVAILABILITY_CUSTOM_ASSERTION_HANDLER_PROVIDED) 311# define _LIBCPP_AVAILABILITY_ASSERTION_HANDLER /* nothing */ 312#else 313# define _LIBCPP_AVAILABILITY_ASSERTION_HANDLER _LIBCPP_AVAILABILITY_DEFAULT_ASSERTION_HANDLER 314#endif 315 316#endif // _LIBCPP___AVAILABILITY 317