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, two macros are added below to allow marking the feature 43// as unavailable: 44// 1. A macro named `_LIBCPP_AVAILABILITY_HAS_NO_<feature>` which must be defined 45// exactly when compiling for a target that doesn't support the feature. 46// 2. A macro named `_LIBCPP_AVAILABILITY_<feature>`, which must always be defined 47// and must expand to the proper availability attribute for the platform. 48// 49// When vendors decide to ship the feature as part of their shared library, they 50// can update these macros appropriately for their platform, and the library will 51// use those to provide an optimal user experience. 52// 53// Furthermore, many features in the standard library have corresponding 54// feature-test macros. The `_LIBCPP_AVAILABILITY_HAS_NO_<feature>` macros 55// are checked by the corresponding feature-test macros generated by 56// generate_feature_test_macro_components.py to ensure that the library 57// doesn't announce a feature as being implemented if it is unavailable on 58// the deployment target. 59// 60// Note that this mechanism is disabled by default in the "upstream" libc++. 61// Availability annotations are only meaningful when shipping libc++ inside 62// a platform (i.e. as a system library), and so vendors that want them should 63// turn those annotations on at CMake configuration time. 64// 65// [1]: https://clang.llvm.org/docs/AttributeReference.html#availability 66 67// For backwards compatibility, allow users to define _LIBCPP_DISABLE_AVAILABILITY 68// for a while. 69#if defined(_LIBCPP_DISABLE_AVAILABILITY) 70# if !defined(_LIBCPP_HAS_NO_VENDOR_AVAILABILITY_ANNOTATIONS) 71# define _LIBCPP_HAS_NO_VENDOR_AVAILABILITY_ANNOTATIONS 72# endif 73#endif 74 75// Availability markup is disabled when building the library, or when a non-Clang 76// compiler is used because only Clang supports the necessary attributes. 77// doesn't support the proper attributes. 78#if defined(_LIBCPP_BUILDING_LIBRARY) || defined(_LIBCXXABI_BUILDING_LIBRARY) || !defined(_LIBCPP_COMPILER_CLANG_BASED) 79# if !defined(_LIBCPP_HAS_NO_VENDOR_AVAILABILITY_ANNOTATIONS) 80# define _LIBCPP_HAS_NO_VENDOR_AVAILABILITY_ANNOTATIONS 81# endif 82#endif 83 84#if defined(_LIBCPP_HAS_NO_VENDOR_AVAILABILITY_ANNOTATIONS) 85 86// These macros control the availability of std::bad_optional_access and 87// other exception types. These were put in the shared library to prevent 88// code bloat from every user program defining the vtable for these exception 89// types. 90// 91// Note that when exceptions are disabled, the methods that normally throw 92// these exceptions can be used even on older deployment targets, but those 93// methods will abort instead of throwing. 94# define _LIBCPP_AVAILABILITY_HAS_BAD_OPTIONAL_ACCESS 1 95# define _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS 96 97# define _LIBCPP_AVAILABILITY_HAS_BAD_VARIANT_ACCESS 1 98# define _LIBCPP_AVAILABILITY_BAD_VARIANT_ACCESS 99 100# define _LIBCPP_AVAILABILITY_HAS_BAD_ANY_CAST 1 101# define _LIBCPP_AVAILABILITY_BAD_ANY_CAST 102 103// These macros controls the availability of __cxa_init_primary_exception 104// in the built library, which std::make_exception_ptr might use 105// (see libcxx/include/__exception/exception_ptr.h). 106# define _LIBCPP_AVAILABILITY_HAS_INIT_PRIMARY_EXCEPTION 1 107# define _LIBCPP_AVAILABILITY_INIT_PRIMARY_EXCEPTION 108 109// These macros control the availability of all parts of <filesystem> that 110// depend on something in the dylib. 111# define _LIBCPP_AVAILABILITY_HAS_FILESYSTEM_LIBRARY 1 112# define _LIBCPP_AVAILABILITY_FILESYSTEM_LIBRARY 113# define _LIBCPP_AVAILABILITY_FILESYSTEM_LIBRARY_PUSH 114# define _LIBCPP_AVAILABILITY_FILESYSTEM_LIBRARY_POP 115 116// This controls the availability of floating-point std::to_chars functions. 117// These overloads were added later than the integer overloads. 118# define _LIBCPP_AVAILABILITY_HAS_TO_CHARS_FLOATING_POINT 1 119# define _LIBCPP_AVAILABILITY_TO_CHARS_FLOATING_POINT 120 121// This controls the availability of the C++20 synchronization library, 122// which requires shared library support for various operations 123// (see libcxx/src/atomic.cpp). This includes <barier>, <latch>, 124// <semaphore>, and notification functions on std::atomic. 125# define _LIBCPP_AVAILABILITY_HAS_SYNC 1 126# define _LIBCPP_AVAILABILITY_SYNC 127 128// This controls whether the library claims to provide a default verbose 129// termination function, and consequently whether the headers will try 130// to use it when the mechanism isn't overriden at compile-time. 131# define _LIBCPP_AVAILABILITY_HAS_VERBOSE_ABORT 1 132# define _LIBCPP_AVAILABILITY_VERBOSE_ABORT 133 134// This controls the availability of the C++17 std::pmr library, 135// which is implemented in large part in the built library. 136# define _LIBCPP_AVAILABILITY_HAS_PMR 1 137# define _LIBCPP_AVAILABILITY_PMR 138 139// This controls the availability of the C++20 time zone database. 140// The parser code is built in the library. 141# define _LIBCPP_AVAILABILITY_HAS_TZDB 1 142# define _LIBCPP_AVAILABILITY_TZDB 143 144// This controls the availability of C++23 <print>, which 145// has a dependency on the built library (it needs access to 146// the underlying buffer types of std::cout, std::cerr, and std::clog. 147# define _LIBCPP_AVAILABILITY_HAS_PRINT 1 148# define _LIBCPP_AVAILABILITY_PRINT 149 150// Enable additional explicit instantiations of iostreams components. This 151// reduces the number of weak definitions generated in programs that use 152// iostreams by providing a single strong definition in the shared library. 153// 154// TODO: Enable additional explicit instantiations on GCC once it supports exclude_from_explicit_instantiation, 155// or once libc++ doesn't use the attribute anymore. 156// TODO: Enable them on Windows once https://llvm.org/PR41018 has been fixed. 157# if !defined(_LIBCPP_COMPILER_GCC) && !defined(_WIN32) 158# define _LIBCPP_AVAILABILITY_HAS_ADDITIONAL_IOSTREAM_EXPLICIT_INSTANTIATIONS_1 1 159# else 160# define _LIBCPP_AVAILABILITY_HAS_ADDITIONAL_IOSTREAM_EXPLICIT_INSTANTIATIONS_1 0 161# endif 162 163#elif defined(__APPLE__) 164 165# define _LIBCPP_AVAILABILITY_HAS_BAD_OPTIONAL_ACCESS \ 166 (!defined(__ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__) || __ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__ >= 50000) 167 168# define _LIBCPP_AVAILABILITY_HAS_BAD_VARIANT_ACCESS _LIBCPP_AVAILABILITY_HAS_BAD_OPTIONAL_ACCESS 169# define _LIBCPP_AVAILABILITY_HAS_BAD_ANY_CAST _LIBCPP_AVAILABILITY_HAS_BAD_OPTIONAL_ACCESS 170 171# define _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS __attribute__((availability(watchos, strict, introduced = 5.0))) 172# define _LIBCPP_AVAILABILITY_BAD_VARIANT_ACCESS _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS 173# define _LIBCPP_AVAILABILITY_BAD_ANY_CAST _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS 174 175// TODO: Update once this is released 176# define _LIBCPP_AVAILABILITY_HAS_INIT_PRIMARY_EXCEPTION 0 177# define _LIBCPP_AVAILABILITY_INIT_PRIMARY_EXCEPTION __attribute__((unavailable)) 178 179// <filesystem> 180// clang-format off 181# if (defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 101500) || \ 182 (defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__ < 130000) || \ 183 (defined(__ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__ < 130000) || \ 184 (defined(__ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__ < 60000) 185// clang-format on 186# define _LIBCPP_AVAILABILITY_HAS_FILESYSTEM_LIBRARY 0 187# else 188# define _LIBCPP_AVAILABILITY_HAS_FILESYSTEM_LIBRARY 1 189# endif 190# define _LIBCPP_AVAILABILITY_FILESYSTEM_LIBRARY \ 191 __attribute__((availability(macos, strict, introduced = 10.15))) \ 192 __attribute__((availability(ios, strict, introduced = 13.0))) \ 193 __attribute__((availability(tvos, strict, introduced = 13.0))) \ 194 __attribute__((availability(watchos, strict, introduced = 6.0))) 195// clang-format off 196# define _LIBCPP_AVAILABILITY_FILESYSTEM_LIBRARY_PUSH \ 197 _Pragma("clang attribute push(__attribute__((availability(macos,strict,introduced=10.15))), apply_to=any(function,record))") \ 198 _Pragma("clang attribute push(__attribute__((availability(ios,strict,introduced=13.0))), apply_to=any(function,record))") \ 199 _Pragma("clang attribute push(__attribute__((availability(tvos,strict,introduced=13.0))), apply_to=any(function,record))") \ 200 _Pragma("clang attribute push(__attribute__((availability(watchos,strict,introduced=6.0))), apply_to=any(function,record))") 201# define _LIBCPP_AVAILABILITY_FILESYSTEM_LIBRARY_POP \ 202 _Pragma("clang attribute pop") \ 203 _Pragma("clang attribute pop") \ 204 _Pragma("clang attribute pop") \ 205 _Pragma("clang attribute pop") 206// clang-format on 207 208// std::to_chars(floating-point) 209// clang-format off 210# if (defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 130300) || \ 211 (defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__ < 160300) || \ 212 (defined(__ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__ < 160300) || \ 213 (defined(__ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__ < 90300) 214// clang-format on 215# define _LIBCPP_AVAILABILITY_HAS_TO_CHARS_FLOATING_POINT 0 216# else 217# define _LIBCPP_AVAILABILITY_HAS_TO_CHARS_FLOATING_POINT 1 218# endif 219# define _LIBCPP_AVAILABILITY_TO_CHARS_FLOATING_POINT \ 220 __attribute__((availability(macos, strict, introduced = 13.3))) \ 221 __attribute__((availability(ios, strict, introduced = 16.3))) \ 222 __attribute__((availability(tvos, strict, introduced = 16.3))) \ 223 __attribute__((availability(watchos, strict, introduced = 9.3))) 224 225// c++20 synchronization library 226// clang-format off 227# if (defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 110000) || \ 228 (defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__ < 140000) || \ 229 (defined(__ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__ < 140000) || \ 230 (defined(__ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__ < 70000) 231// clang-format on 232# define _LIBCPP_AVAILABILITY_HAS_SYNC 0 233# else 234# define _LIBCPP_AVAILABILITY_HAS_SYNC 1 235# endif 236# define _LIBCPP_AVAILABILITY_SYNC \ 237 __attribute__((availability(macos, strict, introduced = 11.0))) \ 238 __attribute__((availability(ios, strict, introduced = 14.0))) \ 239 __attribute__((availability(tvos, strict, introduced = 14.0))) \ 240 __attribute__((availability(watchos, strict, introduced = 7.0))) 241 242// __libcpp_verbose_abort 243// TODO: Update once this is released 244# define _LIBCPP_AVAILABILITY_HAS_VERBOSE_ABORT 0 245 246# define _LIBCPP_AVAILABILITY_VERBOSE_ABORT __attribute__((unavailable)) 247 248// std::pmr 249// clang-format off 250# if (defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 140000) || \ 251 (defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__ < 170000) || \ 252 (defined(__ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__ < 170000) || \ 253 (defined(__ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__ < 100000) 254// clang-format on 255# define _LIBCPP_AVAILABILITY_HAS_PMR 0 256# else 257# define _LIBCPP_AVAILABILITY_HAS_PMR 1 258# endif 259// TODO: Enable std::pmr markup once https://github.com/llvm/llvm-project/issues/40340 has been fixed 260// Until then, it is possible for folks to try to use `std::pmr` when back-deploying to targets that don't support 261// it and it'll be a load-time error, but we don't have a good alternative because the library won't compile if we 262// use availability annotations until that bug has been fixed. 263# if 0 264# define _LIBCPP_AVAILABILITY_PMR \ 265 __attribute__((availability(macos, strict, introduced = 14.0))) \ 266 __attribute__((availability(ios, strict, introduced = 17.0))) \ 267 __attribute__((availability(tvos, strict, introduced = 17.0))) \ 268 __attribute__((availability(watchos, strict, introduced = 10.0))) 269# else 270# define _LIBCPP_AVAILABILITY_PMR 271# endif 272 273# define _LIBCPP_AVAILABILITY_HAS_TZDB 0 274# define _LIBCPP_AVAILABILITY_TZDB __attribute__((unavailable)) 275 276// Warning: This availability macro works differently than the other macros. 277// The dylib part of print is not needed on Apple platforms. Therefore when 278// the macro is not available the code calling the dylib is commented out. 279// The macro _LIBCPP_AVAILABILITY_PRINT is not used. 280# define _LIBCPP_AVAILABILITY_HAS_PRINT 0 281# define _LIBCPP_AVAILABILITY_PRINT __attribute__((unavailable)) 282 283// clang-format off 284# if (defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 120000) || \ 285 (defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__ < 150000) || \ 286 (defined(__ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__ < 150000) || \ 287 (defined(__ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__ < 80000) 288// clang-format on 289# define _LIBCPP_AVAILABILITY_HAS_ADDITIONAL_IOSTREAM_EXPLICIT_INSTANTIATIONS_1 0 290# else 291# define _LIBCPP_AVAILABILITY_HAS_ADDITIONAL_IOSTREAM_EXPLICIT_INSTANTIATIONS_1 1 292# endif 293#else 294 295// ...New vendors can add availability markup here... 296 297# error \ 298 "It looks like you're trying to enable vendor availability markup, but you haven't defined the corresponding macros yet!" 299 300#endif 301 302// Define availability attributes that depend on _LIBCPP_HAS_NO_EXCEPTIONS. 303// Those are defined in terms of the availability attributes above, and 304// should not be vendor-specific. 305#if defined(_LIBCPP_HAS_NO_EXCEPTIONS) 306# define _LIBCPP_AVAILABILITY_THROW_BAD_ANY_CAST 307# define _LIBCPP_AVAILABILITY_THROW_BAD_OPTIONAL_ACCESS 308# define _LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS 309#else 310# define _LIBCPP_AVAILABILITY_THROW_BAD_ANY_CAST _LIBCPP_AVAILABILITY_BAD_ANY_CAST 311# define _LIBCPP_AVAILABILITY_THROW_BAD_OPTIONAL_ACCESS _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS 312# define _LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS _LIBCPP_AVAILABILITY_BAD_VARIANT_ACCESS 313#endif 314 315// Define availability attributes that depend on both 316// _LIBCPP_HAS_NO_EXCEPTIONS and _LIBCPP_HAS_NO_RTTI. 317#if defined(_LIBCPP_HAS_NO_EXCEPTIONS) || defined(_LIBCPP_HAS_NO_RTTI) 318# undef _LIBCPP_AVAILABILITY_HAS_INIT_PRIMARY_EXCEPTION 319# undef _LIBCPP_AVAILABILITY_INIT_PRIMARY_EXCEPTION 320# define _LIBCPP_AVAILABILITY_HAS_INIT_PRIMARY_EXCEPTION 0 321# define _LIBCPP_AVAILABILITY_INIT_PRIMARY_EXCEPTION 322#endif 323 324#endif // _LIBCPP___AVAILABILITY 325