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 the C++20 synchronization library, 133 // which requires shared library support for various operations 134 // (see libcxx/src/atomic.cpp). 135# define _LIBCPP_AVAILABILITY_SYNC 136// # define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_atomic_wait 137// # define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_barrier 138// # define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_latch 139// # define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_semaphore 140 141 // This controls the availability of the C++20 format library. 142 // The library is in development and not ABI stable yet. Currently 143 // P2216 is aiming to be retroactively accepted in C++20. This paper 144 // contains ABI breaking changes. 145# define _LIBCPP_AVAILABILITY_FORMAT 146// # define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_format 147 148#elif defined(__APPLE__) 149 150# define _LIBCPP_AVAILABILITY_SHARED_MUTEX \ 151 __attribute__((availability(macosx,strict,introduced=10.12))) \ 152 __attribute__((availability(ios,strict,introduced=10.0))) \ 153 __attribute__((availability(tvos,strict,introduced=10.0))) \ 154 __attribute__((availability(watchos,strict,introduced=3.0))) 155# if (defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 101200) || \ 156 (defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__ < 100000) || \ 157 (defined(__ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__ < 100000) || \ 158 (defined(__ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__ < 30000) 159# define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_shared_mutex 160# define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_shared_timed_mutex 161# endif 162 163# define _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS \ 164 __attribute__((availability(macosx,strict,introduced=10.13))) \ 165 __attribute__((availability(ios,strict,introduced=11.0))) \ 166 __attribute__((availability(tvos,strict,introduced=11.0))) \ 167 __attribute__((availability(watchos,strict,introduced=4.0))) 168# define _LIBCPP_AVAILABILITY_BAD_VARIANT_ACCESS \ 169 _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS 170# define _LIBCPP_AVAILABILITY_BAD_ANY_CAST \ 171 _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS 172 173# define _LIBCPP_AVAILABILITY_UNCAUGHT_EXCEPTIONS \ 174 __attribute__((availability(macosx,strict,introduced=10.12))) \ 175 __attribute__((availability(ios,strict,introduced=10.0))) \ 176 __attribute__((availability(tvos,strict,introduced=10.0))) \ 177 __attribute__((availability(watchos,strict,introduced=3.0))) 178 179# define _LIBCPP_AVAILABILITY_SIZED_NEW_DELETE \ 180 __attribute__((availability(macosx,strict,introduced=10.12))) \ 181 __attribute__((availability(ios,strict,introduced=10.0))) \ 182 __attribute__((availability(tvos,strict,introduced=10.0))) \ 183 __attribute__((availability(watchos,strict,introduced=3.0))) 184 185# define _LIBCPP_AVAILABILITY_FUTURE_ERROR \ 186 __attribute__((availability(ios,strict,introduced=6.0))) 187 188# define _LIBCPP_AVAILABILITY_TYPEINFO_VTABLE \ 189 __attribute__((availability(macosx,strict,introduced=10.9))) \ 190 __attribute__((availability(ios,strict,introduced=7.0))) 191 192# define _LIBCPP_AVAILABILITY_LOCALE_CATEGORY \ 193 __attribute__((availability(macosx,strict,introduced=10.9))) \ 194 __attribute__((availability(ios,strict,introduced=7.0))) 195 196# define _LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR \ 197 __attribute__((availability(macosx,strict,introduced=10.9))) \ 198 __attribute__((availability(ios,strict,introduced=7.0))) 199 200# define _LIBCPP_AVAILABILITY_FILESYSTEM \ 201 __attribute__((availability(macosx,strict,introduced=10.15))) \ 202 __attribute__((availability(ios,strict,introduced=13.0))) \ 203 __attribute__((availability(tvos,strict,introduced=13.0))) \ 204 __attribute__((availability(watchos,strict,introduced=6.0))) 205# define _LIBCPP_AVAILABILITY_FILESYSTEM_PUSH \ 206 _Pragma("clang attribute push(__attribute__((availability(macosx,strict,introduced=10.15))), apply_to=any(function,record))") \ 207 _Pragma("clang attribute push(__attribute__((availability(ios,strict,introduced=13.0))), apply_to=any(function,record))") \ 208 _Pragma("clang attribute push(__attribute__((availability(tvos,strict,introduced=13.0))), apply_to=any(function,record))") \ 209 _Pragma("clang attribute push(__attribute__((availability(watchos,strict,introduced=6.0))), apply_to=any(function,record))") 210# define _LIBCPP_AVAILABILITY_FILESYSTEM_POP \ 211 _Pragma("clang attribute pop") \ 212 _Pragma("clang attribute pop") \ 213 _Pragma("clang attribute pop") \ 214 _Pragma("clang attribute pop") 215# if (defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 101500) || \ 216 (defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__ < 130000) || \ 217 (defined(__ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__ < 130000) || \ 218 (defined(__ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__ < 60000) 219# define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_filesystem 220# endif 221 222# define _LIBCPP_AVAILABILITY_TO_CHARS \ 223 _LIBCPP_AVAILABILITY_FILESYSTEM 224 225# define _LIBCPP_AVAILABILITY_SYNC \ 226 __attribute__((availability(macosx,strict,introduced=11.0))) \ 227 __attribute__((availability(ios,strict,introduced=14.0))) \ 228 __attribute__((availability(tvos,strict,introduced=14.0))) \ 229 __attribute__((availability(watchos,strict,introduced=7.0))) 230# if (defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 110000) || \ 231 (defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__ < 140000) || \ 232 (defined(__ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__ < 140000) || \ 233 (defined(__ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__ < 70000) 234# define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_atomic_wait 235# define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_barrier 236# define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_latch 237# define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_semaphore 238# endif 239 240 // This controls the availability of the C++20 format library. 241 // The library is in development and not ABI stable yet. Currently 242 // P2216 is aiming to be retroactively accepted in C++20. This paper 243 // contains ABI breaking changes. 244# define _LIBCPP_AVAILABILITY_FORMAT \ 245 __attribute__((unavailable)) 246# define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_format 247#else 248 249// ...New vendors can add availability markup here... 250 251# error "It looks like you're trying to enable vendor availability markup, but you haven't defined the corresponding macros yet!" 252 253#endif 254 255// Define availability attributes that depend on _LIBCPP_NO_EXCEPTIONS. 256// Those are defined in terms of the availability attributes above, and 257// should not be vendor-specific. 258#if defined(_LIBCPP_NO_EXCEPTIONS) 259# define _LIBCPP_AVAILABILITY_FUTURE 260# define _LIBCPP_AVAILABILITY_THROW_BAD_ANY_CAST 261# define _LIBCPP_AVAILABILITY_THROW_BAD_OPTIONAL_ACCESS 262# define _LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS 263#else 264# define _LIBCPP_AVAILABILITY_FUTURE _LIBCPP_AVAILABILITY_FUTURE_ERROR 265# define _LIBCPP_AVAILABILITY_THROW_BAD_ANY_CAST _LIBCPP_AVAILABILITY_BAD_ANY_CAST 266# define _LIBCPP_AVAILABILITY_THROW_BAD_OPTIONAL_ACCESS _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS 267# define _LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS _LIBCPP_AVAILABILITY_BAD_VARIANT_ACCESS 268#endif 269 270#endif // _LIBCPP___AVAILABILITY 271