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 68// For backwards compatibility, allow users to define _LIBCPP_DISABLE_AVAILABILITY 69// for a while. 70#if defined(_LIBCPP_DISABLE_AVAILABILITY) 71# if !defined(_LIBCPP_HAS_NO_VENDOR_AVAILABILITY_ANNOTATIONS) 72# define _LIBCPP_HAS_NO_VENDOR_AVAILABILITY_ANNOTATIONS 73# endif 74#endif 75 76// Availability markup is disabled when building the library, or when the compiler 77// doesn't support the proper attributes. 78#if defined(_LIBCPP_BUILDING_LIBRARY) || \ 79 defined(_LIBCXXABI_BUILDING_LIBRARY) || \ 80 !__has_feature(attribute_availability_with_strict) || \ 81 !__has_feature(attribute_availability_in_templates) || \ 82 !__has_extension(pragma_clang_attribute_external_declaration) 83# if !defined(_LIBCPP_HAS_NO_VENDOR_AVAILABILITY_ANNOTATIONS) 84# define _LIBCPP_HAS_NO_VENDOR_AVAILABILITY_ANNOTATIONS 85# endif 86#endif 87 88#if defined(_LIBCPP_HAS_NO_VENDOR_AVAILABILITY_ANNOTATIONS) 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_HAS_BAD_OPTIONAL_ACCESS 1 99# define _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS 100 101# define _LIBCPP_AVAILABILITY_HAS_BAD_VARIANT_ACCESS 1 102# define _LIBCPP_AVAILABILITY_BAD_VARIANT_ACCESS 103 104# define _LIBCPP_AVAILABILITY_HAS_BAD_ANY_CAST 1 105# define _LIBCPP_AVAILABILITY_BAD_ANY_CAST 106 107// These macros control the availability of all parts of <filesystem> that 108// depend on something in the dylib. 109# define _LIBCPP_AVAILABILITY_HAS_FILESYSTEM_LIBRARY 1 110# define _LIBCPP_AVAILABILITY_FILESYSTEM_LIBRARY 111# define _LIBCPP_AVAILABILITY_FILESYSTEM_LIBRARY_PUSH 112# define _LIBCPP_AVAILABILITY_FILESYSTEM_LIBRARY_POP 113 114// This controls the availability of floating-point std::to_chars functions. 115// These overloads were added later than the integer overloads. 116# define _LIBCPP_AVAILABILITY_HAS_TO_CHARS_FLOATING_POINT 1 117# define _LIBCPP_AVAILABILITY_TO_CHARS_FLOATING_POINT 118 119// This controls the availability of the C++20 synchronization library, 120// which requires shared library support for various operations 121// (see libcxx/src/atomic.cpp). This includes <barier>, <latch>, 122// <semaphore>, and notification functions on std::atomic. 123# define _LIBCPP_AVAILABILITY_HAS_SYNC 1 124# define _LIBCPP_AVAILABILITY_SYNC 125 126// This controls whether the library claims to provide a default verbose 127// termination function, and consequently whether the headers will try 128// to use it when the mechanism isn't overriden at compile-time. 129# define _LIBCPP_AVAILABILITY_HAS_VERBOSE_ABORT 1 130# define _LIBCPP_AVAILABILITY_VERBOSE_ABORT 131 132// This controls the availability of the C++17 std::pmr library, 133// which is implemented in large part in the built library. 134# define _LIBCPP_AVAILABILITY_HAS_PMR 1 135# define _LIBCPP_AVAILABILITY_PMR 136 137// This controls the availability of the C++20 time zone database. 138// The parser code is built in the library. 139# define _LIBCPP_AVAILABILITY_HAS_TZDB 1 140# define _LIBCPP_AVAILABILITY_TZDB 141 142// Enable additional explicit instantiations of iostreams components. This 143// reduces the number of weak definitions generated in programs that use 144// iostreams by providing a single strong definition in the shared library. 145// 146// TODO: Enable additional explicit instantiations on GCC once it supports exclude_from_explicit_instantiation, 147// or once libc++ doesn't use the attribute anymore. 148// TODO: Enable them on Windows once https://llvm.org/PR41018 has been fixed. 149# if !defined(_LIBCPP_COMPILER_GCC) && !defined(_WIN32) 150# define _LIBCPP_AVAILABILITY_HAS_ADDITIONAL_IOSTREAM_EXPLICIT_INSTANTIATIONS_1 1 151# else 152# define _LIBCPP_AVAILABILITY_HAS_ADDITIONAL_IOSTREAM_EXPLICIT_INSTANTIATIONS_1 0 153# endif 154 155#elif defined(__APPLE__) 156 157# define _LIBCPP_AVAILABILITY_HAS_BAD_OPTIONAL_ACCESS \ 158 (!defined(__ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__) || __ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__ >= 50000) 159 160# define _LIBCPP_AVAILABILITY_HAS_BAD_VARIANT_ACCESS _LIBCPP_AVAILABILITY_HAS_BAD_OPTIONAL_ACCESS 161# define _LIBCPP_AVAILABILITY_HAS_BAD_ANY_CAST _LIBCPP_AVAILABILITY_HAS_BAD_OPTIONAL_ACCESS 162 163# define _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS __attribute__((availability(watchos,strict,introduced=5.0))) 164# define _LIBCPP_AVAILABILITY_BAD_VARIANT_ACCESS _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS 165# define _LIBCPP_AVAILABILITY_BAD_ANY_CAST _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS 166 167// <filesystem> 168# if (defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 101500) || \ 169 (defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__ < 130000) || \ 170 (defined(__ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__ < 130000) || \ 171 (defined(__ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__ < 60000) 172# define _LIBCPP_AVAILABILITY_HAS_FILESYSTEM_LIBRARY 0 173# else 174# define _LIBCPP_AVAILABILITY_HAS_FILESYSTEM_LIBRARY 1 175# endif 176# define _LIBCPP_AVAILABILITY_FILESYSTEM_LIBRARY \ 177 __attribute__((availability(macos,strict,introduced=10.15))) \ 178 __attribute__((availability(ios,strict,introduced=13.0))) \ 179 __attribute__((availability(tvos,strict,introduced=13.0))) \ 180 __attribute__((availability(watchos,strict,introduced=6.0))) 181# define _LIBCPP_AVAILABILITY_FILESYSTEM_LIBRARY_PUSH \ 182 _Pragma("clang attribute push(__attribute__((availability(macos,strict,introduced=10.15))), apply_to=any(function,record))") \ 183 _Pragma("clang attribute push(__attribute__((availability(ios,strict,introduced=13.0))), apply_to=any(function,record))") \ 184 _Pragma("clang attribute push(__attribute__((availability(tvos,strict,introduced=13.0))), apply_to=any(function,record))") \ 185 _Pragma("clang attribute push(__attribute__((availability(watchos,strict,introduced=6.0))), apply_to=any(function,record))") 186# define _LIBCPP_AVAILABILITY_FILESYSTEM_LIBRARY_POP \ 187 _Pragma("clang attribute pop") \ 188 _Pragma("clang attribute pop") \ 189 _Pragma("clang attribute pop") \ 190 _Pragma("clang attribute pop") 191 192// std::to_chars(floating-point) 193# if (defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 130300) || \ 194 (defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__ < 160300) || \ 195 (defined(__ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__ < 160300) || \ 196 (defined(__ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__ < 90300) 197# define _LIBCPP_AVAILABILITY_HAS_TO_CHARS_FLOATING_POINT 0 198# else 199# define _LIBCPP_AVAILABILITY_HAS_TO_CHARS_FLOATING_POINT 1 200# endif 201# define _LIBCPP_AVAILABILITY_TO_CHARS_FLOATING_POINT \ 202 __attribute__((availability(macos,strict,introduced=13.3))) \ 203 __attribute__((availability(ios,strict,introduced=16.3))) \ 204 __attribute__((availability(tvos,strict,introduced=16.3))) \ 205 __attribute__((availability(watchos,strict,introduced=9.3))) 206 207 // c++20 synchronization library 208# if (defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 110000) || \ 209 (defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__ < 140000) || \ 210 (defined(__ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__ < 140000) || \ 211 (defined(__ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__ < 70000) 212# define _LIBCPP_AVAILABILITY_HAS_SYNC 0 213# else 214# define _LIBCPP_AVAILABILITY_HAS_SYNC 1 215# endif 216# define _LIBCPP_AVAILABILITY_SYNC \ 217 __attribute__((availability(macos,strict,introduced=11.0))) \ 218 __attribute__((availability(ios,strict,introduced=14.0))) \ 219 __attribute__((availability(tvos,strict,introduced=14.0))) \ 220 __attribute__((availability(watchos,strict,introduced=7.0))) 221 222// __libcpp_verbose_abort 223// TODO: Update once this is released 224# define _LIBCPP_AVAILABILITY_HAS_VERBOSE_ABORT 0 225 226# define _LIBCPP_AVAILABILITY_VERBOSE_ABORT \ 227 __attribute__((unavailable)) 228 229// std::pmr 230# if (defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 140000) || \ 231 (defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__ < 170000) || \ 232 (defined(__ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__ < 170000) || \ 233 (defined(__ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__ < 100000) 234# define _LIBCPP_AVAILABILITY_HAS_PMR 0 235# else 236# define _LIBCPP_AVAILABILITY_HAS_PMR 1 237# endif 238// TODO: Enable std::pmr markup once https://github.com/llvm/llvm-project/issues/40340 has been fixed 239// Until then, it is possible for folks to try to use `std::pmr` when back-deploying to targets that don't support 240// 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 241// use availability annotations until that bug has been fixed. 242# if 0 243# define _LIBCPP_AVAILABILITY_PMR \ 244 __attribute__((availability(macos, strict, introduced = 14.0))) \ 245 __attribute__((availability(ios, strict, introduced = 17.0))) \ 246 __attribute__((availability(tvos, strict, introduced = 17.0))) \ 247 __attribute__((availability(watchos, strict, introduced = 10.0))) 248# else 249# define _LIBCPP_AVAILABILITY_PMR 250# endif 251 252# define _LIBCPP_AVAILABILITY_HAS_TZDB 0 253# define _LIBCPP_AVAILABILITY_TZDB __attribute__((unavailable)) 254 255# if (defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 120000) || \ 256 (defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__ < 150000) || \ 257 (defined(__ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__ < 150000) || \ 258 (defined(__ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__ < 80000) 259# define _LIBCPP_AVAILABILITY_HAS_ADDITIONAL_IOSTREAM_EXPLICIT_INSTANTIATIONS_1 0 260# else 261# define _LIBCPP_AVAILABILITY_HAS_ADDITIONAL_IOSTREAM_EXPLICIT_INSTANTIATIONS_1 1 262# endif 263#else 264 265// ...New vendors can add availability markup here... 266 267# error "It looks like you're trying to enable vendor availability markup, but you haven't defined the corresponding macros yet!" 268 269#endif 270 271// Define availability attributes that depend on _LIBCPP_HAS_NO_EXCEPTIONS. 272// Those are defined in terms of the availability attributes above, and 273// should not be vendor-specific. 274#if defined(_LIBCPP_HAS_NO_EXCEPTIONS) 275# define _LIBCPP_AVAILABILITY_THROW_BAD_ANY_CAST 276# define _LIBCPP_AVAILABILITY_THROW_BAD_OPTIONAL_ACCESS 277# define _LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS 278#else 279# define _LIBCPP_AVAILABILITY_THROW_BAD_ANY_CAST _LIBCPP_AVAILABILITY_BAD_ANY_CAST 280# define _LIBCPP_AVAILABILITY_THROW_BAD_OPTIONAL_ACCESS _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS 281# define _LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS _LIBCPP_AVAILABILITY_BAD_VARIANT_ACCESS 282#endif 283 284#endif // _LIBCPP___AVAILABILITY 285