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

source code of flutter_engine/third_party/libcxx/include/__availability