xref: /aosp_15_r20/external/webrtc/third_party/abseil-cpp/absl/base/config.h (revision d9f758449e529ab9291ac668be2861e7a55c2422)
1 //
2 // Copyright 2017 The Abseil Authors.
3 //
4 // Licensed under the Apache License, Version 2.0 (the "License");
5 // you may not use this file except in compliance with the License.
6 // You may obtain a copy of the License at
7 //
8 //      https://www.apache.org/licenses/LICENSE-2.0
9 //
10 // Unless required by applicable law or agreed to in writing, software
11 // distributed under the License is distributed on an "AS IS" BASIS,
12 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 // See the License for the specific language governing permissions and
14 // limitations under the License.
15 //
16 // -----------------------------------------------------------------------------
17 // File: config.h
18 // -----------------------------------------------------------------------------
19 //
20 // This header file defines a set of macros for checking the presence of
21 // important compiler and platform features. Such macros can be used to
22 // produce portable code by parameterizing compilation based on the presence or
23 // lack of a given feature.
24 //
25 // We define a "feature" as some interface we wish to program to: for example,
26 // a library function or system call. A value of `1` indicates support for
27 // that feature; any other value indicates the feature support is undefined.
28 //
29 // Example:
30 //
31 // Suppose a programmer wants to write a program that uses the 'mmap()' system
32 // call. The Abseil macro for that feature (`ABSL_HAVE_MMAP`) allows you to
33 // selectively include the `mmap.h` header and bracket code using that feature
34 // in the macro:
35 //
36 //   #include "absl/base/config.h"
37 //
38 //   #ifdef ABSL_HAVE_MMAP
39 //   #include "sys/mman.h"
40 //   #endif  //ABSL_HAVE_MMAP
41 //
42 //   ...
43 //   #ifdef ABSL_HAVE_MMAP
44 //   void *ptr = mmap(...);
45 //   ...
46 //   #endif  // ABSL_HAVE_MMAP
47 
48 #ifndef ABSL_BASE_CONFIG_H_
49 #define ABSL_BASE_CONFIG_H_
50 
51 // Included for the __GLIBC__ macro (or similar macros on other systems).
52 #include <limits.h>
53 
54 #ifdef __cplusplus
55 // Included for __GLIBCXX__, _LIBCPP_VERSION
56 #include <cstddef>
57 #endif  // __cplusplus
58 
59 // ABSL_INTERNAL_CPLUSPLUS_LANG
60 //
61 // MSVC does not set the value of __cplusplus correctly, but instead uses
62 // _MSVC_LANG as a stand-in.
63 // https://docs.microsoft.com/en-us/cpp/preprocessor/predefined-macros
64 //
65 // However, there are reports that MSVC even sets _MSVC_LANG incorrectly at
66 // times, for example:
67 // https://github.com/microsoft/vscode-cpptools/issues/1770
68 // https://reviews.llvm.org/D70996
69 //
70 // For this reason, this symbol is considered INTERNAL and code outside of
71 // Abseil must not use it.
72 #if defined(_MSVC_LANG)
73 #define ABSL_INTERNAL_CPLUSPLUS_LANG _MSVC_LANG
74 #elif defined(__cplusplus)
75 #define ABSL_INTERNAL_CPLUSPLUS_LANG __cplusplus
76 #endif
77 
78 #if defined(__APPLE__)
79 // Included for TARGET_OS_IPHONE, __IPHONE_OS_VERSION_MIN_REQUIRED,
80 // __IPHONE_8_0.
81 #include <Availability.h>
82 #include <TargetConditionals.h>
83 #endif
84 
85 #include "absl/base/options.h"
86 #include "absl/base/policy_checks.h"
87 
88 // Abseil long-term support (LTS) releases will define
89 // `ABSL_LTS_RELEASE_VERSION` to the integer representing the date string of the
90 // LTS release version, and will define `ABSL_LTS_RELEASE_PATCH_LEVEL` to the
91 // integer representing the patch-level for that release.
92 //
93 // For example, for LTS release version "20300401.2", this would give us
94 // ABSL_LTS_RELEASE_VERSION == 20300401 && ABSL_LTS_RELEASE_PATCH_LEVEL == 2
95 //
96 // These symbols will not be defined in non-LTS code.
97 //
98 // Abseil recommends that clients live-at-head. Therefore, if you are using
99 // these symbols to assert a minimum version requirement, we recommend you do it
100 // as
101 //
102 // #if defined(ABSL_LTS_RELEASE_VERSION) && ABSL_LTS_RELEASE_VERSION < 20300401
103 // #error Project foo requires Abseil LTS version >= 20300401
104 // #endif
105 //
106 // The `defined(ABSL_LTS_RELEASE_VERSION)` part of the check excludes
107 // live-at-head clients from the minimum version assertion.
108 //
109 // See https://abseil.io/about/releases for more information on Abseil release
110 // management.
111 //
112 // LTS releases can be obtained from
113 // https://github.com/abseil/abseil-cpp/releases.
114 #undef ABSL_LTS_RELEASE_VERSION
115 #undef ABSL_LTS_RELEASE_PATCH_LEVEL
116 
117 // Helper macro to convert a CPP variable to a string literal.
118 #define ABSL_INTERNAL_DO_TOKEN_STR(x) #x
119 #define ABSL_INTERNAL_TOKEN_STR(x) ABSL_INTERNAL_DO_TOKEN_STR(x)
120 
121 // -----------------------------------------------------------------------------
122 // Abseil namespace annotations
123 // -----------------------------------------------------------------------------
124 
125 // ABSL_NAMESPACE_BEGIN/ABSL_NAMESPACE_END
126 //
127 // An annotation placed at the beginning/end of each `namespace absl` scope.
128 // This is used to inject an inline namespace.
129 //
130 // The proper way to write Abseil code in the `absl` namespace is:
131 //
132 // namespace absl {
133 // ABSL_NAMESPACE_BEGIN
134 //
135 // void Foo();  // absl::Foo().
136 //
137 // ABSL_NAMESPACE_END
138 // }  // namespace absl
139 //
140 // Users of Abseil should not use these macros, because users of Abseil should
141 // not write `namespace absl {` in their own code for any reason.  (Abseil does
142 // not support forward declarations of its own types, nor does it support
143 // user-provided specialization of Abseil templates.  Code that violates these
144 // rules may be broken without warning.)
145 #if !defined(ABSL_OPTION_USE_INLINE_NAMESPACE) || \
146     !defined(ABSL_OPTION_INLINE_NAMESPACE_NAME)
147 #error options.h is misconfigured.
148 #endif
149 
150 // Check that ABSL_OPTION_INLINE_NAMESPACE_NAME is neither "head" nor ""
151 #if defined(__cplusplus) && ABSL_OPTION_USE_INLINE_NAMESPACE == 1
152 
153 #define ABSL_INTERNAL_INLINE_NAMESPACE_STR \
154   ABSL_INTERNAL_TOKEN_STR(ABSL_OPTION_INLINE_NAMESPACE_NAME)
155 
156 static_assert(ABSL_INTERNAL_INLINE_NAMESPACE_STR[0] != '\0',
157               "options.h misconfigured: ABSL_OPTION_INLINE_NAMESPACE_NAME must "
158               "not be empty.");
159 static_assert(ABSL_INTERNAL_INLINE_NAMESPACE_STR[0] != 'h' ||
160                   ABSL_INTERNAL_INLINE_NAMESPACE_STR[1] != 'e' ||
161                   ABSL_INTERNAL_INLINE_NAMESPACE_STR[2] != 'a' ||
162                   ABSL_INTERNAL_INLINE_NAMESPACE_STR[3] != 'd' ||
163                   ABSL_INTERNAL_INLINE_NAMESPACE_STR[4] != '\0',
164               "options.h misconfigured: ABSL_OPTION_INLINE_NAMESPACE_NAME must "
165               "be changed to a new, unique identifier name.");
166 
167 #endif
168 
169 #if ABSL_OPTION_USE_INLINE_NAMESPACE == 0
170 #define ABSL_NAMESPACE_BEGIN
171 #define ABSL_NAMESPACE_END
172 #define ABSL_INTERNAL_C_SYMBOL(x) x
173 #elif ABSL_OPTION_USE_INLINE_NAMESPACE == 1
174 #define ABSL_NAMESPACE_BEGIN \
175   inline namespace ABSL_OPTION_INLINE_NAMESPACE_NAME {
176 #define ABSL_NAMESPACE_END }
177 #define ABSL_INTERNAL_C_SYMBOL_HELPER_2(x, v) x##_##v
178 #define ABSL_INTERNAL_C_SYMBOL_HELPER_1(x, v) \
179   ABSL_INTERNAL_C_SYMBOL_HELPER_2(x, v)
180 #define ABSL_INTERNAL_C_SYMBOL(x) \
181   ABSL_INTERNAL_C_SYMBOL_HELPER_1(x, ABSL_OPTION_INLINE_NAMESPACE_NAME)
182 #else
183 #error options.h is misconfigured.
184 #endif
185 
186 // -----------------------------------------------------------------------------
187 // Compiler Feature Checks
188 // -----------------------------------------------------------------------------
189 
190 // ABSL_HAVE_BUILTIN()
191 //
192 // Checks whether the compiler supports a Clang Feature Checking Macro, and if
193 // so, checks whether it supports the provided builtin function "x" where x
194 // is one of the functions noted in
195 // https://clang.llvm.org/docs/LanguageExtensions.html
196 //
197 // Note: Use this macro to avoid an extra level of #ifdef __has_builtin check.
198 // http://releases.llvm.org/3.3/tools/clang/docs/LanguageExtensions.html
199 #ifdef __has_builtin
200 #define ABSL_HAVE_BUILTIN(x) __has_builtin(x)
201 #else
202 #define ABSL_HAVE_BUILTIN(x) 0
203 #endif
204 
205 #ifdef __has_feature
206 #define ABSL_HAVE_FEATURE(f) __has_feature(f)
207 #else
208 #define ABSL_HAVE_FEATURE(f) 0
209 #endif
210 
211 // Portable check for GCC minimum version:
212 // https://gcc.gnu.org/onlinedocs/cpp/Common-Predefined-Macros.html
213 #if defined(__GNUC__) && defined(__GNUC_MINOR__)
214 #define ABSL_INTERNAL_HAVE_MIN_GNUC_VERSION(x, y) \
215   (__GNUC__ > (x) || __GNUC__ == (x) && __GNUC_MINOR__ >= (y))
216 #else
217 #define ABSL_INTERNAL_HAVE_MIN_GNUC_VERSION(x, y) 0
218 #endif
219 
220 #if defined(__clang__) && defined(__clang_major__) && defined(__clang_minor__)
221 #define ABSL_INTERNAL_HAVE_MIN_CLANG_VERSION(x, y) \
222   (__clang_major__ > (x) || __clang_major__ == (x) && __clang_minor__ >= (y))
223 #else
224 #define ABSL_INTERNAL_HAVE_MIN_CLANG_VERSION(x, y) 0
225 #endif
226 
227 // ABSL_HAVE_TLS is defined to 1 when __thread should be supported.
228 // We assume __thread is supported on Linux or Asylo when compiled with Clang or
229 // compiled against libstdc++ with _GLIBCXX_HAVE_TLS defined.
230 #ifdef ABSL_HAVE_TLS
231 #error ABSL_HAVE_TLS cannot be directly set
232 #elif (defined(__linux__) || defined(__ASYLO__)) && \
233     (defined(__clang__) || defined(_GLIBCXX_HAVE_TLS))
234 #define ABSL_HAVE_TLS 1
235 #endif
236 
237 // ABSL_HAVE_STD_IS_TRIVIALLY_DESTRUCTIBLE
238 //
239 // Checks whether `std::is_trivially_destructible<T>` is supported.
240 //
241 // Notes: All supported compilers using libc++ support this feature, as does
242 // gcc >= 4.8.1 using libstdc++, and Visual Studio.
243 #ifdef ABSL_HAVE_STD_IS_TRIVIALLY_DESTRUCTIBLE
244 #error ABSL_HAVE_STD_IS_TRIVIALLY_DESTRUCTIBLE cannot be directly set
245 #elif defined(_LIBCPP_VERSION) || defined(_MSC_VER) || \
246     (defined(__clang__) && __clang_major__ >= 15) ||   \
247     (!defined(__clang__) && defined(__GLIBCXX__) &&    \
248      ABSL_INTERNAL_HAVE_MIN_GNUC_VERSION(4, 8))
249 #define ABSL_HAVE_STD_IS_TRIVIALLY_DESTRUCTIBLE 1
250 #endif
251 
252 // ABSL_HAVE_STD_IS_TRIVIALLY_CONSTRUCTIBLE
253 //
254 // Checks whether `std::is_trivially_default_constructible<T>` and
255 // `std::is_trivially_copy_constructible<T>` are supported.
256 
257 // ABSL_HAVE_STD_IS_TRIVIALLY_ASSIGNABLE
258 //
259 // Checks whether `std::is_trivially_copy_assignable<T>` is supported.
260 
261 // Notes: Clang with libc++ supports these features, as does gcc >= 7.4 with
262 // libstdc++, or gcc >= 8.2 with libc++, and Visual Studio (but not NVCC).
263 #if defined(ABSL_HAVE_STD_IS_TRIVIALLY_CONSTRUCTIBLE)
264 #error ABSL_HAVE_STD_IS_TRIVIALLY_CONSTRUCTIBLE cannot be directly set
265 #elif defined(ABSL_HAVE_STD_IS_TRIVIALLY_ASSIGNABLE)
266 #error ABSL_HAVE_STD_IS_TRIVIALLY_ASSIGNABLE cannot directly set
267 #elif (defined(__clang__) && defined(_LIBCPP_VERSION)) ||                    \
268     (defined(__clang__) && __clang_major__ >= 15) ||                         \
269     (!defined(__clang__) &&                                                  \
270      ((ABSL_INTERNAL_HAVE_MIN_GNUC_VERSION(7, 4) && defined(__GLIBCXX__)) || \
271       (ABSL_INTERNAL_HAVE_MIN_GNUC_VERSION(8, 2) &&                          \
272        defined(_LIBCPP_VERSION)))) ||                                        \
273     (defined(_MSC_VER) && !defined(__NVCC__) && !defined(__clang__))
274 #define ABSL_HAVE_STD_IS_TRIVIALLY_CONSTRUCTIBLE 1
275 #define ABSL_HAVE_STD_IS_TRIVIALLY_ASSIGNABLE 1
276 #endif
277 
278 // ABSL_HAVE_STD_IS_TRIVIALLY_COPYABLE
279 //
280 // Checks whether `std::is_trivially_copyable<T>` is supported.
281 //
282 // Notes: Clang 15+ with libc++ supports these features, GCC hasn't been tested.
283 #if defined(ABSL_HAVE_STD_IS_TRIVIALLY_COPYABLE)
284 #error ABSL_HAVE_STD_IS_TRIVIALLY_COPYABLE cannot be directly set
285 #elif defined(__clang__) && (__clang_major__ >= 15)
286 #define ABSL_HAVE_STD_IS_TRIVIALLY_COPYABLE 1
287 #endif
288 
289 // ABSL_HAVE_THREAD_LOCAL
290 //
291 // Checks whether C++11's `thread_local` storage duration specifier is
292 // supported.
293 #ifdef ABSL_HAVE_THREAD_LOCAL
294 #error ABSL_HAVE_THREAD_LOCAL cannot be directly set
295 #elif defined(__APPLE__)
296 // Notes:
297 // * Xcode's clang did not support `thread_local` until version 8, and
298 //   even then not for all iOS < 9.0.
299 // * Xcode 9.3 started disallowing `thread_local` for 32-bit iOS simulator
300 //   targeting iOS 9.x.
301 // * Xcode 10 moves the deployment target check for iOS < 9.0 to link time
302 //   making ABSL_HAVE_FEATURE unreliable there.
303 //
304 #if ABSL_HAVE_FEATURE(cxx_thread_local) && \
305     !(TARGET_OS_IPHONE && __IPHONE_OS_VERSION_MIN_REQUIRED < __IPHONE_9_0)
306 #define ABSL_HAVE_THREAD_LOCAL 1
307 #endif
308 #else  // !defined(__APPLE__)
309 #define ABSL_HAVE_THREAD_LOCAL 1
310 #endif
311 
312 // There are platforms for which TLS should not be used even though the compiler
313 // makes it seem like it's supported (Android NDK < r12b for example).
314 // This is primarily because of linker problems and toolchain misconfiguration:
315 // Abseil does not intend to support this indefinitely. Currently, the newest
316 // toolchain that we intend to support that requires this behavior is the
317 // r11 NDK - allowing for a 5 year support window on that means this option
318 // is likely to be removed around June of 2021.
319 // TLS isn't supported until NDK r12b per
320 // https://developer.android.com/ndk/downloads/revision_history.html
321 // Since NDK r16, `__NDK_MAJOR__` and `__NDK_MINOR__` are defined in
322 // <android/ndk-version.h>. For NDK < r16, users should define these macros,
323 // e.g. `-D__NDK_MAJOR__=11 -D__NKD_MINOR__=0` for NDK r11.
324 #if defined(__ANDROID__) && defined(__clang__)
325 #if __has_include(<android/ndk-version.h>)
326 #include <android/ndk-version.h>
327 #endif  // __has_include(<android/ndk-version.h>)
328 #if defined(__ANDROID__) && defined(__clang__) && defined(__NDK_MAJOR__) && \
329     defined(__NDK_MINOR__) &&                                               \
330     ((__NDK_MAJOR__ < 12) || ((__NDK_MAJOR__ == 12) && (__NDK_MINOR__ < 1)))
331 #undef ABSL_HAVE_TLS
332 #undef ABSL_HAVE_THREAD_LOCAL
333 #endif
334 #endif  // defined(__ANDROID__) && defined(__clang__)
335 
336 // ABSL_HAVE_INTRINSIC_INT128
337 //
338 // Checks whether the __int128 compiler extension for a 128-bit integral type is
339 // supported.
340 //
341 // Note: __SIZEOF_INT128__ is defined by Clang and GCC when __int128 is
342 // supported, but we avoid using it in certain cases:
343 // * On Clang:
344 //   * Building using Clang for Windows, where the Clang runtime library has
345 //     128-bit support only on LP64 architectures, but Windows is LLP64.
346 // * On Nvidia's nvcc:
347 //   * nvcc also defines __GNUC__ and __SIZEOF_INT128__, but not all versions
348 //     actually support __int128.
349 #ifdef ABSL_HAVE_INTRINSIC_INT128
350 #error ABSL_HAVE_INTRINSIC_INT128 cannot be directly set
351 #elif defined(__SIZEOF_INT128__)
352 #if (defined(__clang__) && !defined(_WIN32)) || \
353     (defined(__CUDACC__) && __CUDACC_VER_MAJOR__ >= 9) ||                \
354     (defined(__GNUC__) && !defined(__clang__) && !defined(__CUDACC__))
355 #define ABSL_HAVE_INTRINSIC_INT128 1
356 #elif defined(__CUDACC__)
357 // __CUDACC_VER__ is a full version number before CUDA 9, and is defined to a
358 // string explaining that it has been removed starting with CUDA 9. We use
359 // nested #ifs because there is no short-circuiting in the preprocessor.
360 // NOTE: `__CUDACC__` could be undefined while `__CUDACC_VER__` is defined.
361 #if __CUDACC_VER__ >= 70000
362 #define ABSL_HAVE_INTRINSIC_INT128 1
363 #endif  // __CUDACC_VER__ >= 70000
364 #endif  // defined(__CUDACC__)
365 #endif  // ABSL_HAVE_INTRINSIC_INT128
366 
367 // ABSL_HAVE_EXCEPTIONS
368 //
369 // Checks whether the compiler both supports and enables exceptions. Many
370 // compilers support a "no exceptions" mode that disables exceptions.
371 //
372 // Generally, when ABSL_HAVE_EXCEPTIONS is not defined:
373 //
374 // * Code using `throw` and `try` may not compile.
375 // * The `noexcept` specifier will still compile and behave as normal.
376 // * The `noexcept` operator may still return `false`.
377 //
378 // For further details, consult the compiler's documentation.
379 #ifdef ABSL_HAVE_EXCEPTIONS
380 #error ABSL_HAVE_EXCEPTIONS cannot be directly set.
381 #elif ABSL_INTERNAL_HAVE_MIN_CLANG_VERSION(3, 6)
382 // Clang >= 3.6
383 #if ABSL_HAVE_FEATURE(cxx_exceptions)
384 #define ABSL_HAVE_EXCEPTIONS 1
385 #endif  // ABSL_HAVE_FEATURE(cxx_exceptions)
386 #elif defined(__clang__)
387 // Clang < 3.6
388 // http://releases.llvm.org/3.6.0/tools/clang/docs/ReleaseNotes.html#the-exceptions-macro
389 #if defined(__EXCEPTIONS) && ABSL_HAVE_FEATURE(cxx_exceptions)
390 #define ABSL_HAVE_EXCEPTIONS 1
391 #endif  // defined(__EXCEPTIONS) && ABSL_HAVE_FEATURE(cxx_exceptions)
392 // Handle remaining special cases and default to exceptions being supported.
393 #elif !(defined(__GNUC__) && (__GNUC__ < 5) && !defined(__EXCEPTIONS)) && \
394     !(ABSL_INTERNAL_HAVE_MIN_GNUC_VERSION(5, 0) &&                        \
395       !defined(__cpp_exceptions)) &&                                      \
396     !(defined(_MSC_VER) && !defined(_CPPUNWIND))
397 #define ABSL_HAVE_EXCEPTIONS 1
398 #endif
399 
400 // -----------------------------------------------------------------------------
401 // Platform Feature Checks
402 // -----------------------------------------------------------------------------
403 
404 // Currently supported operating systems and associated preprocessor
405 // symbols:
406 //
407 //   Linux and Linux-derived           __linux__
408 //   Android                           __ANDROID__ (implies __linux__)
409 //   Linux (non-Android)               __linux__ && !__ANDROID__
410 //   Darwin (macOS and iOS)            __APPLE__
411 //   Akaros (http://akaros.org)        __ros__
412 //   Windows                           _WIN32
413 //   NaCL                              __native_client__
414 //   AsmJS                             __asmjs__
415 //   WebAssembly                       __wasm__
416 //   Fuchsia                           __Fuchsia__
417 //
418 // Note that since Android defines both __ANDROID__ and __linux__, one
419 // may probe for either Linux or Android by simply testing for __linux__.
420 
421 // ABSL_HAVE_MMAP
422 //
423 // Checks whether the platform has an mmap(2) implementation as defined in
424 // POSIX.1-2001.
425 #ifdef ABSL_HAVE_MMAP
426 #error ABSL_HAVE_MMAP cannot be directly set
427 #elif defined(__linux__) || defined(__APPLE__) || defined(__FreeBSD__) || \
428     defined(_AIX) || defined(__ros__) || defined(__native_client__) ||    \
429     defined(__asmjs__) || defined(__wasm__) || defined(__Fuchsia__) ||    \
430     defined(__sun) || defined(__ASYLO__) || defined(__myriad2__) ||       \
431     defined(__HAIKU__) || defined(__OpenBSD__) || defined(__NetBSD__) ||  \
432     defined(__QNX__)
433 #define ABSL_HAVE_MMAP 1
434 #endif
435 
436 // ABSL_HAVE_PTHREAD_GETSCHEDPARAM
437 //
438 // Checks whether the platform implements the pthread_(get|set)schedparam(3)
439 // functions as defined in POSIX.1-2001.
440 #ifdef ABSL_HAVE_PTHREAD_GETSCHEDPARAM
441 #error ABSL_HAVE_PTHREAD_GETSCHEDPARAM cannot be directly set
442 #elif defined(__linux__) || defined(__APPLE__) || defined(__FreeBSD__) || \
443     defined(_AIX) || defined(__ros__) || defined(__OpenBSD__) ||          \
444     defined(__NetBSD__)
445 #define ABSL_HAVE_PTHREAD_GETSCHEDPARAM 1
446 #endif
447 
448 // ABSL_HAVE_SCHED_GETCPU
449 //
450 // Checks whether sched_getcpu is available.
451 #ifdef ABSL_HAVE_SCHED_GETCPU
452 #error ABSL_HAVE_SCHED_GETCPU cannot be directly set
453 #elif defined(__linux__)
454 #define ABSL_HAVE_SCHED_GETCPU 1
455 #endif
456 
457 // ABSL_HAVE_SCHED_YIELD
458 //
459 // Checks whether the platform implements sched_yield(2) as defined in
460 // POSIX.1-2001.
461 #ifdef ABSL_HAVE_SCHED_YIELD
462 #error ABSL_HAVE_SCHED_YIELD cannot be directly set
463 #elif defined(__linux__) || defined(__ros__) || defined(__native_client__)
464 #define ABSL_HAVE_SCHED_YIELD 1
465 #endif
466 
467 // ABSL_HAVE_SEMAPHORE_H
468 //
469 // Checks whether the platform supports the <semaphore.h> header and sem_init(3)
470 // family of functions as standardized in POSIX.1-2001.
471 //
472 // Note: While Apple provides <semaphore.h> for both iOS and macOS, it is
473 // explicitly deprecated and will cause build failures if enabled for those
474 // platforms.  We side-step the issue by not defining it here for Apple
475 // platforms.
476 #ifdef ABSL_HAVE_SEMAPHORE_H
477 #error ABSL_HAVE_SEMAPHORE_H cannot be directly set
478 #elif defined(__linux__) || defined(__ros__)
479 #define ABSL_HAVE_SEMAPHORE_H 1
480 #endif
481 
482 // ABSL_HAVE_ALARM
483 //
484 // Checks whether the platform supports the <signal.h> header and alarm(2)
485 // function as standardized in POSIX.1-2001.
486 #ifdef ABSL_HAVE_ALARM
487 #error ABSL_HAVE_ALARM cannot be directly set
488 #elif defined(__GOOGLE_GRTE_VERSION__)
489 // feature tests for Google's GRTE
490 #define ABSL_HAVE_ALARM 1
491 #elif defined(__GLIBC__)
492 // feature test for glibc
493 #define ABSL_HAVE_ALARM 1
494 #elif defined(_MSC_VER)
495 // feature tests for Microsoft's library
496 #elif defined(__MINGW32__)
497 // mingw32 doesn't provide alarm(2):
498 // https://osdn.net/projects/mingw/scm/git/mingw-org-wsl/blobs/5.2-trunk/mingwrt/include/unistd.h
499 // mingw-w64 provides a no-op implementation:
500 // https://sourceforge.net/p/mingw-w64/mingw-w64/ci/master/tree/mingw-w64-crt/misc/alarm.c
501 #elif defined(__EMSCRIPTEN__)
502 // emscripten doesn't support signals
503 #elif defined(__Fuchsia__)
504 // Signals don't exist on fuchsia.
505 #elif defined(__native_client__)
506 #else
507 // other standard libraries
508 #define ABSL_HAVE_ALARM 1
509 #endif
510 
511 // ABSL_IS_LITTLE_ENDIAN
512 // ABSL_IS_BIG_ENDIAN
513 //
514 // Checks the endianness of the platform.
515 //
516 // Notes: uses the built in endian macros provided by GCC (since 4.6) and
517 // Clang (since 3.2); see
518 // https://gcc.gnu.org/onlinedocs/cpp/Common-Predefined-Macros.html.
519 // Otherwise, if _WIN32, assume little endian. Otherwise, bail with an error.
520 #if defined(ABSL_IS_BIG_ENDIAN)
521 #error "ABSL_IS_BIG_ENDIAN cannot be directly set."
522 #endif
523 #if defined(ABSL_IS_LITTLE_ENDIAN)
524 #error "ABSL_IS_LITTLE_ENDIAN cannot be directly set."
525 #endif
526 
527 #if (defined(__BYTE_ORDER__) && defined(__ORDER_LITTLE_ENDIAN__) && \
528      __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__)
529 #define ABSL_IS_LITTLE_ENDIAN 1
530 #elif defined(__BYTE_ORDER__) && defined(__ORDER_BIG_ENDIAN__) && \
531     __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
532 #define ABSL_IS_BIG_ENDIAN 1
533 #elif defined(_WIN32)
534 #define ABSL_IS_LITTLE_ENDIAN 1
535 #else
536 #error "absl endian detection needs to be set up for your compiler"
537 #endif
538 
539 // macOS < 10.13 and iOS < 11 don't let you use <any>, <optional>, or <variant>
540 // even though the headers exist and are publicly noted to work, because the
541 // libc++ shared library shipped on the system doesn't have the requisite
542 // exported symbols.  See https://github.com/abseil/abseil-cpp/issues/207 and
543 // https://developer.apple.com/documentation/xcode_release_notes/xcode_10_release_notes
544 //
545 // libc++ spells out the availability requirements in the file
546 // llvm-project/libcxx/include/__config via the #define
547 // _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS.
548 //
549 // Unfortunately, Apple initially mis-stated the requirements as macOS < 10.14
550 // and iOS < 12 in the libc++ headers. This was corrected by
551 // https://github.com/llvm/llvm-project/commit/7fb40e1569dd66292b647f4501b85517e9247953
552 // which subsequently made it into the XCode 12.5 release. We need to match the
553 // old (incorrect) conditions when built with old XCode, but can use the
554 // corrected earlier versions with new XCode.
555 #if defined(__APPLE__) && defined(_LIBCPP_VERSION) &&               \
556     ((_LIBCPP_VERSION >= 11000 && /* XCode 12.5 or later: */        \
557       ((defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) &&   \
558         __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 101300) ||  \
559        (defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__) &&  \
560         __ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__ < 110000) || \
561        (defined(__ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__) &&   \
562         __ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__ < 40000) ||   \
563        (defined(__ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__) &&      \
564         __ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__ < 110000))) ||   \
565      (_LIBCPP_VERSION < 11000 && /* Pre-XCode 12.5: */              \
566       ((defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) &&   \
567         __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 101400) ||  \
568        (defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__) &&  \
569         __ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__ < 120000) || \
570        (defined(__ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__) &&   \
571         __ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__ < 50000) ||   \
572        (defined(__ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__) &&      \
573         __ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__ < 120000))))
574 #define ABSL_INTERNAL_APPLE_CXX17_TYPES_UNAVAILABLE 1
575 #else
576 #define ABSL_INTERNAL_APPLE_CXX17_TYPES_UNAVAILABLE 0
577 #endif
578 
579 // ABSL_HAVE_STD_ANY
580 //
581 // Checks whether C++17 std::any is available by checking whether <any> exists.
582 #ifdef ABSL_HAVE_STD_ANY
583 #error "ABSL_HAVE_STD_ANY cannot be directly set."
584 #endif
585 
586 #ifdef __has_include
587 #if __has_include(<any>) && defined(__cplusplus) && __cplusplus >= 201703L && \
588     !ABSL_INTERNAL_APPLE_CXX17_TYPES_UNAVAILABLE
589 #define ABSL_HAVE_STD_ANY 1
590 #endif
591 #endif
592 
593 // ABSL_HAVE_STD_OPTIONAL
594 //
595 // Checks whether C++17 std::optional is available.
596 #ifdef ABSL_HAVE_STD_OPTIONAL
597 #error "ABSL_HAVE_STD_OPTIONAL cannot be directly set."
598 #endif
599 
600 #ifdef __has_include
601 #if __has_include(<optional>) && defined(__cplusplus) && \
602     __cplusplus >= 201703L && !ABSL_INTERNAL_APPLE_CXX17_TYPES_UNAVAILABLE
603 #define ABSL_HAVE_STD_OPTIONAL 1
604 #endif
605 #endif
606 
607 // ABSL_HAVE_STD_VARIANT
608 //
609 // Checks whether C++17 std::variant is available.
610 #ifdef ABSL_HAVE_STD_VARIANT
611 #error "ABSL_HAVE_STD_VARIANT cannot be directly set."
612 #endif
613 
614 #ifdef __has_include
615 #if __has_include(<variant>) && defined(__cplusplus) && \
616     __cplusplus >= 201703L && !ABSL_INTERNAL_APPLE_CXX17_TYPES_UNAVAILABLE
617 #define ABSL_HAVE_STD_VARIANT 1
618 #endif
619 #endif
620 
621 // ABSL_HAVE_STD_STRING_VIEW
622 //
623 // Checks whether C++17 std::string_view is available.
624 #ifdef ABSL_HAVE_STD_STRING_VIEW
625 #error "ABSL_HAVE_STD_STRING_VIEW cannot be directly set."
626 #endif
627 
628 #ifdef __has_include
629 #if __has_include(<string_view>) && defined(__cplusplus) && \
630     __cplusplus >= 201703L
631 #define ABSL_HAVE_STD_STRING_VIEW 1
632 #endif
633 #endif
634 
635 // For MSVC, `__has_include` is supported in VS 2017 15.3, which is later than
636 // the support for <optional>, <any>, <string_view>, <variant>. So we use
637 // _MSC_VER to check whether we have VS 2017 RTM (when <optional>, <any>,
638 // <string_view>, <variant> is implemented) or higher. Also, `__cplusplus` is
639 // not correctly set by MSVC, so we use `_MSVC_LANG` to check the language
640 // version.
641 // TODO(zhangxy): fix tests before enabling aliasing for `std::any`.
642 #if defined(_MSC_VER) && _MSC_VER >= 1910 &&         \
643     ((defined(_MSVC_LANG) && _MSVC_LANG > 201402) || \
644      (defined(__cplusplus) && __cplusplus > 201402))
645 // #define ABSL_HAVE_STD_ANY 1
646 #define ABSL_HAVE_STD_OPTIONAL 1
647 #define ABSL_HAVE_STD_VARIANT 1
648 #define ABSL_HAVE_STD_STRING_VIEW 1
649 #endif
650 
651 // ABSL_USES_STD_ANY
652 //
653 // Indicates whether absl::any is an alias for std::any.
654 #if !defined(ABSL_OPTION_USE_STD_ANY)
655 #error options.h is misconfigured.
656 #elif ABSL_OPTION_USE_STD_ANY == 0 || \
657     (ABSL_OPTION_USE_STD_ANY == 2 && !defined(ABSL_HAVE_STD_ANY))
658 #undef ABSL_USES_STD_ANY
659 #elif ABSL_OPTION_USE_STD_ANY == 1 || \
660     (ABSL_OPTION_USE_STD_ANY == 2 && defined(ABSL_HAVE_STD_ANY))
661 #define ABSL_USES_STD_ANY 1
662 #else
663 #error options.h is misconfigured.
664 #endif
665 
666 // ABSL_USES_STD_OPTIONAL
667 //
668 // Indicates whether absl::optional is an alias for std::optional.
669 #if !defined(ABSL_OPTION_USE_STD_OPTIONAL)
670 #error options.h is misconfigured.
671 #elif ABSL_OPTION_USE_STD_OPTIONAL == 0 || \
672     (ABSL_OPTION_USE_STD_OPTIONAL == 2 && !defined(ABSL_HAVE_STD_OPTIONAL))
673 #undef ABSL_USES_STD_OPTIONAL
674 #elif ABSL_OPTION_USE_STD_OPTIONAL == 1 || \
675     (ABSL_OPTION_USE_STD_OPTIONAL == 2 && defined(ABSL_HAVE_STD_OPTIONAL))
676 #define ABSL_USES_STD_OPTIONAL 1
677 #else
678 #error options.h is misconfigured.
679 #endif
680 
681 // ABSL_USES_STD_VARIANT
682 //
683 // Indicates whether absl::variant is an alias for std::variant.
684 #if !defined(ABSL_OPTION_USE_STD_VARIANT)
685 #error options.h is misconfigured.
686 #elif ABSL_OPTION_USE_STD_VARIANT == 0 || \
687     (ABSL_OPTION_USE_STD_VARIANT == 2 && !defined(ABSL_HAVE_STD_VARIANT))
688 #undef ABSL_USES_STD_VARIANT
689 #elif ABSL_OPTION_USE_STD_VARIANT == 1 || \
690     (ABSL_OPTION_USE_STD_VARIANT == 2 && defined(ABSL_HAVE_STD_VARIANT))
691 #define ABSL_USES_STD_VARIANT 1
692 #else
693 #error options.h is misconfigured.
694 #endif
695 
696 // ABSL_USES_STD_STRING_VIEW
697 //
698 // Indicates whether absl::string_view is an alias for std::string_view.
699 #if !defined(ABSL_OPTION_USE_STD_STRING_VIEW)
700 #error options.h is misconfigured.
701 #elif ABSL_OPTION_USE_STD_STRING_VIEW == 0 || \
702     (ABSL_OPTION_USE_STD_STRING_VIEW == 2 &&  \
703      !defined(ABSL_HAVE_STD_STRING_VIEW))
704 #undef ABSL_USES_STD_STRING_VIEW
705 #elif ABSL_OPTION_USE_STD_STRING_VIEW == 1 || \
706     (ABSL_OPTION_USE_STD_STRING_VIEW == 2 &&  \
707      defined(ABSL_HAVE_STD_STRING_VIEW))
708 #define ABSL_USES_STD_STRING_VIEW 1
709 #else
710 #error options.h is misconfigured.
711 #endif
712 
713 // In debug mode, MSVC 2017's std::variant throws a EXCEPTION_ACCESS_VIOLATION
714 // SEH exception from emplace for variant<SomeStruct> when constructing the
715 // struct can throw. This defeats some of variant_test and
716 // variant_exception_safety_test.
717 #if defined(_MSC_VER) && _MSC_VER >= 1700 && defined(_DEBUG)
718 #define ABSL_INTERNAL_MSVC_2017_DBG_MODE
719 #endif
720 
721 // ABSL_INTERNAL_MANGLED_NS
722 // ABSL_INTERNAL_MANGLED_BACKREFERENCE
723 //
724 // Internal macros for building up mangled names in our internal fork of CCTZ.
725 // This implementation detail is only needed and provided for the MSVC build.
726 //
727 // These macros both expand to string literals.  ABSL_INTERNAL_MANGLED_NS is
728 // the mangled spelling of the `absl` namespace, and
729 // ABSL_INTERNAL_MANGLED_BACKREFERENCE is a back-reference integer representing
730 // the proper count to skip past the CCTZ fork namespace names.  (This number
731 // is one larger when there is an inline namespace name to skip.)
732 #if defined(_MSC_VER)
733 #if ABSL_OPTION_USE_INLINE_NAMESPACE == 0
734 #define ABSL_INTERNAL_MANGLED_NS "absl"
735 #define ABSL_INTERNAL_MANGLED_BACKREFERENCE "5"
736 #else
737 #define ABSL_INTERNAL_MANGLED_NS \
738   ABSL_INTERNAL_TOKEN_STR(ABSL_OPTION_INLINE_NAMESPACE_NAME) "@absl"
739 #define ABSL_INTERNAL_MANGLED_BACKREFERENCE "6"
740 #endif
741 #endif
742 
743 // ABSL_DLL
744 //
745 // When building Abseil as a DLL, this macro expands to `__declspec(dllexport)`
746 // so we can annotate symbols appropriately as being exported. When used in
747 // headers consuming a DLL, this macro expands to `__declspec(dllimport)` so
748 // that consumers know the symbol is defined inside the DLL. In all other cases,
749 // the macro expands to nothing.
750 #if defined(_MSC_VER)
751 #if defined(ABSL_BUILD_DLL)
752 #define ABSL_DLL __declspec(dllexport)
753 #elif defined(ABSL_CONSUME_DLL)
754 #define ABSL_DLL __declspec(dllimport)
755 #else
756 #define ABSL_DLL
757 #endif
758 #else
759 #define ABSL_DLL
760 #endif  // defined(_MSC_VER)
761 
762 // ABSL_HAVE_MEMORY_SANITIZER
763 //
764 // MemorySanitizer (MSan) is a detector of uninitialized reads. It consists of
765 // a compiler instrumentation module and a run-time library.
766 #ifdef ABSL_HAVE_MEMORY_SANITIZER
767 #error "ABSL_HAVE_MEMORY_SANITIZER cannot be directly set."
768 #elif !defined(__native_client__) && ABSL_HAVE_FEATURE(memory_sanitizer)
769 #define ABSL_HAVE_MEMORY_SANITIZER 1
770 #endif
771 
772 // ABSL_HAVE_THREAD_SANITIZER
773 //
774 // ThreadSanitizer (TSan) is a fast data race detector.
775 #ifdef ABSL_HAVE_THREAD_SANITIZER
776 #error "ABSL_HAVE_THREAD_SANITIZER cannot be directly set."
777 #elif defined(__SANITIZE_THREAD__)
778 #define ABSL_HAVE_THREAD_SANITIZER 1
779 #elif ABSL_HAVE_FEATURE(thread_sanitizer)
780 #define ABSL_HAVE_THREAD_SANITIZER 1
781 #endif
782 
783 // ABSL_HAVE_ADDRESS_SANITIZER
784 //
785 // AddressSanitizer (ASan) is a fast memory error detector.
786 #ifdef ABSL_HAVE_ADDRESS_SANITIZER
787 #error "ABSL_HAVE_ADDRESS_SANITIZER cannot be directly set."
788 #elif defined(__SANITIZE_ADDRESS__)
789 #define ABSL_HAVE_ADDRESS_SANITIZER 1
790 #elif ABSL_HAVE_FEATURE(address_sanitizer)
791 #define ABSL_HAVE_ADDRESS_SANITIZER 1
792 #endif
793 
794 // ABSL_HAVE_HWADDRESS_SANITIZER
795 //
796 // Hardware-Assisted AddressSanitizer (or HWASAN) is even faster than asan
797 // memory error detector which can use CPU features like ARM TBI, Intel LAM or
798 // AMD UAI.
799 #ifdef ABSL_HAVE_HWADDRESS_SANITIZER
800 #error "ABSL_HAVE_HWADDRESS_SANITIZER cannot be directly set."
801 #elif defined(__SANITIZE_HWADDRESS__)
802 #define ABSL_HAVE_HWADDRESS_SANITIZER 1
803 #elif ABSL_HAVE_FEATURE(hwaddress_sanitizer)
804 #define ABSL_HAVE_HWADDRESS_SANITIZER 1
805 #endif
806 
807 // ABSL_HAVE_LEAK_SANITIZER
808 //
809 // LeakSanitizer (or lsan) is a detector of memory leaks.
810 // https://clang.llvm.org/docs/LeakSanitizer.html
811 // https://github.com/google/sanitizers/wiki/AddressSanitizerLeakSanitizer
812 //
813 // The macro ABSL_HAVE_LEAK_SANITIZER can be used to detect at compile-time
814 // whether the LeakSanitizer is potentially available. However, just because the
815 // LeakSanitizer is available does not mean it is active. Use the
816 // always-available run-time interface in //absl/debugging/leak_check.h for
817 // interacting with LeakSanitizer.
818 #ifdef ABSL_HAVE_LEAK_SANITIZER
819 #error "ABSL_HAVE_LEAK_SANITIZER cannot be directly set."
820 #elif defined(LEAK_SANITIZER)
821 // GCC provides no method for detecting the presense of the standalone
822 // LeakSanitizer (-fsanitize=leak), so GCC users of -fsanitize=leak should also
823 // use -DLEAK_SANITIZER.
824 #define ABSL_HAVE_LEAK_SANITIZER 1
825 // Clang standalone LeakSanitizer (-fsanitize=leak)
826 #elif ABSL_HAVE_FEATURE(leak_sanitizer)
827 #define ABSL_HAVE_LEAK_SANITIZER 1
828 #elif defined(ABSL_HAVE_ADDRESS_SANITIZER)
829 // GCC or Clang using the LeakSanitizer integrated into AddressSanitizer.
830 #define ABSL_HAVE_LEAK_SANITIZER 1
831 #endif
832 
833 // ABSL_HAVE_CLASS_TEMPLATE_ARGUMENT_DEDUCTION
834 //
835 // Class template argument deduction is a language feature added in C++17.
836 #ifdef ABSL_HAVE_CLASS_TEMPLATE_ARGUMENT_DEDUCTION
837 #error "ABSL_HAVE_CLASS_TEMPLATE_ARGUMENT_DEDUCTION cannot be directly set."
838 #elif defined(__cpp_deduction_guides)
839 #define ABSL_HAVE_CLASS_TEMPLATE_ARGUMENT_DEDUCTION 1
840 #endif
841 
842 // ABSL_INTERNAL_NEED_REDUNDANT_CONSTEXPR_DECL
843 //
844 // Prior to C++17, static constexpr variables defined in classes required a
845 // separate definition outside of the class body, for example:
846 //
847 // class Foo {
848 //   static constexpr int kBar = 0;
849 // };
850 // constexpr int Foo::kBar;
851 //
852 // In C++17, these variables defined in classes are considered inline variables,
853 // and the extra declaration is redundant. Since some compilers warn on the
854 // extra declarations, ABSL_INTERNAL_NEED_REDUNDANT_CONSTEXPR_DECL can be used
855 // conditionally ignore them:
856 //
857 // #ifdef ABSL_INTERNAL_NEED_REDUNDANT_CONSTEXPR_DECL
858 // constexpr int Foo::kBar;
859 // #endif
860 #if defined(ABSL_INTERNAL_CPLUSPLUS_LANG) && \
861     ABSL_INTERNAL_CPLUSPLUS_LANG < 201703L
862 #define ABSL_INTERNAL_NEED_REDUNDANT_CONSTEXPR_DECL 1
863 #endif
864 
865 // `ABSL_INTERNAL_HAS_RTTI` determines whether abseil is being compiled with
866 // RTTI support.
867 #ifdef ABSL_INTERNAL_HAS_RTTI
868 #error ABSL_INTERNAL_HAS_RTTI cannot be directly set
869 #elif !defined(__GNUC__) || defined(__GXX_RTTI)
870 #define ABSL_INTERNAL_HAS_RTTI 1
871 #endif  // !defined(__GNUC__) || defined(__GXX_RTTI)
872 
873 // ABSL_INTERNAL_HAVE_SSE is used for compile-time detection of SSE support.
874 // See https://gcc.gnu.org/onlinedocs/gcc/x86-Options.html for an overview of
875 // which architectures support the various x86 instruction sets.
876 #ifdef ABSL_INTERNAL_HAVE_SSE
877 #error ABSL_INTERNAL_HAVE_SSE cannot be directly set
878 #elif defined(__SSE__)
879 #define ABSL_INTERNAL_HAVE_SSE 1
880 #elif defined(_M_X64) || (defined(_M_IX86_FP) && _M_IX86_FP >= 1)
881 // MSVC only defines _M_IX86_FP for x86 32-bit code, and _M_IX86_FP >= 1
882 // indicates that at least SSE was targeted with the /arch:SSE option.
883 // All x86-64 processors support SSE, so support can be assumed.
884 // https://docs.microsoft.com/en-us/cpp/preprocessor/predefined-macros
885 #define ABSL_INTERNAL_HAVE_SSE 1
886 #endif
887 
888 // ABSL_INTERNAL_HAVE_SSE2 is used for compile-time detection of SSE2 support.
889 // See https://gcc.gnu.org/onlinedocs/gcc/x86-Options.html for an overview of
890 // which architectures support the various x86 instruction sets.
891 #ifdef ABSL_INTERNAL_HAVE_SSE2
892 #error ABSL_INTERNAL_HAVE_SSE2 cannot be directly set
893 #elif defined(__SSE2__)
894 #define ABSL_INTERNAL_HAVE_SSE2 1
895 #elif defined(_M_X64) || (defined(_M_IX86_FP) && _M_IX86_FP >= 2)
896 // MSVC only defines _M_IX86_FP for x86 32-bit code, and _M_IX86_FP >= 2
897 // indicates that at least SSE2 was targeted with the /arch:SSE2 option.
898 // All x86-64 processors support SSE2, so support can be assumed.
899 // https://docs.microsoft.com/en-us/cpp/preprocessor/predefined-macros
900 #define ABSL_INTERNAL_HAVE_SSE2 1
901 #endif
902 
903 // ABSL_INTERNAL_HAVE_SSSE3 is used for compile-time detection of SSSE3 support.
904 // See https://gcc.gnu.org/onlinedocs/gcc/x86-Options.html for an overview of
905 // which architectures support the various x86 instruction sets.
906 //
907 // MSVC does not have a mode that targets SSSE3 at compile-time. To use SSSE3
908 // with MSVC requires either assuming that the code will only every run on CPUs
909 // that support SSSE3, otherwise __cpuid() can be used to detect support at
910 // runtime and fallback to a non-SSSE3 implementation when SSSE3 is unsupported
911 // by the CPU.
912 #ifdef ABSL_INTERNAL_HAVE_SSSE3
913 #error ABSL_INTERNAL_HAVE_SSSE3 cannot be directly set
914 #elif defined(__SSSE3__)
915 #define ABSL_INTERNAL_HAVE_SSSE3 1
916 #endif
917 
918 // ABSL_INTERNAL_HAVE_ARM_NEON is used for compile-time detection of NEON (ARM
919 // SIMD).
920 //
921 // If __CUDA_ARCH__ is defined, then we are compiling CUDA code in device mode.
922 // In device mode, NEON intrinsics are not available, regardless of host
923 // platform.
924 // https://llvm.org/docs/CompileCudaWithLLVM.html#detecting-clang-vs-nvcc-from-code
925 #ifdef ABSL_INTERNAL_HAVE_ARM_NEON
926 #error ABSL_INTERNAL_HAVE_ARM_NEON cannot be directly set
927 #elif defined(__ARM_NEON) && !defined(__CUDA_ARCH__)
928 #define ABSL_INTERNAL_HAVE_ARM_NEON 1
929 #endif
930 
931 #endif  // ABSL_BASE_CONFIG_H_
932