config.h
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00001 //
00002 // Copyright 2017 The Abseil Authors.
00003 //
00004 // Licensed under the Apache License, Version 2.0 (the "License");
00005 // you may not use this file except in compliance with the License.
00006 // You may obtain a copy of the License at
00007 //
00008 //      https://www.apache.org/licenses/LICENSE-2.0
00009 //
00010 // Unless required by applicable law or agreed to in writing, software
00011 // distributed under the License is distributed on an "AS IS" BASIS,
00012 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
00013 // See the License for the specific language governing permissions and
00014 // limitations under the License.
00015 //
00016 // -----------------------------------------------------------------------------
00017 // File: config.h
00018 // -----------------------------------------------------------------------------
00019 //
00020 // This header file defines a set of macros for checking the presence of
00021 // important compiler and platform features. Such macros can be used to
00022 // produce portable code by parameterizing compilation based on the presence or
00023 // lack of a given feature.
00024 //
00025 // We define a "feature" as some interface we wish to program to: for example,
00026 // a library function or system call. A value of `1` indicates support for
00027 // that feature; any other value indicates the feature support is undefined.
00028 //
00029 // Example:
00030 //
00031 // Suppose a programmer wants to write a program that uses the 'mmap()' system
00032 // call. The Abseil macro for that feature (`ABSL_HAVE_MMAP`) allows you to
00033 // selectively include the `mmap.h` header and bracket code using that feature
00034 // in the macro:
00035 //
00036 //   #include "absl/base/config.h"
00037 //
00038 //   #ifdef ABSL_HAVE_MMAP
00039 //   #include "sys/mman.h"
00040 //   #endif  //ABSL_HAVE_MMAP
00041 //
00042 //   ...
00043 //   #ifdef ABSL_HAVE_MMAP
00044 //   void *ptr = mmap(...);
00045 //   ...
00046 //   #endif  // ABSL_HAVE_MMAP
00047 
00048 #ifndef ABSL_BASE_CONFIG_H_
00049 #define ABSL_BASE_CONFIG_H_
00050 
00051 // Included for the __GLIBC__ macro (or similar macros on other systems).
00052 #include <limits.h>
00053 
00054 #ifdef __cplusplus
00055 // Included for __GLIBCXX__, _LIBCPP_VERSION
00056 #include <cstddef>
00057 #endif  // __cplusplus
00058 
00059 #if defined(__APPLE__)
00060 // Included for TARGET_OS_IPHONE, __IPHONE_OS_VERSION_MIN_REQUIRED,
00061 // __IPHONE_8_0.
00062 #include <Availability.h>
00063 #include <TargetConditionals.h>
00064 #endif
00065 
00066 #include "absl/base/policy_checks.h"
00067 
00068 // -----------------------------------------------------------------------------
00069 // Compiler Feature Checks
00070 // -----------------------------------------------------------------------------
00071 
00072 // ABSL_HAVE_BUILTIN()
00073 //
00074 // Checks whether the compiler supports a Clang Feature Checking Macro, and if
00075 // so, checks whether it supports the provided builtin function "x" where x
00076 // is one of the functions noted in
00077 // https://clang.llvm.org/docs/LanguageExtensions.html
00078 //
00079 // Note: Use this macro to avoid an extra level of #ifdef __has_builtin check.
00080 // http://releases.llvm.org/3.3/tools/clang/docs/LanguageExtensions.html
00081 #ifdef __has_builtin
00082 #define ABSL_HAVE_BUILTIN(x) __has_builtin(x)
00083 #else
00084 #define ABSL_HAVE_BUILTIN(x) 0
00085 #endif
00086 
00087 // ABSL_HAVE_TLS is defined to 1 when __thread should be supported.
00088 // We assume __thread is supported on Linux when compiled with Clang or compiled
00089 // against libstdc++ with _GLIBCXX_HAVE_TLS defined.
00090 #ifdef ABSL_HAVE_TLS
00091 #error ABSL_HAVE_TLS cannot be directly set
00092 #elif defined(__linux__) && (defined(__clang__) || defined(_GLIBCXX_HAVE_TLS))
00093 #define ABSL_HAVE_TLS 1
00094 #endif
00095 
00096 // ABSL_HAVE_STD_IS_TRIVIALLY_DESTRUCTIBLE
00097 //
00098 // Checks whether `std::is_trivially_destructible<T>` is supported.
00099 //
00100 // Notes: All supported compilers using libc++ support this feature, as does
00101 // gcc >= 4.8.1 using libstdc++, and Visual Studio.
00102 #ifdef ABSL_HAVE_STD_IS_TRIVIALLY_DESTRUCTIBLE
00103 #error ABSL_HAVE_STD_IS_TRIVIALLY_DESTRUCTIBLE cannot be directly set
00104 #elif defined(_LIBCPP_VERSION) ||                                        \
00105     (!defined(__clang__) && defined(__GNUC__) && defined(__GLIBCXX__) && \
00106      (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 8))) ||        \
00107     defined(_MSC_VER)
00108 #define ABSL_HAVE_STD_IS_TRIVIALLY_DESTRUCTIBLE 1
00109 #endif
00110 
00111 // ABSL_HAVE_STD_IS_TRIVIALLY_CONSTRUCTIBLE
00112 //
00113 // Checks whether `std::is_trivially_default_constructible<T>` and
00114 // `std::is_trivially_copy_constructible<T>` are supported.
00115 
00116 // ABSL_HAVE_STD_IS_TRIVIALLY_ASSIGNABLE
00117 //
00118 // Checks whether `std::is_trivially_copy_assignable<T>` is supported.
00119 
00120 // Notes: Clang with libc++ supports these features, as does gcc >= 5.1 with
00121 // either libc++ or libstdc++, and Visual Studio (but not NVCC).
00122 #if defined(ABSL_HAVE_STD_IS_TRIVIALLY_CONSTRUCTIBLE)
00123 #error ABSL_HAVE_STD_IS_TRIVIALLY_CONSTRUCTIBLE cannot be directly set
00124 #elif defined(ABSL_HAVE_STD_IS_TRIVIALLY_ASSIGNABLE)
00125 #error ABSL_HAVE_STD_IS_TRIVIALLY_ASSIGNABLE cannot directly set
00126 #elif (defined(__clang__) && defined(_LIBCPP_VERSION)) ||        \
00127     (!defined(__clang__) && defined(__GNUC__) &&                 \
00128      (__GNUC__ > 5 || (__GNUC__ == 5 && __GNUC_MINOR__ >= 1)) && \
00129      (defined(_LIBCPP_VERSION) || defined(__GLIBCXX__))) ||      \
00130     (defined(_MSC_VER) && !defined(__NVCC__))
00131 #define ABSL_HAVE_STD_IS_TRIVIALLY_CONSTRUCTIBLE 1
00132 #define ABSL_HAVE_STD_IS_TRIVIALLY_ASSIGNABLE 1
00133 #endif
00134 
00135 // ABSL_HAVE_THREAD_LOCAL
00136 //
00137 // Checks whether C++11's `thread_local` storage duration specifier is
00138 // supported.
00139 #ifdef ABSL_HAVE_THREAD_LOCAL
00140 #error ABSL_HAVE_THREAD_LOCAL cannot be directly set
00141 #elif defined(__APPLE__)
00142 // Notes:
00143 // * Xcode's clang did not support `thread_local` until version 8, and
00144 //   even then not for all iOS < 9.0.
00145 // * Xcode 9.3 started disallowing `thread_local` for 32-bit iOS simulator
00146 //   targeting iOS 9.x.
00147 // * Xcode 10 moves the deployment target check for iOS < 9.0 to link time
00148 //   making __has_feature unreliable there.
00149 //
00150 // Otherwise, `__has_feature` is only supported by Clang so it has be inside
00151 // `defined(__APPLE__)` check.
00152 #if __has_feature(cxx_thread_local) && \
00153     !(TARGET_OS_IPHONE && __IPHONE_OS_VERSION_MIN_REQUIRED < __IPHONE_9_0)
00154 #define ABSL_HAVE_THREAD_LOCAL 1
00155 #endif
00156 #else  // !defined(__APPLE__)
00157 #define ABSL_HAVE_THREAD_LOCAL 1
00158 #endif
00159 
00160 // There are platforms for which TLS should not be used even though the compiler
00161 // makes it seem like it's supported (Android NDK < r12b for example).
00162 // This is primarily because of linker problems and toolchain misconfiguration:
00163 // Abseil does not intend to support this indefinitely. Currently, the newest
00164 // toolchain that we intend to support that requires this behavior is the
00165 // r11 NDK - allowing for a 5 year support window on that means this option
00166 // is likely to be removed around June of 2021.
00167 // TLS isn't supported until NDK r12b per
00168 // https://developer.android.com/ndk/downloads/revision_history.html
00169 // Since NDK r16, `__NDK_MAJOR__` and `__NDK_MINOR__` are defined in
00170 // <android/ndk-version.h>. For NDK < r16, users should define these macros,
00171 // e.g. `-D__NDK_MAJOR__=11 -D__NKD_MINOR__=0` for NDK r11.
00172 #if defined(__ANDROID__) && defined(__clang__)
00173 #if __has_include(<android/ndk-version.h>)
00174 #include <android/ndk-version.h>
00175 #endif  // __has_include(<android/ndk-version.h>)
00176 #if defined(__ANDROID__) && defined(__clang__) && defined(__NDK_MAJOR__) && \
00177     defined(__NDK_MINOR__) &&                                               \
00178     ((__NDK_MAJOR__ < 12) || ((__NDK_MAJOR__ == 12) && (__NDK_MINOR__ < 1)))
00179 #undef ABSL_HAVE_TLS
00180 #undef ABSL_HAVE_THREAD_LOCAL
00181 #endif
00182 #endif  // defined(__ANDROID__) && defined(__clang__)
00183 
00184 // ABSL_HAVE_INTRINSIC_INT128
00185 //
00186 // Checks whether the __int128 compiler extension for a 128-bit integral type is
00187 // supported.
00188 //
00189 // Note: __SIZEOF_INT128__ is defined by Clang and GCC when __int128 is
00190 // supported, but we avoid using it in certain cases:
00191 // * On Clang:
00192 //   * Building using Clang for Windows, where the Clang runtime library has
00193 //     128-bit support only on LP64 architectures, but Windows is LLP64.
00194 // * On Nvidia's nvcc:
00195 //   * nvcc also defines __GNUC__ and __SIZEOF_INT128__, but not all versions
00196 //     actually support __int128.
00197 #ifdef ABSL_HAVE_INTRINSIC_INT128
00198 #error ABSL_HAVE_INTRINSIC_INT128 cannot be directly set
00199 #elif defined(__SIZEOF_INT128__)
00200 #if (defined(__clang__) && !defined(_WIN32)) || \
00201     (defined(__CUDACC__) && __CUDACC_VER_MAJOR__ >= 9) ||                \
00202     (defined(__GNUC__) && !defined(__clang__) && !defined(__CUDACC__))
00203 #define ABSL_HAVE_INTRINSIC_INT128 1
00204 #elif defined(__CUDACC__)
00205 // __CUDACC_VER__ is a full version number before CUDA 9, and is defined to a
00206 // string explaining that it has been removed starting with CUDA 9. We use
00207 // nested #ifs because there is no short-circuiting in the preprocessor.
00208 // NOTE: `__CUDACC__` could be undefined while `__CUDACC_VER__` is defined.
00209 #if __CUDACC_VER__ >= 70000
00210 #define ABSL_HAVE_INTRINSIC_INT128 1
00211 #endif  // __CUDACC_VER__ >= 70000
00212 #endif  // defined(__CUDACC__)
00213 #endif  // ABSL_HAVE_INTRINSIC_INT128
00214 
00215 // ABSL_HAVE_EXCEPTIONS
00216 //
00217 // Checks whether the compiler both supports and enables exceptions. Many
00218 // compilers support a "no exceptions" mode that disables exceptions.
00219 //
00220 // Generally, when ABSL_HAVE_EXCEPTIONS is not defined:
00221 //
00222 // * Code using `throw` and `try` may not compile.
00223 // * The `noexcept` specifier will still compile and behave as normal.
00224 // * The `noexcept` operator may still return `false`.
00225 //
00226 // For further details, consult the compiler's documentation.
00227 #ifdef ABSL_HAVE_EXCEPTIONS
00228 #error ABSL_HAVE_EXCEPTIONS cannot be directly set.
00229 
00230 #elif defined(__clang__)
00231 // TODO(calabrese)
00232 // Switch to using __cpp_exceptions when we no longer support versions < 3.6.
00233 // For details on this check, see:
00234 //   http://releases.llvm.org/3.6.0/tools/clang/docs/ReleaseNotes.html#the-exceptions-macro
00235 #if defined(__EXCEPTIONS) && __has_feature(cxx_exceptions)
00236 #define ABSL_HAVE_EXCEPTIONS 1
00237 #endif  // defined(__EXCEPTIONS) && __has_feature(cxx_exceptions)
00238 
00239 // Handle remaining special cases and default to exceptions being supported.
00240 #elif !(defined(__GNUC__) && (__GNUC__ < 5) && !defined(__EXCEPTIONS)) &&    \
00241     !(defined(__GNUC__) && (__GNUC__ >= 5) && !defined(__cpp_exceptions)) && \
00242     !(defined(_MSC_VER) && !defined(_CPPUNWIND))
00243 #define ABSL_HAVE_EXCEPTIONS 1
00244 #endif
00245 
00246 // -----------------------------------------------------------------------------
00247 // Platform Feature Checks
00248 // -----------------------------------------------------------------------------
00249 
00250 // Currently supported operating systems and associated preprocessor
00251 // symbols:
00252 //
00253 //   Linux and Linux-derived           __linux__
00254 //   Android                           __ANDROID__ (implies __linux__)
00255 //   Linux (non-Android)               __linux__ && !__ANDROID__
00256 //   Darwin (Mac OS X and iOS)         __APPLE__
00257 //   Akaros (http://akaros.org)        __ros__
00258 //   Windows                           _WIN32
00259 //   NaCL                              __native_client__
00260 //   AsmJS                             __asmjs__
00261 //   WebAssembly                       __wasm__
00262 //   Fuchsia                           __Fuchsia__
00263 //
00264 // Note that since Android defines both __ANDROID__ and __linux__, one
00265 // may probe for either Linux or Android by simply testing for __linux__.
00266 
00267 // ABSL_HAVE_MMAP
00268 //
00269 // Checks whether the platform has an mmap(2) implementation as defined in
00270 // POSIX.1-2001.
00271 #ifdef ABSL_HAVE_MMAP
00272 #error ABSL_HAVE_MMAP cannot be directly set
00273 #elif defined(__linux__) || defined(__APPLE__) || defined(__FreeBSD__) ||   \
00274     defined(__ros__) || defined(__native_client__) || defined(__asmjs__) || \
00275     defined(__wasm__) || defined(__Fuchsia__) || defined(__sun) || \
00276     defined(__ASYLO__)
00277 #define ABSL_HAVE_MMAP 1
00278 #endif
00279 
00280 // ABSL_HAVE_PTHREAD_GETSCHEDPARAM
00281 //
00282 // Checks whether the platform implements the pthread_(get|set)schedparam(3)
00283 // functions as defined in POSIX.1-2001.
00284 #ifdef ABSL_HAVE_PTHREAD_GETSCHEDPARAM
00285 #error ABSL_HAVE_PTHREAD_GETSCHEDPARAM cannot be directly set
00286 #elif defined(__linux__) || defined(__APPLE__) || defined(__FreeBSD__) || \
00287     defined(__ros__)
00288 #define ABSL_HAVE_PTHREAD_GETSCHEDPARAM 1
00289 #endif
00290 
00291 // ABSL_HAVE_SCHED_YIELD
00292 //
00293 // Checks whether the platform implements sched_yield(2) as defined in
00294 // POSIX.1-2001.
00295 #ifdef ABSL_HAVE_SCHED_YIELD
00296 #error ABSL_HAVE_SCHED_YIELD cannot be directly set
00297 #elif defined(__linux__) || defined(__ros__) || defined(__native_client__)
00298 #define ABSL_HAVE_SCHED_YIELD 1
00299 #endif
00300 
00301 // ABSL_HAVE_SEMAPHORE_H
00302 //
00303 // Checks whether the platform supports the <semaphore.h> header and sem_open(3)
00304 // family of functions as standardized in POSIX.1-2001.
00305 //
00306 // Note: While Apple provides <semaphore.h> for both iOS and macOS, it is
00307 // explicitly deprecated and will cause build failures if enabled for those
00308 // platforms.  We side-step the issue by not defining it here for Apple
00309 // platforms.
00310 #ifdef ABSL_HAVE_SEMAPHORE_H
00311 #error ABSL_HAVE_SEMAPHORE_H cannot be directly set
00312 #elif defined(__linux__) || defined(__ros__)
00313 #define ABSL_HAVE_SEMAPHORE_H 1
00314 #endif
00315 
00316 // ABSL_HAVE_ALARM
00317 //
00318 // Checks whether the platform supports the <signal.h> header and alarm(2)
00319 // function as standardized in POSIX.1-2001.
00320 #ifdef ABSL_HAVE_ALARM
00321 #error ABSL_HAVE_ALARM cannot be directly set
00322 #elif defined(__GOOGLE_GRTE_VERSION__)
00323 // feature tests for Google's GRTE
00324 #define ABSL_HAVE_ALARM 1
00325 #elif defined(__GLIBC__)
00326 // feature test for glibc
00327 #define ABSL_HAVE_ALARM 1
00328 #elif defined(_MSC_VER)
00329 // feature tests for Microsoft's library
00330 #elif defined(__EMSCRIPTEN__)
00331 // emscripten doesn't support signals
00332 #elif defined(__native_client__)
00333 #else
00334 // other standard libraries
00335 #define ABSL_HAVE_ALARM 1
00336 #endif
00337 
00338 // ABSL_IS_LITTLE_ENDIAN
00339 // ABSL_IS_BIG_ENDIAN
00340 //
00341 // Checks the endianness of the platform.
00342 //
00343 // Notes: uses the built in endian macros provided by GCC (since 4.6) and
00344 // Clang (since 3.2); see
00345 // https://gcc.gnu.org/onlinedocs/cpp/Common-Predefined-Macros.html.
00346 // Otherwise, if _WIN32, assume little endian. Otherwise, bail with an error.
00347 #if defined(ABSL_IS_BIG_ENDIAN)
00348 #error "ABSL_IS_BIG_ENDIAN cannot be directly set."
00349 #endif
00350 #if defined(ABSL_IS_LITTLE_ENDIAN)
00351 #error "ABSL_IS_LITTLE_ENDIAN cannot be directly set."
00352 #endif
00353 
00354 #if (defined(__BYTE_ORDER__) && defined(__ORDER_LITTLE_ENDIAN__) && \
00355      __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__)
00356 #define ABSL_IS_LITTLE_ENDIAN 1
00357 #elif defined(__BYTE_ORDER__) && defined(__ORDER_BIG_ENDIAN__) && \
00358     __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
00359 #define ABSL_IS_BIG_ENDIAN 1
00360 #elif defined(_WIN32)
00361 #define ABSL_IS_LITTLE_ENDIAN 1
00362 #else
00363 #error "absl endian detection needs to be set up for your compiler"
00364 #endif
00365 
00366 // MacOS 10.13 doesn't let you use <any>, <optional>, or <variant> even though
00367 // the headers exist and are publicly noted to work.  See
00368 // https://github.com/abseil/abseil-cpp/issues/207 and
00369 // https://developer.apple.com/documentation/xcode_release_notes/xcode_10_release_notes
00370 #if defined(__APPLE__) && defined(_LIBCPP_VERSION) && \
00371     defined(__MAC_OS_X_VERSION_MIN_REQUIRED__) &&     \
00372     __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 101400
00373 #define ABSL_INTERNAL_MACOS_CXX17_TYPES_UNAVAILABLE 1
00374 #else
00375 #define ABSL_INTERNAL_MACOS_CXX17_TYPES_UNAVAILABLE 0
00376 #endif
00377 
00378 // ABSL_HAVE_STD_ANY
00379 //
00380 // Checks whether C++17 std::any is available by checking whether <any> exists.
00381 #ifdef ABSL_HAVE_STD_ANY
00382 #error "ABSL_HAVE_STD_ANY cannot be directly set."
00383 #endif
00384 
00385 #ifdef __has_include
00386 #if __has_include(<any>) && __cplusplus >= 201703L && \
00387     !ABSL_INTERNAL_MACOS_CXX17_TYPES_UNAVAILABLE
00388 #define ABSL_HAVE_STD_ANY 1
00389 #endif
00390 #endif
00391 
00392 // ABSL_HAVE_STD_OPTIONAL
00393 //
00394 // Checks whether C++17 std::optional is available.
00395 #ifdef ABSL_HAVE_STD_OPTIONAL
00396 #error "ABSL_HAVE_STD_OPTIONAL cannot be directly set."
00397 #endif
00398 
00399 #ifdef __has_include
00400 #if __has_include(<optional>) && __cplusplus >= 201703L && \
00401     !ABSL_INTERNAL_MACOS_CXX17_TYPES_UNAVAILABLE
00402 #define ABSL_HAVE_STD_OPTIONAL 1
00403 #endif
00404 #endif
00405 
00406 // ABSL_HAVE_STD_VARIANT
00407 //
00408 // Checks whether C++17 std::variant is available.
00409 #ifdef ABSL_HAVE_STD_VARIANT
00410 #error "ABSL_HAVE_STD_VARIANT cannot be directly set."
00411 #endif
00412 
00413 #ifdef __has_include
00414 #if __has_include(<variant>) && __cplusplus >= 201703L && \
00415     !ABSL_INTERNAL_MACOS_CXX17_TYPES_UNAVAILABLE
00416 #define ABSL_HAVE_STD_VARIANT 1
00417 #endif
00418 #endif
00419 
00420 // ABSL_HAVE_STD_STRING_VIEW
00421 //
00422 // Checks whether C++17 std::string_view is available.
00423 #ifdef ABSL_HAVE_STD_STRING_VIEW
00424 #error "ABSL_HAVE_STD_STRING_VIEW cannot be directly set."
00425 #endif
00426 
00427 #ifdef __has_include
00428 #if __has_include(<string_view>) && __cplusplus >= 201703L
00429 #define ABSL_HAVE_STD_STRING_VIEW 1
00430 #endif
00431 #endif
00432 
00433 // For MSVC, `__has_include` is supported in VS 2017 15.3, which is later than
00434 // the support for <optional>, <any>, <string_view>, <variant>. So we use
00435 // _MSC_VER to check whether we have VS 2017 RTM (when <optional>, <any>,
00436 // <string_view>, <variant> is implemented) or higher. Also, `__cplusplus` is
00437 // not correctly set by MSVC, so we use `_MSVC_LANG` to check the language
00438 // version.
00439 // TODO(zhangxy): fix tests before enabling aliasing for `std::any`.
00440 #if defined(_MSC_VER) && _MSC_VER >= 1910 && \
00441     ((defined(_MSVC_LANG) && _MSVC_LANG > 201402) || __cplusplus > 201402)
00442 // #define ABSL_HAVE_STD_ANY 1
00443 #define ABSL_HAVE_STD_OPTIONAL 1
00444 #define ABSL_HAVE_STD_VARIANT 1
00445 #define ABSL_HAVE_STD_STRING_VIEW 1
00446 #endif
00447 
00448 // In debug mode, MSVC 2017's std::variant throws a EXCEPTION_ACCESS_VIOLATION
00449 // SEH exception from emplace for variant<SomeStruct> when constructing the
00450 // struct can throw. This defeats some of variant_test and
00451 // variant_exception_safety_test.
00452 #if defined(_MSC_VER) && _MSC_VER >= 1700 && defined(_DEBUG)
00453 #define ABSL_INTERNAL_MSVC_2017_DBG_MODE
00454 #endif
00455 
00456 #endif  // ABSL_BASE_CONFIG_H_


abseil_cpp
Author(s):
autogenerated on Wed Jun 19 2019 19:42:14