Abseil Common Libraries (C++) (grcp 依赖)
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375 lines
14 KiB
375 lines
14 KiB
// |
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// Copyright 2017 The Abseil Authors. |
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// |
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// Licensed under the Apache License, Version 2.0 (the "License"); |
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// you may not use this file except in compliance with the License. |
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// You may obtain a copy of the License at |
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// |
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// http://www.apache.org/licenses/LICENSE-2.0 |
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// |
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// Unless required by applicable law or agreed to in writing, software |
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// distributed under the License is distributed on an "AS IS" BASIS, |
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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// See the License for the specific language governing permissions and |
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// limitations under the License. |
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// |
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// ----------------------------------------------------------------------------- |
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// File: config.h |
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// ----------------------------------------------------------------------------- |
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// |
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// This header file defines a set of macros for checking the presence of |
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// important compiler and platform features. Such macros can be used to |
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// produce portable code by parameterizing compilation based on the presence or |
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// lack of a given feature. |
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// |
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// We define a "feature" as some interface we wish to program to: for example, |
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// a library function or system call. A value of `1` indicates support for |
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// that feature; any other value indicates the feature support is undefined. |
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// |
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// Example: |
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// |
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// Suppose a programmer wants to write a program that uses the 'mmap()' system |
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// call. The Abseil macro for that feature (`ABSL_HAVE_MMAP`) allows you to |
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// selectively include the `mmap.h` header and bracket code using that feature |
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// in the macro: |
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// |
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// #include "absl/base/config.h" |
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// |
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// #ifdef ABSL_HAVE_MMAP |
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// #include "sys/mman.h" |
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// #endif //ABSL_HAVE_MMAP |
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// |
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// ... |
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// #ifdef ABSL_HAVE_MMAP |
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// void *ptr = mmap(...); |
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// ... |
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// #endif // ABSL_HAVE_MMAP |
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#ifndef ABSL_BASE_CONFIG_H_ |
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#define ABSL_BASE_CONFIG_H_ |
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// Included for the __GLIBC__ macro (or similar macros on other systems). |
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#include <limits.h> |
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#ifdef __cplusplus |
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// Included for __GLIBCXX__, _LIBCPP_VERSION |
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#include <cstddef> |
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#endif // __cplusplus |
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#if defined(__APPLE__) |
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// Included for TARGET_OS_IPHONE, __IPHONE_OS_VERSION_MIN_REQUIRED, |
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// __IPHONE_8_0. |
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#include <Availability.h> |
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#include <TargetConditionals.h> |
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#endif |
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#include "absl/base/policy_checks.h" |
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// ----------------------------------------------------------------------------- |
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// Compiler Feature Checks |
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// ----------------------------------------------------------------------------- |
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// ABSL_HAVE_BUILTIN() |
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// |
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// Checks whether the compiler supports a Clang Feature Checking Macro, and if |
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// so, checks whether it supports the provided builtin function "x" where x |
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// is one of the functions noted in |
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// https://clang.llvm.org/docs/LanguageExtensions.html |
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// |
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// Note: Use this macro to avoid an extra level of #ifdef __has_builtin check. |
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// http://releases.llvm.org/3.3/tools/clang/docs/LanguageExtensions.html |
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#ifdef __has_builtin |
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#define ABSL_HAVE_BUILTIN(x) __has_builtin(x) |
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#else |
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#define ABSL_HAVE_BUILTIN(x) 0 |
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#endif |
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// ABSL_HAVE_TLS is defined to 1 when __thread should be supported. |
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// We assume __thread is supported on Linux when compiled with Clang or compiled |
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// against libstdc++ with _GLIBCXX_HAVE_TLS defined. |
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#ifdef ABSL_HAVE_TLS |
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#error ABSL_HAVE_TLS cannot be directly set |
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#elif defined(__linux__) && (defined(__clang__) || defined(_GLIBCXX_HAVE_TLS)) |
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#define ABSL_HAVE_TLS 1 |
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#endif |
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// There are platforms for which TLS should not be used even though the compiler |
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// makes it seem like it's supported (Android NDK < r12b for example). |
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// This is primarily because of linker problems and toolchain misconfiguration: |
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// Abseil does not intend to support this indefinitely. Currently, the newest |
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// toolchain that we intend to support that requires this behavior is the |
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// r11 NDK - allowing for a 5 year support window on that means this option |
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// is likely to be removed around June of 2021. |
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#if defined(__ANDROID__) && defined(__clang__) |
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#if __has_include(<android/ndk-version.h>) |
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#include <android/ndk-version.h> |
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#endif |
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// TLS isn't supported until NDK r12b per |
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// https://developer.android.com/ndk/downloads/revision_history.html |
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// Since NDK r16, `__NDK_MAJOR__` and `__NDK_MINOR__` are defined in |
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// <android/ndk-version.h>. For NDK < r16, users should define these macros, |
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// e.g. `-D__NDK_MAJOR__=11 -D__NKD_MINOR__=0` for NDK r11. |
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#if defined(__NDK_MAJOR__) && defined(__NDK_MINOR__) && \ |
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((__NDK_MAJOR__ < 12) || ((__NDK_MAJOR__ == 12) && (__NDK_MINOR__ < 1))) |
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#undef ABSL_HAVE_TLS |
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#endif |
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#endif // defined(__ANDROID__) && defined(__clang__) |
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// ABSL_HAVE_STD_IS_TRIVIALLY_DESTRUCTIBLE |
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// |
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// Checks whether `std::is_trivially_destructible<T>` is supported. |
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// |
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// Notes: All supported compilers using libc++ support this feature, as does |
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// gcc >= 4.8.1 using libstdc++, and Visual Studio. |
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#ifdef ABSL_HAVE_STD_IS_TRIVIALLY_DESTRUCTIBLE |
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#error ABSL_HAVE_STD_IS_TRIVIALLY_DESTRUCTIBLE cannot be directly set |
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#elif defined(_LIBCPP_VERSION) || \ |
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(!defined(__clang__) && defined(__GNUC__) && defined(__GLIBCXX__) && \ |
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(__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 8))) || \ |
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defined(_MSC_VER) |
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#define ABSL_HAVE_STD_IS_TRIVIALLY_DESTRUCTIBLE 1 |
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#endif |
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// ABSL_HAVE_STD_IS_TRIVIALLY_CONSTRUCTIBLE |
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// |
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// Checks whether `std::is_trivially_default_constructible<T>` and |
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// `std::is_trivially_copy_constructible<T>` are supported. |
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// ABSL_HAVE_STD_IS_TRIVIALLY_ASSIGNABLE |
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// |
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// Checks whether `std::is_trivially_copy_assignable<T>` is supported. |
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// Notes: Clang with libc++ supports these features, as does gcc >= 5.1 with |
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// either libc++ or libstdc++, and Visual Studio. |
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#if defined(ABSL_HAVE_STD_IS_TRIVIALLY_CONSTRUCTIBLE) |
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#error ABSL_HAVE_STD_IS_TRIVIALLY_CONSTRUCTIBLE cannot be directly set |
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#elif defined(ABSL_HAVE_STD_IS_TRIVIALLY_ASSIGNABLE) |
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#error ABSL_HAVE_STD_IS_TRIVIALLY_ASSIGNABLE cannot directly set |
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#elif (defined(__clang__) && defined(_LIBCPP_VERSION)) || \ |
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(!defined(__clang__) && defined(__GNUC__) && \ |
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(__GNUC__ > 5 || (__GNUC__ == 5 && __GNUC_MINOR__ >= 1)) && \ |
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(defined(_LIBCPP_VERSION) || defined(__GLIBCXX__))) || \ |
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defined(_MSC_VER) |
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#define ABSL_HAVE_STD_IS_TRIVIALLY_CONSTRUCTIBLE 1 |
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#define ABSL_HAVE_STD_IS_TRIVIALLY_ASSIGNABLE 1 |
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#endif |
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// ABSL_HAVE_THREAD_LOCAL |
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// |
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// Checks whether C++11's `thread_local` storage duration specifier is |
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// supported. |
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#ifdef ABSL_HAVE_THREAD_LOCAL |
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#error ABSL_HAVE_THREAD_LOCAL cannot be directly set |
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#elif !defined(__apple_build_version__) || \ |
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((__apple_build_version__ >= 8000042) && \ |
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!(TARGET_OS_IPHONE && __IPHONE_OS_VERSION_MIN_REQUIRED < __IPHONE_9_0)) |
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// Notes: Xcode's clang did not support `thread_local` until version |
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// 8, and even then not for all iOS < 9.0. |
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#define ABSL_HAVE_THREAD_LOCAL 1 |
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#endif |
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// ABSL_HAVE_INTRINSIC_INT128 |
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// |
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// Checks whether the __int128 compiler extension for a 128-bit integral type is |
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// supported. |
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// |
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// Notes: __SIZEOF_INT128__ is defined by Clang and GCC when __int128 is |
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// supported, except on ppc64 and aarch64 where __int128 exists but has exhibits |
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// a sporadic compiler crashing bug. Nvidia's nvcc also defines __GNUC__ and |
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// __SIZEOF_INT128__ but not all versions actually support __int128. |
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#ifdef ABSL_HAVE_INTRINSIC_INT128 |
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#error ABSL_HAVE_INTRINSIC_INT128 cannot be directly set |
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#elif (defined(__clang__) && defined(__SIZEOF_INT128__) && \ |
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!defined(__aarch64__)) || \ |
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(defined(__CUDACC__) && defined(__SIZEOF_INT128__) && \ |
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__CUDACC_VER__ >= 70000) || \ |
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(!defined(__clang__) && !defined(__CUDACC__) && defined(__GNUC__) && \ |
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defined(__SIZEOF_INT128__)) |
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#define ABSL_HAVE_INTRINSIC_INT128 1 |
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#endif |
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// ABSL_HAVE_EXCEPTIONS |
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// |
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// Checks whether the compiler both supports and enables exceptions. Many |
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// compilers support a "no exceptions" mode that disables exceptions. |
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// |
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// Generally, when ABSL_HAVE_EXCEPTIONS is not defined: |
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// |
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// * Code using `throw` and `try` may not compile. |
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// * The `noexcept` specifier will still compile and behave as normal. |
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// * The `noexcept` operator may still return `false`. |
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// |
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// For further details, consult the compiler's documentation. |
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#ifdef ABSL_HAVE_EXCEPTIONS |
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#error ABSL_HAVE_EXCEPTIONS cannot be directly set. |
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#elif defined(__clang__) |
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// TODO(calabrese) |
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// Switch to using __cpp_exceptions when we no longer support versions < 3.6. |
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// For details on this check, see: |
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// http://releases.llvm.org/3.6.0/tools/clang/docs/ReleaseNotes.html#the-exceptions-macro |
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#if defined(__EXCEPTIONS) && __has_feature(cxx_exceptions) |
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#define ABSL_HAVE_EXCEPTIONS 1 |
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#endif // defined(__EXCEPTIONS) && __has_feature(cxx_exceptions) |
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// Handle remaining special cases and default to exceptions being supported. |
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#elif !(defined(__GNUC__) && (__GNUC__ < 5) && !defined(__EXCEPTIONS)) && \ |
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!(defined(__GNUC__) && (__GNUC__ >= 5) && !defined(__cpp_exceptions)) && \ |
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!(defined(_MSC_VER) && !defined(_CPPUNWIND)) |
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#define ABSL_HAVE_EXCEPTIONS 1 |
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#endif |
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// ----------------------------------------------------------------------------- |
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// Platform Feature Checks |
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// ----------------------------------------------------------------------------- |
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// Currently supported operating systems and associated preprocessor |
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// symbols: |
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// |
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// Linux and Linux-derived __linux__ |
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// Android __ANDROID__ (implies __linux__) |
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// Linux (non-Android) __linux__ && !__ANDROID__ |
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// Darwin (Mac OS X and iOS) __APPLE__ |
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// Akaros (http://akaros.org) __ros__ |
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// Windows _WIN32 |
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// NaCL __native_client__ |
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// AsmJS __asmjs__ |
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// Fuschia __Fuchsia__ |
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// |
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// Note that since Android defines both __ANDROID__ and __linux__, one |
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// may probe for either Linux or Android by simply testing for __linux__. |
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// ABSL_HAVE_MMAP |
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// |
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// Checks whether the platform has an mmap(2) implementation as defined in |
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// POSIX.1-2001. |
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#ifdef ABSL_HAVE_MMAP |
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#error ABSL_HAVE_MMAP cannot be directly set |
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#elif defined(__linux__) || defined(__APPLE__) || defined(__ros__) || \ |
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defined(__native_client__) || defined(__asmjs__) || defined(__Fuchsia__) |
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#define ABSL_HAVE_MMAP 1 |
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#endif |
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// ABSL_HAVE_PTHREAD_GETSCHEDPARAM |
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// |
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// Checks whether the platform implements the pthread_(get|set)schedparam(3) |
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// functions as defined in POSIX.1-2001. |
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#ifdef ABSL_HAVE_PTHREAD_GETSCHEDPARAM |
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#error ABSL_HAVE_PTHREAD_GETSCHEDPARAM cannot be directly set |
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#elif defined(__linux__) || defined(__APPLE__) || defined(__ros__) |
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#define ABSL_HAVE_PTHREAD_GETSCHEDPARAM 1 |
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#endif |
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// ABSL_HAVE_SCHED_YIELD |
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// |
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// Checks whether the platform implements sched_yield(2) as defined in |
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// POSIX.1-2001. |
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#ifdef ABSL_HAVE_SCHED_YIELD |
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#error ABSL_HAVE_SCHED_YIELD cannot be directly set |
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#elif defined(__linux__) || defined(__ros__) || defined(__native_client__) |
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#define ABSL_HAVE_SCHED_YIELD 1 |
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#endif |
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// ABSL_HAVE_SEMAPHORE_H |
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// |
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// Checks whether the platform supports the <semaphore.h> header and sem_open(3) |
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// family of functions as standardized in POSIX.1-2001. |
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// |
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// Note: While Apple provides <semaphore.h> for both iOS and macOS, it is |
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// explicity deprecated and will cause build failures if enabled for those |
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// platforms. We side-step the issue by not defining it here for Apple |
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// platforms. |
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#ifdef ABSL_HAVE_SEMAPHORE_H |
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#error ABSL_HAVE_SEMAPHORE_H cannot be directly set |
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#elif defined(__linux__) || defined(__ros__) |
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#define ABSL_HAVE_SEMAPHORE_H 1 |
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#endif |
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// ABSL_HAVE_ALARM |
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// |
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// Checks whether the platform supports the <signal.h> header and alarm(2) |
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// function as standardized in POSIX.1-2001. |
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#ifdef ABSL_HAVE_ALARM |
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#error ABSL_HAVE_ALARM cannot be directly set |
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#elif defined(__GOOGLE_GRTE_VERSION__) |
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// feature tests for Google's GRTE |
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#define ABSL_HAVE_ALARM 1 |
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#elif defined(__GLIBC__) |
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// feature test for glibc |
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#define ABSL_HAVE_ALARM 1 |
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#elif defined(_MSC_VER) |
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// feature tests for Microsoft's library |
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#elif defined(__native_client__) |
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#else |
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// other standard libraries |
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#define ABSL_HAVE_ALARM 1 |
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#endif |
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// ABSL_IS_LITTLE_ENDIAN |
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// ABSL_IS_BIG_ENDIAN |
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// |
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// Checks the endianness of the platform. |
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// |
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// Notes: uses the built in endian macros provided by GCC (since 4.6) and |
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// Clang (since 3.2); see |
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// https://gcc.gnu.org/onlinedocs/cpp/Common-Predefined-Macros.html. |
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// Otherwise, if _WIN32, assume little endian. Otherwise, bail with an error. |
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#if defined(ABSL_IS_BIG_ENDIAN) |
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#error "ABSL_IS_BIG_ENDIAN cannot be directly set." |
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#endif |
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#if defined(ABSL_IS_LITTLE_ENDIAN) |
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#error "ABSL_IS_LITTLE_ENDIAN cannot be directly set." |
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#endif |
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#if (defined(__BYTE_ORDER__) && defined(__ORDER_LITTLE_ENDIAN__) && \ |
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__BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__) |
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#define ABSL_IS_LITTLE_ENDIAN 1 |
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#elif defined(__BYTE_ORDER__) && defined(__ORDER_BIG_ENDIAN__) && \ |
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__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__ |
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#define ABSL_IS_BIG_ENDIAN 1 |
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#elif defined(_WIN32) |
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#define ABSL_IS_LITTLE_ENDIAN 1 |
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#else |
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#error "absl endian detection needs to be set up for your compiler" |
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#endif |
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// ABSL_HAVE_STD_ANY |
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// |
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// Checks whether C++17 std::any is available by checking whether <any> exists. |
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#ifdef ABSL_HAVE_STD_ANY |
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#error "ABSL_HAVE_STD_ANY cannot be directly set." |
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#endif |
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#ifdef __has_include |
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#if __has_include(<any>) && __cplusplus >= 201703L |
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#define ABSL_HAVE_STD_ANY 1 |
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#endif |
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#endif |
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// ABSL_HAVE_STD_OPTIONAL |
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// |
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// Checks whether C++17 std::optional is available. |
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#ifdef ABSL_HAVE_STD_OPTIONAL |
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#error "ABSL_HAVE_STD_OPTIONAL cannot be directly set." |
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#endif |
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#ifdef __has_include |
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#if __has_include(<optional>) && __cplusplus >= 201703L |
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#define ABSL_HAVE_STD_OPTIONAL 1 |
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#endif |
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#endif |
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// ABSL_HAVE_STD_STRING_VIEW |
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// |
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// Checks whether C++17 std::string_view is available. |
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#ifdef ABSL_HAVE_STD_STRING_VIEW |
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#error "ABSL_HAVE_STD_STRING_VIEW cannot be directly set." |
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#endif |
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#ifdef __has_include |
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#if __has_include(<string_view>) && __cplusplus >= 201703L |
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#define ABSL_HAVE_STD_STRING_VIEW 1 |
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#endif |
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#endif |
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#endif // ABSL_BASE_CONFIG_H_
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