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tvl-depot/absl/base/config.h
Abseil Team aae8143cf9 Export of internal Abseil changes 
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f28b989d5161230c6561e923b458c797a96bcf90 by Greg Falcon <gfalcon@google.com>:

Import of CCTZ from GitHub.

PiperOrigin-RevId: 263586488

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8259484025b7de45358719fc6182a48cac8044c6 by Andy Soffer <asoffer@google.com>:

Internal changes and combine namespaces into a single namespace.

PiperOrigin-RevId: 263560576

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8d19f41661984a600d1f8bbfeb8a30fcb4dee7d6 by Mark Barolak <mbar@google.com>:

Inside of absl::string_view::copy, use absl::string_view::traits_type::copy instead of std:copy to do the actual work.  This both follows the C++ standard more closely and avoids avoid MSVC unchecked iterator warnings.

PiperOrigin-RevId: 263430502

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c06bf74236e12c7c1c97bfcbbc9d29bd65d6b36c by Andy Soffer <asoffer@google.com>:

Remove force-inlining attributes. Benchmarking results indicate that they are creating meaningful performance differences.

PiperOrigin-RevId: 263364896

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ec4fa6eac958a9521456201b138784f55d3b17bc by Abseil Team <absl-team@google.com>:

Make BM_Fill benchmarks more representative.

PiperOrigin-RevId: 263349482

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4ae280b4eb31d9cb58e847eb670473340f7778c1 by Derek Mauro <dmauro@google.com>:

Fix new -Wdeprecated-copy warning in gcc9

PiperOrigin-RevId: 263348118

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d238a92f452a5c35686f9c71596fdd1fe62090a2 by Matt Calabrese <calabrese@google.com>:

The std::is_trivially_xxx fail on versions of GCC up until 7.4 due to faulty underlying intrinsics, but our emulation succeeds. Update our traits to not compare against the standard library implementation in these versions.

PiperOrigin-RevId: 263209457
GitOrigin-RevId: f28b989d5161230c6561e923b458c797a96bcf90
Change-Id: I4c41db5928ba71e243aeace4420e06d1a2df0b5b
2019-08-15 14:36:45 -04:00

472 lines
18 KiB
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//
// Copyright 2017 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// -----------------------------------------------------------------------------
// File: config.h
// -----------------------------------------------------------------------------
//
// This header file defines a set of macros for checking the presence of
// important compiler and platform features. Such macros can be used to
// produce portable code by parameterizing compilation based on the presence or
// lack of a given feature.
//
// We define a "feature" as some interface we wish to program to: for example,
// a library function or system call. A value of `1` indicates support for
// that feature; any other value indicates the feature support is undefined.
//
// Example:
//
// Suppose a programmer wants to write a program that uses the 'mmap()' system
// call. The Abseil macro for that feature (`ABSL_HAVE_MMAP`) allows you to
// selectively include the `mmap.h` header and bracket code using that feature
// in the macro:
//
// #include "absl/base/config.h"
//
// #ifdef ABSL_HAVE_MMAP
// #include "sys/mman.h"
// #endif //ABSL_HAVE_MMAP
//
// ...
// #ifdef ABSL_HAVE_MMAP
// void *ptr = mmap(...);
// ...
// #endif // ABSL_HAVE_MMAP
#ifndef ABSL_BASE_CONFIG_H_
#define ABSL_BASE_CONFIG_H_
// Included for the __GLIBC__ macro (or similar macros on other systems).
#include <limits.h>
#ifdef __cplusplus
// Included for __GLIBCXX__, _LIBCPP_VERSION
#include <cstddef>
#endif // __cplusplus
#if defined(__APPLE__)
// Included for TARGET_OS_IPHONE, __IPHONE_OS_VERSION_MIN_REQUIRED,
// __IPHONE_8_0.
#include <Availability.h>
#include <TargetConditionals.h>
#endif
#include "absl/base/policy_checks.h"
// -----------------------------------------------------------------------------
// Compiler Feature Checks
// -----------------------------------------------------------------------------
// ABSL_HAVE_BUILTIN()
//
// Checks whether the compiler supports a Clang Feature Checking Macro, and if
// so, checks whether it supports the provided builtin function "x" where x
// is one of the functions noted in
// https://clang.llvm.org/docs/LanguageExtensions.html
//
// Note: Use this macro to avoid an extra level of #ifdef __has_builtin check.
// http://releases.llvm.org/3.3/tools/clang/docs/LanguageExtensions.html
#ifdef __has_builtin
#define ABSL_HAVE_BUILTIN(x) __has_builtin(x)
#else
#define ABSL_HAVE_BUILTIN(x) 0
#endif
// ABSL_HAVE_TLS is defined to 1 when __thread should be supported.
// We assume __thread is supported on Linux when compiled with Clang or compiled
// against libstdc++ with _GLIBCXX_HAVE_TLS defined.
#ifdef ABSL_HAVE_TLS
#error ABSL_HAVE_TLS cannot be directly set
#elif defined(__linux__) && (defined(__clang__) || defined(_GLIBCXX_HAVE_TLS))
#define ABSL_HAVE_TLS 1
#endif
// ABSL_HAVE_STD_IS_TRIVIALLY_DESTRUCTIBLE
//
// Checks whether `std::is_trivially_destructible<T>` is supported.
//
// Notes: All supported compilers using libc++ support this feature, as does
// gcc >= 4.8.1 using libstdc++, and Visual Studio.
#ifdef ABSL_HAVE_STD_IS_TRIVIALLY_DESTRUCTIBLE
#error ABSL_HAVE_STD_IS_TRIVIALLY_DESTRUCTIBLE cannot be directly set
#elif defined(_LIBCPP_VERSION) || \
(!defined(__clang__) && defined(__GNUC__) && defined(__GLIBCXX__) && \
(__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 8))) || \
defined(_MSC_VER)
#define ABSL_HAVE_STD_IS_TRIVIALLY_DESTRUCTIBLE 1
#endif
// ABSL_HAVE_STD_IS_TRIVIALLY_CONSTRUCTIBLE
//
// Checks whether `std::is_trivially_default_constructible<T>` and
// `std::is_trivially_copy_constructible<T>` are supported.
// ABSL_HAVE_STD_IS_TRIVIALLY_ASSIGNABLE
//
// Checks whether `std::is_trivially_copy_assignable<T>` is supported.
// Notes: Clang with libc++ supports these features, as does gcc >= 5.1 with
// either libc++ or libstdc++, and Visual Studio (but not NVCC).
#if defined(ABSL_HAVE_STD_IS_TRIVIALLY_CONSTRUCTIBLE)
#error ABSL_HAVE_STD_IS_TRIVIALLY_CONSTRUCTIBLE cannot be directly set
#elif defined(ABSL_HAVE_STD_IS_TRIVIALLY_ASSIGNABLE)
#error ABSL_HAVE_STD_IS_TRIVIALLY_ASSIGNABLE cannot directly set
#elif (defined(__clang__) && defined(_LIBCPP_VERSION)) || \
(!defined(__clang__) && defined(__GNUC__) && \
(__GNUC__ > 7 || (__GNUC__ == 7 && __GNUC_MINOR__ >= 4)) && \
(defined(_LIBCPP_VERSION) || defined(__GLIBCXX__))) || \
(defined(_MSC_VER) && !defined(__NVCC__))
#define ABSL_HAVE_STD_IS_TRIVIALLY_CONSTRUCTIBLE 1
#define ABSL_HAVE_STD_IS_TRIVIALLY_ASSIGNABLE 1
#endif
// ABSL_HAVE_THREAD_LOCAL
//
// Checks whether C++11's `thread_local` storage duration specifier is
// supported.
#ifdef ABSL_HAVE_THREAD_LOCAL
#error ABSL_HAVE_THREAD_LOCAL cannot be directly set
#elif defined(__APPLE__)
// Notes:
// * Xcode's clang did not support `thread_local` until version 8, and
// even then not for all iOS < 9.0.
// * Xcode 9.3 started disallowing `thread_local` for 32-bit iOS simulator
// targeting iOS 9.x.
// * Xcode 10 moves the deployment target check for iOS < 9.0 to link time
// making __has_feature unreliable there.
//
// Otherwise, `__has_feature` is only supported by Clang so it has be inside
// `defined(__APPLE__)` check.
#if __has_feature(cxx_thread_local) && \
!(TARGET_OS_IPHONE && __IPHONE_OS_VERSION_MIN_REQUIRED < __IPHONE_9_0)
#define ABSL_HAVE_THREAD_LOCAL 1
#endif
#else // !defined(__APPLE__)
#define ABSL_HAVE_THREAD_LOCAL 1
#endif
// There are platforms for which TLS should not be used even though the compiler
// makes it seem like it's supported (Android NDK < r12b for example).
// This is primarily because of linker problems and toolchain misconfiguration:
// Abseil does not intend to support this indefinitely. Currently, the newest
// toolchain that we intend to support that requires this behavior is the
// r11 NDK - allowing for a 5 year support window on that means this option
// is likely to be removed around June of 2021.
// TLS isn't supported until NDK r12b per
// https://developer.android.com/ndk/downloads/revision_history.html
// Since NDK r16, `__NDK_MAJOR__` and `__NDK_MINOR__` are defined in
// <android/ndk-version.h>. For NDK < r16, users should define these macros,
// e.g. `-D__NDK_MAJOR__=11 -D__NKD_MINOR__=0` for NDK r11.
#if defined(__ANDROID__) && defined(__clang__)
#if __has_include(<android/ndk-version.h>)
#include <android/ndk-version.h>
#endif // __has_include(<android/ndk-version.h>)
#if defined(__ANDROID__) && defined(__clang__) && defined(__NDK_MAJOR__) && \
defined(__NDK_MINOR__) && \
((__NDK_MAJOR__ < 12) || ((__NDK_MAJOR__ == 12) && (__NDK_MINOR__ < 1)))
#undef ABSL_HAVE_TLS
#undef ABSL_HAVE_THREAD_LOCAL
#endif
#endif // defined(__ANDROID__) && defined(__clang__)
// Emscripten doesn't yet support `thread_local` or `__thread`.
// https://github.com/emscripten-core/emscripten/issues/3502
#if defined(__EMSCRIPTEN__)
#undef ABSL_HAVE_TLS
#undef ABSL_HAVE_THREAD_LOCAL
#endif // defined(__EMSCRIPTEN__)
// ABSL_HAVE_INTRINSIC_INT128
//
// Checks whether the __int128 compiler extension for a 128-bit integral type is
// supported.
//
// Note: __SIZEOF_INT128__ is defined by Clang and GCC when __int128 is
// supported, but we avoid using it in certain cases:
// * On Clang:
// * Building using Clang for Windows, where the Clang runtime library has
// 128-bit support only on LP64 architectures, but Windows is LLP64.
// * On Nvidia's nvcc:
// * nvcc also defines __GNUC__ and __SIZEOF_INT128__, but not all versions
// actually support __int128.
#ifdef ABSL_HAVE_INTRINSIC_INT128
#error ABSL_HAVE_INTRINSIC_INT128 cannot be directly set
#elif defined(__SIZEOF_INT128__)
#if (defined(__clang__) && !defined(_WIN32)) || \
(defined(__CUDACC__) && __CUDACC_VER_MAJOR__ >= 9) || \
(defined(__GNUC__) && !defined(__clang__) && !defined(__CUDACC__))
#define ABSL_HAVE_INTRINSIC_INT128 1
#elif defined(__CUDACC__)
// __CUDACC_VER__ is a full version number before CUDA 9, and is defined to a
// string explaining that it has been removed starting with CUDA 9. We use
// nested #ifs because there is no short-circuiting in the preprocessor.
// NOTE: `__CUDACC__` could be undefined while `__CUDACC_VER__` is defined.
#if __CUDACC_VER__ >= 70000
#define ABSL_HAVE_INTRINSIC_INT128 1
#endif // __CUDACC_VER__ >= 70000
#endif // defined(__CUDACC__)
#endif // ABSL_HAVE_INTRINSIC_INT128
// ABSL_HAVE_EXCEPTIONS
//
// Checks whether the compiler both supports and enables exceptions. Many
// compilers support a "no exceptions" mode that disables exceptions.
//
// Generally, when ABSL_HAVE_EXCEPTIONS is not defined:
//
// * Code using `throw` and `try` may not compile.
// * The `noexcept` specifier will still compile and behave as normal.
// * The `noexcept` operator may still return `false`.
//
// For further details, consult the compiler's documentation.
#ifdef ABSL_HAVE_EXCEPTIONS
#error ABSL_HAVE_EXCEPTIONS cannot be directly set.
#elif defined(__clang__)
// TODO(calabrese)
// Switch to using __cpp_exceptions when we no longer support versions < 3.6.
// For details on this check, see:
// http://releases.llvm.org/3.6.0/tools/clang/docs/ReleaseNotes.html#the-exceptions-macro
#if defined(__EXCEPTIONS) && __has_feature(cxx_exceptions)
#define ABSL_HAVE_EXCEPTIONS 1
#endif // defined(__EXCEPTIONS) && __has_feature(cxx_exceptions)
// Handle remaining special cases and default to exceptions being supported.
#elif !(defined(__GNUC__) && (__GNUC__ < 5) && !defined(__EXCEPTIONS)) && \
!(defined(__GNUC__) && (__GNUC__ >= 5) && !defined(__cpp_exceptions)) && \
!(defined(_MSC_VER) && !defined(_CPPUNWIND))
#define ABSL_HAVE_EXCEPTIONS 1
#endif
// -----------------------------------------------------------------------------
// Platform Feature Checks
// -----------------------------------------------------------------------------
// Currently supported operating systems and associated preprocessor
// symbols:
//
// Linux and Linux-derived __linux__
// Android __ANDROID__ (implies __linux__)
// Linux (non-Android) __linux__ && !__ANDROID__
// Darwin (macOS and iOS) __APPLE__
// Akaros (http://akaros.org) __ros__
// Windows _WIN32
// NaCL __native_client__
// AsmJS __asmjs__
// WebAssembly __wasm__
// Fuchsia __Fuchsia__
//
// Note that since Android defines both __ANDROID__ and __linux__, one
// may probe for either Linux or Android by simply testing for __linux__.
// ABSL_HAVE_MMAP
//
// Checks whether the platform has an mmap(2) implementation as defined in
// POSIX.1-2001.
#ifdef ABSL_HAVE_MMAP
#error ABSL_HAVE_MMAP cannot be directly set
#elif defined(__linux__) || defined(__APPLE__) || defined(__FreeBSD__) || \
defined(__ros__) || defined(__native_client__) || defined(__asmjs__) || \
defined(__wasm__) || defined(__Fuchsia__) || defined(__sun) || \
defined(__ASYLO__)
#define ABSL_HAVE_MMAP 1
#endif
// ABSL_HAVE_PTHREAD_GETSCHEDPARAM
//
// Checks whether the platform implements the pthread_(get|set)schedparam(3)
// functions as defined in POSIX.1-2001.
#ifdef ABSL_HAVE_PTHREAD_GETSCHEDPARAM
#error ABSL_HAVE_PTHREAD_GETSCHEDPARAM cannot be directly set
#elif defined(__linux__) || defined(__APPLE__) || defined(__FreeBSD__) || \
defined(__ros__)
#define ABSL_HAVE_PTHREAD_GETSCHEDPARAM 1
#endif
// ABSL_HAVE_SCHED_YIELD
//
// Checks whether the platform implements sched_yield(2) as defined in
// POSIX.1-2001.
#ifdef ABSL_HAVE_SCHED_YIELD
#error ABSL_HAVE_SCHED_YIELD cannot be directly set
#elif defined(__linux__) || defined(__ros__) || defined(__native_client__)
#define ABSL_HAVE_SCHED_YIELD 1
#endif
// ABSL_HAVE_SEMAPHORE_H
//
// Checks whether the platform supports the <semaphore.h> header and sem_open(3)
// family of functions as standardized in POSIX.1-2001.
//
// Note: While Apple provides <semaphore.h> for both iOS and macOS, it is
// explicitly deprecated and will cause build failures if enabled for those
// platforms. We side-step the issue by not defining it here for Apple
// platforms.
#ifdef ABSL_HAVE_SEMAPHORE_H
#error ABSL_HAVE_SEMAPHORE_H cannot be directly set
#elif defined(__linux__) || defined(__ros__)
#define ABSL_HAVE_SEMAPHORE_H 1
#endif
// ABSL_HAVE_ALARM
//
// Checks whether the platform supports the <signal.h> header and alarm(2)
// function as standardized in POSIX.1-2001.
#ifdef ABSL_HAVE_ALARM
#error ABSL_HAVE_ALARM cannot be directly set
#elif defined(__GOOGLE_GRTE_VERSION__)
// feature tests for Google's GRTE
#define ABSL_HAVE_ALARM 1
#elif defined(__GLIBC__)
// feature test for glibc
#define ABSL_HAVE_ALARM 1
#elif defined(_MSC_VER)
// feature tests for Microsoft's library
#elif defined(__EMSCRIPTEN__)
// emscripten doesn't support signals
#elif defined(__native_client__)
#else
// other standard libraries
#define ABSL_HAVE_ALARM 1
#endif
// ABSL_IS_LITTLE_ENDIAN
// ABSL_IS_BIG_ENDIAN
//
// Checks the endianness of the platform.
//
// Notes: uses the built in endian macros provided by GCC (since 4.6) and
// Clang (since 3.2); see
// https://gcc.gnu.org/onlinedocs/cpp/Common-Predefined-Macros.html.
// Otherwise, if _WIN32, assume little endian. Otherwise, bail with an error.
#if defined(ABSL_IS_BIG_ENDIAN)
#error "ABSL_IS_BIG_ENDIAN cannot be directly set."
#endif
#if defined(ABSL_IS_LITTLE_ENDIAN)
#error "ABSL_IS_LITTLE_ENDIAN cannot be directly set."
#endif
#if (defined(__BYTE_ORDER__) && defined(__ORDER_LITTLE_ENDIAN__) && \
__BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__)
#define ABSL_IS_LITTLE_ENDIAN 1
#elif defined(__BYTE_ORDER__) && defined(__ORDER_BIG_ENDIAN__) && \
__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
#define ABSL_IS_BIG_ENDIAN 1
#elif defined(_WIN32)
#define ABSL_IS_LITTLE_ENDIAN 1
#else
#error "absl endian detection needs to be set up for your compiler"
#endif
// macOS 10.13 and iOS 10.11 don't let you use <any>, <optional>, or <variant>
// even though the headers exist and are publicly noted to work. See
// https://github.com/abseil/abseil-cpp/issues/207 and
// https://developer.apple.com/documentation/xcode_release_notes/xcode_10_release_notes
// libc++ spells out the availability requirements in the file
// llvm-project/libcxx/include/__config via the #define
// _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS.
#if defined(__APPLE__) && defined(_LIBCPP_VERSION) && \
((defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) && \
__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 101400) || \
(defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__) && \
__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__ < 120000) || \
(defined(__ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__) && \
__ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__ < 120000) || \
(defined(__ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__) && \
__ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__ < 50000))
#define ABSL_INTERNAL_APPLE_CXX17_TYPES_UNAVAILABLE 1
#else
#define ABSL_INTERNAL_APPLE_CXX17_TYPES_UNAVAILABLE 0
#endif
// ABSL_HAVE_STD_ANY
//
// Checks whether C++17 std::any is available by checking whether <any> exists.
#ifdef ABSL_HAVE_STD_ANY
#error "ABSL_HAVE_STD_ANY cannot be directly set."
#endif
#ifdef __has_include
#if __has_include(<any>) && __cplusplus >= 201703L && \
!ABSL_INTERNAL_APPLE_CXX17_TYPES_UNAVAILABLE
#define ABSL_HAVE_STD_ANY 1
#endif
#endif
// ABSL_HAVE_STD_OPTIONAL
//
// Checks whether C++17 std::optional is available.
#ifdef ABSL_HAVE_STD_OPTIONAL
#error "ABSL_HAVE_STD_OPTIONAL cannot be directly set."
#endif
#ifdef __has_include
#if __has_include(<optional>) && __cplusplus >= 201703L && \
!ABSL_INTERNAL_APPLE_CXX17_TYPES_UNAVAILABLE
#define ABSL_HAVE_STD_OPTIONAL 1
#endif
#endif
// ABSL_HAVE_STD_VARIANT
//
// Checks whether C++17 std::variant is available.
#ifdef ABSL_HAVE_STD_VARIANT
#error "ABSL_HAVE_STD_VARIANT cannot be directly set."
#endif
#ifdef __has_include
#if __has_include(<variant>) && __cplusplus >= 201703L && \
!ABSL_INTERNAL_APPLE_CXX17_TYPES_UNAVAILABLE
#define ABSL_HAVE_STD_VARIANT 1
#endif
#endif
// ABSL_HAVE_STD_STRING_VIEW
//
// Checks whether C++17 std::string_view is available.
#ifdef ABSL_HAVE_STD_STRING_VIEW
#error "ABSL_HAVE_STD_STRING_VIEW cannot be directly set."
#endif
#ifdef __has_include
#if __has_include(<string_view>) && __cplusplus >= 201703L
#define ABSL_HAVE_STD_STRING_VIEW 1
#endif
#endif
// For MSVC, `__has_include` is supported in VS 2017 15.3, which is later than
// the support for <optional>, <any>, <string_view>, <variant>. So we use
// _MSC_VER to check whether we have VS 2017 RTM (when <optional>, <any>,
// <string_view>, <variant> is implemented) or higher. Also, `__cplusplus` is
// not correctly set by MSVC, so we use `_MSVC_LANG` to check the language
// version.
// TODO(zhangxy): fix tests before enabling aliasing for `std::any`.
#if defined(_MSC_VER) && _MSC_VER >= 1910 && \
((defined(_MSVC_LANG) && _MSVC_LANG > 201402) || __cplusplus > 201402)
// #define ABSL_HAVE_STD_ANY 1
#define ABSL_HAVE_STD_OPTIONAL 1
#define ABSL_HAVE_STD_VARIANT 1
#define ABSL_HAVE_STD_STRING_VIEW 1
#endif
// In debug mode, MSVC 2017's std::variant throws a EXCEPTION_ACCESS_VIOLATION
// SEH exception from emplace for variant<SomeStruct> when constructing the
// struct can throw. This defeats some of variant_test and
// variant_exception_safety_test.
#if defined(_MSC_VER) && _MSC_VER >= 1700 && defined(_DEBUG)
#define ABSL_INTERNAL_MSVC_2017_DBG_MODE
#endif
#endif // ABSL_BASE_CONFIG_H_
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