Source/WTF/wtf/Compiler.h - WebKit - Git at Google

 /*
  * Copyright (C) 2011-2020 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  *
  * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */

 #pragma once

 /* COMPILER() - the compiler being used to build the project */
 #define COMPILER(WTF_FEATURE) (defined WTF_COMPILER_##WTF_FEATURE  && WTF_COMPILER_##WTF_FEATURE)

 /* COMPILER_SUPPORTS() - whether the compiler being used to build the project supports the given feature. */
 #define COMPILER_SUPPORTS(WTF_COMPILER_FEATURE) (defined WTF_COMPILER_SUPPORTS_##WTF_COMPILER_FEATURE  && WTF_COMPILER_SUPPORTS_##WTF_COMPILER_FEATURE)

 /* COMPILER_QUIRK() - whether the compiler being used to build the project requires a given quirk. */
 #define COMPILER_QUIRK(WTF_COMPILER_QUIRK) (defined WTF_COMPILER_QUIRK_##WTF_COMPILER_QUIRK  && WTF_COMPILER_QUIRK_##WTF_COMPILER_QUIRK)

 /* COMPILER_HAS_CLANG_BUILTIN() - whether the compiler supports a particular clang builtin. */
 #ifdef __has_builtin
 #define COMPILER_HAS_CLANG_BUILTIN(x) __has_builtin(x)
 #else
 #define COMPILER_HAS_CLANG_BUILTIN(x) 0
 #endif

 /* COMPILER_HAS_CLANG_FEATURE() - whether the compiler supports a particular language or library feature. */
 /* http://clang.llvm.org/docs/LanguageExtensions.html#has-feature-and-has-extension */
 #ifdef __has_feature
 #define COMPILER_HAS_CLANG_FEATURE(x) __has_feature(x)
 #else
 #define COMPILER_HAS_CLANG_FEATURE(x) 0
 #endif

 /* COMPILER_HAS_CLANG_DECLSPEC() - whether the compiler supports a Microsoft style __declspec attribute. */
 /* https://clang.llvm.org/docs/LanguageExtensions.html#has-declspec-attribute */
 #ifdef __has_declspec_attribute
 #define COMPILER_HAS_CLANG_DECLSPEC(x) __has_declspec_attribute(x)
 #else
 #define COMPILER_HAS_CLANG_DECLSPEC(x) 0
 #endif

 /* ==== COMPILER() - primary detection of the compiler being used to build the project, in alphabetical order ==== */

 /* COMPILER(CLANG) - Clang  */

 #if defined(__clang__)
 #define WTF_COMPILER_CLANG 1
 #define WTF_COMPILER_SUPPORTS_BLOCKS COMPILER_HAS_CLANG_FEATURE(blocks)
 #define WTF_COMPILER_SUPPORTS_C_STATIC_ASSERT COMPILER_HAS_CLANG_FEATURE(c_static_assert)
 #define WTF_COMPILER_SUPPORTS_CXX_EXCEPTIONS COMPILER_HAS_CLANG_FEATURE(cxx_exceptions)
 #define WTF_COMPILER_SUPPORTS_BUILTIN_IS_TRIVIALLY_COPYABLE COMPILER_HAS_CLANG_FEATURE(is_trivially_copyable)

 #ifdef __cplusplus
 #if __cplusplus <= 201103L
 #define WTF_CPP_STD_VER 11
 #elif __cplusplus <= 201402L
 #define WTF_CPP_STD_VER 14
 #elif __cplusplus <= 201703L
 #define WTF_CPP_STD_VER 17
 #endif
 #endif

 #endif // defined(__clang__)

 /* COMPILER(GCC_COMPATIBLE) - GNU Compiler Collection or compatibles */
 #if defined(__GNUC__)
 #define WTF_COMPILER_GCC_COMPATIBLE 1
 #endif

 /* COMPILER(GCC) - GNU Compiler Collection */
 /* Note: This section must come after the Clang section since we check !COMPILER(CLANG) here. */
 #if COMPILER(GCC_COMPATIBLE) && !COMPILER(CLANG)
 #define WTF_COMPILER_GCC 1

 #define GCC_VERSION (__GNUC__ * 10000 + __GNUC_MINOR__ * 100 + __GNUC_PATCHLEVEL__)
 #define GCC_VERSION_AT_LEAST(major, minor, patch) (GCC_VERSION >= (major * 10000 + minor * 100 + patch))

 #if defined(__STDC_VERSION__) && __STDC_VERSION__ >= 201112L
 #define WTF_COMPILER_SUPPORTS_C_STATIC_ASSERT 1
 #endif

 #endif /* COMPILER(GCC) */

 #if COMPILER(GCC_COMPATIBLE) && defined(NDEBUG) && !defined(__OPTIMIZE__) && !defined(RELEASE_WITHOUT_OPTIMIZATIONS)
 #error "Building release without compiler optimizations: WebKit will be slow. Set -DRELEASE_WITHOUT_OPTIMIZATIONS if this is intended."
 #endif

 /* COMPILER(MINGW) - MinGW GCC */

 #if defined(__MINGW32__)
 #define WTF_COMPILER_MINGW 1
 #include <_mingw.h>
 #endif

 /* COMPILER(MINGW64) - mingw-w64 GCC - used as additional check to exclude mingw.org specific functions */

 /* Note: This section must come after the MinGW section since we check COMPILER(MINGW) here. */

 #if COMPILER(MINGW) && defined(__MINGW64_VERSION_MAJOR) /* best way to check for mingw-w64 vs mingw.org */
 #define WTF_COMPILER_MINGW64 1
 #endif

 /* COMPILER(MSVC) - Microsoft Visual C++ */

 #if defined(_MSC_VER)

 #define WTF_COMPILER_MSVC 1

 #if _MSC_VER < 1910
 #error "Please use a newer version of Visual Studio. WebKit requires VS2017 or newer to compile."
 #endif

 #endif

 #if !COMPILER(CLANG) && !COMPILER(MSVC)
 #define WTF_COMPILER_QUIRK_CONSIDERS_UNREACHABLE_CODE 1
 #endif

 /* ==== COMPILER_SUPPORTS - additional compiler feature detection, in alphabetical order ==== */

 /* COMPILER_SUPPORTS(EABI) */

 #if defined(__ARM_EABI__) || defined(__EABI__)
 #define WTF_COMPILER_SUPPORTS_EABI 1
 #endif

 /* ASAN_ENABLED and SUPPRESS_ASAN */

 #ifdef __SANITIZE_ADDRESS__
 #define ASAN_ENABLED 1
 #else
 #define ASAN_ENABLED COMPILER_HAS_CLANG_FEATURE(address_sanitizer)
 #endif

 #if ASAN_ENABLED
 #define SUPPRESS_ASAN __attribute__((no_sanitize_address))
 #else
 #define SUPPRESS_ASAN
 #endif

 /* TSAN_ENABLED and SUPPRESS_TSAN */

 #ifdef __SANITIZE_THREAD__
 #define TSAN_ENABLED 1
 #else
 #define TSAN_ENABLED COMPILER_HAS_CLANG_FEATURE(thread_sanitizer)
 #endif

 #if TSAN_ENABLED
 #define SUPPRESS_TSAN __attribute__((no_sanitize_thread))
 #else
 #define SUPPRESS_TSAN
 #endif

 /* ==== Compiler-independent macros for various compiler features, in alphabetical order ==== */

 /* ALWAYS_INLINE */

 /* In GCC functions marked with no_sanitize_address cannot call functions that are marked with always_inline and not marked with no_sanitize_address.
  * Therefore we need to give up on the enforcement of ALWAYS_INLINE when bulding with ASAN. https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67368 */
 #if !defined(ALWAYS_INLINE) && COMPILER(GCC_COMPATIBLE) && defined(NDEBUG) && !COMPILER(MINGW) && !(COMPILER(GCC) && ASAN_ENABLED)
 #define ALWAYS_INLINE inline __attribute__((__always_inline__))
 #endif

 #if !defined(ALWAYS_INLINE) && COMPILER(MSVC) && defined(NDEBUG)
 #define ALWAYS_INLINE __forceinline
 #endif

 #if !defined(ALWAYS_INLINE)
 #define ALWAYS_INLINE inline
 #endif

 #if COMPILER(MSVC)
 #define ALWAYS_INLINE_EXCEPT_MSVC inline
 #else
 #define ALWAYS_INLINE_EXCEPT_MSVC ALWAYS_INLINE
 #endif

 /* WTF_EXTERN_C_{BEGIN, END} */

 #ifdef __cplusplus
 #define WTF_EXTERN_C_BEGIN extern "C" {
 #define WTF_EXTERN_C_END }
 #else
 #define WTF_EXTERN_C_BEGIN
 #define WTF_EXTERN_C_END
 #endif

 /* FALLTHROUGH */

 #if !defined(FALLTHROUGH) && defined(__cplusplus) && defined(__has_cpp_attribute)

 #if __has_cpp_attribute(fallthrough)
 #define FALLTHROUGH [[fallthrough]]
 #elif __has_cpp_attribute(clang::fallthrough)
 #define FALLTHROUGH [[clang::fallthrough]]
 #elif __has_cpp_attribute(gnu::fallthrough)
 #define FALLTHROUGH [[gnu::fallthrough]]
 #endif

 #elif !defined(FALLTHROUGH) && !defined(__cplusplus)

 #if COMPILER(GCC_COMPATIBLE) && defined(__has_attribute)
 // Break out this #if to satisy some versions Windows compilers.
 #if __has_attribute(fallthrough)
 #define FALLTHROUGH __attribute__ ((fallthrough))
 #endif
 #endif

 #endif // !defined(FALLTHROUGH) && defined(__cplusplus) && defined(__has_cpp_attribute)

 #if !defined(FALLTHROUGH)
 #define FALLTHROUGH
 #endif

 /* LIKELY */

 #if !defined(LIKELY) && COMPILER(GCC_COMPATIBLE)
 #define LIKELY(x) __builtin_expect(!!(x), 1)
 #endif

 #if !defined(LIKELY)
 #define LIKELY(x) (x)
 #endif

 /* NEVER_INLINE */

 #if !defined(NEVER_INLINE) && COMPILER(GCC_COMPATIBLE)
 #define NEVER_INLINE __attribute__((__noinline__))
 #endif

 #if !defined(NEVER_INLINE) && COMPILER(MSVC)
 #define NEVER_INLINE __declspec(noinline)
 #endif

 #if !defined(NEVER_INLINE)
 #define NEVER_INLINE
 #endif

 /* NO_RETURN */

 #if !defined(NO_RETURN) && COMPILER(GCC_COMPATIBLE)
 #define NO_RETURN __attribute((__noreturn__))
 #endif

 #if !defined(NO_RETURN) && COMPILER(MSVC)
 #define NO_RETURN __declspec(noreturn)
 #endif

 #if !defined(NO_RETURN)
 #define NO_RETURN
 #endif

 /* NOT_TAIL_CALLED */

 #if !defined(NOT_TAIL_CALLED) && defined(__has_attribute)
 #if __has_attribute(not_tail_called)
 #define NOT_TAIL_CALLED __attribute__((not_tail_called))
 #endif
 #endif

 #if !defined(NOT_TAIL_CALLED)
 #define NOT_TAIL_CALLED
 #endif

 /* RETURNS_NONNULL */
 #if !defined(RETURNS_NONNULL) && COMPILER(GCC_COMPATIBLE)
 #define RETURNS_NONNULL __attribute__((returns_nonnull))
 #endif

 #if !defined(RETURNS_NONNULL)
 #define RETURNS_NONNULL
 #endif

 /* NO_RETURN_WITH_VALUE */

 #if !defined(NO_RETURN_WITH_VALUE) && !COMPILER(MSVC)
 #define NO_RETURN_WITH_VALUE NO_RETURN
 #endif

 #if !defined(NO_RETURN_WITH_VALUE)
 #define NO_RETURN_WITH_VALUE
 #endif

 /* OBJC_CLASS */

 #if !defined(OBJC_CLASS) && defined(__OBJC__)
 #define OBJC_CLASS @class
 #endif

 #if !defined(OBJC_CLASS)
 #define OBJC_CLASS class
 #endif

 /* OBJC_PROTOCOL */

 #if !defined(OBJC_PROTOCOL) && defined(__OBJC__)
 /* This forward-declares a protocol, then also creates a type of the same name based on NSObject.
  * This allows us to use "NSObject<MyProtocol> *" or "MyProtocol *" more-or-less interchangably. */
 #define OBJC_PROTOCOL(protocolName) @protocol protocolName; using protocolName = NSObject<protocolName>
 #endif

 #if !defined(OBJC_PROTOCOL)
 #define OBJC_PROTOCOL(protocolName) class protocolName
 #endif

 /* PURE_FUNCTION */

 #if !defined(PURE_FUNCTION) && COMPILER(GCC_COMPATIBLE)
 #define PURE_FUNCTION __attribute__((__pure__))
 #endif

 #if !defined(PURE_FUNCTION)
 #define PURE_FUNCTION
 #endif

 /* WK_UNUSED_INSTANCE_VARIABLE */

 #if !defined(WK_UNUSED_INSTANCE_VARIABLE) && COMPILER(GCC_COMPATIBLE)
 #define WK_UNUSED_INSTANCE_VARIABLE __attribute__((unused))
 #endif

 #if !defined(WK_UNUSED_INSTANCE_VARIABLE)
 #define WK_UNUSED_INSTANCE_VARIABLE
 #endif

 /* UNUSED_FUNCTION */

 #if !defined(UNUSED_FUNCTION) && COMPILER(GCC_COMPATIBLE)
 #define UNUSED_FUNCTION __attribute__((unused))
 #endif

 #if !defined(UNUSED_FUNCTION)
 #define UNUSED_FUNCTION
 #endif

 /* UNUSED_TYPE_ALIAS */

 #if !defined(UNUSED_TYPE_ALIAS) && COMPILER(GCC_COMPATIBLE)
 #define UNUSED_TYPE_ALIAS __attribute__((unused))
 #endif

 #if !defined(UNUSED_TYPE_ALIAS)
 #define UNUSED_TYPE_ALIAS
 #endif

 /* REFERENCED_FROM_ASM */

 #if !defined(REFERENCED_FROM_ASM) && COMPILER(GCC_COMPATIBLE)
 #define REFERENCED_FROM_ASM __attribute__((__used__))
 #endif

 #if !defined(REFERENCED_FROM_ASM)
 #define REFERENCED_FROM_ASM
 #endif

 /* UNLIKELY */

 #if !defined(UNLIKELY) && COMPILER(GCC_COMPATIBLE)
 #define UNLIKELY(x) __builtin_expect(!!(x), 0)
 #endif

 #if !defined(UNLIKELY)
 #define UNLIKELY(x) (x)
 #endif

 /* UNUSED_LABEL */

 /* Keep the compiler from complaining for a local label that is defined but not referenced. */
 /* Helpful when mixing hand-written and autogenerated code. */

 #if !defined(UNUSED_LABEL) && COMPILER(MSVC)
 #define UNUSED_LABEL(label) if (false) goto label
 #endif

 #if !defined(UNUSED_LABEL)
 #define UNUSED_LABEL(label) UNUSED_PARAM(&& label)
 #endif

 /* UNUSED_PARAM */

 #if !defined(UNUSED_PARAM)
 #define UNUSED_PARAM(variable) (void)variable
 #endif

 /* UNUSED_VARIABLE */
 #if !defined(UNUSED_VARIABLE)
 #define UNUSED_VARIABLE(variable) UNUSED_PARAM(variable)
 #endif

 /* WARN_UNUSED_RETURN */

 #if !defined(WARN_UNUSED_RETURN) && COMPILER(GCC_COMPATIBLE)
 #define WARN_UNUSED_RETURN __attribute__((__warn_unused_result__))
 #endif

 #if !defined(WARN_UNUSED_RETURN)
 #define WARN_UNUSED_RETURN
 #endif

 /* DEBUGGER_ANNOTATION_MARKER */

 #if !defined(DEBUGGER_ANNOTATION_MARKER) && COMPILER(GCC)
 #define DEBUGGER_ANNOTATION_MARKER(name) \
     __attribute__((__no_reorder__)) void name(void) { __asm__(""); }
 #endif

 #if !defined(DEBUGGER_ANNOTATION_MARKER)
 #define DEBUGGER_ANNOTATION_MARKER(name)
 #endif

 #if !defined(__has_include) && COMPILER(MSVC)
 #define __has_include(path) 0
 #endif

 /* IGNORE_WARNINGS */

 /* Can't use WTF_CONCAT() and STRINGIZE() because they are defined in
  * StdLibExtras.h, which includes this file. */
 #define _COMPILER_CONCAT_I(a, b) a ## b
 #define _COMPILER_CONCAT(a, b) _COMPILER_CONCAT_I(a, b)

 #define _COMPILER_STRINGIZE(exp) #exp

 #define _COMPILER_WARNING_NAME(warning) "-W" warning

 #if COMPILER(GCC) || COMPILER(CLANG)
 #define IGNORE_WARNINGS_BEGIN_COND(cond, compiler, warning) \
     _Pragma(_COMPILER_STRINGIZE(compiler diagnostic push)) \
     _COMPILER_CONCAT(IGNORE_WARNINGS_BEGIN_IMPL_, cond)(compiler, warning)

 /* Condition is either 1 (true) or 0 (false, do nothing). */
 #define IGNORE_WARNINGS_BEGIN_IMPL_1(compiler, warning) \
     _Pragma(_COMPILER_STRINGIZE(compiler diagnostic ignored warning))
 #define IGNORE_WARNINGS_BEGIN_IMPL_0(compiler, warning)

 #if defined(__has_warning)
 #define IGNORE_WARNINGS_END_IMPL(compiler) _Pragma(_COMPILER_STRINGIZE(compiler diagnostic pop))
 #else
 #define IGNORE_WARNINGS_END_IMPL(compiler) \
     _Pragma(_COMPILER_STRINGIZE(compiler diagnostic pop)) \
     _Pragma(_COMPILER_STRINGIZE(compiler diagnostic pop))
 #endif

 #if defined(__has_warning)
 #define _IGNORE_WARNINGS_BEGIN_IMPL(compiler, warning) \
     IGNORE_WARNINGS_BEGIN_COND(__has_warning(warning), compiler, warning)
 #else
 /* Suppress -Wpragmas to dodge warnings about attempts to suppress unrecognized warnings. */
 #define _IGNORE_WARNINGS_BEGIN_IMPL(compiler, warning) \
     IGNORE_WARNINGS_BEGIN_COND(1, compiler, "-Wpragmas") \
     IGNORE_WARNINGS_BEGIN_COND(1, compiler, warning)
 #endif

 #define IGNORE_WARNINGS_BEGIN_IMPL(compiler, warning) \
     _IGNORE_WARNINGS_BEGIN_IMPL(compiler, _COMPILER_WARNING_NAME(warning))

 #endif /* COMPILER(GCC) || COMPILER(CLANG) */


 #if COMPILER(GCC)
 #define IGNORE_GCC_WARNINGS_BEGIN(warning) IGNORE_WARNINGS_BEGIN_IMPL(GCC, warning)
 #define IGNORE_GCC_WARNINGS_END IGNORE_WARNINGS_END_IMPL(GCC)
 #else
 #define IGNORE_GCC_WARNINGS_BEGIN(warning)
 #define IGNORE_GCC_WARNINGS_END
 #endif

 #if COMPILER(CLANG)
 #define IGNORE_CLANG_WARNINGS_BEGIN(warning) IGNORE_WARNINGS_BEGIN_IMPL(clang, warning)
 #define IGNORE_CLANG_WARNINGS_END IGNORE_WARNINGS_END_IMPL(clang)
 #else
 #define IGNORE_CLANG_WARNINGS_BEGIN(warning)
 #define IGNORE_CLANG_WARNINGS_END
 #endif

 #if COMPILER(GCC) || COMPILER(CLANG)
 #define IGNORE_WARNINGS_BEGIN(warning) IGNORE_WARNINGS_BEGIN_IMPL(GCC, warning)
 #define IGNORE_WARNINGS_END IGNORE_WARNINGS_END_IMPL(GCC)
 #else
 #define IGNORE_WARNINGS_BEGIN(warning)
 #define IGNORE_WARNINGS_END
 #endif

 #define ALLOW_DEPRECATED_DECLARATIONS_BEGIN IGNORE_WARNINGS_BEGIN("deprecated-declarations")
 #define ALLOW_DEPRECATED_DECLARATIONS_END IGNORE_WARNINGS_END

 #define ALLOW_DEPRECATED_IMPLEMENTATIONS_BEGIN IGNORE_WARNINGS_BEGIN("deprecated-implementations")
 #define ALLOW_DEPRECATED_IMPLEMENTATIONS_END IGNORE_WARNINGS_END

 #define ALLOW_NEW_API_WITHOUT_GUARDS_BEGIN IGNORE_CLANG_WARNINGS_BEGIN("unguarded-availability-new")
 #define ALLOW_NEW_API_WITHOUT_GUARDS_END IGNORE_CLANG_WARNINGS_END

 #define ALLOW_UNUSED_PARAMETERS_BEGIN IGNORE_WARNINGS_BEGIN("unused-parameter")
 #define ALLOW_UNUSED_PARAMETERS_END IGNORE_WARNINGS_END

 #define ALLOW_NONLITERAL_FORMAT_BEGIN IGNORE_WARNINGS_BEGIN("format-nonliteral")
 #define ALLOW_NONLITERAL_FORMAT_END IGNORE_WARNINGS_END

 #define IGNORE_RETURN_TYPE_WARNINGS_BEGIN IGNORE_WARNINGS_BEGIN("return-type")
 #define IGNORE_RETURN_TYPE_WARNINGS_END IGNORE_WARNINGS_END

 #define IGNORE_NULL_CHECK_WARNINGS_BEGIN IGNORE_WARNINGS_BEGIN("nonnull")
 #define IGNORE_NULL_CHECK_WARNINGS_END IGNORE_WARNINGS_END

 /* NO_UNIQUE_ADDRESS */

 #if !defined(NO_UNIQUE_ADDRESS) && defined(__has_cpp_attribute)
 #if __has_cpp_attribute(no_unique_address)
 #define NO_UNIQUE_ADDRESS [[no_unique_address]] // NOLINT: check-webkit-style does not understand annotations.
 #endif
 #endif

 #if !defined(NO_UNIQUE_ADDRESS)
 #define NO_UNIQUE_ADDRESS
 #endif

 /* TLS_MODEL_INITIAL_EXEC */

 #if !defined(TLS_MODEL_INITIAL_EXEC) && defined(__has_attribute)
 #if __has_attribute(tls_model)
 #define TLS_MODEL_INITIAL_EXEC __attribute__((tls_model("initial-exec")))
 #endif
 #endif

 #if !defined(TLS_MODEL_INITIAL_EXEC)
 #define TLS_MODEL_INITIAL_EXEC
 #endif
	/*
	* Copyright (C) 2011-2020 Apple Inc. All rights reserved.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions
	* are met:
	* 1. Redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer.
	* 2. Redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer in the
	* documentation and/or other materials provided with the distribution.
	*
	* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
	* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
	* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
	* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
	* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
	* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
	* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
	* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
	* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	*/

	#pragma once

	/* COMPILER() - the compiler being used to build the project */
	#define COMPILER(WTF_FEATURE) (defined WTF_COMPILER_##WTF_FEATURE && WTF_COMPILER_##WTF_FEATURE)

	/* COMPILER_SUPPORTS() - whether the compiler being used to build the project supports the given feature. */
	#define COMPILER_SUPPORTS(WTF_COMPILER_FEATURE) (defined WTF_COMPILER_SUPPORTS_##WTF_COMPILER_FEATURE && WTF_COMPILER_SUPPORTS_##WTF_COMPILER_FEATURE)

	/* COMPILER_QUIRK() - whether the compiler being used to build the project requires a given quirk. */
	#define COMPILER_QUIRK(WTF_COMPILER_QUIRK) (defined WTF_COMPILER_QUIRK_##WTF_COMPILER_QUIRK && WTF_COMPILER_QUIRK_##WTF_COMPILER_QUIRK)

	/* COMPILER_HAS_CLANG_BUILTIN() - whether the compiler supports a particular clang builtin. */
	#ifdef __has_builtin
	#define COMPILER_HAS_CLANG_BUILTIN(x) __has_builtin(x)
	#else
	#define COMPILER_HAS_CLANG_BUILTIN(x) 0
	#endif

	/* COMPILER_HAS_CLANG_FEATURE() - whether the compiler supports a particular language or library feature. */
	/* http://clang.llvm.org/docs/LanguageExtensions.html#has-feature-and-has-extension */
	#ifdef __has_feature
	#define COMPILER_HAS_CLANG_FEATURE(x) __has_feature(x)
	#else
	#define COMPILER_HAS_CLANG_FEATURE(x) 0
	#endif

	/* COMPILER_HAS_CLANG_DECLSPEC() - whether the compiler supports a Microsoft style __declspec attribute. */
	/* https://clang.llvm.org/docs/LanguageExtensions.html#has-declspec-attribute */
	#ifdef __has_declspec_attribute
	#define COMPILER_HAS_CLANG_DECLSPEC(x) __has_declspec_attribute(x)
	#else
	#define COMPILER_HAS_CLANG_DECLSPEC(x) 0
	#endif

	/* ==== COMPILER() - primary detection of the compiler being used to build the project, in alphabetical order ==== */

	/* COMPILER(CLANG) - Clang */

	#if defined(__clang__)
	#define WTF_COMPILER_CLANG 1
	#define WTF_COMPILER_SUPPORTS_BLOCKS COMPILER_HAS_CLANG_FEATURE(blocks)
	#define WTF_COMPILER_SUPPORTS_C_STATIC_ASSERT COMPILER_HAS_CLANG_FEATURE(c_static_assert)
	#define WTF_COMPILER_SUPPORTS_CXX_EXCEPTIONS COMPILER_HAS_CLANG_FEATURE(cxx_exceptions)
	#define WTF_COMPILER_SUPPORTS_BUILTIN_IS_TRIVIALLY_COPYABLE COMPILER_HAS_CLANG_FEATURE(is_trivially_copyable)

	#ifdef __cplusplus
	#if __cplusplus <= 201103L
	#define WTF_CPP_STD_VER 11
	#elif __cplusplus <= 201402L
	#define WTF_CPP_STD_VER 14
	#elif __cplusplus <= 201703L
	#define WTF_CPP_STD_VER 17
	#endif
	#endif

	#endif // defined(__clang__)

	/* COMPILER(GCC_COMPATIBLE) - GNU Compiler Collection or compatibles */
	#if defined(__GNUC__)
	#define WTF_COMPILER_GCC_COMPATIBLE 1
	#endif

	/* COMPILER(GCC) - GNU Compiler Collection */
	/* Note: This section must come after the Clang section since we check !COMPILER(CLANG) here. */
	#if COMPILER(GCC_COMPATIBLE) && !COMPILER(CLANG)
	#define WTF_COMPILER_GCC 1

	#define GCC_VERSION (__GNUC__ * 10000 + __GNUC_MINOR__ * 100 + __GNUC_PATCHLEVEL__)
	#define GCC_VERSION_AT_LEAST(major, minor, patch) (GCC_VERSION >= (major * 10000 + minor * 100 + patch))

	#if defined(__STDC_VERSION__) && __STDC_VERSION__ >= 201112L
	#define WTF_COMPILER_SUPPORTS_C_STATIC_ASSERT 1
	#endif

	#endif /* COMPILER(GCC) */

	#if COMPILER(GCC_COMPATIBLE) && defined(NDEBUG) && !defined(__OPTIMIZE__) && !defined(RELEASE_WITHOUT_OPTIMIZATIONS)
	#error "Building release without compiler optimizations: WebKit will be slow. Set -DRELEASE_WITHOUT_OPTIMIZATIONS if this is intended."
	#endif

	/* COMPILER(MINGW) - MinGW GCC */

	#if defined(__MINGW32__)
	#define WTF_COMPILER_MINGW 1
	#include <_mingw.h>
	#endif

	/* COMPILER(MINGW64) - mingw-w64 GCC - used as additional check to exclude mingw.org specific functions */

	/* Note: This section must come after the MinGW section since we check COMPILER(MINGW) here. */

	#if COMPILER(MINGW) && defined(__MINGW64_VERSION_MAJOR) /* best way to check for mingw-w64 vs mingw.org */
	#define WTF_COMPILER_MINGW64 1
	#endif

	/* COMPILER(MSVC) - Microsoft Visual C++ */

	#if defined(_MSC_VER)

	#define WTF_COMPILER_MSVC 1

	#if _MSC_VER < 1910
	#error "Please use a newer version of Visual Studio. WebKit requires VS2017 or newer to compile."
	#endif

	#endif

	#if !COMPILER(CLANG) && !COMPILER(MSVC)
	#define WTF_COMPILER_QUIRK_CONSIDERS_UNREACHABLE_CODE 1
	#endif

	/* ==== COMPILER_SUPPORTS - additional compiler feature detection, in alphabetical order ==== */

	/* COMPILER_SUPPORTS(EABI) */

	#if defined(__ARM_EABI__) \|\| defined(__EABI__)
	#define WTF_COMPILER_SUPPORTS_EABI 1
	#endif

	/* ASAN_ENABLED and SUPPRESS_ASAN */

	#ifdef __SANITIZE_ADDRESS__
	#define ASAN_ENABLED 1
	#else
	#define ASAN_ENABLED COMPILER_HAS_CLANG_FEATURE(address_sanitizer)
	#endif

	#if ASAN_ENABLED
	#define SUPPRESS_ASAN __attribute__((no_sanitize_address))
	#else
	#define SUPPRESS_ASAN
	#endif

	/* TSAN_ENABLED and SUPPRESS_TSAN */

	#ifdef __SANITIZE_THREAD__
	#define TSAN_ENABLED 1
	#else
	#define TSAN_ENABLED COMPILER_HAS_CLANG_FEATURE(thread_sanitizer)
	#endif

	#if TSAN_ENABLED
	#define SUPPRESS_TSAN __attribute__((no_sanitize_thread))
	#else
	#define SUPPRESS_TSAN
	#endif

	/* ==== Compiler-independent macros for various compiler features, in alphabetical order ==== */

	/* ALWAYS_INLINE */

	/* In GCC functions marked with no_sanitize_address cannot call functions that are marked with always_inline and not marked with no_sanitize_address.
	* Therefore we need to give up on the enforcement of ALWAYS_INLINE when bulding with ASAN. https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67368 */
	#if !defined(ALWAYS_INLINE) && COMPILER(GCC_COMPATIBLE) && defined(NDEBUG) && !COMPILER(MINGW) && !(COMPILER(GCC) && ASAN_ENABLED)
	#define ALWAYS_INLINE inline __attribute__((__always_inline__))
	#endif

	#if !defined(ALWAYS_INLINE) && COMPILER(MSVC) && defined(NDEBUG)
	#define ALWAYS_INLINE __forceinline
	#endif

	#if !defined(ALWAYS_INLINE)
	#define ALWAYS_INLINE inline
	#endif

	#if COMPILER(MSVC)
	#define ALWAYS_INLINE_EXCEPT_MSVC inline
	#else
	#define ALWAYS_INLINE_EXCEPT_MSVC ALWAYS_INLINE
	#endif

	/* WTF_EXTERN_C_{BEGIN, END} */

	#ifdef __cplusplus
	#define WTF_EXTERN_C_BEGIN extern "C" {
	#define WTF_EXTERN_C_END }
	#else
	#define WTF_EXTERN_C_BEGIN
	#define WTF_EXTERN_C_END
	#endif

	/* FALLTHROUGH */

	#if !defined(FALLTHROUGH) && defined(__cplusplus) && defined(__has_cpp_attribute)

	#if __has_cpp_attribute(fallthrough)
	#define FALLTHROUGH [[fallthrough]]
	#elif __has_cpp_attribute(clang::fallthrough)
	#define FALLTHROUGH [[clang::fallthrough]]
	#elif __has_cpp_attribute(gnu::fallthrough)
	#define FALLTHROUGH [[gnu::fallthrough]]
	#endif

	#elif !defined(FALLTHROUGH) && !defined(__cplusplus)

	#if COMPILER(GCC_COMPATIBLE) && defined(__has_attribute)
	// Break out this #if to satisy some versions Windows compilers.
	#if __has_attribute(fallthrough)
	#define FALLTHROUGH __attribute__ ((fallthrough))
	#endif
	#endif

	#endif // !defined(FALLTHROUGH) && defined(__cplusplus) && defined(__has_cpp_attribute)

	#if !defined(FALLTHROUGH)
	#define FALLTHROUGH
	#endif

	/* LIKELY */

	#if !defined(LIKELY) && COMPILER(GCC_COMPATIBLE)
	#define LIKELY(x) __builtin_expect(!!(x), 1)
	#endif

	#if !defined(LIKELY)
	#define LIKELY(x) (x)
	#endif

	/* NEVER_INLINE */

	#if !defined(NEVER_INLINE) && COMPILER(GCC_COMPATIBLE)
	#define NEVER_INLINE __attribute__((__noinline__))
	#endif

	#if !defined(NEVER_INLINE) && COMPILER(MSVC)
	#define NEVER_INLINE __declspec(noinline)
	#endif

	#if !defined(NEVER_INLINE)
	#define NEVER_INLINE
	#endif

	/* NO_RETURN */

	#if !defined(NO_RETURN) && COMPILER(GCC_COMPATIBLE)
	#define NO_RETURN __attribute((__noreturn__))
	#endif

	#if !defined(NO_RETURN) && COMPILER(MSVC)
	#define NO_RETURN __declspec(noreturn)
	#endif

	#if !defined(NO_RETURN)
	#define NO_RETURN
	#endif

	/* NOT_TAIL_CALLED */

	#if !defined(NOT_TAIL_CALLED) && defined(__has_attribute)
	#if __has_attribute(not_tail_called)
	#define NOT_TAIL_CALLED __attribute__((not_tail_called))
	#endif
	#endif

	#if !defined(NOT_TAIL_CALLED)
	#define NOT_TAIL_CALLED
	#endif

	/* RETURNS_NONNULL */
	#if !defined(RETURNS_NONNULL) && COMPILER(GCC_COMPATIBLE)
	#define RETURNS_NONNULL __attribute__((returns_nonnull))
	#endif

	#if !defined(RETURNS_NONNULL)
	#define RETURNS_NONNULL
	#endif

	/* NO_RETURN_WITH_VALUE */

	#if !defined(NO_RETURN_WITH_VALUE) && !COMPILER(MSVC)
	#define NO_RETURN_WITH_VALUE NO_RETURN
	#endif

	#if !defined(NO_RETURN_WITH_VALUE)
	#define NO_RETURN_WITH_VALUE
	#endif

	/* OBJC_CLASS */

	#if !defined(OBJC_CLASS) && defined(__OBJC__)
	#define OBJC_CLASS @class
	#endif

	#if !defined(OBJC_CLASS)
	#define OBJC_CLASS class
	#endif

	/* OBJC_PROTOCOL */

	#if !defined(OBJC_PROTOCOL) && defined(__OBJC__)
	/* This forward-declares a protocol, then also creates a type of the same name based on NSObject.
	* This allows us to use "NSObject<MyProtocol> " or "MyProtocol " more-or-less interchangably. */
	#define OBJC_PROTOCOL(protocolName) @protocol protocolName; using protocolName = NSObject<protocolName>
	#endif

	#if !defined(OBJC_PROTOCOL)
	#define OBJC_PROTOCOL(protocolName) class protocolName
	#endif

	/* PURE_FUNCTION */

	#if !defined(PURE_FUNCTION) && COMPILER(GCC_COMPATIBLE)
	#define PURE_FUNCTION __attribute__((__pure__))
	#endif

	#if !defined(PURE_FUNCTION)
	#define PURE_FUNCTION
	#endif

	/* WK_UNUSED_INSTANCE_VARIABLE */

	#if !defined(WK_UNUSED_INSTANCE_VARIABLE) && COMPILER(GCC_COMPATIBLE)
	#define WK_UNUSED_INSTANCE_VARIABLE __attribute__((unused))
	#endif

	#if !defined(WK_UNUSED_INSTANCE_VARIABLE)
	#define WK_UNUSED_INSTANCE_VARIABLE
	#endif

	/* UNUSED_FUNCTION */

	#if !defined(UNUSED_FUNCTION) && COMPILER(GCC_COMPATIBLE)
	#define UNUSED_FUNCTION __attribute__((unused))
	#endif

	#if !defined(UNUSED_FUNCTION)
	#define UNUSED_FUNCTION
	#endif

	/* UNUSED_TYPE_ALIAS */

	#if !defined(UNUSED_TYPE_ALIAS) && COMPILER(GCC_COMPATIBLE)
	#define UNUSED_TYPE_ALIAS __attribute__((unused))
	#endif

	#if !defined(UNUSED_TYPE_ALIAS)
	#define UNUSED_TYPE_ALIAS
	#endif

	/* REFERENCED_FROM_ASM */

	#if !defined(REFERENCED_FROM_ASM) && COMPILER(GCC_COMPATIBLE)
	#define REFERENCED_FROM_ASM __attribute__((__used__))
	#endif

	#if !defined(REFERENCED_FROM_ASM)
	#define REFERENCED_FROM_ASM
	#endif

	/* UNLIKELY */

	#if !defined(UNLIKELY) && COMPILER(GCC_COMPATIBLE)
	#define UNLIKELY(x) __builtin_expect(!!(x), 0)
	#endif

	#if !defined(UNLIKELY)
	#define UNLIKELY(x) (x)
	#endif

	/* UNUSED_LABEL */

	/* Keep the compiler from complaining for a local label that is defined but not referenced. */
	/* Helpful when mixing hand-written and autogenerated code. */

	#if !defined(UNUSED_LABEL) && COMPILER(MSVC)
	#define UNUSED_LABEL(label) if (false) goto label
	#endif

	#if !defined(UNUSED_LABEL)
	#define UNUSED_LABEL(label) UNUSED_PARAM(&& label)
	#endif

	/* UNUSED_PARAM */

	#if !defined(UNUSED_PARAM)
	#define UNUSED_PARAM(variable) (void)variable
	#endif

	/* UNUSED_VARIABLE */
	#if !defined(UNUSED_VARIABLE)
	#define UNUSED_VARIABLE(variable) UNUSED_PARAM(variable)
	#endif

	/* WARN_UNUSED_RETURN */

	#if !defined(WARN_UNUSED_RETURN) && COMPILER(GCC_COMPATIBLE)
	#define WARN_UNUSED_RETURN __attribute__((__warn_unused_result__))
	#endif

	#if !defined(WARN_UNUSED_RETURN)
	#define WARN_UNUSED_RETURN
	#endif

	/* DEBUGGER_ANNOTATION_MARKER */

	#if !defined(DEBUGGER_ANNOTATION_MARKER) && COMPILER(GCC)
	#define DEBUGGER_ANNOTATION_MARKER(name) \
	__attribute__((__no_reorder__)) void name(void) { __asm__(""); }
	#endif

	#if !defined(DEBUGGER_ANNOTATION_MARKER)
	#define DEBUGGER_ANNOTATION_MARKER(name)
	#endif

	#if !defined(__has_include) && COMPILER(MSVC)
	#define __has_include(path) 0
	#endif

	/* IGNORE_WARNINGS */

	/* Can't use WTF_CONCAT() and STRINGIZE() because they are defined in
	* StdLibExtras.h, which includes this file. */
	#define _COMPILER_CONCAT_I(a, b) a ## b
	#define _COMPILER_CONCAT(a, b) _COMPILER_CONCAT_I(a, b)

	#define _COMPILER_STRINGIZE(exp) #exp

	#define _COMPILER_WARNING_NAME(warning) "-W" warning

	#if COMPILER(GCC) \|\| COMPILER(CLANG)
	#define IGNORE_WARNINGS_BEGIN_COND(cond, compiler, warning) \
	_Pragma(_COMPILER_STRINGIZE(compiler diagnostic push)) \
	_COMPILER_CONCAT(IGNORE_WARNINGS_BEGIN_IMPL_, cond)(compiler, warning)

	/* Condition is either 1 (true) or 0 (false, do nothing). */
	#define IGNORE_WARNINGS_BEGIN_IMPL_1(compiler, warning) \
	_Pragma(_COMPILER_STRINGIZE(compiler diagnostic ignored warning))
	#define IGNORE_WARNINGS_BEGIN_IMPL_0(compiler, warning)

	#if defined(__has_warning)
	#define IGNORE_WARNINGS_END_IMPL(compiler) _Pragma(_COMPILER_STRINGIZE(compiler diagnostic pop))
	#else
	#define IGNORE_WARNINGS_END_IMPL(compiler) \
	_Pragma(_COMPILER_STRINGIZE(compiler diagnostic pop)) \
	_Pragma(_COMPILER_STRINGIZE(compiler diagnostic pop))
	#endif

	#if defined(__has_warning)
	#define _IGNORE_WARNINGS_BEGIN_IMPL(compiler, warning) \
	IGNORE_WARNINGS_BEGIN_COND(__has_warning(warning), compiler, warning)
	#else
	/* Suppress -Wpragmas to dodge warnings about attempts to suppress unrecognized warnings. */
	#define _IGNORE_WARNINGS_BEGIN_IMPL(compiler, warning) \
	IGNORE_WARNINGS_BEGIN_COND(1, compiler, "-Wpragmas") \
	IGNORE_WARNINGS_BEGIN_COND(1, compiler, warning)
	#endif

	#define IGNORE_WARNINGS_BEGIN_IMPL(compiler, warning) \
	_IGNORE_WARNINGS_BEGIN_IMPL(compiler, _COMPILER_WARNING_NAME(warning))

	#endif /* COMPILER(GCC) \|\| COMPILER(CLANG) */


	#if COMPILER(GCC)
	#define IGNORE_GCC_WARNINGS_BEGIN(warning) IGNORE_WARNINGS_BEGIN_IMPL(GCC, warning)
	#define IGNORE_GCC_WARNINGS_END IGNORE_WARNINGS_END_IMPL(GCC)
	#else
	#define IGNORE_GCC_WARNINGS_BEGIN(warning)
	#define IGNORE_GCC_WARNINGS_END
	#endif

	#if COMPILER(CLANG)
	#define IGNORE_CLANG_WARNINGS_BEGIN(warning) IGNORE_WARNINGS_BEGIN_IMPL(clang, warning)
	#define IGNORE_CLANG_WARNINGS_END IGNORE_WARNINGS_END_IMPL(clang)
	#else
	#define IGNORE_CLANG_WARNINGS_BEGIN(warning)
	#define IGNORE_CLANG_WARNINGS_END
	#endif

	#if COMPILER(GCC) \|\| COMPILER(CLANG)
	#define IGNORE_WARNINGS_BEGIN(warning) IGNORE_WARNINGS_BEGIN_IMPL(GCC, warning)
	#define IGNORE_WARNINGS_END IGNORE_WARNINGS_END_IMPL(GCC)
	#else
	#define IGNORE_WARNINGS_BEGIN(warning)
	#define IGNORE_WARNINGS_END
	#endif

	#define ALLOW_DEPRECATED_DECLARATIONS_BEGIN IGNORE_WARNINGS_BEGIN("deprecated-declarations")
	#define ALLOW_DEPRECATED_DECLARATIONS_END IGNORE_WARNINGS_END

	#define ALLOW_DEPRECATED_IMPLEMENTATIONS_BEGIN IGNORE_WARNINGS_BEGIN("deprecated-implementations")
	#define ALLOW_DEPRECATED_IMPLEMENTATIONS_END IGNORE_WARNINGS_END

	#define ALLOW_NEW_API_WITHOUT_GUARDS_BEGIN IGNORE_CLANG_WARNINGS_BEGIN("unguarded-availability-new")
	#define ALLOW_NEW_API_WITHOUT_GUARDS_END IGNORE_CLANG_WARNINGS_END

	#define ALLOW_UNUSED_PARAMETERS_BEGIN IGNORE_WARNINGS_BEGIN("unused-parameter")
	#define ALLOW_UNUSED_PARAMETERS_END IGNORE_WARNINGS_END

	#define ALLOW_NONLITERAL_FORMAT_BEGIN IGNORE_WARNINGS_BEGIN("format-nonliteral")
	#define ALLOW_NONLITERAL_FORMAT_END IGNORE_WARNINGS_END

	#define IGNORE_RETURN_TYPE_WARNINGS_BEGIN IGNORE_WARNINGS_BEGIN("return-type")
	#define IGNORE_RETURN_TYPE_WARNINGS_END IGNORE_WARNINGS_END

	#define IGNORE_NULL_CHECK_WARNINGS_BEGIN IGNORE_WARNINGS_BEGIN("nonnull")
	#define IGNORE_NULL_CHECK_WARNINGS_END IGNORE_WARNINGS_END

	/* NO_UNIQUE_ADDRESS */

	#if !defined(NO_UNIQUE_ADDRESS) && defined(__has_cpp_attribute)
	#if __has_cpp_attribute(no_unique_address)
	#define NO_UNIQUE_ADDRESS [[no_unique_address]] // NOLINT: check-webkit-style does not understand annotations.
	#endif
	#endif

	#if !defined(NO_UNIQUE_ADDRESS)
	#define NO_UNIQUE_ADDRESS
	#endif

	/* TLS_MODEL_INITIAL_EXEC */

	#if !defined(TLS_MODEL_INITIAL_EXEC) && defined(__has_attribute)
	#if __has_attribute(tls_model)
	#define TLS_MODEL_INITIAL_EXEC __attribute__((tls_model("initial-exec")))
	#endif
	#endif

	#if !defined(TLS_MODEL_INITIAL_EXEC)
	#define TLS_MODEL_INITIAL_EXEC
	#endif