boost/config/compiler/clang.hpp
// (C) Copyright Douglas Gregor 2010
//
// Use, modification and distribution are subject to the
// Boost Software License, Version 1.0. (See accompanying file
// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
// See http://www.boost.org for most recent version.
// Clang compiler setup.
#define BOOST_HAS_PRAGMA_ONCE
// Detecting `-fms-extension` compiler flag assuming that _MSC_VER defined when that flag is used.
#if defined (_MSC_VER) && (__clang_major__ > 3 || (__clang_major__ == 3 && __clang_minor__ >= 4))
# define BOOST_HAS_PRAGMA_DETECT_MISMATCH
#endif
// When compiling with clang before __has_extension was defined,
// even if one writes 'defined(__has_extension) && __has_extension(xxx)',
// clang reports a compiler error. So the only workaround found is:
#ifndef __has_extension
#define __has_extension __has_feature
#endif
#ifndef __has_attribute
#define __has_attribute(x) 0
#endif
#ifndef __has_cpp_attribute
#define __has_cpp_attribute(x) 0
#endif
#if !__has_feature(cxx_exceptions) && !defined(BOOST_NO_EXCEPTIONS)
# define BOOST_NO_EXCEPTIONS
#endif
#if !__has_feature(cxx_rtti) && !defined(BOOST_NO_RTTI)
# define BOOST_NO_RTTI
#endif
#if !__has_feature(cxx_rtti) && !defined(BOOST_NO_TYPEID)
# define BOOST_NO_TYPEID
#endif
#if !__has_feature(cxx_thread_local)
# define BOOST_NO_CXX11_THREAD_LOCAL
#endif
#ifdef __is_identifier
#if !__is_identifier(__int64) && !defined(__GNUC__)
# define BOOST_HAS_MS_INT64
#endif
#endif
#if __has_include(<stdint.h>)
# define BOOST_HAS_STDINT_H
#endif
#define BOOST_HAS_NRVO
// Branch prediction hints
#if !defined (__c2__) && defined(__has_builtin)
#if __has_builtin(__builtin_expect)
#define BOOST_LIKELY(x) __builtin_expect(x, 1)
#define BOOST_UNLIKELY(x) __builtin_expect(x, 0)
#endif
#endif
// Clang supports "long long" in all compilation modes.
#define BOOST_HAS_LONG_LONG
//
// We disable this if the compiler is really nvcc with C++03 as it
// doesn't actually support __int128 as of CUDA_VERSION=7500
// even though it defines __SIZEOF_INT128__.
// See https://svn.boost.org/trac/boost/ticket/10418
// https://svn.boost.org/trac/boost/ticket/11852
// Only re-enable this for nvcc if you're absolutely sure
// of the circumstances under which it's supported.
// Similarly __SIZEOF_INT128__ is defined when targetting msvc
// compatibility even though the required support functions are absent.
//
#if defined(__CUDACC__)
# if defined(BOOST_GCC_CXX11)
# define BOOST_NVCC_CXX11
# else
# define BOOST_NVCC_CXX03
# endif
#endif
#if defined(__SIZEOF_INT128__) && !defined(BOOST_NVCC_CXX03) && !defined(_MSC_VER)
# define BOOST_HAS_INT128
#endif
//
// Dynamic shared object (DSO) and dynamic-link library (DLL) support
//
#if defined(_WIN32) || defined(__WIN32__) || defined(WIN32) || defined(__CYGWIN__)
# define BOOST_HAS_DECLSPEC
# define BOOST_SYMBOL_EXPORT __attribute__((__dllexport__))
# define BOOST_SYMBOL_IMPORT __attribute__((__dllimport__))
#else
# define BOOST_SYMBOL_EXPORT __attribute__((__visibility__("default")))
# define BOOST_SYMBOL_IMPORT
#endif
#define BOOST_SYMBOL_VISIBLE __attribute__((__visibility__("default")))
//
// The BOOST_FALLTHROUGH macro can be used to annotate implicit fall-through
// between switch labels.
//
#if __cplusplus >= 201103L && defined(__has_warning)
# if __has_feature(cxx_attributes) && __has_warning("-Wimplicit-fallthrough")
# define BOOST_FALLTHROUGH [[clang::fallthrough]]
# endif
#endif
#if !__has_feature(cxx_auto_type)
# define BOOST_NO_CXX11_AUTO_DECLARATIONS
# define BOOST_NO_CXX11_AUTO_MULTIDECLARATIONS
#endif
//
// Currently clang on Windows using VC++ RTL does not support C++11's char16_t or char32_t
//
#if (defined(_MSC_VER) && (_MSC_VER < 1900)) || !(defined(__GXX_EXPERIMENTAL_CXX0X__) || __cplusplus >= 201103L)
# define BOOST_NO_CXX11_CHAR16_T
# define BOOST_NO_CXX11_CHAR32_T
#endif
#if defined(_MSC_VER) && (_MSC_VER >= 1800) && !defined(__GNUC__)
#define BOOST_HAS_EXPM1
#define BOOST_HAS_LOG1P
#endif
#if !__has_feature(cxx_constexpr)
# define BOOST_NO_CXX11_CONSTEXPR
#endif
#if !__has_feature(cxx_decltype)
# define BOOST_NO_CXX11_DECLTYPE
#endif
#if !__has_feature(cxx_decltype_incomplete_return_types)
# define BOOST_NO_CXX11_DECLTYPE_N3276
#endif
#if !__has_feature(cxx_defaulted_functions)
# define BOOST_NO_CXX11_DEFAULTED_FUNCTIONS
#endif
#if !__has_feature(cxx_deleted_functions)
# define BOOST_NO_CXX11_DELETED_FUNCTIONS
#endif
#if !__has_feature(cxx_explicit_conversions)
# define BOOST_NO_CXX11_EXPLICIT_CONVERSION_OPERATORS
#endif
#if !__has_feature(cxx_default_function_template_args)
# define BOOST_NO_CXX11_FUNCTION_TEMPLATE_DEFAULT_ARGS
#endif
#if !__has_feature(cxx_generalized_initializers)
# define BOOST_NO_CXX11_HDR_INITIALIZER_LIST
#endif
#if !__has_feature(cxx_lambdas)
# define BOOST_NO_CXX11_LAMBDAS
#endif
#if !__has_feature(cxx_local_type_template_args)
# define BOOST_NO_CXX11_LOCAL_CLASS_TEMPLATE_PARAMETERS
#endif
#if !__has_feature(cxx_noexcept)
# define BOOST_NO_CXX11_NOEXCEPT
#endif
#if !__has_feature(cxx_nullptr)
# define BOOST_NO_CXX11_NULLPTR
#endif
#if !__has_feature(cxx_range_for)
# define BOOST_NO_CXX11_RANGE_BASED_FOR
#endif
#if !__has_feature(cxx_raw_string_literals)
# define BOOST_NO_CXX11_RAW_LITERALS
#endif
#if !__has_feature(cxx_reference_qualified_functions)
# define BOOST_NO_CXX11_REF_QUALIFIERS
#endif
#if !__has_feature(cxx_generalized_initializers)
# define BOOST_NO_CXX11_UNIFIED_INITIALIZATION_SYNTAX
#endif
#if !__has_feature(cxx_rvalue_references)
# define BOOST_NO_CXX11_RVALUE_REFERENCES
#endif
#if !__has_feature(cxx_strong_enums)
# define BOOST_NO_CXX11_SCOPED_ENUMS
#endif
#if !__has_feature(cxx_static_assert)
# define BOOST_NO_CXX11_STATIC_ASSERT
#endif
#if !__has_feature(cxx_alias_templates)
# define BOOST_NO_CXX11_TEMPLATE_ALIASES
#endif
#if !__has_feature(cxx_unicode_literals)
# define BOOST_NO_CXX11_UNICODE_LITERALS
#endif
#if !__has_feature(cxx_variadic_templates)
# define BOOST_NO_CXX11_VARIADIC_TEMPLATES
#endif
#if !__has_feature(cxx_user_literals)
# define BOOST_NO_CXX11_USER_DEFINED_LITERALS
#endif
#if !__has_feature(cxx_alignas)
# define BOOST_NO_CXX11_ALIGNAS
#endif
#if !__has_feature(cxx_trailing_return)
# define BOOST_NO_CXX11_TRAILING_RESULT_TYPES
#endif
#if !__has_feature(cxx_inline_namespaces)
# define BOOST_NO_CXX11_INLINE_NAMESPACES
#endif
#if !__has_feature(cxx_override_control)
# define BOOST_NO_CXX11_FINAL
#endif
#if !(__has_feature(__cxx_binary_literals__) || __has_extension(__cxx_binary_literals__))
# define BOOST_NO_CXX14_BINARY_LITERALS
#endif
#if !__has_feature(__cxx_decltype_auto__)
# define BOOST_NO_CXX14_DECLTYPE_AUTO
#endif
#if !__has_feature(__cxx_aggregate_nsdmi__)
# define BOOST_NO_CXX14_AGGREGATE_NSDMI
#endif
#if !__has_feature(__cxx_init_captures__)
# define BOOST_NO_CXX14_INITIALIZED_LAMBDA_CAPTURES
#endif
#if !__has_feature(__cxx_generic_lambdas__)
# define BOOST_NO_CXX14_GENERIC_LAMBDAS
#endif
// clang < 3.5 has a defect with dependent type, like following.
//
// template <class T>
// constexpr typename enable_if<pred<T> >::type foo(T &)
// { } // error: no return statement in constexpr function
//
// This issue also affects C++11 mode, but C++11 constexpr requires return stmt.
// Therefore we don't care such case.
//
// Note that we can't check Clang version directly as the numbering system changes depending who's
// creating the Clang release (see https://github.com/boostorg/config/pull/39#issuecomment-59927873)
// so instead verify that we have a feature that was introduced at the same time as working C++14
// constexpr (generic lambda's in this case):
//
#if !__has_feature(__cxx_generic_lambdas__) || !__has_feature(__cxx_relaxed_constexpr__)
# define BOOST_NO_CXX14_CONSTEXPR
#endif
#if !__has_feature(__cxx_return_type_deduction__)
# define BOOST_NO_CXX14_RETURN_TYPE_DEDUCTION
#endif
#if !__has_feature(__cxx_variable_templates__)
# define BOOST_NO_CXX14_VARIABLE_TEMPLATES
#endif
#if !defined(__cpp_structured_bindings) || (__cpp_structured_bindings < 201606)
# define BOOST_NO_CXX17_STRUCTURED_BINDINGS
#endif
#if !defined(__cpp_if_constexpr) || (__cpp_if_constexpr < 201606)
# define BOOST_NO_CXX17_IF_CONSTEXPR
#endif
// Clang 3.9+ in c++1z
#if !__has_cpp_attribute(fallthrough) || __cplusplus < 201406L
# define BOOST_NO_CXX17_INLINE_VARIABLES
# define BOOST_NO_CXX17_FOLD_EXPRESSIONS
#endif
#if __cplusplus < 201103L
#define BOOST_NO_CXX11_SFINAE_EXPR
#endif
#if __cplusplus < 201400
// All versions with __cplusplus above this value seem to support this:
# define BOOST_NO_CXX14_DIGIT_SEPARATORS
#endif
//
// __builtin_unreachable:
#if defined(__has_builtin) && __has_builtin(__builtin_unreachable)
#define BOOST_UNREACHABLE_RETURN(x) __builtin_unreachable();
#endif
#if (__clang_major__ == 3) && (__clang_minor__ == 0)
// Apparently a clang bug:
# define BOOST_NO_CXX11_FIXED_LENGTH_VARIADIC_TEMPLATE_EXPANSION_PACKS
#endif
// Clang has supported the 'unused' attribute since the first release.
#define BOOST_ATTRIBUTE_UNUSED __attribute__((__unused__))
// Type aliasing hint.
#if __has_attribute(__may_alias__)
# define BOOST_MAY_ALIAS __attribute__((__may_alias__))
#endif
#ifndef BOOST_COMPILER
# define BOOST_COMPILER "Clang version " __clang_version__
#endif
// Macro used to identify the Clang compiler.
#define BOOST_CLANG 1