text: // (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.
  
  //  compiler setup for IBM XL C/C++ for Linux (Little Endian) based on clang.
  
  #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_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 defined(__int64) && !defined(__GNUC__)
  #define BOOST_HAS_MS_INT64
  #endif
  
  #define BOOST_HAS_NRVO
  
  // Branch prediction hints
  #if 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
  
  //
  // Dynamic shared object (DSO) and dynamic-link library (DLL) support
  //
  #if !defined(_WIN32) && !defined(__WIN32__) && !defined(WIN32)
  #define BOOST_SYMBOL_EXPORT __attribute__((__visibility__("default")))
  #define BOOST_SYMBOL_IMPORT
  #define BOOST_SYMBOL_VISIBLE __attribute__((__visibility__("default")))
  #endif
  
  //
  // 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) ||                                                       \
      !(defined(__GXX_EXPERIMENTAL_CXX0X__) || __cplusplus >= 201103L)
  #define BOOST_NO_CXX11_CHAR16_T
  #define BOOST_NO_CXX11_CHAR32_T
  #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 !__has_feature(cxx_thread_local)
  #define BOOST_NO_CXX11_THREAD_LOCAL
  #endif
  
  #if __cplusplus < 201400
  // All versions with __cplusplus above this value seem to support this:
  #define BOOST_NO_CXX14_DIGIT_SEPARATORS
  #endif
  
  // Unused attribute:
  #if defined(__GNUC__) && (__GNUC__ >= 4)
  #define BOOST_ATTRIBUTE_UNUSED __attribute__((unused))
  #endif
  
  // 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
  