text: //  (C) Copyright John Maddock 2001 - 2003.
  //  (C) Copyright Darin Adler 2001 - 2002.
  //  (C) Copyright Jens Maurer 2001 - 2002.
  //  (C) Copyright Beman Dawes 2001 - 2003.
  //  (C) Copyright Douglas Gregor 2002.
  //  (C) Copyright David Abrahams 2002 - 2003.
  //  (C) Copyright Synge Todo 2003.
  //  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.
  
  //  GNU C++ compiler setup.
  
  //
  // Define BOOST_GCC so we know this is "real" GCC and not some pretender:
  //
  #define BOOST_GCC_VERSION (__GNUC__ * 10000 + __GNUC_MINOR__ * 100 + __GNUC_PATCHLEVEL__)
  #if !defined(__CUDACC__)
  #define BOOST_GCC BOOST_GCC_VERSION
  #endif
  
  #if defined(__GXX_EXPERIMENTAL_CXX0X__) || (__cplusplus >= 201103L)
  #  define BOOST_GCC_CXX11
  #endif
  
  #if __GNUC__ == 3
  #  if defined (__PATHSCALE__)
  #     define BOOST_NO_TWO_PHASE_NAME_LOOKUP
  #     define BOOST_NO_IS_ABSTRACT
  #  endif
  
  #  if __GNUC_MINOR__ < 4
  #     define BOOST_NO_IS_ABSTRACT
  #  endif
  #  define BOOST_NO_CXX11_EXTERN_TEMPLATE
  #endif
  #if __GNUC__ < 4
  //
  // All problems to gcc-3.x and earlier here:
  //
  #define BOOST_NO_TWO_PHASE_NAME_LOOKUP
  #  ifdef __OPEN64__
  #     define BOOST_NO_IS_ABSTRACT
  #  endif
  #endif
  
  // GCC prior to 3.4 had #pragma once too but it didn't work well with filesystem links
  #if BOOST_GCC_VERSION >= 30400
  #define BOOST_HAS_PRAGMA_ONCE
  #endif
  
  #if BOOST_GCC_VERSION < 40400
  // Previous versions of GCC did not completely implement value-initialization:
  // GCC Bug 30111, "Value-initialization of POD base class doesn't initialize
  // members", reported by Jonathan Wakely in 2006,
  // http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30111 (fixed for GCC 4.4)
  // GCC Bug 33916, "Default constructor fails to initialize array members",
  // reported by Michael Elizabeth Chastain in 2007,
  // http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33916 (fixed for GCC 4.2.4)
  // See also: http://www.boost.org/libs/utility/value_init.htm#compiler_issues
  #define BOOST_NO_COMPLETE_VALUE_INITIALIZATION
  #endif
  
  #if !defined(__EXCEPTIONS) && !defined(BOOST_NO_EXCEPTIONS)
  # define BOOST_NO_EXCEPTIONS
  #endif
  
  
  //
  // Threading support: Turn this on unconditionally here (except for
  // those platforms where we can know for sure). It will get turned off again
  // later if no threading API is detected.
  //
  #if !defined(__MINGW32__) && !defined(linux) && !defined(__linux) && !defined(__linux__)
  # define BOOST_HAS_THREADS
  #endif
  
  //
  // gcc has "long long"
  // Except on Darwin with standard compliance enabled (-pedantic)
  // Apple gcc helpfully defines this macro we can query
  //
  #if !defined(__DARWIN_NO_LONG_LONG)
  # define BOOST_HAS_LONG_LONG
  #endif
  
  //
  // gcc implements the named return value optimization since version 3.1
  //
  #define BOOST_HAS_NRVO
  
  // Branch prediction hints
  #define BOOST_LIKELY(x) __builtin_expect(x, 1)
  #define BOOST_UNLIKELY(x) __builtin_expect(x, 0)
  
  //
  // Dynamic shared object (DSO) and dynamic-link library (DLL) support
  //
  #if __GNUC__ >= 4
  #  if defined(_WIN32) || defined(__WIN32__) || defined(WIN32) || defined(__CYGWIN__)
       // All Win32 development environments, including 64-bit Windows and MinGW, define
       // _WIN32 or one of its variant spellings. Note that Cygwin is a POSIX environment,
       // so does not define _WIN32 or its variants, but still supports dllexport/dllimport.
  #    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")))
  #else
  // config/platform/win32.hpp will define BOOST_SYMBOL_EXPORT, etc., unless already defined
  #  define BOOST_SYMBOL_EXPORT
  #endif
  
  //
  // RTTI and typeinfo detection is possible post gcc-4.3:
  //
  #if BOOST_GCC_VERSION > 40300
  #  ifndef __GXX_RTTI
  #     ifndef BOOST_NO_TYPEID
  #        define BOOST_NO_TYPEID
  #     endif
  #     ifndef BOOST_NO_RTTI
  #        define BOOST_NO_RTTI
  #     endif
  #  endif
  #endif
  
  //
  // Recent GCC versions have __int128 when in 64-bit mode.
  //
  // 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/8048
  //     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:
  //
  #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)
  #  define BOOST_HAS_INT128
  #endif
  //
  // Recent GCC versions have a __float128 native type, we need to
  // include a std lib header to detect this - not ideal, but we'll
  // be including <cstddef> later anyway when we select the std lib.
  //
  // Nevertheless, as of CUDA 7.5, using __float128 with the host
  // compiler in pre-C++11 mode is still not supported.
  // See https://svn.boost.org/trac/boost/ticket/11852
  //
  #ifdef __cplusplus
  #include <cstddef>
  #else
  #include <stddef.h>
  #endif
  #if defined(_GLIBCXX_USE_FLOAT128) && !defined(__STRICT_ANSI__) && !defined(BOOST_NVCC_CXX03)
  # define BOOST_HAS_FLOAT128
  #endif
  
  // C++0x features in 4.3.n and later
  //
  #if (BOOST_GCC_VERSION >= 40300) && defined(BOOST_GCC_CXX11)
  // C++0x features are only enabled when -std=c++0x or -std=gnu++0x are
  // passed on the command line, which in turn defines
  // __GXX_EXPERIMENTAL_CXX0X__.
  #  define BOOST_HAS_DECLTYPE
  #  define BOOST_HAS_RVALUE_REFS
  #  define BOOST_HAS_STATIC_ASSERT
  #  define BOOST_HAS_VARIADIC_TMPL
  #else
  #  define BOOST_NO_CXX11_DECLTYPE
  #  define BOOST_NO_CXX11_FUNCTION_TEMPLATE_DEFAULT_ARGS
  #  define BOOST_NO_CXX11_RVALUE_REFERENCES
  #  define BOOST_NO_CXX11_STATIC_ASSERT
  #endif
  
  // C++0x features in 4.4.n and later
  //
  #if (BOOST_GCC_VERSION < 40400) || !defined(BOOST_GCC_CXX11)
  #  define BOOST_NO_CXX11_AUTO_DECLARATIONS
  #  define BOOST_NO_CXX11_AUTO_MULTIDECLARATIONS
  #  define BOOST_NO_CXX11_CHAR16_T
  #  define BOOST_NO_CXX11_CHAR32_T
  #  define BOOST_NO_CXX11_HDR_INITIALIZER_LIST
  #  define BOOST_NO_CXX11_DEFAULTED_FUNCTIONS
  #  define BOOST_NO_CXX11_DELETED_FUNCTIONS
  #  define BOOST_NO_CXX11_TRAILING_RESULT_TYPES
  #  define BOOST_NO_CXX11_INLINE_NAMESPACES
  #  define BOOST_NO_CXX11_VARIADIC_TEMPLATES
  #endif
  
  #if BOOST_GCC_VERSION < 40500
  #  define BOOST_NO_SFINAE_EXPR
  #endif
  
  // GCC 4.5 forbids declaration of defaulted functions in private or protected sections
  #if __GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ == 5) || !defined(BOOST_GCC_CXX11)
  #  define BOOST_NO_CXX11_NON_PUBLIC_DEFAULTED_FUNCTIONS
  #endif
  
  // C++0x features in 4.5.0 and later
  //
  #if (BOOST_GCC_VERSION < 40500) || !defined(BOOST_GCC_CXX11)
  #  define BOOST_NO_CXX11_EXPLICIT_CONVERSION_OPERATORS
  #  define BOOST_NO_CXX11_LAMBDAS
  #  define BOOST_NO_CXX11_LOCAL_CLASS_TEMPLATE_PARAMETERS
  #  define BOOST_NO_CXX11_RAW_LITERALS
  #  define BOOST_NO_CXX11_UNICODE_LITERALS
  #endif
  
  // C++0x features in 4.5.1 and later
  //
  #if (BOOST_GCC_VERSION < 40501) || !defined(BOOST_GCC_CXX11)
  // scoped enums have a serious bug in 4.4.0, so define BOOST_NO_CXX11_SCOPED_ENUMS before 4.5.1
  // See http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38064
  #  define BOOST_NO_CXX11_SCOPED_ENUMS
  #endif
  
  // C++0x features in 4.6.n and later
  //
  #if (BOOST_GCC_VERSION < 40600) || !defined(BOOST_GCC_CXX11)
  #define BOOST_NO_CXX11_DEFAULTED_MOVES
  #define BOOST_NO_CXX11_NOEXCEPT
  #define BOOST_NO_CXX11_NULLPTR
  #define BOOST_NO_CXX11_RANGE_BASED_FOR
  #define BOOST_NO_CXX11_UNIFIED_INITIALIZATION_SYNTAX
  #endif
  
  // C++0x features in 4.7.n and later
  //
  #if (BOOST_GCC_VERSION < 40700) || !defined(BOOST_GCC_CXX11)
  // Note that while constexpr is partly supported in gcc-4.6 it's a 
  // pre-std version with several bugs:
  #  define BOOST_NO_CXX11_CONSTEXPR
  #  define BOOST_NO_CXX11_FINAL
  #  define BOOST_NO_CXX11_TEMPLATE_ALIASES
  #  define BOOST_NO_CXX11_USER_DEFINED_LITERALS
  #  define BOOST_NO_CXX11_FIXED_LENGTH_VARIADIC_TEMPLATE_EXPANSION_PACKS
  #  define BOOST_NO_CXX11_OVERRIDE
  #endif
  
  // C++0x features in 4.8.n and later
  //
  #if (BOOST_GCC_VERSION < 40800) || !defined(BOOST_GCC_CXX11)
  #  define BOOST_NO_CXX11_THREAD_LOCAL
  #  define BOOST_NO_CXX11_SFINAE_EXPR
  #endif
  
  // C++0x features in 4.8.1 and later
  //
  #if (BOOST_GCC_VERSION < 40801) || !defined(BOOST_GCC_CXX11)
  #  define BOOST_NO_CXX11_DECLTYPE_N3276
  #  define BOOST_NO_CXX11_REF_QUALIFIERS
  #  define BOOST_NO_CXX14_BINARY_LITERALS
  #endif
  
  // C++0x features in 4.9.n and later
  //
  #if (BOOST_GCC_VERSION < 40900) || !defined(BOOST_GCC_CXX11)
  // Although alignas support is added in gcc 4.8, it does not accept
  // dependent constant expressions as an argument until gcc 4.9.
  #  define BOOST_NO_CXX11_ALIGNAS
  #endif
  
  // C++0x features in 5.1 and later
  //
  #if (BOOST_GCC_VERSION < 50100) || !defined(BOOST_GCC_CXX11)
  #  define BOOST_NO_CXX11_UNRESTRICTED_UNION
  #endif
  
  // C++14 features in 4.9.0 and later
  //
  #if (BOOST_GCC_VERSION < 40900) || (__cplusplus < 201300)
  #  define BOOST_NO_CXX14_RETURN_TYPE_DEDUCTION
  #  define BOOST_NO_CXX14_GENERIC_LAMBDAS
  #  define BOOST_NO_CXX14_DIGIT_SEPARATORS
  #  define BOOST_NO_CXX14_DECLTYPE_AUTO
  #  if !((BOOST_GCC_VERSION >= 40801) && (BOOST_GCC_VERSION < 40900) && defined(BOOST_GCC_CXX11))
  #     define BOOST_NO_CXX14_INITIALIZED_LAMBDA_CAPTURES
  #  endif
  #endif
  
  
  // C++ 14:
  #if !defined(__cpp_aggregate_nsdmi) || (__cpp_aggregate_nsdmi < 201304)
  #  define BOOST_NO_CXX14_AGGREGATE_NSDMI
  #endif
  #if !defined(__cpp_constexpr) || (__cpp_constexpr < 201304)
  #  define BOOST_NO_CXX14_CONSTEXPR
  #endif
  #if (BOOST_GCC_VERSION < 50200) || !defined(__cpp_variable_templates) || (__cpp_variable_templates < 201304)
  #  define BOOST_NO_CXX14_VARIABLE_TEMPLATES
  #endif
  
  // C++17
  #if !defined(__cpp_structured_bindings) || (__cpp_structured_bindings < 201606)
  #  define BOOST_NO_CXX17_STRUCTURED_BINDINGS
  #endif
  #if !defined(__cpp_inline_variables) || (__cpp_inline_variables < 201606)
  #  define BOOST_NO_CXX17_INLINE_VARIABLES
  #endif
  #if !defined(__cpp_fold_expressions) || (__cpp_fold_expressions < 201603)
  #  define BOOST_NO_CXX17_FOLD_EXPRESSIONS
  #endif
  #if !defined(__cpp_if_constexpr) || (__cpp_if_constexpr < 201606)
  #  define BOOST_NO_CXX17_IF_CONSTEXPR
  #endif
  
  #if __GNUC__ >= 7
  #  define BOOST_FALLTHROUGH __attribute__((fallthrough))
  #endif
  
  #if (__GNUC__ < 11) && defined(__MINGW32__) && !defined(__MINGW64__)
  // thread_local was broken on mingw for all 32bit compiler releases prior to 11.x, see
  // https://sourceforge.net/p/mingw-w64/bugs/527/
  // https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83562
  // Not setting this causes program termination on thread exit.
  #define BOOST_NO_CXX11_THREAD_LOCAL
  #endif
  
  //
  // Unused attribute:
  #if __GNUC__ >= 4
  #  define BOOST_ATTRIBUTE_UNUSED __attribute__((__unused__))
  #endif
  
  // Type aliasing hint. Supported since gcc 3.3.
  #define BOOST_MAY_ALIAS __attribute__((__may_alias__))
  
  //
  // __builtin_unreachable:
  #if BOOST_GCC_VERSION >= 40500
  #define BOOST_UNREACHABLE_RETURN(x) __builtin_unreachable();
  #endif
  
  #ifndef BOOST_COMPILER
  #  define BOOST_COMPILER "GNU C++ version " __VERSION__
  #endif
  
  // ConceptGCC compiler:
  //   http://www.generic-programming.org/software/ConceptGCC/
  #ifdef __GXX_CONCEPTS__
  #  define BOOST_HAS_CONCEPTS
  #  define BOOST_COMPILER "ConceptGCC version " __VERSION__
  #endif
  
  // versions check:
  // we don't know gcc prior to version 3.30:
  #if (BOOST_GCC_VERSION< 30300)
  #  error "Compiler not configured - please reconfigure"
  #endif
  //
  // last known and checked version is 8.1:
  #if (BOOST_GCC_VERSION > 80100)
  #  if defined(BOOST_ASSERT_CONFIG)
  #     error "Boost.Config is older than your compiler - please check for an updated Boost release."
  #  else
  // we don't emit warnings here anymore since there are no defect macros defined for
  // gcc post 3.4, so any failures are gcc regressions...
  //#     warning "boost: Unknown compiler version - please run the configure tests and report the results"
  #  endif
  #endif
  
  