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boost/static_assert.hpp

//  (C) Copyright John Maddock 2000.
//  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/libs/static_assert for documentation.

/*
 Revision history:
   02 August 2000
      Initial version.
*/

#ifndef BOOST_STATIC_ASSERT_HPP
#define BOOST_STATIC_ASSERT_HPP

#include <boost/config.hpp>
#include <boost/detail/workaround.hpp>

#if defined(__GNUC__) && !defined(__GXX_EXPERIMENTAL_CXX0X__)
//
// This is horrible, but it seems to be the only we can shut up the
// "anonymous variadic macros were introduced in C99 [-Wvariadic-macros]"
// warning that get spewed out otherwise in non-C++11 mode.
//
#pragma GCC system_header
#endif

#ifndef BOOST_NO_CXX11_STATIC_ASSERT
#  ifndef BOOST_NO_CXX11_VARIADIC_MACROS
#     define BOOST_STATIC_ASSERT_MSG( ... ) static_assert(__VA_ARGS__)
#  else
#     define BOOST_STATIC_ASSERT_MSG( B, Msg ) static_assert( B, Msg )
#  endif
#else
#     define BOOST_STATIC_ASSERT_MSG( B, Msg ) BOOST_STATIC_ASSERT( B )
#endif

#ifdef BOOST_BORLANDC
//
// workaround for buggy integral-constant expression support:
#define BOOST_BUGGY_INTEGRAL_CONSTANT_EXPRESSIONS
#endif

#if defined(__GNUC__) && (__GNUC__ == 3) && ((__GNUC_MINOR__ == 3) || (__GNUC_MINOR__ == 4))
// gcc 3.3 and 3.4 don't produce good error messages with the default version:
#  define BOOST_SA_GCC_WORKAROUND
#endif

//
// If the compiler issues warnings about old C style casts,
// then enable this:
//
#if defined(__GNUC__) && ((__GNUC__ > 3) || ((__GNUC__ == 3) && (__GNUC_MINOR__ >= 4)))
#  ifndef BOOST_NO_CXX11_VARIADIC_MACROS
#     define BOOST_STATIC_ASSERT_BOOL_CAST( ... ) ((__VA_ARGS__) != 0)
#  else
#     define BOOST_STATIC_ASSERT_BOOL_CAST( x ) ((x) != 0)
#  endif
#else
#  ifndef BOOST_NO_CXX11_VARIADIC_MACROS
#     define BOOST_STATIC_ASSERT_BOOL_CAST( ... ) (bool)(__VA_ARGS__)
#  else
#     define BOOST_STATIC_ASSERT_BOOL_CAST(x) (bool)(x)
#  endif
#endif

#ifndef BOOST_NO_CXX11_STATIC_ASSERT
#  ifndef BOOST_NO_CXX11_VARIADIC_MACROS
#     define BOOST_STATIC_ASSERT( ... ) static_assert(__VA_ARGS__, #__VA_ARGS__)
#  else
#     define BOOST_STATIC_ASSERT( B ) static_assert(B, #B)
#  endif
#else

namespace boost{

// HP aCC cannot deal with missing names for template value parameters
template <bool x> struct STATIC_ASSERTION_FAILURE;

template <> struct STATIC_ASSERTION_FAILURE<true> { enum { value = 1 }; };

// HP aCC cannot deal with missing names for template value parameters
template<int x> struct static_assert_test{};

}

//
// Implicit instantiation requires that all member declarations be
// instantiated, but that the definitions are *not* instantiated.
//
// It's not particularly clear how this applies to enum's or typedefs;
// both are described as declarations [7.1.3] and [7.2] in the standard,
// however some compilers use "delayed evaluation" of one or more of
// these when implicitly instantiating templates.  We use typedef declarations
// by default, but try defining BOOST_USE_ENUM_STATIC_ASSERT if the enum
// version gets better results from your compiler...
//
// Implementation:
// Both of these versions rely on sizeof(incomplete_type) generating an error
// message containing the name of the incomplete type.  We use
// "STATIC_ASSERTION_FAILURE" as the type name here to generate
// an eye catching error message.  The result of the sizeof expression is either
// used as an enum initialiser, or as a template argument depending which version
// is in use...
// Note that the argument to the assert is explicitly cast to bool using old-
// style casts: too many compilers currently have problems with static_cast
// when used inside integral constant expressions.
//
#if !defined(BOOST_BUGGY_INTEGRAL_CONSTANT_EXPRESSIONS)

#if defined(BOOST_MSVC) && defined(BOOST_NO_CXX11_VARIADIC_MACROS)
#define BOOST_STATIC_ASSERT( B ) \
   typedef ::boost::static_assert_test<\
      sizeof(::boost::STATIC_ASSERTION_FAILURE< BOOST_STATIC_ASSERT_BOOL_CAST ( B ) >)>\
         BOOST_JOIN(boost_static_assert_typedef_, __COUNTER__)
#elif defined(BOOST_MSVC)
#define BOOST_STATIC_ASSERT(...) \
   typedef ::boost::static_assert_test<\
      sizeof(::boost::STATIC_ASSERTION_FAILURE< BOOST_STATIC_ASSERT_BOOL_CAST (__VA_ARGS__) >)>\
         BOOST_JOIN(boost_static_assert_typedef_, __COUNTER__)
#elif (defined(BOOST_INTEL_CXX_VERSION) || defined(BOOST_SA_GCC_WORKAROUND))  && defined(BOOST_NO_CXX11_VARIADIC_MACROS)
// agurt 15/sep/02: a special care is needed to force Intel C++ issue an error 
// instead of warning in case of failure
# define BOOST_STATIC_ASSERT( B ) \
    typedef char BOOST_JOIN(boost_static_assert_typedef_, __LINE__) \
        [ ::boost::STATIC_ASSERTION_FAILURE< BOOST_STATIC_ASSERT_BOOL_CAST( B ) >::value ]
#elif (defined(BOOST_INTEL_CXX_VERSION) || defined(BOOST_SA_GCC_WORKAROUND))  && !defined(BOOST_NO_CXX11_VARIADIC_MACROS)
// agurt 15/sep/02: a special care is needed to force Intel C++ issue an error 
// instead of warning in case of failure
# define BOOST_STATIC_ASSERT(...) \
    typedef char BOOST_JOIN(boost_static_assert_typedef_, __LINE__) \
        [ ::boost::STATIC_ASSERTION_FAILURE< BOOST_STATIC_ASSERT_BOOL_CAST( __VA_ARGS__ ) >::value ]
#elif defined(__sgi)
// special version for SGI MIPSpro compiler
#define BOOST_STATIC_ASSERT( B ) \
   BOOST_STATIC_CONSTANT(bool, \
     BOOST_JOIN(boost_static_assert_test_, __LINE__) = ( B )); \
   typedef ::boost::static_assert_test<\
     sizeof(::boost::STATIC_ASSERTION_FAILURE< \
       BOOST_JOIN(boost_static_assert_test_, __LINE__) >)>\
         BOOST_JOIN(boost_static_assert_typedef_, __LINE__)
#elif BOOST_WORKAROUND(__MWERKS__, <= 0x3003)
// special version for CodeWarrior <= 8.x
#define BOOST_STATIC_ASSERT( B ) \
   BOOST_STATIC_CONSTANT(int, \
     BOOST_JOIN(boost_static_assert_test_, __LINE__) = \
       sizeof(::boost::STATIC_ASSERTION_FAILURE< BOOST_STATIC_ASSERT_BOOL_CAST( B ) >) )
#else
// generic version
#  ifndef BOOST_NO_CXX11_VARIADIC_MACROS
#     define BOOST_STATIC_ASSERT( ... ) \
         typedef ::boost::static_assert_test<\
            sizeof(::boost::STATIC_ASSERTION_FAILURE< BOOST_STATIC_ASSERT_BOOL_CAST( __VA_ARGS__ ) >)>\
               BOOST_JOIN(boost_static_assert_typedef_, __LINE__) BOOST_ATTRIBUTE_UNUSED
#  else
#     define BOOST_STATIC_ASSERT( B ) \
         typedef ::boost::static_assert_test<\
            sizeof(::boost::STATIC_ASSERTION_FAILURE< BOOST_STATIC_ASSERT_BOOL_CAST( B ) >)>\
               BOOST_JOIN(boost_static_assert_typedef_, __LINE__) BOOST_ATTRIBUTE_UNUSED
#  endif
#endif

#else
// alternative enum based implementation:
#  ifndef BOOST_NO_CXX11_VARIADIC_MACROS
#    define BOOST_STATIC_ASSERT( ... ) \
         enum { BOOST_JOIN(boost_static_assert_enum_, __LINE__) \
            = sizeof(::boost::STATIC_ASSERTION_FAILURE< (bool)( __VA_ARGS__ ) >) }
#  else
#    define BOOST_STATIC_ASSERT(B) \
         enum { BOOST_JOIN(boost_static_assert_enum_, __LINE__) \
            = sizeof(::boost::STATIC_ASSERTION_FAILURE< (bool)( B ) >) }
#  endif
#endif
#endif // defined(BOOST_NO_CXX11_STATIC_ASSERT)

#endif // BOOST_STATIC_ASSERT_HPP