boost/boost/static_assert.hpp

   1 //  (C) Copyright John Maddock 2000.
   2 //  Use, modification and distribution are subject to the
   3 //  Boost Software License, Version 1.0. (See accompanying file
   4 //  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   5
   6 //  See http://www.boost.org/libs/static_assert for documentation.
   7
   8 /*
   9  Revision history:
  10    02 August 2000
  11       Initial version.
  12 */
  13
  14 #ifndef BOOST_STATIC_ASSERT_HPP
  15 #define BOOST_STATIC_ASSERT_HPP
  16
  17 #include <boost/config.hpp>
  18 #include <boost/detail/workaround.hpp>
  19
  20 #ifdef __BORLANDC__
  21 //
  22 // workaround for buggy integral-constant expression support:
  23 #define BOOST_BUGGY_INTEGRAL_CONSTANT_EXPRESSIONS
  24 #endif
  25
  26 namespace boost{
  27
  28 // HP aCC cannot deal with missing names for template value parameters
  29 template <bool x> struct STATIC_ASSERTION_FAILURE;
  30
  31 template <> struct STATIC_ASSERTION_FAILURE<true> { enum { value = 1 }; };
  32
  33 // HP aCC cannot deal with missing names for template value parameters
  34 template<int x> struct static_assert_test{};
  35
  36 }
  37
  38 //
  39 // Implicit instantiation requires that all member declarations be
  40 // instantiated, but that the definitions are *not* instantiated.
  41 //
  42 // It's not particularly clear how this applies to enum's or typedefs;
  43 // both are described as declarations [7.1.3] and [7.2] in the standard,
  44 // however some compilers use "delayed evaluation" of one or more of
  45 // these when implicitly instantiating templates.  We use typedef declarations
  46 // by default, but try defining BOOST_USE_ENUM_STATIC_ASSERT if the enum
  47 // version gets better results from your compiler...
  48 //
  49 // Implementation:
  50 // Both of these versions rely on sizeof(incomplete_type) generating an error
  51 // message containing the name of the incomplete type.  We use
  52 // "STATIC_ASSERTION_FAILURE" as the type name here to generate
  53 // an eye catching error message.  The result of the sizeof expression is either
  54 // used as an enum initialiser, or as a template argument depending which version
  55 // is in use...
  56 // Note that the argument to the assert is explicitly cast to bool using old-
  57 // style casts: too many compilers currently have problems with static_cast
  58 // when used inside integral constant expressions.
  59 //
  60 #if !defined(BOOST_BUGGY_INTEGRAL_CONSTANT_EXPRESSIONS) && \
  61     !BOOST_WORKAROUND(__MWERKS__, < 0x3003)
  62
  63 #if defined(BOOST_MSVC) && (BOOST_MSVC < 1300)
  64 // __LINE__ macro broken when -ZI is used see Q199057
  65 // fortunately MSVC ignores duplicate typedef's.
  66 #define BOOST_STATIC_ASSERT( B ) \
  67    typedef ::boost::static_assert_test<\
  68       sizeof(::boost::STATIC_ASSERTION_FAILURE< (bool)( B ) >)\
  69       > boost_static_assert_typedef_
  70 #elif defined(BOOST_MSVC)
  71 #define BOOST_STATIC_ASSERT( B ) \
  72    typedef ::boost::static_assert_test<\
  73       sizeof(::boost::STATIC_ASSERTION_FAILURE< (bool)( B ) >)>\
  74          BOOST_JOIN(boost_static_assert_typedef_, __COUNTER__)
  75 #elif defined(BOOST_INTEL_CXX_VERSION)
  76 // agurt 15/sep/02: a special care is needed to force Intel C++ issue an error
  77 // instead of warning in case of failure
  78 # define BOOST_STATIC_ASSERT( B ) \
  79     typedef char BOOST_JOIN(boost_static_assert_typedef_, __LINE__) \
  80         [ ::boost::STATIC_ASSERTION_FAILURE< (bool)( B ) >::value ]
  81 #elif defined(__sgi)
  82 // special version for SGI MIPSpro compiler
  83 #define BOOST_STATIC_ASSERT( B ) \
  84    BOOST_STATIC_CONSTANT(bool, \
  85      BOOST_JOIN(boost_static_assert_test_, __LINE__) = ( B )); \
  86    typedef ::boost::static_assert_test<\
  87      sizeof(::boost::STATIC_ASSERTION_FAILURE< \
  88        BOOST_JOIN(boost_static_assert_test_, __LINE__) >)>\
  89          BOOST_JOIN(boost_static_assert_typedef_, __LINE__)
  90 #else
  91 // generic version
  92 #define BOOST_STATIC_ASSERT( B ) \
  93    typedef ::boost::static_assert_test<\
  94       sizeof(::boost::STATIC_ASSERTION_FAILURE< (bool)( B ) >)>\
  95          BOOST_JOIN(boost_static_assert_typedef_, __LINE__)
  96 #endif
  97
  98 #else
  99 // alternative enum based implementation:
 100 #define BOOST_STATIC_ASSERT( B ) \
 101    enum { BOOST_JOIN(boost_static_assert_enum_, __LINE__) \
 102       = sizeof(::boost::STATIC_ASSERTION_FAILURE< (bool)( B ) >) }
 103 #endif
 104
 105
 106 #endif // BOOST_STATIC_ASSERT_HPP
 107
 108