[Boost-bugs] [Boost C++ Libraries] #2826: constant boost::mpl::aux::template_arity_impl::value causes 64 bit truncation warning

Subject: [Boost-bugs] [Boost C++ Libraries] #2826: constant boost::mpl::aux::template_arity_impl::value causes 64 bit truncation warning
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2009-03-03 22:29:56

#2826: constant boost::mpl::aux::template_arity_impl::value causes 64 bit
truncation warning
----------------------------------+-----------------------------------------
 Reporter:  pelee_at_[hidden]       |       Owner:  agurtovoy
     Type:  Bugs                  |      Status:  new      
Milestone:  Boost 1.39.0          |   Component:  mpl      
  Version:  Boost Release Branch  |    Severity:  Problem  
 Keywords:                        |  
----------------------------------+-----------------------------------------
 When compiled for a 64 bit target, the constant
 boost::mpl::aux::template_arity_impl::value causes a warning about
 possible truncation of a 64 bit value to 32 bits. This is because size_t
 (returned by sizeof()) is 64 bits, while value is declared as an int. One
 fix would be to declare the constant as a size_t. Instead I added a
 static_cast on the assumption that it would be less disruptive and the
 value returned by sizeof() was unlikely to require more than 32 bits.


 {{{
 typename arity_tag<6>::type
 arity_helper(type_wrapper< F< T1,T2,T3,T4,T5,T6 > >, arity_tag<6>);
 template< typename F, int N >
 struct template_arity_impl
 {
     BOOST_STATIC_CONSTANT(int, value =
           static_cast<int>(sizeof(arity_helper(type_wrapper<F>(),
 arity_tag<N>())) - 1)
         );
 };

 }}}

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/2826>
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