Re: First problems with 1.30.0

From: klapshin (klapshin_at_[hidden])
Date: 2003-03-21 12:00:45

--- In Boost-Users_at_[hidden], Kevlin Henney <kevlin_at_c...> 
wrote:
> Is the runtime behaviour correct? Have you been able to reproduce 
the
> warning with a smaller example based just on lexical_cast?

I have not tried to run program yet because of much bigger problems 
with random library -- it simply fails to compile (see my original 
post).

Reproducing warning with lexical cast is straightforward:

#include <boost/lexical_cast.hpp>
#include <iostream>
int main()
{
        std::cout << boost::lexical_cast<int>("7") << std::endl;
        return 0;
}

reports the same warning

I:\SW\EXTERNAL\BOOST_1_30_0\boost/lexical_cast.hpp(147) : warning 
C4800: 'void *' : forcing value to bool 'true' or 'false' 
(performance warning)
        I:\SW\EXTERNAL\BOOST_1_30_0\boost/lexical_cast.hpp(146) : 
while compiling class-template member function 'bool __thiscall 
boost::detail::lexical_stream<int,char *>::operator <<(char *const 
& )'

Runtime behaviour of this program is correct. The warning is rather 
innocent, but annoying.
Moreover the warning is abolutely correct -- returning stream from 
method with bool return type will convert void* to bool. Also it 
should be rather easy to fix, by explicitely casting it to bool.