call_traits and MSVC 7.1

8 May 2003

      We have been using call_traits from Boost version 1.29.0 in 
conjunction with MSVC 7.0.  When attempting to recompile this code 
under MSVC 7.1, using either Boost 1.29.0 or 1.30.0, we now 
encounter compilation errors.  A simple example of the usage pattern 
is:

###############################################################
#include <boost/call_traits.hpp>

class A
{
public:
    template<typename _Source>
    void doSomething
    (
        typename boost::call_traits<_Source>::param_type value
    )
    {
    }
};

class B
{
public:
    explicit B(double d = 1.0, int i = 42) : _d(d), _i(i) {}
    B(B const& b) : _d(b._d), _i(b._i) {}

private:
    double _d;
    int _i;
};

extern "C" int main(int argc, char* argv[])
{
    A a;
    B b;
    a.doSomething(b);
    return 0;
}
#############################################################

The new compiler generates the error message:

c:\Documents and Settings\rbowen\My 
Documents\Projects\CallTraitsTest\CallTraitsTest.cpp(34) : error 
C2783: 'void A::doSomething
(boost::call_traits<_Source>::param_type)' : could not deduce 
template argument for '_Source'
        c:\Documents and Settings\rbowen\My 
Documents\Projects\CallTraitsTest\CallTraitsTest.cpp(11) : see 
declaration of 'A::doSomething'

As an experiment, I manually included the older logic for 
call_traits by cutting and pasting the relevant classes into my 
source from 'detail/ob_call_traits.hpp' and still encountered the 
same error.

Has anyone else experienced this?  Is this (yet another) MS compiler 
bug?

call_traits and MSVC 7.1

Randy Bowen