Re: VC8 Compiler bizarreness

"Murrgon" wrote:


I made shorter example that exhbits the problem:

<code>
#include <vector>

template<typename T>
class X
{
    friend bool operator !=(T*, const X<T>&)
    { return true; }
};

typedef X<double> XD;
typedef std::vector<XD> XDVec;

int main()
{
    XDVec vec;
    XD d;

    bool b1 = (NULL != vec[0]);
    bool b2 = (NULL != d);
}
</code>

Here are compilation results:

VC++ 2008 (v9.0) - compiles without any problem.
VC++ 2005 (v8.0) - fails to compile as long as global operator is
inline.
Comeau C++ Online - same as VC++ 2008.

So, I think it is indeed a bug in VC++2005. Strangely enough it
happens only with `XDVec' vector instance and not when `XD'
instance is used directly. In order to resolve it you need to do
the folowing:

1. Make global `operator !=' defined outside of class X:

template<typename T>
class X
{
    friend bool operator !=(T*, const X<T>&);
};

template<typename T>
bool operator !=(T*, const X<T>&)
{ return true; }

2. Replace `T*' input parameter type with `int', since VC++2005
fails to deduce parameter type from NULL. I just added another
`operator !=':

template<typename T>
class X
{
    friend bool operator !=(int, const X<T>&);
    ...
};

template<typename T>
bool operator !=(int, const X<T>&)
{ return true; }

With the changes above the code compiles with VC++2005. I think
you could open a bug report with MS and demand a hotfix.

HTH
Alex