Re: Bug with Visual Studio Optimizer?

From:

Ulrich Eckhardt <eckhardt@satorlaser.com>

Newsgroups:

comp.lang.c++.moderated

Date:

Mon, 26 Nov 2007 07:59:29 CST

Message-ID:

<h5oq15-jc6.ln1@satorlaser.homedns.org> <82af091e-9b36-4c42-8e28-82913047803c@e1g2000hsh.googlegroups.com>

Jason Hise wrote:

The following code prints GOOD in debug mode, and BAD in release
mode. Is that allowed by the standard? This was the root cause of a
very difficult to hunt down bug in my program, where I was using the
function addresses as keys into a map. I am wondering if I should
submit a bug report to Microsoft.

#include <iostream>

template<typename Type>
void foo() { }

int main()
{
    std::cout << (&foo<int> == &foo<float>
        ? "BAD" : "GOOD") << std::endl;
    return 0;
}

Just wondering, you aren't using that ten year old, unsupported and
deprecated VC6, are you? In that case, this behaviour is a known bug and
you're not going to get it fixed except by upgrading.

The problem there seems to boil down to VC6 not mangling the template
parameters into the name. The typical workaround looks like this:

#if defined(_MSC_VER) && _MSC_VER < 1300
   template<typename T>
   void foo( T* = 0)
#else
   ... // normal C++ code
#endif

However, in that case your code will stop compiling because it compares
pointers to functions with different arguments.

Uli

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