These warnings occurs because of inaccurate C compiler behaviour.
In case you look into zend\zend_vm_execute.h(17488) and the whole function, you would see that free_op1 is used in this function, however the code which references the variable is unreachable.

A general solution to eliminate such warnings would require parsing of C source code. I don't think it make sense to invest time into it to just to remove warnings.

It is not that important to fix, you asked me to open a bug about it :)

However, there is no inaccurate behavior, if the code using this variable is unreachable, then the variable is not used at all (typically if (0) will striped out).

Dmitry, I looked at the MSDN for C4101 for example:

struct a {
 static int b() {
  return 1;
 }
};

int main() {
 A c;
 int d = c.func();

 return d;
}

The "A c;" line generates a C4101 because b is a static function and therefore no instance is needed to call it, in C++ that would mean main should looks like:

int main() {
 int d = A::func();

 return d;
}


Its documentation is at:
http://msdn.microsoft.com/en-us/library/c733d5h9(VS.80).aspx

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