foo needs a function signature with the right type.

And yes I know that subs can be redefined, but change of prototype is also emitting a warning.

Really complicated are lvalue situations like aliasing!

But hey, I never said it's easy... ;)

You call a sub which is declared as accepting an integer arg - so perl pushes an int value dircectly onto the stack rather than the usual pointer to SV. But if someone in the meantime has redefined foo() to be a sub accepting a normal SV argument, then perl won't just do the wrong thing - it will likely crash with a SEGV, or even be a security hole, when it tries to interpret that integer value as the address of an SV.

Dave.

That's why I mentioned

> > And yes I know that subs can be redefined, but change of prototype is also emitting a warning.

Warnings to Fatals.

> it will likely crash with a SEGV, or even be a security hole, when it tries to interpret that integer value as the address of an SV.

I suppose using Inline::C or Inline::CPP is even worse, when it comes to such risks.

Cheers Rolf
_{(addicted to the Perl Programming Language :)
Wikisyntax for the Monastery FootballPerl is like chess, only without the dice}