Hi Martin,
> In all cases all the information necessary to detect and diagnose
> or even avoid the problem is available. In fact, one might argue
> that optimizing such calls (expanding them inline) would be
> preferable to doing nothing and allowing the undefined behavior
> to cause a bug at runtime.
I think the right thing to do here would emit a warning for
declaring the builtin with the wrong prototype.
If you try to do the equivalent in C++ you get this:
cat test.cc
extern "C" void* memcpy (...);
void p (void *d, const void *s)
{
memcpy (d, s, 0);
}
g++ -S test.cc
test.cc:1:18: warning: declaration of ‘void* memcpy(...)’ conflicts with
built-in declaration ‘void* memcpy(void*, const void*, long unsigned int)’
[-Wbuiltin-declaration-mismatch]
extern "C" void* memcpy (...);
^~~~~~
You get the same warning in C when the Prototype does not match,
but unfortunately not when the prototype is missing.
I would prefer the same warning in C whenever the declaration does
not match.
Bernd.
