Why does casting a function generate a run-time abort?

[Ziemowit Laski]

On 17 Jun 2004, at 22.55, Eric Botcazou wrote:

>> Could someone shed some light on this?
>
> The behaviour is undefined in C at run-time (6.3.2.3 §8) so generating 
> an
> abort is permitted.  This should not trigger in Objective-C (at least 
> that's
> how it was written for 3.4).

Right; there is an ugly 'if(!c_dialect_objc())' in front of the whole 
thing.  Although I do see that an abort is indeed permitted under the 
circumstances, I'm still mystified as to why this became an issue in 
the first place.  Why not just construct a function call using the 
signature specified in the cast?  Aside from not being able to inline 
the call, I'm not quite sure what the problem is...

> For the records, Geoff first suggested a compile-time abort, then 
> Joseph
> pointed out that this was only undefined at run-time, hence the 
> run-time
> abort (modelled on the va_arg stuff).

Yes, that's what my sleuthing uncovered also. :-)

--Zem