Re: [PATCH, PR 60640] When creating virtual clones, clone thunks too

[Jan Hubicka <hubicka at ucw dot cz>]

> On 04/04/2014 04:05 PM, Jan Hubicka wrote:
> >Ah, yes, it is what I was discussing this with Jason, but apparently the
> >discussion died out.  According to his comment __cxa_pure_virtual is a
> >synonym for undefined behaviour so it may be correct to unconditionally
> >devirtualize here (changing runtime behaviour from terminate() to random method
> >call), but at the moment we don't do that.  Somewhere back in my head I have
> >burned in from C++ lessons that calling pure virtual method should result in
> >terminate () call, so I am considering __cxa_pure_virtual to be legitimate call
> >target (as opposed to any non-function or __builtin_unreachable that I drop
> >from the list).
> >
> >I would be happy to change this behaviour, since there are quite few extra
> >cases where we could devirtualize well then.
> 
> It's definitely undefined.
> 
> 10.4/6:
> 
> Member functions can be called from a constructor (or destructor) of
> an abstract class; the effect of making a virtual call (10.3) to a
> pure virtual function directly or indirectly for the object being
> created (or destroyed) from such a constructor (or destructor) is
> undefined.

OK, I will change the behaviour then, thanks!

Thanks,
Honza
> 
> Jason