[Xcb] xcb-proto commit f91186b9f3 (dri2 padding) breaks build

[Josh Triplett]

On Mon, May 17, 2010 at 03:49:57PM -0700, Alan Coopersmith wrote:
> I cannot build libxcb when commit f91186b9f3e55e1d478476749c929b86e2865cc8
> is present, but going back to the previous commit allows it to build fine.
> 
> With that commit in place, building gives the error:
> 
> "dri2.c", line 332: cannot take sizeof void
> 
> The code from the generated dri2.c here is:
> 
>     328 void *
>     329 xcb_dri2_connect_alignment_pad (const xcb_dri2_connect_reply_t *R  /**< */)
>     330 {
>     331     xcb_generic_iterator_t prev = xcb_dri2_connect_driver_name_end(R);
>     332     return (void *) ((char *) prev.data + XCB_TYPE_PAD(void, prev.index)
> + 0);
>     333 }
> 
> After cpp expansion the last line has become:
> 
> return (void *) ((char *) prev.data +  ( - ( prev . index ) & ( sizeof ( void )
> > 4 ? 3 : sizeof ( void ) - 1 ) ) + 0);
> 
> and like the compiler, I have no idea what size a "void" is.
> 
> Is something wrong in the code generator that's generating different code here
> for me, or does gcc allow taking the size of sizeless types like void?
> 
> (I'm building on OpenSolaris with the Sun compilers.)

Not a bug in the code generator, but a bug in the descriptions for using
type void, I think.   <list type="void" ...> seems inherently wrong.
Odd that you can build XCB before that commit, though, since a few other
lists of type void seem to exist as well.

- Josh Triplett