ports/137373: x11/libX11: make dependance on x11/libxcb

[Marcin Wisnicki]

On Tue, 17 Nov 2009 14:11:53 -0700, John Hein wrote:

> Carlos A. M. dos Santos wrote at 18:22 -0200 on Nov 17, 2009:
>  > On Tue, Nov 17, 2009 at 3:07 PM, Robert Noland <rnoland at freebsd.org>
>  > wrote:
>  > > There is a pretty fair risk of breaking several other ports with
>  > > this. Other ports that also expect xcb to be present would need to
>  > > be modified to either have xcb disabled or fail if libX11 does not
>  > > have the needed functionality.
>  > 
>  > That's exactly why I made it optional, default on, keeping the
>  > default behavior.
> 
> I think that what Robert may be saying is that even if it's default is
> 'on', people will turn it off, and we might see lots of questions about
> why this port or that port isn't working.
> 
> Maybe you can investigate a few ports that may need the xcb-ness of
> libX11 and see what it takes to make them work in an xcb-free flavor of
> libX11 (or hint at build time that they won't work if libX11 doesn't
> have xcb).
> 

Maybe something like this:
1. Add CONFLICTS=libxcb-* to x11/libX11 when XCB=off
2. Any port that needs xcb should depend on it explicitly

Thus any software that needs xcb will not build (or even install from 
prebuilt package) if your libX11 was made without XCB.

> The alternative is to commit this change and just see what breaks. But
> doing a little investigation ahead of time to give us a heads up about
> what to expect would be useful.