Qt4 shouldn't require X11, even on Unix

[Alexander Neundorf]

On Monday 07 July 2008, you wrote:
> Alexander Neundorf wrote:
> >I just checked, a check for X11 is part of FindQt4.cmake since rev 1.1
> > in cmake cvs, almost exactly 3 years old.
> >Do you think it's worth changing this ?
> >(adds a difference to the version from cmake and might break some builds
> > which accidentially use the X11 vars defined by this FIND_PACKAGE(X11)
> > )
>
> This would be akin to a source-incompatible change in CMake, I understand.

Yes, but only a small one (which could maybe be called a bug) (small 
incompatibility, hmmm, ... sounds like a "little bit pregnant"....).

> But this isn't beyond the gcc developers, though: with gcc 4.3, they've
> made their headers a lot more strict, meaning you cannot assume that
> #including a file will bring another along. (For example, #include
> <string> will not #include <string.h> anymore, so no memcpy will be
> defined)

Yes, gcc developers dare to break a lot of stuff (relatively). Actually I 
wonder why they get away with this.

> But that requirement there makes using Qt require the X11 headers, which
> isn't always so. You're fully allowed to do development with Qt without
> X11 headers installed (provided you're not using static builds). You
> can't build Qt without them -- but once you have, you can remove them.
>
> Of course, this means you can't pass -lX11 on the linking command-line
> when linking to QtGui... and qmake itself isn't generating the proper
> Makefiles yet.
>
> This again goes back to what I've been saying: all applications must
> declare all of its direct dependencies. It uses X11? FIND_PACKAGE +
> TARGET_LINK_LIBRARIES and whatever else.

Yes.
Well, I don't have a strong opinion on this.
If you think it's somewhat important, I'd say we do this after 4.1.

Alex