[vlc-devel] [PATCH] Configure script learn "--with-qt-version=(4|5)" option.

[Paweł Stankowski]

Hi Jean and Remi,

> On 10 Nov, Paweł Stankowski wrote :
> > New option may be used to enforce installation of specific Qt version.
> > This is useful when both qt4 and qt5 are installed in the system.
>
> What's the use case?
Use case here is Gentoo Linux where we have the possibility to compile
against both qt versions using qt4 and qt5 use flags. This use flag is
needed to ensure that:
- qt5 is used when qt5 use flag is active (and qt4 is not used as fallback)
- qt4 is used when qt4 use flag is active and both qt4 and qt5 are
installed in the system
Moreover, I can imagine that this is useful when compiling for target
machine that has only one  of the Qt versions available on host
machine.

> If you have both, it will compile for Qt5, which is the expected.
> If you have both, and really want Qt4 (why?), just set the PKG_CONFIG so
> it takes only Qt4.
I described why above. What do you mean by setting PKG_CONFIG? I can
imagine that I could write wrapper for pkg-config that exits with
error code when "Qt5*" package is searched for. And we will probably
do such or other workaround if this patch is not accepted.
However I wanted to enable that option upstream, as it is useful not
only for Gentoo, but also for cross-compiling and for everyone that
needs more control over configuration process.
I also think that such nasty wrapper for pkg-config would be a way to
replace any --enable/--with configure option, so we could delete all
of existing ones when thinking this way.
I think that '--with' option is used correctly here - it is suggested
by autoconf documentation to be used when few alternatives exist - and
that's the case here.

> Debian and Ubuntu have a package dedicated to that already.
Remi, what is the name of that tool? Does it work the same way that I
described above?

Regards,
Paweł Stankowski