[Development] Proposing CMake as build tool for Qt 6

[Lisandro Damián Nicanor Pérez Meyer]

On Fri, 14 Jun 2019 at 16:06, Thiago Macieira <thiago.macieira at intel.com> wrote:
>
> On Friday, 14 June 2019 11:35:20 PDT Lisandro Damián Nicanor Pérez Meyer
> wrote:
> > > That means you
> > > should NOT do that strong dependency. app5 should require qdbus >= Qt5,
> > > which means Qt 6's should suffice.
> >
> > Except you can't ship both version in the same binary-package, so
> > there is no way to express that relationship *with versioning*. The
> > package will need to depend upon qdbus (qt4) or qdbus-qt5. A virtual
> > package might be considered, but only for applications that will not
> > change their backwards behavior *ever*.
>
> THAT's a good point.
>
> I was thinking that you'd split the package so that Qt 3, 4 and 5's qdbus is
> never installed, but instead you always get the one from Qt 6. That means Qt 6
> is always installed in a system that needs qdbus, regardless of whether any
> applications use it.

And now I get your point here. I think we never thought in this
because qdbus is the only tool we have a promise of backwards
compatibility.

> This is not always a good solution.

But at the same time the only place in which this can not be good
would be in Yocto, but in those cases you will certainly ship only one
Qt version.

> But we should consider splitting qdbus and qdbusviewer out of qtbase and
> giving them their separate, independent releases.

That really sounds like a nice solution. I don't know if it uses
private headers or not. If it does it might need to be updated in case
a future revision breaks it, otherwise it should be quite
straightforward. And make Qt a little bit slimmer too.