[Development] Qt 6 co-installability with Qt 5

[Shawn Rutledge]

> On 2021 Feb 16, at 14:31, Kai Köhne <Kai.Koehne at qt.io> wrote:
> 
> Well, let's just realize that, by renaming qmake to qmake6 everywhere (including in the documentation), we actually create some confusion for our existing users, too. Also, I think adding version numbers to the name of tools is just no good user experience, and creates unnecessary friction when switching between Qt versions.
> 
> To be honest, the whole discussion feels to me that we are being held hostage right now for the fraction of Linux users that cannot use update-alternatives (because they are not administrators). If having different names of tools is such a big problem, why wasn't this addressed by now in Linux itself?
> 
> And again, this is not something limited to Qt. Last time I checked, the executable to run Python 3 on Windows is python.exe, not python3.exe. On Debian at least it's python3. This hasn't blocked Python from being perceived as overall beginner friendly ...
> 
> So, I would stick to qmake as canonical name, also in the documentation. We can mention that it's sometimes called qmake6 on Linux. But forcing everyone to change their habit and scripts just for the sake of consistency with a fraction of the users that use a global installation on Linux, and do not use update-alternatives, is IMO not a good move.

I’m not fond of the renaming either.  But as long as the non-suffix tools get installed into /usr/lib/qt6/bin and the ones with suffixes are links in /usr/bin, it looks like we get a decent compromise.  I’m happy to go on using qtchooser and configuring it to point to non-suffix binaries.  But the distros need to get in sync to have the suffix be simply 6, not -qt6, IMO.