[Development] QButtonGroup: When the "right thing to do" is absolutely the wrong thing to do

[boud at valdyas.org]

So, there's this commit:

https://git.qt.io/consulting-usa/qtbase-xcb-rendering/commit/69335920f724d2d4a49924f373c4fef57c942831

"
Move QButtonGroup implementation from qabstractbutton.cpp to 
qbuttongroup.cpp

Because it's the right thing to do.

Needed to introduce qbuttongroup_p.h because QAbstractButton
likes to poke around in QButtonGroup's private parts.

Fixed includes of qabstractbutton_p.h so it compiles on it's
own.

Change-Id: Ic7725277d2419754de273b2abd4790476edd0eb4
Reviewed-by: Olivier Goffart's avatarOlivier Goffart (Woboq GmbH) 
<ogoffart at woboq.com>

"

Which of course breaks source compatibility. It's bad enough to have to 
adapt one's codebase; but this also makes it impossible to bisect code 
when Qt 5.11 is installed that had to be adapted.

I'm constantly running into this problem. Would it be too much to ask 
that things like this just never ever happen again?


Boudewijn