[Development] qsizetype

Volker Hilsheimer volker.hilsheimer at qt.io
Wed Sep 7 11:00:09 CEST 2022

> On 7 Sep 2022, at 09:00, Andreas Aardal Hanssen <andreas at hanssen.name> wrote:
> On Wed, Sep 7, 2022, at 08:45, Kevin Kofler via Development wrote:
>> Alex Blasche wrote:
>>> 2.) An alternative might be to make this change in one go for Qt 7. We
>>> would keep Qt 6.x on the status quo but start adding compatible
>>> replacement APi with an absolute change at 7.0 (ifdefs or typedefs come to
>>> mind). Users would only be burdened one time (though it being one BIG time
>>> effort). Such a change would be much simpler in Qt headers.
>> It scares me that a Qt 7 is already being planned or discussed at all, 
>> considering that your major consumers such as KDE Plasma are not even ported 
>> to Qt 6 yet! (Note that I am talking about *consumers* here, not only about 
>> (paying) customers. The former includes FOSS projects such as KDE.)
>> Those major/BIC releases need to happen a lot less frequently, or ideally, 
>> stop entirely. At least if you want your consumers to keep up (and you 
>> clearly do or you would not have restricted access to Qt 5.15 LTS).
>> You should plan for Qt 6.x releases (rather than 7.x) for at least 10 more 
>> years, if not indefinitely.
> I second this, considering the breakages in APIs and behavior, and bugs introduced, in Qt 6, I feel discussions about Qt 7 send a very poor signal. Porting to Qt 6 is a huge and costly effort. With so much care being made not to break BC, I would hope more care would be taken to preserve behavioral (QVariant/QMetaType) and API compatibility. I hope KDE not using Qt 6 yet sends a message taken seriously on the Qt side. Stay on Qt 6 for a long time guys.
> Andreas

I understand that seeing Qt 7 in discussions is raising eyebrows, given where we are with Qt 6. But we need to be able to discuss what we can do without BiC breakage within Qt 6, and what we can only do for Qt 7, and what lessons we learned from the Qt 6 work. That doesn’t mean that we don’t plan to continue to focus on Qt 6!

Whether, and how often, we will break compatibility (be it binary, or behavior, or the result of significant, “world changing” rework) in the future deserves a separate discussion thread anyway.


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