[Development] Making Binary Incompatible Changes after Qt 6.0

[André Somers]

Hi,

On 07-12-2020 10:24, Volker Hilsheimer wrote:
> Hi,
>
> Given the scale of Qt 6.0 it’s perhaps no surprise that in spite of careful reviews, we are seeing the first API issues popping up, fixing of which would require a breakage of binary compatibility. For example:
>
> https://bugreports.qt.io/browse/QTBUG-87465
>
> I’ve now created an EPIC type JIRA ticket through which we can keep track of such issues, so that we can understand the scale and impact of the overall problem.
>
> https://bugreports.qt.io/browse/QTBUG-89157
>
> The data collected there should then help us understand whether we should relax our binary compatibility guarantees for Qt 6.0. If you are aware of any, please link them to this ticket.

Perhaps it's just me, but I don't see an official Qt 6.0 released yet. 
Isn't it exactly the point of releasing beta's and release candidates to 
find and then be able to iron out issues? I did not realize that the 
binary compatibility guarantee held for these as well?

Or, is the issue that fixing these issues before the scheduled release 
date is not feasible? Well, perhaps then the conclusion should simply be 
that that scheduled release date is not feasible? Would it not be better 
to release something that is ok going forward, rather than something 
that is broken but due to our own rules we cannot fix for the 
foreseeable future?

>
> If we decide here to break BC before 6.1 because the available workarounds [1] are not applicable or not something we want to live with until Qt 7, then we might just as well go “all in” with such changes (as long as we maintain source compatibility).
>
>
> Cheers,
> Volker
>
> [1] https://wiki.qt.io/Binary_Compatibility_Workarounds - that page is perhaps not as useful as it could be (but the KDE page linked is excellent)

André


P.S. /me is of the opinion the that item widgets should have been 
removed completely in Qt 6.