[Development] Changing Qt's Binary Compatibility policy

[Giuseppe D'Angelo]

Hi,

On 18/06/2024 10:15, Alex Blasche via Development wrote:
> Our biggest issue is the adoption of Qt by users moving from one major
> release to the next. The deprecations start to become a liability and
> while they keep SC compatibility in check for Qt 6 they become a serious
>   concern for any adoption of Qt 7. While doing changes when it is
> necessary is OK as part of a major patch release, I totally agree with
> Andre that a lot of deprecations are nice to have and not mandatory. I
> would like to propose a far more restrictive process on when a
> deprecation is accepted (unless somebody has a better idea on how to
> curb this flood gate any other way).
> 
> If you need any further prove of the seriousness of this problem, have a
>   look at how long it took for KDE to adopt Qt 6 or look at the still
> incoming issues for Qt 5.15. Based on what I see, performance
> differences are the most common reason why Qt 6 is not ported to. The
> second one is the effort to port to Qt 6 due to mechanical porting from
> one API to the next.
> 
> Qt 7 deprecations show an alarming trend and those mostly don't even
> involve truly needed architecture changes like potential QIODevice or
> QFileSystemEngine changes yet. (I only use these two classes examples to
>   highlight the point and not that there is actual work being decided or
> ongoing)

I think this is now effectively a separate thread of discussion, since 
these deprecations create source incompatibilities, not binary 
incompatibilities.

Should we discuss it at the QtCS in a couple of slots?

Thanks,

-- 
Giuseppe D'Angelo | giuseppe.dangelo at kdab.com | Senior Software Engineer
KDAB (France) S.A.S., a KDAB Group company
Tel. France +33 (0)4 90 84 08 53, http://www.kdab.com
KDAB - Trusted Software Excellence

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