[Development] Finishing the transition to the cherry-pick model

Volker Hilsheimer volker.hilsheimer at qt.io
Tue May 19 12:56:56 CEST 2020

> On 19 May 2020, at 12:38, Marc Mutz <marc.mutz at kdab.com> wrote:
> On 2020-04-17 13:21, Volker Hilsheimer wrote:
>> The development and testing of the cherry-pick bot over the last month
>> in a selected number of repositories [3] has given us confidence that
>> things are working well.
> I cannot say the same about qtbase. Cherry-picking back might be a good idea within Qt 5, but it certainly is a PITA for picking 6-era patches back to 5. A surprising number of mine needed adjustments, because Qt 5 still compiles under C++11 while 6 requires C++17. These adjustments void the CI verification performed on dev, and they would've been completely unnecessary had the change gone to Qt 5 first (as valid C++11 is also valid C++17). Splitting the patch into a fix that is C++11 compatible and a cleanup that uses C++17 is a possibility _if you're aware you're using post C++14-features, or for that matter, post-Qt-5 features_.
> The process is broken. I will not add Pick-to: headers any more.
> Thanks,
> Marc

I think the changes you made to some very old QString code that we have been living with for a long time are good for Qt 6, but not needed for Qt 5.15. 

You can split things up just the same way today, if you want your change to land in Qt 5.15: one commit using only C++11 that you Pick-to; and a second commit to improve on it in dev only using C++ 17 features. Not sure why that would be a problem; it’s additional work, just as making a change first in Qt 5.15, and then following up in dev, is additional work.

A very large number of the cherry-picks have already merged into 5.15 during the last 24 hours, with no dependency to a single person like Liang hand-holding a gigantic merge through, and without any single change blocking all other changes. In addition, dev has been quite stable, thanks to a lot of people developing actively against it.

It’s probably too early to pop the champagne, but it’s also too early to condemn the new process.


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