no luck with Qt 5.9.2

[Jan Mulder]

On 24-10-17 18:29, Thiago Macieira wrote:
> On Tuesday, 24 October 2017 08:30:14 PDT Tomaz Canabrava wrote:
>>> I found one commit that is in Qt 5.9.2 (and not in 5.9.1) called "Fix qml
>>> cache invalidation when changing dependent C++ registered QML singletons"
>>> (commit 98358715930739ca8de172d88c5ce6941c275ff3 in qtdeclarative).
>>> Related
>>> to QTBUG-62243.
>>>
>>> The rationale of that commit is fully sane to me, but ... I reverted this
>>> one, and my problem of unable to start Subsurface-mobile build with 5.9.2
>>> (on desktop, for now) due to a silent failure of engine.load("main.qml")
>>> is
>>> gone, and the mobile-on-desktop app runs correctly as before.
>>>
>>> So, now the big question is ... how to proceed? I still cannot rule out
>>> that
>>> the whole issue is a result of some (still unknown) bug in Subsurface
>>> itself, or Kirigami or ... But, building a tiny bug demonstrator for Qt
>>> might be over my skill set :-)
>>>
>>> For anyone that might wonder how I found this suspicious commit ... I
>>> found
>>> earlier that the Kirigami file Units.qml was involved, and that is a
>>> singleton type object. That made me search for singleton related code
>>> changes in Qt.
>>
>> This is something that we can poke thiago, and thiago can poke more people.
>> And it's a serious issue as this can break a lot of usecases of qt.
> 
> And he did.
> 
> The first thing we should do is file a bug with the findings so far and the
> symptoms, even if we can't provide a reduced testcase.
> 
> Further from that, I can't directly help, since I have no idea about the QML
> internals. I do know that the QML caching feature is something I have problems
> with, but that's usually because I build from sources and not from releases.
> Intermediary builds can leave corrupt caches.
> 
> I can help poke people, though. Can you report the current findings so I'll
> poke people?
created QTBUG-64017

--jan