[MU3] Fix deprecation warnings with Qt 5.15.2 and some palette qml files

[Jojo-Schmitz]

These warnings (lots of them) show at run time, not at compile time and may be quite irritating esp. for/on Linux, where MuseScore may use a newer Qt version.

Many times during startup and again on palette use:

Warning: qrc:/qml/palettes/Palette.qml:766:13: QML Connections: Implicitly defined onFoo properties in Connections are deprecated. Use this syntax instead: function onFoo(<arguments>) { ... } (qrc:/qml/palettes/Palette.qml:766, )

Once per startup:

Warning: qrc:/qml/palettes/PaletteTree.qml:772:5: QML Connections: Implicitly defined onFoo properties in Connections are deprecated. Use this syntax instead: function onFoo(<arguments>) { ... } (qrc:/qml/palettes/PaletteTree.qml:772, )
Warning: qrc:/qml/palettes/PalettesWidgetHeader.qml:225:5: QML Connections: Implicitly defined onFoo properties in Connections are deprecated. Use this syntax instead: function onFoo(<arguments>) { ... } (qrc:/qml/palettes/PalettesWidgetHeader.qml:225, )

See also https://doc.qt.io/qt-5/qml-qtqml-connections.html

For now a test, need to check the artifacts, which would use the older Qt 5.9.9 (which I don't have installed any more)
As per https://stackoverflow.com/questions/62297192/qml-connections-implicitly-defined-onfoo-properties-in-connections-are-deprecat as of QT 5.15.1 that new warning can get avoided by QT_LOGGING_RULES="qt.qml.connections=false" and that new/changed syntax is not supported by Qt 5.12 :-(

The artifact (for Windows) seems to work just fine though!?
What operations would need to get tested to verify? Selecting a score element and applying a palette element via double click works, as does dragging a palette element to a score element

[dmitrio95]

As far as I can tell lack of these operations will not break palettes entirely, so most basic operations will probably indeed work as expected. Certain UX-related features may however break if these handlers would work incorrectly:

• onHasFocusChanged in PaletteTree.qml ensures that "More" popup gets closed if you click outside of the current palette (or maybe outside of the entire palettes list, but if you select an element in the same palette this popup should stay).
• Another onHasFocusChanged seems to do a similar thing for the "Add Palettes" list at the panel header.
• onElementDraggedToScoreView ensures that when some element gets dragged to a score the corresponding cell should not be somehow hidden or moved — this is only relevant if you trigger palette cells reordering by the same drag first.

So these aspects should probably be tested to ensure that they work properly. But as far as I understand these functions will not be considered signal handlers by Qt 5.9 if they are declared as functions so the corresponding features should likely break.

[Jojo-Schmitz]

Thanks
OK, testing with the artifact (for Windows) shows that the first test succeeds: the "More" popup does vanish when clicking outside the palette and stays as long as elements within get selected.
The second tests succeeds too.
As does the third, as far as I can tell.
And all what with Qt 5.9.9, so your assertion that this would break things seems wrong. Seems to indicate that this change is safe, doesn't it?

[vpereverzev]

I'd prefer to not merge this into 3.x, because it's pretty dangerous and the benefit is small. I also strongly discourage to build the 3.x branch with QT 5.15

[Jojo-Schmitz]

I tend to agree. Linux maintainers may not though.
I 'd leave it open though, for easy cherry-picking

[RomanPudashkin]

I 'd leave it open though, for easy cherry-picking

These warnings are already fixed in master

[Jojo-Schmitz]

Yes, but not for 3.x, not on (Linux) builds from distributors that otherwise use Qt 5.15+
Cherry picking tor those distribution maintainers, not for you ;-)

[vpereverzev]

I'll archive this PR, the link will still persist

[Jojo-Schmitz]

Well, if a 3.6.3 is not planned, merging this won't do any harm either...

[Jojo-Schmitz]

This PR is something @mirabilos might be interested in, for the Debian ports?

[mirabilos]

Really?

I’d have thought this…

onElementDraggedToScoreView: function () { paletteCell.paletteDrag = false; }

But if it works… sure.

[Jojo-Schmitz]

It does for me

[mirabilos]

I don’t doubt that ☻ it’s just that JavaScript continues to irritate me, the more I learn about it ☺

[mirabilos]

@vpereverzev we build with whatever Qt version we have in the distros. That is currently:

• 5.3 on jessie(Debian) ⇒ MuseScore 2.3.2
• 5.5 on precise(PPA), trusty(PPA), xenial(Ubuntu) ⇒ MuseScore 2.3.2
• 5.7 on stretch(Debian) ⇒ MuseScore 2.3.2; MuseScore 3.2.3 with disabled plugin functionality
• 5.9 on bionic(Ubuntu) ⇒ MuseScore 2.3.2 and 3.x
• 5.11 on buster(Debian) ⇒ MuseScore 2.3.2 and 3.2.3; 3.x via backports later
• 5.12 on focal(Ubuntu) ⇒ MuseScore 2.3.2 and 3.x
• 5.14 on groovy(Ubuntu nōn-LTS, dropped soon) ⇒ MuseScore 2.3.2 and 3.x
• 5.15 on hirsute(Ubuntu nōn-LTS), bullseye(Debian), sid(Debian) ⇒ MuseScore 2.3.2 and 3.x

They all work, for what it’s worth, with the occasional patch; I’m ignoring the deprecation warnings for now since there won’t be a Qt 6 in Debian/Ubuntu in the foreseeable future.

[Jojo-Schmitz]

There shouldn't be any deprecation warnings in the latest 3.x codebase, those had been taken care of quite a while ago (but probably after 3.2.3, see #6813), not in the C++ code and at compile time at least. Just those QML ones from this PR, and at runtime.