But in Okular we don't use Qt Quick you'll say!
Well, we actually use Qt Quick in the mobile interface of Okular, but you're right, this was not a patch for the mobile version, so "But in Okular we don't use Qt Quick!"
The story goes like this.
I was reviewing https://invent.kde.org/graphics/okular/-/merge_requests/431 and was not super convinced of the look and feel of it, so Nate gave some examples and one example was "the sidebar in Elisa".
So I started Elisa and saw this
You probably don't speak Catalan so don't see that lesquerra is a mistake it should be l'esquerra.
Oh the translators made a mistake i thought, so i went to the .po file https://websvn.kde.org/trunk/l10n-kf5/ca/messages/elisa/elisa.po?view=markup#l638 and oh surprise! the translators had not made a mistake (well not really a surprise since they're really good).
Ok, so what's wrong then?
I had a look at the .qml code https://invent.kde.org/multimedia/elisa/-/blob/release/21.04/src/qml/MediaPlayListView.qml#L333 and it really looked simple enough.
I had never seen a Kirigami.PlaceholderMessage before but looking at it, well the text ended up in a Kirigami.Heading and then in a QtQuick Label. Nothing really special.
Ok i said, let's replace the the whole xi18nc in there with the translated text and run elisa. And then i could see the ' properly.
Hmmmm, ok then the problem had to be xi18nc right? Well it was and it was not.
The problem is that xi18nc translates ' to ' to be more "html compliant" https://invent.kde.org/frameworks/ki18n/-/blob/master/src/kuitmarkup.cpp#L40
And unfortunately Qt Declarative 5.15 Text item default "html support" is something Qt calls "Styled Text" that only supports five HTML entities, and apos is not one of them https://code.qt.io/cgit/qt/qtdeclarative.git/tree/src/quick/util/qquickstyledtext.cpp?h=5.15.2#n558
So where is the bug?
The Text documentation clearly states that ' is in the list of supported entities.
One could say the bug is that every time we use xi18nc in a Text we should remember to change the "html support" to something Qt calls "RichText" that actually supports '.
But we all know that's never going to happen :D, and in this case it would actually be hard since Kirigami.PlaceholderMessage doesn't even expose the format property of the inner text
So I convinced our friends at Qt that only supporting five entities is not great and now we support six ^_^ in Qt 6.2, 6.1 and 5.15 (if you use the KDE Qt patch collection) https://invent.kde.org/qt/qt/qtdeclarative/-/merge_requests/3/diffs
P.S: I have a patch in the works to support all HTML entities in StyledText but somehow it's breaking the tests, so well, need to work more on it :)