[KDE/Mac] KF5 plugins and PLUGIN_INSTALL_DIR vs QT_PLUGIN_INSTALL_DIR

[René J.V. Bertin]

Hi,

Sorry for this disturbance in the force, but I came across an old message and commit from you (https://mail.kde.org/pipermail/kde-buildsystem/2012-September/008851.html) that seems related to an issue I'm facing.

I'm finally writing MacPorts Portfiles for the KF5 frameworks. The good news is that "our" QSP patch appears to work as intended, including my own activator bit (which I'm simply linking to every KF5 framework).

More annoyingly, I'm running into an issue with KF5 plugin loading, at least in kwindowsystem, which AFAICS is due to the fact that plugins are expected (hardcoded) under QCoreApplication::libraryPaths().
Assuming the MacPorts default prefix, Qt5's plugin path is either /opt/local/share/qt5/plugins (or /opt/local/libexec/qt5-mac/plugins, depends on the Qt5 port). And that's what QCoreApplication::libraryPaths() returns (plus the app path, of course).
However, my KF5 plugins end up in /opt/local/lib/plugins/kf5 (or /opt/local/lib/x86_64-linux-gnu/plugins/kf5 when I use the same packaging on Linux).

Evidently they're not being found.

Reading your old message, I see your commit at the time was intended to "have all plugins in the same dir", which is clearly not what I'm getting.

What is going wrong here, and why? Should I be setting -DPLUGIN_INSTALL_DIR=${QT_PLUGIN_INSTALL_DIR}?

I'm used to Qt4 not finding KDE4's plugins on OS X/MacPorts, but KF5 not finding its own plugins is a whole 'nuther piece of something...

Cheers,
René