KPluginLoader::findPlugins(..) returning empty vector

[Aleix Pol]

On Thu, Aug 11, 2016 at 11:37 AM, Srivatsan Iyer
<supersaiyanmode.rox at gmail.com> wrote:
> Hello,
>
> I checked out the kdeconnect-kde repository and have been trying to compile
> from sources. I have been able to get it running. However, when I connect
> via the phone, I see an empty list in the main activity. I spent a few hours
> digging -- from the PluginFactory Java class (in Android) to
> pluginloader.cpp. I am stuck at the point where
> KPluginLoader::findPlugins("kdeconnect/") in PluginLoader constructor
> returns an empty vector causing all downstream capabilities listing to
> silently fail. From the documentation I, sort of, understand that it is a
> directory -- but where is it? The docs say it looks for JSON files within
> the subdirectories under it. Should this be plugins directory instead? I
> tried passing in, without any success, the absolute path to my local
> kdeconnect-kde/plugins directory. I would really appreciate any pointers or
> help.
>
> Details about my environment:
>  - KDE Plasma version: 5.6.5
>  - KDE Frameworks version: 5.23.0
>  - QT Version: 5.5.1
>  - Kernel version: 4.4.0-31-generic
>
> My method to run and debug:
>  - make && sudo make install
>  - (kill kdeconnectd)
>  - call "kdeconnect-cli -l" (seems to have a side effect of starting the
> daemon if not running)
>  - check logs using "tail -f /var/log/syslog | grep kdeconn"

Can you make sure that you're installing to /usr or that
QT_PLUGIN_PATH is properly initialized?

> On a slightly different note: I had compile issues with pluginloader.cpp
> within the function "pluginsForCapabilities(..)" for that's using
> qSet1.intersects(qSet2). This is unavailable in Qt5.5. I replaced it with an
> inefficient equivalent:
>     if ((pluginIncomingCapabilities.isEmpty()
>         && pluginOutgoingCapabilities.isEmpty())
>         || (incoming & pluginOutgoingCapabilities).size()
>         || (outgoing & pluginIncomingCapabilities).size()) { .. }
>
> Would it make sense to not use .intersects(..) -- because that is the only
> line of code in the entire source that causes the compile to fail on QT
> version 5.5 - 5.6 ?

It compiles fine with Qt 5.6, not Qt 5.5 indeed. I'd recommend you to
use a distribution with the stable version of the packages.
We discussed patching it up, but it doesn't really improve things,
since already released distributions won't pick up the package anyway.

Aleix