I see that you went C++ route and not simple QML way.

I would suggest to install
https://build.merproject.org/package...s/mapboxgl-qml and just use MapboxMap together with the gesture area as in https://github.com/rinigus/mapbox-de...y/MainPage.qml . Then you don't even need to include MapboxGL as a submodule, can use regular gcc, and its all very simple. mapboxgl-qml would register the module in the system and all should just work. Please report bugs if it doesn't.

C++ way, as you did, is also possible, but more complicated and will lead to all apps having different versions of the plugin (since you are compiling it in) and would end up having larger requirements in the root partition (everyone installing plugin under their /usr/share/harbour... folder). Note that QMaboxGL (which plugin interfaces), requires QLocation. So, there is no-go into Jolla Harbour until its allowed (Jolla's soon^TM comes into mind). So, I would suggest to go via QML plugin installation, enjoy programming and using it!

As for the error that you get, I think you are very close. You seem to miss c++14 in PRO configuration file, as I can deduce from compile messages. See https://github.com/rinigus/mapbox-de...x-sfos.pro#L15