I managed to compile indi an Kstars on my system very old ubuntu 16.04 ..
I needed only to change 3 source files (around 10 lines of code) by substituting QOverload with static_cast. (for those who need to do this: change "QOverload<YYY &>::of(&XXX" "static_cast<void (XXX::*)(YYY)>(&XXX" whery YYY is type and XXX name.