thanks for your fast response. The project is intended to be made open but it is currently in a very early stage and more a playground for OO programming for me. I will try to boil it down to a reproducer.
It seems that C::B itself is hanging. GFortran has 0 CPU load, while C::B has 100% thread load. The issue occurs, if I compile a module (without OO things in there) , where the interface of a contained routine is changed or if I add an arbitrary new subroutine/function. After freeze/kill/restart I can compile even without compiling everything. C::B hangs with arbitrary last build message. Sometimes this, sometimes that module routine. I assume that this depends on the build order. I've to do some further checks with a blank, new project.
Are there some debug modes, which I can activate or does there exist log files for further investigation. I read in an older threads that there are 'weights', which define the build order. If these are logged, maybe this give me a hint?
As soon as I've a reproducer or find a solution on my own I will share it.