How is symbol visibility set in KF5 and KDE?

Hi all,

I just realised that the Python binding effort is not setting the default
visibility for symbols using the -fvisibility=xxx option when processing
the header files [1]. Of course I can see the export macros set by the
likes of attica_exports.h, but I don't see where the compiler default is
set. Can somebody kindly point that out?

Thanks, Shaheed

[1] I'm also a bit mystified by the fact that I am deliberately querying
CMake for the COMPILE_FLAGS to use, but I have not seen -fvisibility
anywhere...