g++ undefined reference although symbol is present in *.so file

Question

I found a number of similar questions (e.g. this, that or this), but none of them helped me solve my problem. I have a *.so file (from the core of gnss-sdr) that, as indicat

Answer 1

I have found in the past that this type of error is caused by the lack of proper extern "C" { ... } bracketing in an include file.

Answer 2

The pedantically correct way to check that a .so exports a symbol is nm --demangle --dynamic --defined-only --extern-only <lib.so> | grep <symbol>.

Without --defined-only your command also shows undefined symbols.

Without --extern-only it also shows symbols with internal linkage which are unavailable for linking.

It looks like you need to link another library because Gps_Ephemeris::Gps_Ephermeris() is not resolved by linking libgnss_system_parameters_dyn.so. A good way to start is that library's documentation and examples.