dynamic_cast fails when used with dlopen/dlsym

I found the answer to my question here. As I understand it, I need to make the typeinfo available in 'testc' available to the library 'testd'. To do this when using dlopen(), two extra things need to be done:

• When linking the library, pass the linker the -E option, to make sure it exports all symbols to the executable, not just the ones that are unresolved in it (because there are none)
• When loading the library with dlopen(), add the RTLD_GLOBAL option, to make sure symbols exported by testc are also available to testd

In general, gcc does not support RTTI across dlopen boundaries. I have personal experience with this messing up try/catch, but your problem looks like more of the same. Sadly, I'm afraid that you need to stick to simple stuff across dlopen.