Declaration attribute: visibility missing

[renlite]

https://github.com/orca-app/orca/blob/main/src/platform/platform.h#L105 defines for callbacks:

#define ORCA_EXPORT __attribute__((visibility("default")))

ORCA_EXPORT void oc_on_init(void){ ... }

I think it's needed for C-binding.
I didn't find a proper macro (declaration attribute) in C3. Is this missing or can I create a user defined attribute?

def @MyAttribute = {  __attribute__((visibility("default"))) };

[lerno]

It has the default visibility, so you should be able to ignore it completely, so declare for example

extern fn void oc_on_init();