- void (*call)(struct psi_context *C, struct psi_call_frame *frame, struct psi_decl *psi_decl, void *rval, void **args);
- void (*call_va)(struct psi_context *C, struct psi_call_frame *frame, struct psi_decl *psi_decl, void *rval, void **args, size_t va_count, void **va_types);