The LIBCAMERA_DECLARE_PRIVATE() macro, used by the library classes that inherit from libcamera::Extensible in order to implement the PIMPL pattern, expands to: public: \ class Private; \ friend class Private; The 'klass' argument is not used and it might confuse developers as it might hint that the class that defines the pattern's implementation can be freely named, while it is actually hardcoded to 'Private'. Drop the argument from the macro definition. Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se> Reviewed-by: Hanlin Chen <hanlinchen@google.com> Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>