Undefined symbol ALTREP_SERIALIZED_STATE

[MarcusKlik]

Apart from the method above, many other ALTREP methods are not exported yet on R-devel on linux.

This seems to be caused by a attribute_hidden definition in front of the function declaration in the R sources, see for example the non-exported ALTREP_INSPECT here.

Exported functions seem to have attribute_hidden commented out. Perhaps a post to [email protected] will clarify the current state.