cph5externs.h Produces GCC 8.1 Error

[richards-joel-e]

cph5externs.h produces the following error:
error: a storage class can only be specified for objects and functions
#define CPH5_EXTERN extern
^~~~~~
../lib/cph5/common_externs/cph5externs.h:84:1: note: in expansion of macro 'CPH5_EXTERN'
CPH5_EXTERN class CPH5CompType;

This seems to compile without problems when I remove the extern declaration from the class definition.