EXTPRENODECL

Message        There is no identifier named "<name>" with external
               linkage declared in this compilation unit.

Description    A #pragma extern_prefix directive specifies an extern
               prefix for an identifier that is not declared with
               external linkage in the compilation unit.  This may
               not have been what you intented.

User Action    Remove the identifier from the #pragma extern_prefix,
               or declare it with external linkage, or set the
               prefix for this identifier to an empty string.