"Wrong C++ default declaration in a method" build failure(s) — clang 13.0.0

The default argument must be set in the definition or the definition done in the method declaration.
class string
{
    friend string foo(int bar = 0);
};
PackageVersionSupposed error messageFull log Bug report
wp2latex 3.100+ds-2../atoms/include/stringa.h:191:23: error: friend declaration specifying a default argument must be a definition Log

1 errors