DirPtr pointer operator overflow fails

[ktnb-netbsd]

Here is the error:

In file included from udir.cc:4:
udir.cc: In member function 'int cdir::descriptor() const':
udir.cc:155:19: error: base operand of '->' has non-pointer type 'DirPtr'
  155 |     return dirp ? dirfd(*dirp) : -1;
         |                          ^~~~~
udir.cc: In member function 'int udir::descriptor() const':
udir.cc:273:19: error: base operand of '->' has non-pointer type 'DirPtr'
  273 |     return dirp ? dirfd(*dirp) : -1;
         |                          ^~~~~
gmake[2]: *** [Makefile:1763: udir.lo] Error 1

Building on NetBSD 10. Is there a certain version of C++ that is required for this?