@itemize
@item
This function is missing on some platforms:
-AIX 5.1, HP-UX 11, OSF/1 5.1, Solaris 10.
+AIX 5.1, HP-UX 11, OSF/1 5.1, Solaris 10, mingw.
@end itemize
Portability problems not fixed by Gnulib:
@itemize
@item
-This function is missing on some platforms:
+This function always fails on some platforms:
mingw.
@end itemize
+
+With the @code{dirfd} module, this functions always sets @code{errno} when it
+fails. (POSIX does not require that @code{dirfd} sets @code{errno} when it
+fails.)