[RFC] DT_WHT

[Rical Jasan]

There is one undocumented DT_* macro in manual/filesys.texi: DT_WHT.  It
is defined in dirent/dirent.h and appears to be used once in io/fts.c:

#if defined FTS_WHITEOUT && 0
                if (dp->d_type == DT_WHT)
                        p->fts_flags |= FTS_ISW;
#endif

For an entry in the manual, I was thinking something along the lines of:

"This macro is obsolete and has no effect.  It was used to..."

but I'm not sure what to say about what it was used for.

Alternatively, could/should it be removed?  It looks like that might
extend beyond just DT_WHT, as FTS_WHITEOUT also appears to be a NOOP:

$ grep -rFn FTS_WHITEOUT .
./io/fts.h:75:#define FTS_WHITEOUT	0x0080		/* return whiteout information */
./io/fts.c:628:#if defined FTS_WHITEOUT && 0
./io/fts.c:629:	if (ISSET(FTS_WHITEOUT))
./io/fts.c:772:#if defined FTS_WHITEOUT && 0
./io/fts.c:881:#if defined FTS_WHITEOUT && 0

Lastly, I can't find a reference to it in any of the standards I've
managed to obtain so far (not to say that's exhaustive at all).  Is this
also BSD?

Thank you,
Rical