Re: [bug-diffutils] diff: support for --no-dereference option

[Paul Eggert]

On 01/07/12 17:47, Bruno Haible wrote:
> But -P currently is equivalent to --unidirectional-new-file.

Yeouch.  I forgot about that.  You're right, we'd need to take the
next step in deprecating -P.  (The first step was taken in 2002, when
it was removed from the documentation, precisely for this reason --
can you tell that this has been on the TODO list for some time?...)

We also would need to deprecate -H and -L.  -H has no effect anyway,
and probably --speed-large-files should be removed from the documentation
too (though still a no-op for backward compatibility).

Given the large set of changes, and the likely use of -P and -L in scripts,
I expect that the first deprecation step should just warn on stderr and 
continue,
rather than having a fatal error.

As far as the long option names go, the GNU utilities aren't
consistent here, but perhaps we should use this for diffutils:

   -P == --no-dereference (as in cp, du)
   -H == --dereference-command-line (as in ls)
   -L == --dereference (as in cp, du, ls, stat)

omitting the short options for now, as the old meanings are being deprecated.

> 'patch' does not break through this additional lines. It simply ignores them.

True, hence the proposed patch can be an intermediate one on
the way to building a better one.  But I suppose that we should
document that the output format is likely to change, so that
people are less likely to depend on it.