Re: [PATCH] rev-parse: have --parseopt callers exit 0 on --help

[Jeff King <peff@peff.net>]

On Tue, Mar 17, 2026 at 10:06:17AM -0700, Junio C Hamano wrote:

> > But this
> > is not just a bug fix for --parseopt, but a change in overall intent. It
> > might be worth digging in the commit history or list archive to see if
> > there's any discussion on why we are using 129 in the first place.
> 
> And if it turns out that old discussion was convincing enough, I'd
> prefer to see us moving to --help/-h exiting with 0 eventually.  I
> do not mind doing so at the Git 3.0 boundary, if an excuse to make
> a big change is needed ;-)

I could not find anything convincing. :)

We should also apply our little grey cells and see if we can think of
any reason somebody would be unhappy with a change of exit code now. The
most I could come up with is a script like:

  #!/bin/sh
  git rev-list "$@" >tmp &&
  do_something <tmp

where you might imagine it is run as "foo.sh --objects HEAD" or
something. Right now, running:

  foo.sh -h

will bail when rev-list returns 129, but in the proposed world it would
keep going and run do_something. And you can further imagine a world
where the script then quietly produces the wrong answer, because
do_something thinks the rev-list output was empty (or actually it is
worse; it gets the help output here).

I think this is mostly a case of "if it hurts, don't do it". The "-h" is
not doing anything useful (the user does not even see the help text!),
and if the script wants to support a usage message, it should parse the
"-h" out separately.

Could somebody maliciously convince you to pass "-h" to such a script?
Maybe, but not only are we getting into a series of increasingly
unlikely events, but I think that means you probably have worse
option-injection risks.

So unless somebody can come up with a more compelling example, I don't
really see much backwards-compatibility risk. But maybe I just lack
imagination. ;)

-Peff