Re: [PATCH] git-merge: mutually match SYNOPSIS and "usage".

From: Junio C Hamano <gitster@pobox.com>
Date: Oct 7, 2014, 21:31 UTC
Message-ID: <xmqq1tqjefd8.fsf@gitster.dls.corp.google.com>
In-Reply-To: <87bnpnsjrw.fsf@osv.gnss.ru>

Sergey Organov <sorganov@gmail.com> writes:

Show 6 quoted lines

> Junio C Hamano <gitster@pobox.com> writes:
> ...
> I was looking at the merge.c code, and that's how it seems to work. You
> can get new semantics without -m, and you can't get old semantics with
> -m, isn't it? It looks like the set of descriptions I produced is
> formally correct.

The thing is, with "-m <msg>" we will never fall into the traditional syntax, hence "git merge -m <msg> <msg> HEAD <commit>" appear to be allowed with "git merge [options] <msg> HEAD <commit>...", but it is not.

And the inverse is not true (an obvious example is "git merge $branch", even though it does not have "-m <msg>" it uses the modern & common.

So the updated SYNOPSIS is not really helping.

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>> In other words, I agree with your motivation to call for attention
>> that the command behaves differently with and without "-m", but I do
>> not think that part of the change in this patch achieves it well.
>
> Any particular suggestion?

I was going to suggest "explain how the traditional syntax is triggered in the DESCRIPTION section", but it turns out that we already do that.

      The second syntax (<msg> HEAD <commit>...) is supported for
      historical reasons. Do not use it from the command line or in
      new scripts. It is the same as git merge -m <msg> <commit>....

Strictly speaking, I think it is not qute "the same"---I recall vaguely that it broke tests if you replace the traditional-style invocation in 'git pull' with the -m <msg> syntax, but I do not have details handy; you may want to try it out if you are interested.

So I would think

	SYNOPSIS
        	git merge [options] <commit>...
		git merge [options] <msg> HEAD <commit>...
                git merge --abort

should be sufficient, possibly with some clarification on "The second syntax" paragraph in the DESCRIPTION section.