Re: --no-decorate and %d in git-log(1)

From: Marc Branchaud <marcnarc@xiplink.com>
Date: Feb 25, 2026, 21:46 UTC
Message-ID: <cf3d274e-7363-4557-809a-a649b1d304ad@xiplink.com>
In-Reply-To: <xmqqcy1sa8mx.fsf@gitster.g>

On 2026-02-25 13:08, Junio C Hamano wrote:

Show 17 quoted lines

> Marc Branchaud <marcnarc@xiplink.com> writes:
> 
>> BTW, --decorate=auto is documented as "if the output is going to a
>> terminal, the ref names are shown as if `short` were given, otherwise no
>> ref names are shown."  But in my experiments %d still shows refs even
>> when the output is piped to a file.  Seems like another symptom of the
>> same bug?
> 
> Isn't that documentation merely referring to "git log" without
> "--format=... %d ..." and not about the case where you explicitly
> ask for "%d"?  That is, the description is there to explain the
> differences between
> 
> 	git log --oneline --decorate=auto -1
> 	git log --oneline --decorate=auto -1 | cat
> 
> isn't it?

I'm sure that's how the code works, but I don't see any indication in the documentation that this is for when --format isn't used or when the format doesn't contain %d. The descriptions of --decorate and --format mostly just ignore each other.

We do have this at the end of the --format section:

	The %d and %D placeholders will use the "short"
	decoration format if --decorate was not already
	provided on the command line.

Given this documented connection between %d/%D and --decorate, it seems reasonable for a reader to assume that --decorate=auto would do the same thing regardless of whether or not a --format=...%d... was present.

Show 9 quoted lines

> I think --decorate=auto is the default so the above
> without --decorate=auto would behave similarly.
> 
>> (Do people who use `--format` (with or without %d) *also* use
>> `--decorate`?  It seems like the two are naturally exclusive, even if
>> the code allows them both.)
> 
> That is an interesting question, but I am not sure if it affects how
> we decide to resolve this discussion.

Yeah, it's more philosophical, though if we did know the answer was "the two are almost never used together" we'd be more comfortable changing how --decorate=no and --format=%d interact.

I note that currently --decorate has no effect at all if the --format doesn't contain %d or %D. To me this bolsters the argument for making --decorate=no suppress %d/%D.

To expand on my earlier point: --decorate=no currently has the same effect on %d/%D as --decorate=short, so it seems to me that we can change what --decorate=no does because if anyone needs to preserve the existing behavior for their favorite --format they can just use --decorate=short. (I'd be surprised if anyone is using --decorate=no to ensure that they get the short ref names).

M.