Re: [PATCH] format-patch: fix From header in cover letter

From: Junio C Hamano <gitster@pobox.com>
Date: Feb 17, 2026, 22:41 UTC
Message-ID: <xmqq7bsb9emn.fsf@gitster.g>
In-Reply-To: <20260217220515.14127-1-mroik@delayed.space>

Mroik <mroik@delayed.space> writes:

Show 6 quoted lines

> From: Mirko Faina <mroik@delayed.space>
>
> "git format-patch" takes "--from=<user ident>" command line option and
> uses the given ident for patch e-mails, but this is not applied to the
> cover letter, the option is ignored and the committer ident of the
> current user is used.

It is worth noting that ever since this "--from" option was introduced, it was not used when generating the cover letter in the proposed log message in the above paragraph somewhere.

> Teach the make_cover_letter() function to honor the option, instead of
> always using the current committer identity.

Also the reasoning behind the rename of "committer" to "from" is worth noting here.

Show 18 quoted lines

> diff --git a/Documentation/git-format-patch.adoc b/Documentation/git-format-patch.adoc
> index 9a7807ca71..05c4192dbc 100644
> --- a/Documentation/git-format-patch.adoc
> +++ b/Documentation/git-format-patch.adoc
> @@ -282,11 +282,11 @@ e.g., `--rfc='-(WIP)'` results in "PATCH (WIP)".
>  
>  --from::
>  --from=<ident>::
> -	Use `ident` in the `From:` header of each commit email. If the
> -	author ident of the commit is not textually identical to the
> -	provided `ident`, place a `From:` header in the body of the
> -	message with the original author. If no `ident` is given, use
> -	the committer ident.
> +	Use `ident` in the `From:` header of each email. In case of a
> +	commit email, if the author ident of the commit is not textually
> +	identical to the provided `ident`, place a `From:` header in the
> +	body of the message with the original author. If no `ident` is
> +	given, use the committer ident.

After reading the above three times, a natural question that comes to mind is what ident is used when this option is not given at all (i.e., "When this option is not given, the committer identity of the current user is used for all messages").

> diff --git a/builtin/log.c b/builtin/log.c
> index d43ca693bf..42648dda54 100644
> --- a/builtin/log.c
> +++ b/builtin/log.c

The code changes all look good.

Show 15 quoted lines

> diff --git a/t/t4014-format-patch.sh b/t/t4014-format-patch.sh
> index 21d6d0cd9e..2135b65cee 100755
> --- a/t/t4014-format-patch.sh
> +++ b/t/t4014-format-patch.sh
> @@ -1472,6 +1472,14 @@ test_expect_success '--from uses committer ident' '
>  	test_cmp expect patch.head
>  '
>  
> +test_expect_success '--from applies to cover letter' '
> +	test_when_finished "rm -rf patches" &&
> +	git format-patch -1 --cover-letter --from="Foo Bar <author@example.com>" -o patches &&
> +	echo "From: Foo Bar <author@example.com>" >expect &&
> +	grep "^From:" patches/0000-cover-letter.patch >patch.head &&
> +	test_cmp expect patch.head
> +'

OK.

We know what filename the cover letter gets, so it is really the matter of how we want to verify the output. We know that a line that matches "^From:" must appear once and only once in the cover letter output, so finding that line and comparing it with what we expect to see is a reasonably way to do this. Good.

Thanks.