Re: [PATCH 2/2] format-patch: allow forcing the use of in-body From: header

[Johannes Schindelin <Johannes.Schindelin@gmx.de>]

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Hi Junio,

On Fri, 26 Aug 2022, Junio C Hamano wrote:

> Users may be authoring and committing their commits under the same
> e-mail address they use to send their patches from, in which case
> they shouldn't need to use the in-body From: line in their outgoing
> e-mails.  At the receiving end, "git am" will use the address on the
> "From:" header of the incoming e-mail and all should be well.
>
> Some mailing lists, however, mangle the From: address from what the
> original sender had; in such an unfortunate situation, the user may
> want to add the in-body "From:" header even for their own patch.
>
> "git format-patch --[no-]force-inbody-from" was invented for such
> users.
>
> Note.  This is an uncooked early draft.

Did you mean to mark the patch as [RFC], then?

> Things to think about include (but not limited to, of course):
>
>  * Should this rather be --use-inbody-from=yes,no,auto tristate,
>    that defaults to "auto", which is the current behaviour i.e.
>    "when --from is given, add it only when it does not match the
>    payload".  "yes" would mean "always emit the --from address as
>    in-body From:" and "no" would mean ... what?  "Ignore --from"?
>    Then why is the user giving --from in the first place?

I would offer up the suggestion `--in-body-from={never,always,auto}` for
consideration.

>  * Should it be "inbody" or "in-body"?

The latter.

>  * Should it have a corresponding configuration variable?

Probably. The commit message talks about mailing lists requiring different
behavior from the default, which is likely to affect all patches generated
from a corresponding local checkout. Having a config variable would lower
the cognitive burden of having to remember this process detail.

>  * Should this patch be scrapped and the feature should be done
>    inside "git send-email" instead?

Since it affects the `--pretty=email` mode, the current patch seems to aim
for the correct layer.

> diff --git a/builtin/log.c b/builtin/log.c
> index 9b937d59b8..83b2d01b49 100644
> --- a/builtin/log.c
> +++ b/builtin/log.c
> @@ -1897,6 +1897,8 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
>  			   N_("show changes against <refspec> in cover letter or single patch")),
>  		OPT_INTEGER(0, "creation-factor", &creation_factor,
>  			    N_("percentage by which creation is weighted")),
> +		OPT_BOOL(0, "force-inbody-from", &rev.force_inbody_from,
> +			 N_("Use in-body From: even for your own commit")),

Please start the usage text in lower-case, to keep it consistent with the
rest of the usage texts.

Also, I would like to avoid the personal address "you" in that text, and
also the verb "use". Maybe something like this:

	show in-body From: even if identical to the header

>  		OPT_END()
>  	};
>
> diff --git a/pretty.c b/pretty.c
> index 51e3fa5736..e266208c0b 100644
> --- a/pretty.c
> +++ b/pretty.c
> @@ -483,6 +483,8 @@ static int use_inbody_from(const struct pretty_print_context *pp, const struct i
>  		return 0;
>  	if (ident_cmp(pp->from_ident, ident))
>  		return 1;
> +	if (pp->rev && pp->rev->force_inbody_from)
> +		return 1;

It would probably make sense to move this before `ident_cmp()`, to avoid
unneeded calls ("is the ident the same? no? well, thank you for your
answer but I'll insert the header anyway!").

>  	return 0;
>  }
>
> diff --git a/revision.h b/revision.h
> index bb91e7ed91..a2d3813a21 100644
> --- a/revision.h
> +++ b/revision.h
> @@ -208,6 +208,7 @@ struct rev_info {
>
>  	/* Format info */
>  	int		show_notes;
> +	unsigned int	force_inbody_from;

The reason why this isn't added to the `:1` bits below is probably the
anticipation of the tri-state, but if that tri-state never materializes,
adding it as a bit is still the right thing to do.

>  	unsigned int	shown_one:1,
>  			shown_dashes:1,
>  			show_merge:1,
> diff --git a/t/t4014-format-patch.sh b/t/t4014-format-patch.sh
> index fbec8ad2ef..a4ecd433e2 100755
> --- a/t/t4014-format-patch.sh
> +++ b/t/t4014-format-patch.sh
> @@ -1400,6 +1400,19 @@ test_expect_success '--from omits redundant in-body header' '
>  	test_cmp expect patch.head
>  '
>
> +test_expect_success 'with --force-inbody-from, --from keeps redundant in-body header' '
> +	git format-patch --force-inbody-from \
> +		-1 --stdout --from="A U Thor <author@example.com>" >patch &&
> +	cat >expect <<-\EOF &&
> +	From: A U Thor <author@example.com>
> +
> +	From: A U Thor <author@example.com>
> +
> +	EOF
> +	sed -ne "/^From:/p; /^$/p; /^---$/q" patch >patch.head &&
> +	test_cmp expect patch.head
> +'

The test script starts to look a bit non-DRY with all those repetitions of
`A U Thor <author@example.com>`, but that's hardly the responsibility of
this here patch to address.

Thank you,
Dscho

> +
>  test_expect_success 'in-body headers trigger content encoding' '
>  	test_env GIT_AUTHOR_NAME="éxötìc" test_commit exotic &&
>  	test_when_finished "git reset --hard HEAD^" &&
> --
> 2.37.2-587-g47adba97a9
>
>