Re: [PATCH v13] [GSOC] commit: add --trailer option

[Christian Couder <christian.couder@gmail.com>]

On Mon, Mar 22, 2021 at 11:23 AM ZheNing Hu <adlternative@gmail.com> wrote:
>
> Christian Couder <christian.couder@gmail.com> 于2021年3月22日周一 下午3:43写道：

> > Nice that you have added such a test!
>
> Thanks.
>
> But at the same time I have two little doubt.
>
> 1.
> If we have your config:
>
> $ git config trailer.sign.key "Signed-off-by: "
> $ git config trailer.sign.ifexists replace
> $ git config trailer.sign.command "git log --author='\$ARG' -1
> --format='format:%aN <%aE>'"
>
> Then I touch a test.c and use:
>
> $ git interpret-trailers --in-place test.c
>
> without `--trailer`, See what is happen:
>
> It seem like your local repo last commit "name <email>" pair
> have been record in `test.c`.
>
> Could this be considered a bug?

First it seems strange to use `git interpret-trailers` on a "test.c"
file. It's supposed to be used on commit messages.

Then, as the doc says, every command specified by any
"trailer.<token>.command" config option is run at least once when `git
interpret-trailers` is run. This is because users might want to
automatically add some trailers all the time.

If you want nothing to happen when $ARG isn't set, you can change the
config option to something like:

$ git config trailer.sign.command "NAME='\$ARG'; test -n \"\$NAME\" &&
git log --author=\"\$NAME\" -1 --format='format:%aN <%aE>' || true"

(This is because it looks like $ARG is replaced only once with the
actual value, which is perhaps a bug. Otherwise something like the
following might work:

git config trailer.sign.command "test -n '\$ARG' && git log
--author='\$ARG' -1 --format='format:%aN <%aE>' || true")

Then you can run `git interpret-trailers` with the --trim-empty option
like this:

------
$ git interpret-trailers --trim-empty --trailer sign=Linus<<EOF
EOF

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
------

or like:

------
$ git interpret-trailers --trim-empty<<EOF
> EOF

------