Re: [PATCH v2 1/1] commit: display advice hints when commit fails

[Emily Shaffer <emilyshaffer@google.com>]

On Thu, Dec 19, 2019 at 11:22:38AM -0800, Junio C Hamano wrote:
> Junio C Hamano <gitster@pobox.com> writes:
> 
> > This fix was about "we do not want to unconditionally drop the
> > advice messages when we reject the attempt to commit and show the
> > output like 'git status'", wasn't it?  The earlier single-liner fix
> > in v1 that flips s->hints just before calling run_status() before
> > rejecting the attempt to commit was a lot easier to reason about, as
> > the fix was very focused and to the point.  Why are we seeing this
> > many (seemingly unrelated) changes?
> 
> In any case, here is what I tentatively have in my tree (with heavy
> rewrite to the proposed log message).

Hm. I'm surprised to see this feedback come in the form of a local
change when making the topic branch, rather than in a reply to the v1
patch. What's the reasoning? (Or is this scissors patch intended to be
the feedback?)

I ask because out of all of us, it seems the Outreachy interns can
benefit the most from advice on how and why to write their commit
messages - that is, part of the point of an internship is to learn best
practices and cultural norms in addition to coding practice. (Plus, I
find being asked to rewrite a commit message tends to force me to
understand my own change even better than before.)

I'll go ahead and look through the changes to the commit message so I
can learn what you're looking for too :)

> 
> -- >8 --
> From: Heba Waly <heba.waly@gmail.com>
> Date: Tue, 17 Dec 2019 09:17:22 +0000
> Subject: [PATCH] commit: honor advice.statusHints when rejecting an empty
>  commit
> 
> In ea9882bfc4 (commit: disable status hints when writing to
> COMMIT_EDITMSG, 2013-09-12) the intent was to disable status hints
> when writing to COMMIT_EDITMSG, because giving the hints in the "git
> status" like output in the commit message template are too late to
> be useful (they say things like "'git add' to stage", but that is
> only possible after aborting the current "git commit" session).

More context on why the previous change was made - "by the time the
editor was open, it was too late to apply hints anyways". Sure.

> 
> But there is one case that the hints can be useful: When the current
> attempt to commit is rejected because no change is recorded in the
> index.  The message is given and "git commit" errors out, so the
> hints can immediately be followed by the user.  Teach the codepath
> to honor the configuration variable.

Expanding the "but" to supply the specific story this commit touches,
including "what happens instead" and "how are we gonna fix it".

And the copy-paste of the output before and the output now is different.
For me, I don't particularly see why we'd want to be rid of it - it sort
of feels like "a picture is worth a thousand words" to include the
actual use case in the commit message. Is there style guidance
suggesting not to do that that I missed?

 - Emily

> 
> Signed-off-by: Heba Waly <heba.waly@gmail.com>
> Signed-off-by: Junio C Hamano <gitster@pobox.com>
> ---
>  builtin/commit.c                          | 1 +
>  t/t7500-commit-template-squash-signoff.sh | 9 +++++++++
>  2 files changed, 10 insertions(+)
> 
> diff --git a/builtin/commit.c b/builtin/commit.c
> index e588bc6ad3..0078faf117 100644
> --- a/builtin/commit.c
> +++ b/builtin/commit.c
> @@ -944,6 +944,7 @@ static int prepare_to_commit(const char *index_file, const char *prefix,
>  	 */
>  	if (!committable && whence != FROM_MERGE && !allow_empty &&
>  	    !(amend && is_a_merge(current_head))) {
> +		s->hints = advice_status_hints;
>  		s->display_comment_prefix = old_display_comment_prefix;
>  		run_status(stdout, index_file, prefix, 0, s);
>  		if (amend)
> diff --git a/t/t7500-commit-template-squash-signoff.sh b/t/t7500-commit-template-squash-signoff.sh
> index 46a5cd4b73..a8179e4074 100755
> --- a/t/t7500-commit-template-squash-signoff.sh
> +++ b/t/t7500-commit-template-squash-signoff.sh
> @@ -382,4 +382,13 @@ test_expect_success 'check commit with unstaged rename and copy' '
>  	)
>  '
>  
> +test_expect_success 'commit without staging files fails and displays hints' '
> +	echo "initial" >>file &&
> +	git add file &&
> +	git commit -m initial &&
> +	echo "changes" >>file &&
> +	test_must_fail git commit -m update >actual &&
> +	test_i18ngrep "no changes added to commit (use \"git add\" and/or \"git commit -a\")" actual
> +'
> +
>  test_done
> -- 
> 2.24.1-732-ga9f9d4909c
>