Re: [PATCH 3/3] commit: give a hint when a commit message has been abandoned

> If we launch an editor for the user to create a commit
> message, they may put significant work into doing so.
> Typically we try to check common mistakes that could cause
> the commit to fail early, so that we die before the user
> goes to the trouble.
>
> We may still experience some errors afterwards, though; in
> this case, the user is given no hint that their commit
> message has been saved. Let's tell them where it is.

>
> Signed-off-by: Jeff King <peff@peff.net>
> ---
> I did not bother protecting this with advice.* config, as it is unlikely
> to come up regularly. If somebody cares, they are welcome to add it on
> top.
>
>  builtin/commit.c | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
>
> diff --git a/builtin/commit.c b/builtin/commit.c
> index 20cef95..149e07d 100644
> --- a/builtin/commit.c
> +++ b/builtin/commit.c
> @@ -116,6 +116,16 @@ static enum {
>  	STATUS_FORMAT_PORCELAIN
>  } status_format = STATUS_FORMAT_LONG;
>  
> +static int mention_abandoned_message;
> +static void maybe_mention_abandoned_message(void)
> +{
> +	if (!mention_abandoned_message)
> +		return;
> +	advise(_("Your commit message has been saved in '%s' and will be\n"
> +		 "overwritten by the next invocation of \"git commit\"."),
> +	       git_path(commit_editmsg));
> +}
> +
>  static int opt_parse_m(const struct option *opt, const char *arg, int unset)
>  {
>  	struct strbuf *buf = opt->value;
> @@ -848,6 +858,8 @@ static int prepare_to_commit(const char *index_file, const char *prefix,
>  			_("Please supply the message using either -m or -F option.\n"));
>  			exit(1);
>  		}
> +		atexit(maybe_mention_abandoned_message);
> +		mention_abandoned_message = 1;
>  	}
>  
>  	if (!no_verify &&
> @@ -1532,11 +1544,13 @@ int cmd_commit(int argc, const char **argv, const char *prefix)
>  	if (template_untouched(&sb) && !allow_empty_message) {
>  		rollback_index_files();
>  		fprintf(stderr, _("Aborting commit; you did not edit the message.\n"));
> +		mention_abandoned_message = 0;
>  		exit(1);
>  	}
>  	if (message_is_empty(&sb) && !allow_empty_message) {
>  		rollback_index_files();
>  		fprintf(stderr, _("Aborting commit due to empty commit message.\n"));
> +		mention_abandoned_message = 0;
>  		exit(1);
>  	}
>  
> @@ -1579,6 +1593,7 @@ int cmd_commit(int argc, const char **argv, const char *prefix)
>  		die(_("cannot update HEAD ref"));
>  	}
>  
> +	mention_abandoned_message = 0;
>  	unlink(git_path("CHERRY_PICK_HEAD"));
>  	unlink(git_path("REVERT_HEAD"));
>  	unlink(git_path("MERGE_HEAD"));