Subject: Re: [PATCH v10 2/2] [GSOC] trailer: add new .cmd config option

From: Junio C Hamano <[email-masked]>
Date: Fri, 16 Apr 2021 12:25:40 -0700

Junio C Hamano <[email-masked]> writes:

> OK.  I think there still will be disagreement on this last point
> between Christian and I, but I'd be happy with this as the first cut
> for newly introduced .cmd and then when it becomes needed add
> something like the attached patch on top to optionally run the given
> command when configured.
>
>
>  trailer.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git c/trailer.c w/trailer.c
> index 7c7cb61a94..39132211cc 100644
> --- c/trailer.c
> +++ w/trailer.c
> @@ -723,7 +723,8 @@ static void process_command_line_args(struct list_head *arg_head,
>  	/* Add an arg item for each configured trailer with a command */
>  	list_for_each(pos, &conf_head) {
>  		item = list_entry(pos, struct arg_item, list);
> -		if (item->conf.command)
> +		if ((item->conf.run_implicitly && item->conf.cmd) ||
> +		    item->conf.command)
>  			add_arg_item(arg_head,
>  				     xstrdup(token_from_item(item, NULL)),
>  				     xstrdup(""),

Actually, if we were to do this, I actually suspect that, unlike the
textual replacement of $ARG in the old .command configuration, we
should take advantage of the fact that the command can tell the
cases between an empty string given as $1 and no positional argument
was given for $1.  So what add_arg_item() does here for .command
(which has to give an empty string, because it will textually
replace an occurrence of $ARG) and for .cmd may have to be different.
Perhaps record NULL here, so that when the command line is formed,
we can tell that we do not want add an extra "" that becomes $1,
when we are dealing with .cmd in this codepath.

Thanks.