Subject: Re: [RFC 1/3] sequencer: Signal failed ff as an aborted, not a conflicted merge

From: Junio C Hamano <[email-masked]>
Date: Tue, 27 May 2014 11:42:22 -0700

Fabian Ruch <[email-masked]> writes:

> `do_pick_commit` handles three situations if it is not fast-forwarding.
> In order for `do_pick_commit` to identify the situation, it examines the
> return value of the selected merge command.
>
> 1. return value 0 stands for a clean merge
> 2. 1 is passed in case of a failed merge due to conflict
> 3. any other return value means that the merge did not even start
>
> So far, the sequencer returns 1 in case of a failed fast-forward, which
> would mean "failed merge due to conflict". However, a fast-forward
> either starts and succeeds or does not start at all. In particular, it
> cannot fail in between like a merge with a dirty index due to conflicts.
>
> In order to signal the three possible situations (not only success and
> failure to complete) after a pick through porcelain commands such as
> `cherry-pick`, exit with a return value that is neither 0 nor 1. -1 was
> chosen in line with the other situations in which the sequencer
> encounters an error.

Hmph... do we still pass negative to exit() anywhere in our codebase?

>
> Signed-off-by: Fabian Ruch <[email-masked]>
> ---
>  sequencer.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/sequencer.c b/sequencer.c
> index 90cac7b..97cecca 100644
> --- a/sequencer.c
> +++ b/sequencer.c
> @@ -278,7 +278,7 @@ static int fast_forward_to(const unsigned char *to, const unsigned char *from,
>  
>  	read_cache();
>  	if (checkout_fast_forward(from, to, 1))
> -		exit(1); /* the callee should have complained already */
> +		exit(-1); /* the callee should have complained already */
>  	ref_lock = lock_any_ref_for_update("HEAD", unborn ? null_sha1 : from,
>  					   0, NULL);
>  	strbuf_addf(&sb, "%s: fast-forward", action_name(opts));