RE: [RFC PATCH 01/35] merge: improve fatal fast-forward message

["Randall S. Becker" <rsbecker@nexbridge.com>]

On July 6, 2021 4:40 PM, Felipe Contreras wrote:
>Subject: Re: [RFC PATCH 01/35] merge: improve fatal fast-forward message
>
>Ævar Arnfjörð Bjarmason wrote:
>>
>> On Mon, Jul 05 2021, Felipe Contreras wrote:
>>
>> > Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
>> > ---
>> >  builtin/merge.c | 2 +-
>> >  1 file changed, 1 insertion(+), 1 deletion(-)
>> >
>> > diff --git a/builtin/merge.c b/builtin/merge.c index
>> > a8a843b1f5..05e631229d 100644
>> > --- a/builtin/merge.c
>> > +++ b/builtin/merge.c
>> > @@ -1620,7 +1620,7 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
>> >  	}
>> >
>> >  	if (fast_forward == FF_ONLY)
>> > -		die(_("Not possible to fast-forward, aborting."));
>> > +		die(_("unable to fast-forward"));
>>
>> I read the existing message a bit more like "this makes no sense
>> anymore" (correct) and the latter more like "we encountered an error".
>
>I mean, this is the documentation of --ff-only:
>
>  With `--ff-only`, resolve the merge as a fast-forward when possible.
>  When not possible, refuse to merge and exit with a non-zero status.
>
>So if you do `git merge --ff-only` you are telling git: "I want you to exit with an error when the fast-forward is not possible".
>
>If you do:
>
>  % git merge --ff-only
>  fatal: Not possible to fast-forward, aborting.
>
>That "aborting" part is redundant; we know `git merge` should abort if the fast-forward is not possible, we explicitely told git to do that.

`git merge` is a special operation where errors (conflicts, for one) may leave the repository in a merge pending state where you subsequently may have to use `git merge --abort` to reset the situation or `git add` to continue. The `aborting` output makes it clear that you do not have to do the `--abort` and *cannot* do the `add` because there was an implicit `--abort` done resulting from the failure. This is important information for the user.