Re: [PATCH] pull: abort if --ff-only is given and fast-forwarding is impossible

From: Phillip Wood <phillip.wood123@gmail.com>
To: Junio C Hamano <gitster@pobox.com>
Cc: Alex Henrie <alexhenrie24@gmail.com>,
	git@vger.kernel.org, avarab@gmail.com,
	felipe.contreras@gmail.com, newren@gmail.com
Subject: Re: [PATCH] pull: abort if --ff-only is given and fast-forwarding is impossible
Date: Mon, 12 Jul 2021 18:54:34 +0100	[thread overview]
Message-ID: <e63d65f4-048e-464b-439c-4f8f48e72216@gmail.com> (raw)
In-Reply-To: <xmqqpmvn5ukj.fsf@gitster.g>

On 12/07/2021 18:08, Junio C Hamano wrote:
> Phillip Wood <phillip.wood123@gmail.com> writes:
> 
>> Thanks for revising this patch, I like this approach much better. I do
>> however have some concerns about the interaction of pull.ff with the
>> rebase config and command line options. I'd naively expect the
>> following behavior (where rebase can fast-forward if possible)
>>
>>    pull.ff  pull.rebase  commandline  action
>>     only     not false                rebase
>>     only     not false   --no-rebase  fast-forward only
>>      *       not false    --ff-only   fast-forward only
>>     only     not false    --ff        merge --ff
>>     only     not false    --no-ff     merge --no-ff
>>     only       false                  fast-forward only
>>     only       false      --rebase    rebase
>>     only       false      --ff        merge --ff
>>     only       false      --no-ff     merge --no-ff
> 
> Do you mean by "not false" something other than "true"?

I mean pull.rebase is set to true/interactive/merges/preserve

>  Are you
> trying to capture what should happen when these configuration
> options are unspecified as well (and your "not false" is "either set
> to true or unspecified")?  I ask because the first row does not make
> any sense to me.  It seems to say
> 
>      "If pull.ff is set to 'only', pull.rebase is not set to 'false',
>      and the command line does not say anything, we will rebase".

Yes because if pull.rebase is not false then the user wants to rebase.

> I do agree with you that the command line options
> 
>      --ff-only
>      --ff (aka "allow ff")
>      --no-ff
> 
> should override pull.ff and
> 
>      --rebase
>      --no-rebase (aka "merge")
> 
> should override pull.rebase configuration settings and also override
> pull.ff set to 'only' (i.e. the user explicitly wants intregration
> of the two histories and at that point "I usually just follow along"
> which is "pull.ff=only" no longer applies).

I'd assumed --no-rebase just meant "merge respecting pull.ff instead of 
rebasing" rather than "merge ignoring pull.ff instead of rebasing"

Best Wishes

Phillip