Re: Can't squash merge with merge.ff set to false

From: Bryan Turner <bturner@atlassian.com>
Date: Jan 5, 2018, 20:12 UTC
Message-ID: <CAGyf7-FHyO9pkEFFguea+B+VMTodF=mg8wJNedvjYdL7e7ORqQ@mail.gmail.com>
In-Reply-To: <CAHd499C=3Y-ykgYZhSJzk=e-Pi6BUFeN8C89krd5T7T5fRB91g@mail.gmail.com>

On Fri, Jan 5, 2018 at 11:59 AM, Robert Dailey <rcdailey.lists@gmail.com> wrote:

Show 19 quoted lines

> Not sure if this is intended or a bug, but with the following configuration:
>
> $ git config --global merge.ff false
>
> I am not able to merge my topic branch into master with squash option:
>
> $ git checkout master
> $ git merge --squash topic
> fatal: You cannot combine --squash with --no-ff.
>
> I'm not sure why a non-fast-forward merge would prevent a squash
> merge, since by its very nature a squashed merge is not a fast forward
> merge (or maybe it is if you only have one commit).
>
> Is there an issue here? I like fast forward merges to be off by
> default, since I want to control when they happen. Most of my merges
> do not use --squash, so I'm catering to the common case.
>
> Need advice on how to get past this issue. Thanks in advance.

The easiest way to move forward is probably to pass "--ff" on the command line to override the config, when you're using "--squash".

As for why the two aren't allowed together, my assumption would be because if you're only squashing a single commit "--squash" and that commit is fast-forward from the target, a new commit is not created and instead the target branch is fast-forwarded. With "--no-ff", it's questionable what "--squash" should do in that case. Fast-forward anyway? Rewrite the commit simply to get new committer details and SHA-1?

Hope this helps! Bryan Turner