Re: pull.rebase config vs. --ff-only on command line

Matthias Baumgarten wrote:

On 7/16/21 8:00 PM, Felipe Contreras wrote:

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Matthias Baumgarten wrote:

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On 7/16/21 6:44 PM, Felipe Contreras wrote:

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Elijah Newren wrote:

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On Fri, Jul 16, 2021 at 7:52 AM Matthias Baumgarten
[off-list ref] wrote:

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this is my first time contacting you guys and girls so I hope this mail
achieves the expected standard. I've discovered the following behaviour
of git:

If pull.rebase is configured to true and git pull --ff-only is executed
it seems like the config wins, i.e. issuing "Successfully rebased and
updated refs/heads/...", which is not what I would expect. I always
believed that command line options would overwrite configured options.

Is my assumption that command line options always win wrong or is this a
bug?

It's a bug.

No it isn't.

Elijah is elevating to fact his opinion of what --ff-only should be
changed to.

But it has not been changed. Today --ff-only is meant only for the merge
mode of `git pull`, and like other merge-only options (e.g. --ff,
--no-ff, and --squash) it's ignored in the rebase mode.

Shouldn't every explicitly given merge option (like --ff-only) overwrite
any configured option that would not even result in a merge, i.e.
forcing a merge and thus forcing ff-only?

Perhaps. Other developers have suggested that before.

The problem is that everyone wants to make --ff-only the default, and
then we start to get into a tricky situation, because what should these
do:

   git -c pull.ff=only pull
   git -c pull.ff=only pull --merge
   git -c pull.ff=only pull --rebase

If my assumption were true, and every explicit (cli given) option would 
overwrite implicitly given ones (i.e. configured options), wouldn't

  * git -c pull.ff=only pull, do a fast-forward (or merge)
  * git -c pull.ff=only pull --merge, force a merge commit
  * git -c pull.ff=only pull --rebase, force rebase

The documentation says --ff-only is meant for merges, therefore these
three should be valid and do the same:

  git pull --ff-only # --merge is the default
  git pull --merge --ff-only
  git pull --ff-only --merge

In order for your assumption above to be correct, the semantics of
--ff-only have to be changed (along with the documentation), but people
are *already* relying on the current semantics:

  [pull]
    ff = only
    rebase = true

I made a poll on reddit [1], and 19% (so far) said they do use both
configurations, and they know what `git pull --no-rebase` would do.

In other words: they would expect `git pull` to do a rebase, but
`git pull --merge` to do a fast-forward merge.

Changing the semantics of --ff-only would break behavior they rely on,
unless we break symmetry from --ff-only and pull.ff=only which would be
very hard to explain the documentation.


However, if --ff-only wasn't mapped to pull.ff=only, but
pull.mode=fast-forward, then we can have both: the configurations people
rely on today wouldn't be broken, and your expectation that
`git pull --ff-only` overrides pull.mode=rebase would be met.

It's the perfect solution.

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One of these will always fail, when it shouldn't

Would this even apply under the above assumption?

[I think you meant to paste this]

Under your assumption it wouldn't fail, but other behavior users rely on
today would be broken.

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I proposed a solution for that, but is has been ignored.

I'm sorry!

It's not me the one that suffers (I don't even use `git pull`), it's the
users that have been negatively affected for more than ten years.

[1] https://www.reddit.com/r/git/comments/omcngl/do_you_use_both_pullff_and_pullrebase/

-- 
Felipe Contreras