Gitlab notes

Simon Peyton Jones simonpj at
Tue Jan 8 18:44:34 UTC 2019

I like your notes.  I’ll add them.

I think that ideally

  *   We’d keep a straight-line history for master
  *   And hence we have to accept force-push to user branches.
  *   Surely we can treat the user branches much as we do HEAD today?  That is, always  pull before pushing; and only force push if you know that you have just pulled; and then rebased, squashed or whatever.
  *   In any case the common case is that only one person is pushing to a user branch

It would be good to agree our normal protocol here.


From: Iavor Diatchki <iavor.diatchki at>
Sent: 08 January 2019 18:10
To: Simon Peyton Jones <simonpj at>
Cc: ghc-devs <ghc-devs at>
Subject: Re: Gitlab notes


a couple of notes about the use of `git` here, which are probably more relevant if you collaborate with other people on a branch:

   1. In general, I think that the model is that you create the branch when you start working on something, and you don't really need
      to do a merge request until later, when you are ready for review.

   2. when you are pushing your branch to the remote (i.e., git-lab), you probably want to say that you branch should "track" the remote by providing the `-u` flag:

       git push -u origin wip/spj-wibbles

     This makes `git` remember the association between your local branch, and the one that lives on git-lab, so later if you can just say `git pull` and `git push` and
     `git` will know what remote you are talking about.

    3. You shouldn't really force push to a remote, especially if you are collaborating with other people.
       If you want to integrate your changes with the current HEAD (aka `master`), you may want to merge it into your working branch.

    4. Once you are finished with the changes and they are ready for review, you can prepare them by doing any of these as needed:
        a)  rebasing to a more relevant starting point (perhaps even the current `master`),
        b) squashing commits as necessary---for simple changes, one should probably end up with a single commit.
      Since those "rewrite history", you are essentially making a new branch, and you could submit *that* for review.  Alternatively,
      you could reuse your working branch (a bit of a hack), and then you'd have to "force" push.

    5. When everything is ready for review, then you create the MR for the appropriate branch (either the new review one, or
        your working one, if you chose to reuse it)

     6. You can continue evolving the branch as usual based on feedback from the reviews.

     7. Once all the reviewers are happy, you can prepare the branch for merging with `master` as in 4.

         I believe in the past GHC has tried to maintain a "straight line" history model, where changes are always made
         on top of the current `master` branch (i.e., there are no visible merges).  If we are still doing that, then you'd
         have to rebase your reviewed changes on top of `master` in preparation for merging.

I didn't add this to the wiki, as they are subjective, but they reflect my understanding of how systems like `git-lab`
are intended to be used.


On Tue, Jan 8, 2019 at 8:30 AM Simon Peyton Jones via ghc-devs <ghc-devs at<mailto:ghc-devs at>> wrote:
I’ve added a Wiki page to summarise things I’ve learned about Gitlab.  Please do correct any errors I’ve made!<>
ghc-devs mailing list
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