How to merge your patch

Simon Peyton Jones simonpj at
Thu Feb 7 09:10:31 UTC 2019

|   2. assign the merge request to @marge-bot using the assignee field in
|      the right-hand sidebar of the merge request page.

This sounds great. What email will we receive in these three cases?

a) the merge is successful
b) the merge fails because I made a mistake and it just doesn't validate
c) the merge failed because the CI infrastructure failed somehow
   (should no longer happen, I know).

Examples would be helpful.



|  -----Original Message-----
|  From: ghc-devs <ghc-devs-bounces at> On Behalf Of Ben Gamari
|  Sent: 07 February 2019 03:58
|  To: GHC developers <ghc-devs at>
|  Subject: How to merge your patch
|  tl;dr. Our beloved @marge-bot is behaving much more reliably now thanks
|         to improvements in CI reliability and build batching. To merge
|         an (accepted) merge request simply designate @marge-bot as its
|         assignee. Marge will handle the rest. If things go awry let me
|         know.
|  Hi everyone,
|  As you may have noticed, over the last weeks we have been feeling out how
|  best to leverage our new CI infrastructure, particularly when it comes to
|  merging patches.
|  As mentioned a few weeks ago, we have introduced a bot, Marge, to help us
|  work around some temporary limitations of GitLab's merge workflow.
|  Unfortunately, Marge had her own set of quirks which have taken a while
|  to sort out. In particular, fragile tests tended to result in repeated
|  merge attempts which tended to clog up CI, leading to an avalanche of
|  waiting, build failures, and general despair.
|  However, we have been working to improve this situation in three ways:
|   * provisioning more builder capacity to reduce wait times
|   * fixing or disabling fragile tests to reduce the need for retries
|   * enable Marge's batched merge functionality, reducing the number of
|     builds necessary per merged patch [1]
|  In light of this I just wanted to reiterate the previous guidance on
|  merging patches. If you have a merge request you would like to merge
|  simply do the following:
|   1. make sure that it has at least one approval. This should
|      happen in the course of code review but do ping if this was
|      forgotten.
|   2. assign the merge request to @marge-bot using the assignee field in
|      the right-hand sidebar of the merge request page.
|   3. next time Marge does a batch of merges she will fold in your MR
|      (leaving a helpful comment to let you know) and, if the batch passes
|      CI, merge it. If not she will leave a comment letting you know there
|      was an issue. I will try to step in to sort out the mess when this
|      happens.
|  Do let me know if you have any questions.
|  Cheers,
|  - Ben
|  [1] thanks to Matthew Pickering for picking this up

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