<div dir="ltr">For one, merge commits tend to be big, annoying, and a problem for anyone who finds themself working on something that someone else just blew away or rewrote because they weren't checking back and you can't pick only part of the merge commit unless it's itself broken into multiple commits per file or sub-change (yes ideally they all would be the latter, but then you just made big changes like refactorings impossible). The more distributed the project is, the more rebase makes a lot of sense vs. merge commits; you need a lot more central planning and organization for merge commits to work well. Which itself seems kinda anti-git.<br></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Sat, Jul 6, 2019 at 1:06 PM Bryan Richter <<a href="mailto:b@chreekat.net">b@chreekat.net</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">I can't help but notice that there are a lot of issues caused by <br>
adhering to a rebase-only workflow. I understand that lots of projects <br>
use this workflow, but I still don't understand its popularity. Git is <br>
just not designed to be used this way (although I admit that git is <br>
flexible enough to make that statement contentious).<br>
<br>
For instance, this current issue is due to how git tracks revisions. Git <br>
doesn't care about Merge Requests or Issue Numbers. It just knows the <br>
cryptographic hashes of the worktree's contents including the set of <br>
commits leading up to the current commit. If you change commits by <br>
rebasing, git just sees brand-new commits.<br>
<br>
GitHub and GitLab seem to be making things worse by relying on git's <br>
design while layering features on top that are only sort-of compatible. <br>
Brand-new commits created by a rebase are no longer tied to the original <br>
Merge Request, since it is reliant on the very hashes that got <br>
obliviated by the rebase. But it's not just GitLab that gets stymied: A <br>
bunch of handy git commands like `git branch --contains` end up being <br>
useless as well. I will resist the urge to stand up even taller on my <br>
soapbox and list all the other convenient features of git that get <br>
broken by rebasing, so suffice to say that the downsides to Plain Old <br>
Merges that do exist seem nonetheless trivial in comparison.<br>
<br>
Rather than argue against GHC's current practices, however, I would like <br>
to understand them better. What issues led to a rebase-only workflow? <br>
Which expert opinions were considered? What happy stories can people <br>
relate? We recently switched away from a rebase-only workflow at <br>
$workplace, and it's already made life so much nicer for us -- so I'm <br>
curious what unforeseen pain we might be in for. :)<br>
<br>
-Bryan<br>
<br>
On 7/5/19 3:14 PM, Matthew Pickering wrote:<br>
> The target branch is already correct. The way to get the merge status<br>
> is to first rebase the branch before pushing the merge commit.<br>
> Unfortunately the rebase API is very slow and buggy so we had to stop<br>
> using it.<br>
><br>
><br>
> On Fri, Jul 5, 2019 at 1:05 PM Elliot Cameron <<a href="mailto:eacameron@gmail.com" target="_blank">eacameron@gmail.com</a>> wrote:<br>
>> Could Marge change the target branch of an MR before merging it? Perhaps this would convince GitLab to show the right info.<br>
>><br>
>> On Fri, Jul 5, 2019, 6:18 AM Simon Peyton Jones via ghc-devs <<a href="mailto:ghc-devs@haskell.org" target="_blank">ghc-devs@haskell.org</a>> wrote:<br>
>>> | You believe the one which marge posts telling you that the patch is<br>
>>> | merged, the commit it links to is on master so you can clearly see the<br>
>>> | patch has been committed.<br>
>>><br>
>>> OK. The earlier one, also from Marge, not the Discussion stream but rather in the panel at the top, says<br>
>>><br>
>>> Closed by Marge Bot 8 hours ago<br>
>>> The changes were not merged into master<br>
>>><br>
>>> So that is an outright lie? Yes it is closed, but contrary to the statement it _has_ been merged.<br>
>>><br>
>>> It's unfortunate that this misleading display is right at top, in the summary material, while the truth (that it has been merged) is buried in the Discussion stream.<br>
>>><br>
>>> Alas. But thank you for clarifying.<br>
>>><br>
>>> Is this something we can raise with the Gitlab folk? It seems so egregiously wrong.<br>
>>><br>
>>> Simon<br>
>>><br>
>>><br>
>>> | -----Original Message-----<br>
>>> | From: Matthew Pickering <<a href="mailto:matthewtpickering@gmail.com" target="_blank">matthewtpickering@gmail.com</a>><br>
>>> | Sent: 05 July 2019 10:55<br>
>>> | To: Simon Peyton Jones <<a href="mailto:simonpj@microsoft.com" target="_blank">simonpj@microsoft.com</a>><br>
>>> | Cc: ghc-devs <<a href="mailto:ghc-devs@haskell.org" target="_blank">ghc-devs@haskell.org</a>><br>
>>> | Subject: Re: Gitlab workflow<br>
>>> |<br>
>>> | It's not possible to make the MR status merged and also have a reliable<br>
>>> | merge bot. We used to try to make the status merged but it caused too<br>
>>> | much instability.<br>
>>> |<br>
>>> | Merge trains might eventually work but the current iteration is not<br>
>>> | suitable as it doesn't work with forks.<br>
>>> |<br>
>>> | You believe the one which marge posts telling you that the patch is<br>
>>> | merged, the commit it links to is on master so you can clearly see the<br>
>>> | patch has been committed.<br>
>>> |<br>
>>> | Matt<br>
>>> |<br>
>>> | On Fri, Jul 5, 2019 at 10:43 AM Simon Peyton Jones<br>
>>> | <<a href="mailto:simonpj@microsoft.com" target="_blank">simonpj@microsoft.com</a>> wrote:<br>
>>> | ><br>
>>> | > | No it is not possible due to the use of Marge to merge patches.<br>
>>> | > | Gitlab<br>
>>> | ><br>
>>> | > By "it" is not possible, you mean that it's not possible to make the MR<br>
>>> | status into "Merged". Worse, I think you are saying that some MRs will<br>
>>> | say "Merged" and some will say "Closed" in some random way depending on<br>
>>> | Marge batching. Sigh.<br>
>>> | ><br>
>>> | > Maybe this will get better with Gitlab's new merge-train feature.<br>
>>> | ><br>
>>> | > Meanwhile, my original message also asked why the MR shows two<br>
>>> | contradictory messages about whether the MR has landed. Is that also un-<br>
>>> | fixable? And if so how do I figure out which one to believe?<br>
>>> | ><br>
>>> | > Thanks<br>
>>> | ><br>
>>> | > Simon<br>
>>> | ><br>
>>> | ><br>
>>> | ><br>
>>> | > | -----Original Message-----<br>
>>> | > | From: Matthew Pickering <<a href="mailto:matthewtpickering@gmail.com" target="_blank">matthewtpickering@gmail.com</a>><br>
>>> | > | Sent: 05 July 2019 10:39<br>
>>> | > | To: Simon Peyton Jones <<a href="mailto:simonpj@microsoft.com" target="_blank">simonpj@microsoft.com</a>><br>
>>> | > | Cc: ghc-devs <<a href="mailto:ghc-devs@haskell.org" target="_blank">ghc-devs@haskell.org</a>><br>
>>> | > | Subject: Re: Gitlab workflow<br>
>>> | > |<br>
>>> | > | Hi Simon,<br>
>>> | > |<br>
>>> | > | No it is not possible due to the use of Marge to merge patches.<br>
>>> | > | Gitlab automatically chooses the merged status as follows:<br>
>>> | > |<br>
>>> | > | Consider two MRs both which target HEAD.<br>
>>> | > |<br>
>>> | > | MR 1: HEAD <- A<br>
>>> | > | MR 2: HEAD <- B<br>
>>> | > |<br>
>>> | > | Marge creates a batch which contains both MR 1 and MR 2. Once the<br>
>>> | > | batch succeeds, firstly MR 1 is merged.<br>
>>> | > |<br>
>>> | > | HEAD <- A<br>
>>> | > |<br>
>>> | > | MR 1 is closed with the *merged* status because A was merged<br>
>>> | > | directly into HEAD and it matches the state of MR 1.<br>
>>> | > |<br>
>>> | > | Then patch B gets merged and now master looks like:<br>
>>> | > |<br>
>>> | > | HEAD <- A <- B<br>
>>> | > |<br>
>>> | > | MR 2 is closed with closed status because B was merged into master<br>
>>> | > | after A, not directly onto HEAD (as the original MR was).<br>
>>> | > |<br>
>>> | > | There is no option to change this status in the gitlab API.<br>
>>> | > |<br>
>>> | > | Cheers,<br>
>>> | > |<br>
>>> | > | Matt<br>
>>> | > |<br>
>>> | > | On Fri, Jul 5, 2019 at 8:38 AM Simon Peyton Jones via ghc-devs<br>
>>> | > | <ghc- <a href="mailto:devs@haskell.org" target="_blank">devs@haskell.org</a>> wrote:<br>
>>> | > | ><br>
>>> | > | > Ben<br>
>>> | > | ><br>
>>> | > | > Still trying to understand GitLab. Look at MR 1352 ><br>
>>> | > | <a href="https://gitl" rel="noreferrer" target="_blank">https://gitl</a> ><br>
>>> | > | <a href="http://ab.haskell.org" rel="noreferrer" target="_blank">ab.haskell.org</a>%2Fghc%2Fghc%2Fmerge_requests%2F1352&data=02%7C01%<br>
>>> | > | 7C ><br>
>>> | > | simonpj%<a href="http://40microsoft.com" rel="noreferrer" target="_blank">40microsoft.com</a>%7Ce03ba07f29c447c1252e08d7012c9b59%7C72f988b<br>
>>> | > | f8 ><br>
>>> | > | 6f141af91ab2d7cd011db47%7C1%7C0%7C636979163409361534&sdata=xZZiF<br>
>>> | > | zO > CRNpEskjO1MVSONbDvug9dyGEQtaHHSpGeCk%3D&reserved=0<br>
>>> | > | ><br>
>>> | > | > It clearly says on the first page “The changes were not merged<br>
>>> | > | into master”<br>
>>> | > | > But lower down (at the end) it says “Merged in 80af...”<br>
>>> | > | ><br>
>>> | > | > What should I believe? Merged or not merged?<br>
>>> | > | ><br>
>>> | > | > Also<br>
>>> | > | ><br>
>>> | > | > It would be really helpful if a MR status, displayed prominently<br>
>>> | > | at the top, had “Merged” as a status, not just “Closed”. If I’m<br>
>>> | > | trying to check if my has landed, and I see “Closed”, that could<br>
>>> | > | mean that someone has (doubtless for good reasons) closed it<br>
>>> | > | manually, and that it will never land.<br>
>>> | > | ><br>
>>> | > | > Would that be possible?<br>
>>> | > | ><br>
>>> | > | > Thanks<br>
>>> | > | ><br>
>>> | > | > Simon<br>
>>> | > | ><br>
>>> | > | > _______________________________________________<br>
>>> | > | > ghc-devs mailing list<br>
>>> | > | > <a href="mailto:ghc-devs@haskell.org" target="_blank">ghc-devs@haskell.org</a><br>
>>> | > | > <a href="http://mail" rel="noreferrer" target="_blank">http://mail</a>.<br>
>>> | > | ><br>
>>> | > | <a href="http://haskell.org" rel="noreferrer" target="_blank">haskell.org</a>%2Fcgi-bin%2Fmailman%2Flistinfo%2Fghc-devs&data=02%7C<br>
>>> | > | 01 ><br>
>>> | > | %7Csimonpj%<a href="http://40microsoft.com" rel="noreferrer" target="_blank">40microsoft.com</a>%7Ce03ba07f29c447c1252e08d7012c9b59%7C72f9<br>
>>> | > | 88 ><br>
>>> | > | bf86f141af91ab2d7cd011db47%7C1%7C0%7C636979163409361534&sdata=2a<br>
>>> | > | Xm > n8ewTaA3S8y5eg0sa0lIed7L7BQRfm4jRTTvoO8%3D&reserved=0<br>
>>> _______________________________________________<br>
>>> ghc-devs mailing list<br>
>>> <a href="mailto:ghc-devs@haskell.org" target="_blank">ghc-devs@haskell.org</a><br>
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</blockquote></div><br clear="all"><div><br></div>-- <br><div dir="ltr" class="gmail_signature"><div dir="ltr"><div><div dir="ltr"><div>brandon s allbery kf8nh</div><div><a href="mailto:allbery.b@gmail.com" target="_blank">allbery.b@gmail.com</a></div></div></div></div></div>