Rebase is more or less stashing and removing all local commits, upgrading the underlying branch to current, then re-applying the local commits. This changes the commit hashes for any re-applied commit that lands on a change to the underlying branch, meaning that old commit hashes can be invalid afterward.
(This is also why force-pushing causes problems, since this is only visible in a local tree *unless* force-pushed upstream, meaning now those changed/deleted commits affect anyone else who has checked out that upstream branch. The normal process of upstreaming commits can't expose local changes like that, since it all goes upstream as a group and becomes a permanent part of the branch's history. Unless someone force-pushes the branch afterward, forcibly overwriting that history with a different one and leaving anyoneelse who'd checked out the branch with dangling commits that no longer exist.) Here, CI is making a copy of someone's branch and testing each commit in turn to ensure consistency between multiple branches that touch the same code, whose commits may end up interleaved. If the branch is rebased or force-pushed during that testing, intermediate commits may become invalid as above and CI would need to start over with a new list of commits. On Thu, Jan 24, 2019 at 5:43 PM Simon Peyton Jones via ghc-devs < ghc-devs@haskell.org> wrote: > | Ah, yes -- I did push a rebase. OK: good to know that this is expected > | behavior after rebasing (makes sense). > > Does not make sense (yet) to me. > > Can someone explain (and perhaps document) the workflow here? > > Simon > > | -----Original Message----- > | From: ghc-devs <ghc-devs-boun...@haskell.org> On Behalf Of Richard > | Eisenberg > | Sent: 24 January 2019 19:22 > | To: Ben Gamari <b...@smart-cactus.org> > | Cc: GHC developers <ghc-devs@haskell.org> > | Subject: Re: "resource exhausted" in CI > | > | Ah, yes -- I did push a rebase. OK: good to know that this is expected > | behavior after rebasing (makes sense). > | > | Thanks, > | Richard > | > | > On Jan 24, 2019, at 2:01 PM, Ben Gamari <b...@smart-cactus.org> wrote: > | > > | > Richard Eisenberg <r...@cs.brynmawr.edu> writes: > | > > | >> Something is awry: > | > https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgitlab.ha > | skell.org%2Frae%2Fghc%2F- > | %2Fjobs%2F16908&data=02%7C01%7Csimonpj%40microsoft.com > %7C375c6daea23444 > | > 7c3d2808d682314861%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C63683954552 > | > 1260172&sdata=8OYI5PAk7B6P%2B%2BoJbqgeqPbTR%2BMH6F8Wm34ThdBhRL0%3D& > | reserved=0 never got off the ground. > | >> > | > It is possible that you pushed a rebase? This error generally means > that > | > the commit is no longer accessible which may happen when you push a > | > rebase. > | > > | > I believe I cited the job for the current version of the patch [1] in > my > | > previous email. Note that the commit SHA is different between [1] and > | > the job you cited. > | > > | > Cheers, > | > > | > - Ben > | > > | > > | > [1] > | > https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgitlab.ha > | skell.org%2Frae%2Fghc%2F- > | %2Fjobs%2F16913&data=02%7C01%7Csimonpj%40microsoft.com > %7C375c6daea23444 > | > 7c3d2808d682314861%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C63683954552 > | > 1260172&sdata=wM0hlN60tQmsDtsXS%2BIqLzeAqhgK6RmUoEDzYG2b%2FhI%3D&re > | served=0 > | > | _______________________________________________ > | ghc-devs mailing list > | ghc-devs@haskell.org > | > https://nam06.safelinks.protection.outlook.com/?url=http%3A%2F%2Fmail.haske > | ll.org%2Fcgi-bin%2Fmailman%2Flistinfo%2Fghc- > | devs&data=02%7C01%7Csimonpj%40microsoft.com > %7C375c6daea234447c3d2808d68 > | > 2314861%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C636839545521260172& > | > ;sdata=R2PHyXMyWDG4mmusi1KLmklGR0b%2FXAE%2BNp%2BwS4ZOmp8%3D&reserved=0 > _______________________________________________ > ghc-devs mailing list > ghc-devs@haskell.org > http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs > -- brandon s allbery kf8nh allber...@gmail.com
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