Re: Amending merge commits?
Nico Williams n...@cryptonector.com writes: On Tue, Jul 29, 2014 at 4:58 AM, Sergei Organov o...@javad.com wrote: Nico Williams n...@cryptonector.com writes: That exception aside, keeping all local commits on top by always rebasing them onto the upstream is extremely useful: a) in simplifying conflict resolution, b) making it easy to identify as-yet-unintegrated local commits, c) making it easy to contribute local commits. But 'pull --rebase=preserve' does rebase local commits onto the upstream, and result is exactly the same as 'pull --rebase=true', unless you have some of your own merges to be rebased. That's where the difference between these two options appears. It's --rebase=false that performs merges rather than rebase. Local merge commits mean that you either didn't rebase to keep all your local commits on top of the upstream, or that you have multiple upstreams (the example exception I gave). I rather have multiple (release) branches on single upstream, say, v2.3 and v2.4. When something needs to be fixed in 2.3, it's fixed there and pushed upstream, then, on 2.4, the 2.3 is merged to it, and result is pushed upstream. When I do this merge, I need to push the merge upstream, and this won't work reliably when --rebase=true is acitve (through pull.merge=rebase). If nothing changes upstream, I can simply push this, and the merge is correctly preserved. However, if somebody makes any changes upstream while I perform the merge, I'll need to pull before pushing, and this immediately flattens-out my merge, that is absolutely not what is needed here. Or I can simply pull before push, just in case, and this flattens history even when there are no any changes upstream! Once again, nobody yet gave any clue of when/why pull.merge=preserve configuration is inferior to pull.merge=rebase, as for all the scenario you seem to care about they bring the same result. Conversely, if you always rebase your local commits on top of the upstream then you won't have merge commits to worry about. Wrong. I do alwys rebase my local commits on top of upstream, but I still do have my own merge commits to worry about, as explained above. -- Sergey. -- To unsubscribe from this list: send the line unsubscribe git in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: Amending merge commits?
On Wed, Jul 30, 2014 at 3:42 AM, Sergei Organov o...@javad.com wrote: Nico Williams n...@cryptonector.com writes: Local merge commits mean that you either didn't rebase to keep all your local commits on top of the upstream, or that you have multiple upstreams (the example exception I gave). I rather have multiple (release) branches on single upstream, say, v2.3 and v2.4. When something needs to be fixed in 2.3, it's fixed there and pushed upstream, then, on 2.4, the 2.3 is merged to it, and result is pushed upstream. When I do this merge, I need to push the merge Hmm, why not cherry-pick the fix? That's how every project I know that ports fixes across release branches does it. upstream, and this won't work reliably when --rebase=true is acitve (through pull.merge=rebase). If nothing changes upstream, I can simply push this, and the merge is correctly preserved. However, if somebody makes any changes upstream while I perform the merge, I'll need to pull before pushing, and this immediately flattens-out my merge, that is absolutely not what is needed here. Or I can simply pull before push, just in case, and this flattens history even when there are no any changes upstream! Does this change if you give your merge commits an different commit message? Conversely, if you always rebase your local commits on top of the upstream then you won't have merge commits to worry about. Wrong. I do alwys rebase my local commits on top of upstream, but I still do have my own merge commits to worry about, as explained above. If you cherry-pick the cross-release-branch commits you'll not have a merge commit to worry about. Nico -- -- To unsubscribe from this list: send the line unsubscribe git in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: Amending merge commits?
Nico Williams n...@cryptonector.com writes: On Wed, Jul 30, 2014 at 3:42 AM, Sergei Organov o...@javad.com wrote: Nico Williams n...@cryptonector.com writes: Local merge commits mean that you either didn't rebase to keep all your local commits on top of the upstream, or that you have multiple upstreams (the example exception I gave). I rather have multiple (release) branches on single upstream, say, v2.3 and v2.4. When something needs to be fixed in 2.3, it's fixed there and pushed upstream, then, on 2.4, the 2.3 is merged to it, and result is pushed upstream. When I do this merge, I need to push the merge Hmm, why not cherry-pick the fix? That's how every project I know that ports fixes across release branches does it. Cherry-pick? Why bother? What problem do we solve, having no merges whatsoever? Why? GIT is so good at merges! My impression is that people mostly rather do topic branches, and merge them wherever they need the fixes, no? upstream, and this won't work reliably when --rebase=true is acitve (through pull.merge=rebase). If nothing changes upstream, I can simply push this, and the merge is correctly preserved. However, if somebody makes any changes upstream while I perform the merge, I'll need to pull before pushing, and this immediately flattens-out my merge, that is absolutely not what is needed here. Or I can simply pull before push, just in case, and this flattens history even when there are no any changes upstream! Does this change if you give your merge commits an different commit message? Different from what? I'm almost sure commit message has nothing to do with it. Please refer to this explanation to see for yourself how git behaves when rebasing: http://www.mail-archive.com/git%40vger.kernel.org/msg55605.html Conversely, if you always rebase your local commits on top of the upstream then you won't have merge commits to worry about. Wrong. I do alwys rebase my local commits on top of upstream, but I still do have my own merge commits to worry about, as explained above. If you cherry-pick the cross-release-branch commits you'll not have a merge commit to worry about. I fail to see why do you consider merge commits to be an evil, really. I didn't think about cherry-picking carefully, but I don't feel cherry-picking is the best tool for the job here. I suspect random cherry-picking would create a mess, sooner or later. -- Sergey. -- To unsubscribe from this list: send the line unsubscribe git in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: Amending merge commits?
Nico Williams n...@cryptonector.com writes: On Mon, Jul 28, 2014 at 3:00 PM, Jonathan Nieder jrnie...@gmail.com wrote: Sergei Organov wrote: Is there any scenario at all where pull --rebase=true wins over preserve? Basically always in my book. ;-) When people turn on 'pull --rebase', they are asking for a clean, simplified history where their changes are small discrete patches in a clump on top of upstream. +1. Words to develop by. There are exceptions. E.g., when you pull commits from multiple [forked] upstreams, then you can't keep your local commits on top. That exception aside, keeping all local commits on top by always rebasing them onto the upstream is extremely useful: a) in simplifying conflict resolution, b) making it easy to identify as-yet-unintegrated local commits, c) making it easy to contribute local commits. But 'pull --rebase=preserve' does rebase local commits onto the upstream, and result is exactly the same as 'pull --rebase=true', unless you have some of your own merges to be rebased. That's where the difference between these two options appears. It's --rebase=false that performs merges rather than rebase. Overall, I still can't see where '--rebase=true' wins over '--rebase=preserve'. -- Sergey. -- To unsubscribe from this list: send the line unsubscribe git in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: Amending merge commits?
On Tue, Jul 29, 2014 at 4:58 AM, Sergei Organov o...@javad.com wrote: Nico Williams n...@cryptonector.com writes: That exception aside, keeping all local commits on top by always rebasing them onto the upstream is extremely useful: a) in simplifying conflict resolution, b) making it easy to identify as-yet-unintegrated local commits, c) making it easy to contribute local commits. But 'pull --rebase=preserve' does rebase local commits onto the upstream, and result is exactly the same as 'pull --rebase=true', unless you have some of your own merges to be rebased. That's where the difference between these two options appears. It's --rebase=false that performs merges rather than rebase. Local merge commits mean that you either didn't rebase to keep all your local commits on top of the upstream, or that you have multiple upstreams (the example exception I gave). Conversely, if you always rebase your local commits on top of the upstream then you won't have merge commits to worry about. Nico -- -- To unsubscribe from this list: send the line unsubscribe git in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: Amending merge commits?
From: Nico Williams n...@cryptonector.com On Tue, Jul 29, 2014 at 4:58 AM, Sergei Organov o...@javad.com wrote: Nico Williams n...@cryptonector.com writes: That exception aside, keeping all local commits on top by always rebasing them onto the upstream is extremely useful: a) in simplifying conflict resolution, b) making it easy to identify as-yet-unintegrated local commits, c) making it easy to contribute local commits. But 'pull --rebase=preserve' does rebase local commits onto the upstream, and result is exactly the same as 'pull --rebase=true', unless you have some of your own merges to be rebased. That's where the difference between these two options appears. It's --rebase=false that performs merges rather than rebase. Local merge commits mean that you either didn't rebase to keep all your local commits on top of the upstream, or that you have multiple upstreams (the example exception I gave). Conversely, if you always rebase your local commits on top of the upstream then you won't have merge commits to worry about. Whilst it may not be the Git Way, I'd expect that in many less well informed companies, the need to keep merge commits fom other lines of development would be quite a common (political ) technique where some preparatory branch needs to be merged in before one's feature can be completed (similar to all those cases on the list when folk say 'builds on top of xy's commit deadbeaf) Philip -- To unsubscribe from this list: send the line unsubscribe git in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: Amending merge commits?
On Tue, Jul 29, 2014 at 2:29 PM, Philip Oakley philipoak...@iee.org wrote: From: Nico Williams n...@cryptonector.com Local merge commits mean that you either didn't rebase to keep all your local commits on top of the upstream, or that you have multiple upstreams (the example exception I gave). Conversely, if you always rebase your local commits on top of the upstream then you won't have merge commits to worry about. Whilst it may not be the Git Way, I'd expect that in many less well informed companies, the need to keep merge commits fom other lines of development would be quite a common (political ) technique where some preparatory branch needs to be merged in before one's feature can be completed (similar to all those cases on the list when folk say 'builds on top of xy's commit deadbeaf) The way we did this at Sun, first with Teamware, then later with Mercurial, was as follows: - projects kept their own clone repos of the upstream - engineers working on a project cloned the project repo (project gate) - engineers pushed/pulled to/from the project gate - each project gate had a gatekeeper whose job it was to periodically rebase onto the latest upstream - then engineers would rebase onto the new project gate No merge turds (Sun speak) were ever allowed in any upstream, whether a project gate or the ultimate upstream. All commits had to be organized according to specific rules, and squashed. These rules applied at the project gate and in the upstream. - when the project was ready for integration the gatekeeper would rebase and squash as necessary, then push to the upstream (I'm eliding some details. In particular when an intermediate upstream rebased the previous head was left available as a snapshot to make the equivalent of git rebase --onto possible.) The upshot was: all local commits were always on top of whatever the next upstream in the chain was. Always. No merge commits ever. That workflow works just fine with git. It worked really well at Sun (with thousands of engineers working on Solaris alone). And it should work well for anyone who doesn't have two or more forked upstreams to follow. Nico -- -- To unsubscribe from this list: send the line unsubscribe git in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: Amending merge commits?
From: Nico Williams n...@cryptonector.com On Tue, Jul 29, 2014 at 2:29 PM, Philip Oakley philipoak...@iee.org wrote: From: Nico Williams n...@cryptonector.com Local merge commits mean that you either didn't rebase to keep all your local commits on top of the upstream, or that you have multiple upstreams (the example exception I gave). Conversely, if you always rebase your local commits on top of the upstream then you won't have merge commits to worry about. Whilst it may not be the Git Way, I'd expect that in many less well informed companies, the need to keep merge commits fom other lines of development would be quite a common (political ) technique where some preparatory branch needs to be merged in before one's feature can be completed (similar to all those cases on the list when folk say 'builds on top of xy's commit deadbeaf) The way we did this at Sun, first with Teamware, then later with Mercurial, was as follows: - projects kept their own clone repos of the upstream - engineers working on a project cloned the project repo (project gate) - engineers pushed/pulled to/from the project gate - each project gate had a gatekeeper whose job it was to periodically rebase onto the latest upstream - then engineers would rebase onto the new project gate No merge turds (Sun speak) were ever allowed in any upstream, whether a project gate or the ultimate upstream. All commits had to be organized according to specific rules, and squashed. These rules applied at the project gate and in the upstream. - when the project was ready for integration the gatekeeper would rebase and squash as necessary, then push to the upstream (I'm eliding some details. In particular when an intermediate upstream rebased the previous head was left available as a snapshot to make the equivalent of git rebase --onto possible.) The upshot was: all local commits were always on top of whatever the next upstream in the chain was. Always. No merge commits ever. That workflow works just fine with git. I'm not saying that it isn't a good technique and can work well. Rather I'm saying we should be tolerant of the rules and techniques of others who do have 'merges' in their workflow organisation. They may have a very long QA delay between feature 'done' and feature 'done done tested merged', which requires maintaining merges of done items that aren't yet merged to master. Such techniques are more common in mixed engineering than pure software environments (where engineering rules apply, and software has to follow) It worked really well at Sun (with thousands of engineers working on Solaris alone). And it should work well for anyone who doesn't have two or more forked upstreams to follow. I'm just cautious of an accidental one size fits all approach, so the ability to rebase lines of development which contain merge commits should be possible (with an appropriate and documented option) without hidden traps. Philip -- To unsubscribe from this list: send the line unsubscribe git in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: Amending merge commits?
On Tue, Jul 29, 2014 at 4:38 PM, Philip Oakley philipoak...@iee.org wrote: From: Nico Williams n...@cryptonector.com That workflow works just fine with git. I'm not saying that it isn't a good technique and can work well. Rather I'm saying we should be tolerant of the rules and techniques of others who do [...] Sure. I was just giving advice as to how to avoid any problems at pull time w.r.t. local merge commits. Better merge commit handling at pull time might be great (I'd not know; I avoid local merge commits!), but I would still strongly recommend keeping all local commits on top because otherwise you lose local history. Even if you use -m to set a better commit message, you might prefer to have kept the original N local -now rebased- commits around so you can tell what each discrete change was, even if you'll eventually squash them (you might not squash them all into one). It worked really well at Sun (with thousands of engineers working on Solaris alone). And it should work well for anyone who doesn't have two or more forked upstreams to follow. I'm just cautious of an accidental one size fits all approach, so the ability to rebase lines of development which contain merge commits should be possible (with an appropriate and documented option) without hidden traps. Thus far the only case I've seen where this approach doesn't work _at all_ is the case where you have multiple forked upstreams. The only other case where it doesn't work is a social problem: rebase allergy. For the repos I maintain I insist on contributed commits applying as fast forward merges, or I'll rebase them myself if need be. Nico -- -- To unsubscribe from this list: send the line unsubscribe git in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: Amending merge commits?
Jonathan Nieder jrnie...@gmail.com writes: David Besen wrote: Jonathan Nieder wrote: This is how pull --rebase works. It turns your single-parent commits into a sequence of patches on top of upstream and completely ignores your merge commits. There is a --rebase=preserve option that makes a halfhearted attempt to preserve your merges --- perhaps that would help? The git-rebase(1) documentation has more details. Ah thanks, I'll RTFM better in the future. No, not a problem. It's very useful to see examples of where git's behavior was counterintuitive and the documentation was more obscure than it could have been. Should documentaion warn that git pull --rebase=true (and pull.merge=true configuration) could be harmful, and that --rebase=preserve (and pull.merge=preserve) should better be used instead? Is there any scenario at all where pull --rebase=true wins over preserve? -- Sergey. -- To unsubscribe from this list: send the line unsubscribe git in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: Amending merge commits?
Sergei Organov wrote: Is there any scenario at all where pull --rebase=true wins over preserve? Basically always in my book. ;-) When people turn on 'pull --rebase', they are asking for a clean, simplified history where their changes are small discrete patches in a clump on top of upstream. When someone has made a merge by mistake (with 'git pull' before remembering to do an autosetuprebase, or with 'git merge' instead of cherry-picking some patches they needed), the current --rebase=true behavior can be a good way of cleaning up. That said, in some specific workflows, --rebase=preserve may work better than --rebase=true. My hunch is that even those workflows are not currently handled well with --rebase=preserve, alas. A clearer explanation of --rebase (maybe with sub-headings for each choice *true*, *false*, and *preserve*?) sounds useful. An illustration in the EXAMPLES section of git-pull(1) of the difference between these three modes and when to use them would be even more helpful. Thanks, Jonathan -- To unsubscribe from this list: send the line unsubscribe git in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: Amending merge commits?
Jonathan Nieder jrnie...@gmail.com writes: Sergei Organov wrote: Is there any scenario at all where pull --rebase=true wins over preserve? Basically always in my book. ;-) When people turn on 'pull --rebase', they are asking for a clean, simplified history where their changes are small discrete patches in a clump on top of upstream. I think they rather ask for avoiding tons of meaningless automatic merges resulting from periodic pulling from upstream. Those subset of the above who only do small discrete patches don't do merges to their tracking branches, except by mistake, right? If so, 'pull --rebase=preserve' makes no difference compared to --rebase=true to their normal workflow. Moreover,if someone merges something to his tracking branch by mistake, how is it different from making merge to any other branch by mistake? Just fix the mistake by resetting to previous state. On the other hand, if someone decides to merge something else to his tracking branch by purpose, both --rebase=preserve and --rebase=false perform as expected, while --rebase=true may easily lead to huge surprise. Please refer also to this thread for one such case: http://www.mail-archive.com/git%40vger.kernel.org/msg55605.html When someone has made a merge by mistake (with 'git pull' before remembering to do an autosetuprebase, or with 'git merge' instead of cherry-picking some patches they needed), the current --rebase=true behavior can be a good way of cleaning up. Once again, in case of mistake they are free to use --rebase=true, and even then using 'git rebase' directly is probably cleaner. That said, I don't argue --rebase=true could be sometimes useful. It's just that I think --rebase=preserve is safer, so it should be a good idea to suggest to use it (in favor of --rebase=true) in general. That said, in some specific workflows, --rebase=preserve may work better than --rebase=true. It does indeed, and I don't think my aforementioned workflow is too specific. My hunch is that even those workflows are not currently handled well with --rebase=preserve, alas. --rebase=preserve works fine for the aforementioned workflow. At least simple tests I performed so far ran fine. I'd like to learn though which nasty drawbacks --rebase=preserve has for tracking branches compared to --rebase=true, if any. A clearer explanation of --rebase (maybe with sub-headings for each choice *true*, *false*, and *preserve*?) sounds useful. An illustration in the EXAMPLES section of git-pull(1) of the difference between these three modes and when to use them would be even more helpful. That would be an improvement anyway, indeed. -- Sergey. -- To unsubscribe from this list: send the line unsubscribe git in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: Amending merge commits?
On Mon, Jul 28, 2014 at 3:00 PM, Jonathan Nieder jrnie...@gmail.com wrote: Sergei Organov wrote: Is there any scenario at all where pull --rebase=true wins over preserve? Basically always in my book. ;-) When people turn on 'pull --rebase', they are asking for a clean, simplified history where their changes are small discrete patches in a clump on top of upstream. +1. Words to develop by. There are exceptions. E.g., when you pull commits from multiple [forked] upstreams, then you can't keep your local commits on top. That exception aside, keeping all local commits on top by always rebasing them onto the upstream is extremely useful: a) in simplifying conflict resolution, b) making it easy to identify as-yet-unintegrated local commits, c) making it easy to contribute local commits. Nico -- -- To unsubscribe from this list: send the line unsubscribe git in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: Amending merge commits?
Besen, David david.besen at hp.com writes: Hi folks, I think one of my coworkers has stumbled on a git bug -- if you amend a merge commit, and then pull, your amends are lost. Is this expected behavior? I've reproduced the problem in a script (attached). I ran it against a couple of versions of git (1.7.1, 1.7.9, 1.8.4, 2.0.0) and in each case it seemed to lose the amend. - Dave Attachment (amend-merge.sh): application/octet-stream, 1061 bytes Whoops, accidentally encoded the script, here it is inline: #!/bin/bash set -ex if [ -z $GIT ]; then GIT=git; fi GIT_MERGE_AUTOEDIT=no # Clean up from the last run rm -rf repo.git repo repo2 || : # Set up a bare remote repo $GIT init --bare repo.git # Check out the remote repo $GIT clone repo.git repo # Add a commit cd repo echo file file.txt $GIT add file.txt $GIT commit -m Add file.txt $GIT push origin master # Make a branch $GIT checkout -b mybranch # Add a commit on the branch echo mybranch file.txt $GIT add . $GIT commit -m Add 'mybranch' line # Go back to master $GIT checkout master # Merge in mybranch to create a merge commit $GIT merge --no-ff mybranch # Push that back $GIT push # Amend the merge commit echo amended file.txt $GIT add . $GIT commit -C HEAD --amend cd .. # Make a second checkout $GIT clone repo.git repo2 cd repo2 # Add some unrelated changes to be pulled echo repo2 file2.txt $GIT add . $GIT commit -m Add file2 $GIT push cd .. cd repo # Pull $GIT pull --rebase # Now, we expect the text amended to be in file.txt grep amended file.txt -- To unsubscribe from this list: send the line unsubscribe git in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: Amending merge commits?
Besen, David wrote: I think one of my coworkers has stumbled on a git bug -- if you amend a merge commit, and then pull, your amends are lost. This is how pull --rebase works. It turns your single-parent commits into a sequence of patches on top of upstream and completely ignores your merge commits. There is a --rebase=preserve option that makes a halfhearted attempt to preserve your merges --- perhaps that would help? The git-rebase(1) documentation has more details. In an ideal world, I think pull --rebase would do the following: 1. Do the same thing it does today 2. Behind the scenes, *also* try a 'pull --merge' but don't save the result. 3. Compare the results. If they differ, show a diff and explain to the user what happened. I may be the only one that wants that, though. Hope that helps, Jonathan -- To unsubscribe from this list: send the line unsubscribe git in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
RE: Amending merge commits?
Ah thanks, I'll RTFM better in the future. - Dave -Original Message- From: Jonathan Nieder [mailto:jrnie...@gmail.com] Sent: Friday, July 25, 2014 4:19 PM To: Besen, David Cc: git@vger.kernel.org Subject: Re: Amending merge commits? Besen, David wrote: I think one of my coworkers has stumbled on a git bug -- if you amend a merge commit, and then pull, your amends are lost. This is how pull --rebase works. It turns your single-parent commits into a sequence of patches on top of upstream and completely ignores your merge commits. There is a --rebase=preserve option that makes a halfhearted attempt to preserve your merges --- perhaps that would help? The git-rebase(1) documentation has more details. In an ideal world, I think pull --rebase would do the following: 1. Do the same thing it does today 2. Behind the scenes, *also* try a 'pull --merge' but don't save the result. 3. Compare the results. If they differ, show a diff and explain to the user what happened. I may be the only one that wants that, though. Hope that helps, Jonathan -- To unsubscribe from this list: send the line unsubscribe git in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: Amending merge commits?
David Besen wrote: Jonathan Nieder wrote: This is how pull --rebase works. It turns your single-parent commits into a sequence of patches on top of upstream and completely ignores your merge commits. There is a --rebase=preserve option that makes a halfhearted attempt to preserve your merges --- perhaps that would help? The git-rebase(1) documentation has more details. Ah thanks, I'll RTFM better in the future. No, not a problem. It's very useful to see examples of where git's behavior was counterintuitive and the documentation was more obscure than it could have been. I should also emphasize the halfhearted above. There's a lot of room for improvement in rebase --preserve-merges's handling of evil and otherwise amended merges. Thanks again, Jonathan -- To unsubscribe from this list: send the line unsubscribe git in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
