5 ms·

I hear a lot of larger teams insist on squash commits for PRs. Fossil isn't a fan of squashing.

by spiffytech 4y ago

cortesoft 4y ago
Squash commits aren’t rewriting history.
- sshine 4y ago
  Squashing literally requires `git rebase`. Perhaps you think of squashing as a GitHub button and not a series of rewriting commands? Technically, any rewrite is equivalent to some arbitrary construction of history from some point in time, but I think a reasonable definition of rewriting history is if you need to rebase or cherry-pick when using the command-line.
  - cortesoft 4y ago
    You can create a squash commit on the main branch while leaving the feature branch untouched.
  - dahart 4y ago
    We don’t need a reasonable definition of rewriting history, we need a better conversation about what our tools are even for. Git isn’t a tool for preserving history, it’s a tool for keeping track of code changes. Git rebase provides a new, second, altered sequence of commits. It doesn’t replace the original. We often choose to preserve the rebased sequence, but this distinction is not academic, it’s critically important because as a part of a version control system, rebase can be undone, precisely because it does not write over the old history. Git never promised a “history” per se, not in the form of an immutable record of events. The framing of git rebase as a history rewrite, the very idea that rewriting history is bad, came from the Fossil team in an attempt to convince people to try Fossil and cast shade on git. I’m in favor of better VCSs, but the claim that rebase is a history rewrite is hyperbolic, and the judgement on top of that is silly and misguided. Rebase is a tool designed to reorder a sequence of commits, mostly for the purposes of making local changes presentable before pushing them, and has other legitimate uses too.
    - sshine 4y ago
      > rebase can be undone, precisely because it does not write over the old history Good point. Perhaps "rewrite history" is not the best metaphor, and does not cover all possible git workflows. I only considered the workflows where a rebased branch is merged back onto master instead of its non-rebased variant, which loses its name, its remote copy/copies and is eventually hit by the GC. > the very idea that rewriting history is bad, came from the Fossil team in an attempt to convince people to try Fossil and cast shade on git. The resistance I've met among developers to adopt rebasing workflows with git have no knowledge of Fossil. My impression is that the main objection to such workflows is that it exceeds some developers' novelty budget [0] and that those developers generally don't read git messages and don't value the history of code to understand its current shape. [0]: https://shimweasel.com/2018/08/25/novelty-budgets https://shimweasel.com/2018/08/25/novelty-budgets
      - dahart 4y ago
        Sorry maybe I got a little ranty there. Rewrite history is an okay metaphor, not great but nothing super wrong with it as an approximation. And you're totally right, there is definitely resistance to rebase outside of Fossil, and even within the git community with people who've never heard of Fossil. Git does have a steep learning curve and a bumpy interface that most people (including yours truly) never get all the way through. FWIW, my intro to rebase came after using Perforce for years. Because git is strict about commit ordering and P4 is not, I was struggling to figure out how to manage multiple in-flight changes like I would in P4, and how to clean up and push something that wasn't a hot mess. Rebasing my local workspace, it turned out, is the answer to that. It is the key to working around git's strict commit parentage, and makes it easy to sculpt changes so they're palatable for me and my team. Above I was referring to some of the anti-rebase messaging Fossil has put out in the past. Some is there still, for example https://www.fossil-scm.org/home/doc/trunk/www/rebaseharm.md https://www.fossil-scm.org/home/doc/trunk/www/rebaseharm.md I'm quite pleased to see that a lot of the most hyperbolic verbiage is gone now, it used to carry on quite a bit. But that page still says rebase is "dishonest", which is a deeply ironic claim, if you catch my drift. That kind of mis-representation ruffles my feathers a little bit, but I've had discussions with the Fossil team right here on HN about it, and they have in fact been open to listening, responsive, and willing to change and improve the messaging.
- spiffytech 4y ago
  Technically, they are: you erased commits from your history. You created a single new commit with equivalent contents, but the timeline has been altered, and if you previously pushed to your remote you now have to force push because the remote remembers a version of history that no longer happened. Fossil heavily discourages (outright forbids?) this kind of stuff.
  - dahart 4y ago
    Technically, commits are not erased after squash/rebase. They remain there and available to use unless they are not reachable from a named branch for like 90 days. Technically, the timeline is not altered, but the commit sequence is altered. Git does not offer an immutable timeline, and thus squash & rebase cannot break it. Fossil does try to discourage rewrites, but does offer ‘purge’ which is a rewrite, because of course, forbidding all rewrites is impractical.
- dmm 4y ago
  It is if someone branches off your pre-squash branch.
- dahart 4y ago
  I saw this was downvoted and tried to help by upvoting, but it is worth talking about what “history” means though. Squash commits rewrite the source branch history, but they don’t rewrite the destination branch history. I would argue the team-wide destination branch history is what should be called “history”, and the only thing that matters. But Fossil’s distinction is more rigid and it considers anything ever committed to be history. Squashing a local branch does, in a way, rewrite local commit history. But this shouldn’t be called “rewriting history” in my book. Rebasing the main branch really is fully rewriting history (and this isn’t a squash commit). Squashing a feature branch that multiple people touch is somewhere in between. It’s a little rewriting. It’s often desirable. Should squashing small feature branch PRs be called “rewriting history” in the sense that Fossil claims that it’s intended to misrepresent the project? I don’t really think so, but since “rewriting history” wasn’t clearly defined, it’s open for debate.
  - cortesoft 4y ago
    You don't even need to rewrite the source branch history. You can leave the source branch as is, and create a single commit on the main branch that is the squashed content of the source branch. It isn't considered a merge in the normal way by git, which can cause issues, but there is no lost history and GitHub and gitlab are able to keep track of the source of the squash commit.
    - dahart 4y ago
      Yeah true! It still goes to clarifying what people mean by the words “history” and “rewrite”, etc. The primary public history of a feature branch might only be preserved in the merge commit, so in some sense the preserved history is different than the branch history. It’s somewhat fair to call that rewritten. I prefer to focus on the fact the git never promised a “history” at all. Git doesn’t offer to capture what happened accurately, it only promised to keep the content of your changes and its relationship to the preceding state of the content. It only promised a sequence of dependent commits, and it allows reordering commits by design.
sshine 4y ago
One of the great things about git is how it allows for complex, dynamic workflows. It is really a consequence of it being a decentralised VCS.
Aeolun 4y ago
Fossil hasn’t worked in my team. I don’t want my history to consist of hundreds of ‘fix tests’ commits with a few features strewn between.

I hear a lot of larger teams insist on squash commits for PRs. Fossil isn't a fan of squashing.

cortesoft 4y ago

Squash commits aren’t rewriting history.

sshine 4y ago
Squashing literally requires `git rebase`. Perhaps you think of squashing as a GitHub button and not a series of rewriting commands? Technically, any rewrite is equivalent to some arbitrary construction of history from some point in time, but I think a reasonable definition of rewriting history is if you need to rebase or cherry-pick when using the command-line.
- cortesoft 4y ago
  You can create a squash commit on the main branch while leaving the feature branch untouched.
- dahart 4y ago
  We don’t need a reasonable definition of rewriting history, we need a better conversation about what our tools are even for. Git isn’t a tool for preserving history, it’s a tool for keeping track of code changes. Git rebase provides a new, second, altered sequence of commits. It doesn’t replace the original. We often choose to preserve the rebased sequence, but this distinction is not academic, it’s critically important because as a part of a version control system, rebase can be undone, precisely because it does not write over the old history. Git never promised a “history” per se, not in the form of an immutable record of events. The framing of git rebase as a history rewrite, the very idea that rewriting history is bad, came from the Fossil team in an attempt to convince people to try Fossil and cast shade on git. I’m in favor of better VCSs, but the claim that rebase is a history rewrite is hyperbolic, and the judgement on top of that is silly and misguided. Rebase is a tool designed to reorder a sequence of commits, mostly for the purposes of making local changes presentable before pushing them, and has other legitimate uses too.
  - sshine 4y ago
    > rebase can be undone, precisely because it does not write over the old history Good point. Perhaps "rewrite history" is not the best metaphor, and does not cover all possible git workflows. I only considered the workflows where a rebased branch is merged back onto master instead of its non-rebased variant, which loses its name, its remote copy/copies and is eventually hit by the GC. > the very idea that rewriting history is bad, came from the Fossil team in an attempt to convince people to try Fossil and cast shade on git. The resistance I've met among developers to adopt rebasing workflows with git have no knowledge of Fossil. My impression is that the main objection to such workflows is that it exceeds some developers' novelty budget [0] and that those developers generally don't read git messages and don't value the history of code to understand its current shape. [0]: https://shimweasel.com/2018/08/25/novelty-budgets https://shimweasel.com/2018/08/25/novelty-budgets
    - dahart 4y ago
      Sorry maybe I got a little ranty there. Rewrite history is an okay metaphor, not great but nothing super wrong with it as an approximation. And you're totally right, there is definitely resistance to rebase outside of Fossil, and even within the git community with people who've never heard of Fossil. Git does have a steep learning curve and a bumpy interface that most people (including yours truly) never get all the way through. FWIW, my intro to rebase came after using Perforce for years. Because git is strict about commit ordering and P4 is not, I was struggling to figure out how to manage multiple in-flight changes like I would in P4, and how to clean up and push something that wasn't a hot mess. Rebasing my local workspace, it turned out, is the answer to that. It is the key to working around git's strict commit parentage, and makes it easy to sculpt changes so they're palatable for me and my team. Above I was referring to some of the anti-rebase messaging Fossil has put out in the past. Some is there still, for example https://www.fossil-scm.org/home/doc/trunk/www/rebaseharm.md https://www.fossil-scm.org/home/doc/trunk/www/rebaseharm.md I'm quite pleased to see that a lot of the most hyperbolic verbiage is gone now, it used to carry on quite a bit. But that page still says rebase is "dishonest", which is a deeply ironic claim, if you catch my drift. That kind of mis-representation ruffles my feathers a little bit, but I've had discussions with the Fossil team right here on HN about it, and they have in fact been open to listening, responsive, and willing to change and improve the messaging.
spiffytech 4y ago
Technically, they are: you erased commits from your history. You created a single new commit with equivalent contents, but the timeline has been altered, and if you previously pushed to your remote you now have to force push because the remote remembers a version of history that no longer happened. Fossil heavily discourages (outright forbids?) this kind of stuff.
- dahart 4y ago
  Technically, commits are not erased after squash/rebase. They remain there and available to use unless they are not reachable from a named branch for like 90 days. Technically, the timeline is not altered, but the commit sequence is altered. Git does not offer an immutable timeline, and thus squash & rebase cannot break it. Fossil does try to discourage rewrites, but does offer ‘purge’ which is a rewrite, because of course, forbidding all rewrites is impractical.
dmm 4y ago
It is if someone branches off your pre-squash branch.
dahart 4y ago
I saw this was downvoted and tried to help by upvoting, but it is worth talking about what “history” means though. Squash commits rewrite the source branch history, but they don’t rewrite the destination branch history. I would argue the team-wide destination branch history is what should be called “history”, and the only thing that matters. But Fossil’s distinction is more rigid and it considers anything ever committed to be history. Squashing a local branch does, in a way, rewrite local commit history. But this shouldn’t be called “rewriting history” in my book. Rebasing the main branch really is fully rewriting history (and this isn’t a squash commit). Squashing a feature branch that multiple people touch is somewhere in between. It’s a little rewriting. It’s often desirable. Should squashing small feature branch PRs be called “rewriting history” in the sense that Fossil claims that it’s intended to misrepresent the project? I don’t really think so, but since “rewriting history” wasn’t clearly defined, it’s open for debate.
- cortesoft 4y ago
  You don't even need to rewrite the source branch history. You can leave the source branch as is, and create a single commit on the main branch that is the squashed content of the source branch. It isn't considered a merge in the normal way by git, which can cause issues, but there is no lost history and GitHub and gitlab are able to keep track of the source of the squash commit.
  - dahart 4y ago
    Yeah true! It still goes to clarifying what people mean by the words “history” and “rewrite”, etc. The primary public history of a feature branch might only be preserved in the merge commit, so in some sense the preserved history is different than the branch history. It’s somewhat fair to call that rewritten. I prefer to focus on the fact the git never promised a “history” at all. Git doesn’t offer to capture what happened accurately, it only promised to keep the content of your changes and its relationship to the preceding state of the content. It only promised a sequence of dependent commits, and it allows reordering commits by design.

sshine 4y ago

One of the great things about git is how it allows for complex, dynamic workflows. It is really a consequence of it being a decentralised VCS.

Aeolun 4y ago

Fossil hasn’t worked in my team. I don’t want my history to consist of hundreds of ‘fix tests’ commits with a few features strewn between.