How to keep a GitHub fork up to date without a merge commit or using CLI?

问题

The normal GitHub flow to contribute to a repo is to create a fork of the upstream, clone a local copy where you make changes, then push back up to your fork and then create a PR to have your changes merged into upstream.

But if upstream changes after that, how do you update your fork without creating a merge commit (and also without using the git CLI)?

I already know how to do this in a way that will create a merge commit or which depend on the git command line interface. This question is specifically about using the GitHub.com website or GitHub Desktop application only (no CLI).

Since this is a very common workflow it seems like there should be some simple way to do it using the GitHub GUI.

To reiterate: any answers that use the CLI or create a merge commit (e.g. this way) will not be answering this question since I'm explicitly looking for a non-CLI solution.

回答1:

This is feasible with GitHub Desktop since version 1.0.7 considering the following:

• If the current branch does not have any commits ahead upstream (the original repo of the fork), the new commits can be pulled without creating a new merge commit

  In GitHub Desktop:

  1. Clone your repository from File > Clone Repository

  2. Fetch origin, which will automatically fetch the upstream as well

  3. Go to Branches by clicking on where it says Current Branch

  4. Click on Choose a branch to merge into <branch> at the bottom

  5. Search for upstream/<branch>, then click Merge upstream/<branch> into <branch>

  6. Push to origin, et voilà!

• Otherwise, ff the current branch has commits ahead of the fork, then of course one has to create a merge commit or rebase and force push. For rebasing which might be more preferable, do the following:

  1. In GItHub Desktop, go to Branch from menu, then Rebase Current Branch

  2. Search for upstream/<branch>, then click Start Rebase

  3. Solve any conflicts that have occurred from the rebase

  4. Force push to origin. You will get a warning for this for obvious reasons.

For avoiding force-pushing to your work when your current branch is both ahead and behind its upstream counterpart, either create a new merge commit or:

• Make a new branch based with all your changes

• If needed, reset the original branch to its original state (before it diverged from the original repo)

• Perform the steps from the first scenario and merge your changes into your branch.

And yes, it seems that pulling via the GitHub website from the original repo without creating a pull request and merge commit is not possible at this moment.

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Demo GIF for first scenario: https://imgur.com/a/8wci2yf

Some GitHub issues related to this:

• Add an upstream to forked repositories

• multi-remote support in Desktop

回答2:

without a merge commit or using CLI?

Not directly with GitHub web UI alone, since it would involve rebasing your PR branch on top of upstream/master

So in short: no.
But in less short... maybe, if you really want to try it.

Rebasing through GitHub web UI is actually possible, since Sept. 2016, ...

• if you are the maintainer of the original repo, wanting to integrate a PR branch
• if none of the replayed commit introduces a conflict

(This differs from GitHub Desktop, which, since June 5th 2019 does support rebasing. But that is a frontend to Git CLI, like other tools provide. For example GitKraken and interactive rebase)

So a convoluted workaround would be:

• to fetch, then push upstream/master to the master branch of your own fork (a CLI operation, but more on that below)
• change the base branch of your current PR to master (so a PR within the same repository: your own fork), provided you haven't pushed to master.
  Meaning: master in your fork represents the updated upstream/master, with upstream being the original repository that you have forked.
• Since you are the owner of that repository (your fork), GitHub can then show you if you can rebase said branch to the base branch of the PR (master), but only if there is no conflict.
• finally, change the base branch again, to <originalRepo>/master (which is the intended target of your PR)

The very first step is typically done through command line, but... there might be a trick to do it (update upstream master in your fork) through web UI: see "Quick Tip: Sync a Fork with the Original via GitHub’s Web UI" by Bruno Skvorc

In short, it involves:

• creating a new branch from your current master (which would be at upstream/master at the time you forked the original repository)

• Making a PR with that new branch and <originalRepo/master>
• doing a base switch before creating the PR

That is the step which artificially forces upstream/master to be refreshed

You can the create and merge it with the “Merge Pull Request” button (and “Confirm Merge” afterwards): the merge will be trivial: no merge commit.

The end result is: your own master branch (in your fork) updated with upstream/master (the master branch of the original repository)!

You can then resume the steps I describe above, and change the base of your current PR to your own (now refreshed) master branch, and see if you can rebase it!

回答3:

Update Note: Non-CLI based approach that might help: Is there a way to make GitHub Desktop rebase a branch against master?

The only key here is doing a rebase, so the above answer should help.

---

CLI way (which is easier and using git, so it should be more comprehensive by default)

There are some practices that you should use to avoid this.

• Don't work on the master branch in your fork.

$ git clone <your fork>
$ git checkout -b feature_branch

You can work in your feature_branch and then raise a Pull Request.

• Once your changes are merged in the upstream master, you can pull from upstream to your origin. Since the master on upstream will have your commits sitting neatly on top of it, there won't be a merge commit.

$ git checkout master
$ git pull upstream master
$ git push origin master

• In the case, where the maintainer has diverged from the master that you have in your fork, that is, it's not linear any more, you need to pull a fresh copy of it. That should not be a problem as your changes are already in the upstream.

• If the master in upstream has moved ahead while you were working on your PR, then you can rebase on you feature_branch.

$ git checkout master
$ git pull upstream master
$ git push origin master
$ git checkout feature_branch
$ git rebase master

Please refer to this document for detailed reference: Fork and pull request workflow

来源：https://stackoverflow.com/questions/56409392/how-to-keep-a-github-fork-up-to-date-without-a-merge-commit-or-using-cli