Allow empty commit when merging pull request with squash style

[lunny]

Before this PR, when merging an empty PR with squash style will result in 500.

How to reproduce the issue:
1. Create a new branch dev from main.
2. Add some changes and commit them on the dev branch.
3. Open a pull request from dev to main.
4. Manually cherry-pick the commit from dev into main.
5. Open the pull request page and attempt a Squash Merge → a 500 error occurs.

This PR will allow the behavior.

[wxiaoguang]

Why user can't provide a message? What's the use case for keeping the message empty?

[lunny]

Why user can't provide a message? What's the use case for keeping the message empty?

It's an empty commit, not an empty commit message.

[wxiaoguang]

Why user can't provide a message? What's the use case for keeping the message empty?

It's an empty commit, not an empty commit message.

OK, then why an empty commit should be supported? What's the use case

[lunny]

Why user can't provide a message? What's the use case for keeping the message empty?

It's an empty commit, not an empty commit message.

OK, then why an empty commit should be supported? What's the use case

I updated the issue content. Looks at the image on that. The previous implementation in Gitea has a warning hint there but it said this will be an empty commit. So that to keep the behavior consistent, it's nature to allow commit the empty commit. I can also change the hint and disable the button but I think that should be break change?

[wxiaoguang]

Without the AddArguments("--allow-empty"), your TestPullSquashMergeEmpty still passes.

If it tests nothing, you can delete the test to avoid wasting CI time.

[silverwind]

I'm confused because the screenshot shows "1 files changed", but a empty commit would actually be "0 files changed". Are you sure it's targeting the correct mechanism?

[wxiaoguang]

I'm confused because the screenshot shows "1 files changed", but a empty commit would actually be "0 files changed". Are you sure it's targeting the correct mechanism?

That's how git works.

• On "main" branch: set "file.txt" content to "dummy"
• Create a new "branch-1", edit "file.txt", change its content to "changed" and create a PR
• On "main" branch: set "file.txt" content to "changed"
• Then "branch-1" can be merged into "main" without conflict or change.

[silverwind]

So basically a branch that once had changes, but was then made to match the target branch. I still think the UI should show "0 changed files" in such a case as I'm pretty sure git diff would also show empty in such a case. In any case, this discussion is offtopic :)

[wxiaoguang]

So basically a branch that once had changes, but was then made to match the target branch. I still think the UI should show "0 changed files" in such a case as I'm pretty sure git diff would also show empty in such a case. In any case, this discussion is offtopic :)

No. The "diff" is from its merge base.

If you want to see 0, click that "Update branch" button.

[lunny]

How to reproduce the issue:
1. Create a new branch dev from main.
2. Add some changes and commit them on the dev branch.
3. Open a pull request from dev to main.
4. Manually cherry-pick the commit from dev into main.
5. Open the pull request page and attempt a Squash Merge → a 500 error occurs.

[wxiaoguang]

Yep, it can be reproduced if there is nothing to merge. My comment #35989 (comment) can also easily reproduce.

But the problem is: your test code is not right

Without the AddArguments("--allow-empty"), your TestPullSquashMergeEmpty still passes.
If it tests nothing, you can delete the test to avoid wasting CI time.