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Sending in a pull request

Once you solved the issue you were working on, you'll likely want to see your changes added to the Scala 3 repo. To do that, you need to prepare a pull request with your changes. Assuming that the team is aware of what you've been working, here are some final steps that you'll want to keep in mind as you create your PR.

1. Sign the CLA

Make sure you have signed the Scala CLA. If you have any questions about what this is and why it's required you can read further about it here.

2. Make sure your work is on its own branch

When submitting your pull request it's always best to ensure the branch name is unique to the changes you're working on. It's important not to submit your PR on your main branch as this blocks maintainers from making any changes to your PR if necessary.

3: Add Tests

Add at least one test that replicates the problem in the issue, and that shows it is now resolved.

You may of course add variations of the test code to try and eliminate edge cases. Become familiar with testing in Scala 3.

4: Add Documentation

Please ensure that all code is documented to explain its use, even if only internal changes are made. This refers to scaladocs and also any changes that might be necessary in the reference docs.

5: Double check everything

Here are a couple tips to keep in mind.

  • DRY (Don't Repeat Yourself)
  • Scouts Rule
  • When adding new code try use [optional braces]. If you're rewriting old code, you should also use optional braces unless it introduces more code changes that necessary.

6: Commit Messages

Here are some guidelines when writing commits for Dotty.

  1. If your work spans multiple local commits (for example; if you do safe point commits while working in a feature branch or work in a branch for long time doing merges/rebases etc.) then please do not commit it all but rewrite the history by squashing the commits into one large commit which is accompanied by a detailed commit message for (as discussed in the following sections). For more info, see the article: Git Workflow. Additionally, every commit should be able to be used in isolation—that is, each commit must build and pass all tests.

  2. The first line should be a descriptive sentence about what the commit is doing. It should be possible to fully understand what the commit does by just reading this single line. It is not ok to only list the ticket number, type "minor fix" or similar. If the commit has a corresponding ticket, include a reference to the ticket number, prefixed with "Closes #", at the beginning of the first line followed by the title of the ticket, assuming that it aptly and concisely summarizes the commit in a single line. If the commit is a small fix, then you are done. If not, go to 3.

  3. Following the single line description (ideally no more than 70 characters long) should be a blank line followed by an enumerated list with the details of the commit.

  4. Add keywords for your commit (depending on the degree of automation we reach, the list may change over time):

    • Review by @githubuser - will notify the reviewer via GitHub. Everyone is encouraged to give feedback, however. (Remember that @-mentions will result in notifications also when pushing to a WIP branch, so please only include this in your commit message when you're ready for your pull request to be reviewed. Alternatively, you may request a review in the pull request's description.)
    • Fix/Fixing/Fixes/Close/Closing/Refs #ticket - if you want to mark the ticket as fixed in the issue tracker (Assembla understands this).
    • backport to _branch name_ - if the fix needs to be cherry-picked to another branch (like 2.9.x, 2.10.x, etc)


fix: here is your pr title briefly mentioning the topic

Here is the body of your pr with some more information
  - Details 1
  - Details 2
  - Details 3

Closes #2

Skipping parts of CI

Depending on what your PR is addressing, sometimes it doesn't make sense to run every part of CI. For example, maybe you're just updating some documentation and there is no need to run the community build for this. We skip parts of the CI by utilizing keywords inside of brackets. The most up-to-date way to see this are by looking in the if statements of jobs. For example you can see some here. Below are commonly used ones:

[skip ci] Skip the entire CI
[skip community_build] Skip the entire community build
[skip community_build_a] Skip the "a" community build
[skip community_build_b] Skip the "b" community build
[skip community_build_c] Skip the "c" community build
[skip docs] Skip the scaladoc tests
[skip test] Skip the unit tests
[skip test_windows_fast] Skip the unit tests subset on Windows
[skip mima] Skip the MiMa checks
[skip test_sbt] Skip the SBT scripted tests

Executes parts of the CI that are skipped on PRs

Depending on what your PR is addressing, sometimes it doesn't make sense to run parts of the CI that usually ony runs on nightly builds.

[test_java8] Execute unit tests on Java 8
[test_windows_full] Execute unit tests on Windows
[test_non_bootstrapped] Execute unit tests using non-bootstrapped compiler

7: Create your PR!

When the feature or fix is completed you should open a Pull Request on GitHub.

If you're not actually finished yet and are just looking for some initial input on your approach, feel free to open a Draft PR. This lets reviewers know that you're not finished yet. It's also a good idea to put a [wip] in front of your PR title to make this extra clear.

Shortly after creating your pull request a maintainer should assign someone to review it. If this doesn't happen after a few days, feel free to ping someone on the Scala Contributors Discord or tag someone on the PR. Depending on the type of pull request there might be multiple people that take a look at your changes. There might also be community input as we try to keep the review process as open as possible.

8: Addressing feedback

More than likely you'll get feedback from the reviewers, so you'll want to make sure to address everything. When in doubt, don't hesitate to ask for clarification or more information.

Once you finally see the "LGTM" (Looks Good To Me or Let's Get This Merged) you're PR will be merged in!