If you wish to use the Checker Framework, see its user manual (HTML, PDF).
This document contains information for Checker Framework developers, including people who wish to edit its source code or make pull requests.
The checker-framework repository contains several related projects:
framework the framework that enables building pluggable type checkers checker the type checkers provided with the Checker Framework javacutil utilities for javac dataflow a dataflow framework
The repository also contains the following directories:
docs documentation: manual, tutorial, examples, developer docs maven-artifacts artifacts to be uploaded to Maven Central
Full instructions for building the Checker Framework from sources appear in the Checker Framework manual. This section describes the build system (the Gradle build tasks).
Don't run the
gradle command, which would use your local
installation of gradle. Instead, use the
gradlew script in
checker-framework directory, also known as
assemble: builds all jars except
jdk8.jar, including javadoc jars and fat jars that contain all dependencies.
assemble, plus runs all JUnit tests.
allTests: runs all tests.
reformat: reformats Java files.
NameOfJUnitTest: runs the JUnit test with that name; for example,
task: lists tasks; use
--allto see all tasks.
If you run a task from the main directory, then it will run that task in all
subprojects with a task by that name. So, if you run
allTests that runs all tests everywhere. But
framework && ../gradlew allTests) only runs tests in
framework. Alternatively, running
:framework:allTests from the
main directory or any subproject runs the
allTests task only in the
Code in this project follows the Google Java Style Guide (except 4 spaces are used for indentation), Michael Ernst's coding style guidelines, and Oracle's Java code conventions.
Code formatting is enforced by a Git pre-commit hook. You can configure your IDE (Eclipse or IntelliJ) to use that formatting.
We don't use
@author Javadoc tags in code files.
Doing so clutters the code, and is misleading once that individual
is no longer maintaining the code.
Authorship (and who has made changes recently) can be obtained from the
version control system, such as by running
git annotate filename.
These instructions are relevant if you use Eclipse as your IDE.
Eclipse should successfully build all the imported projects. If Eclipse reports any errors, ensure you followed the instructions for cloning and building all projects.
Each pull request should address a single concern, rather than (say) addressing multiple concerns such as fixing a bug, adding a feature, and changing formatting. Focusing each pull request on a single concern makes the commit easier to understand and review. It also makes the commit history (after the pull request is merged) easier to understand and (if necessary) revert.
Don't forget to update the changelog if you make changes that are worthy of telling developers about. This makes it much easier for someone to make a release.
Work on a branch if you are going to submit a pull request. This enables others to make changes directly to your branch when that is more efficient than leaving comments in a pull request.
Also see Michael Ernst's advice about creating GitHub pull requests.
When there are related changes in the
checker-framework-inference repositories, use the same
branch name for each. The continuous integration framework uses a branch
of the same name when possible. If you use different branch names
checker-framework-inference, then the continuous
integration tests for both will fail and may mask problems.
It is acceptable to commit small, noncontroversial changes directly to master. (This policy differs from some projects, which require an issue tracker issue and a pull request for every change, however minor.) As with pull requests, each commit should address a single concern. For any change where you want feedback, or where others might have useful comments or might disagree, please submit a pull request. Be conservative in your judgment; others might consider something controversial that you do not.
Try to review pull requests promptly, to avoid stalling others while waiting for your feedback. If you have been waiting for more than a week after the pull request was assigned with no feedback, then ping the assignee, wait at least another business day, and then go ahead and push your changes. It's great if reviewers can give feedback, but if they are too busy to do so, you should recognize that and move on.
The Checker Framework has continuous integration jobs that run in Azure Pipelines, CircleCI, and/or Travis CI on each push to GitHub.
To enable Travis CI continuous integration for your fork:
To enable Azure Pipelines continuous integration for your fork:
Sometimes, CI tests for your pull request may fail even though your local build passed. This is usually because the CI service performed more tests than you ran locally.
First, examine the CI service's logs, which contain diagnostic output from the
failing command. You can determine which command was run from the logs, or
from the CI configuration file (such as
If you have an idea for a code improvement (such as a refactoring), please document it. If it can be described concisely and is low priority, a TODO comment in the code is more appropriate than an enhancement request in the issue tracker. The code comment is more likely to be noticed by someone working with the code, and it is equally easy to search for. Furthermore, it doesn't clutter the issue tracker. Clutter in the issue tracker reduces morale, makes it harder to search, and makes the project appear lower-quality than it actually is.
We maintain annotated versions of some third-party libraries. The source
code appears in a fork in
organization. Binaries are hosted
at Maven Central
Annotated libraries should be based on a released version of the upstream library, not an arbitrary commit in the upstream library's version control system. The library's version number is the same as the upstream version number.
When making a new version of an annotated library, between upstream releases, add ".0.1" to the end of the version number. For example, if we already uploaded version 6.2 to Maven Central, the next version we upload would be 22.214.171.124. This accommodates the possibility that the upstream maintainers release 6.2.1. Our further releases increment the last number, for example to 126.96.36.199.
See a separate document about the Checker Framework release process.