JSpecify Nullness Checker for the Checker Framework
This project is a custom checker plugin for the Checker Framework.
It is a prototype. It is not yet suitable for use on real code. To get it working properly, we will need to do more work, including proposing new configuration hooks in the Checker Framework itself. Running it against the regular version of the Checker Framework will behave incorrectly, as we have made related changes in a temporary fork of the Checker Framework. In fact, even building it against the regular version of the Checker Framework does not work after 8fcc87f5e4e28c2e4511eb8cf26092d935425fea.
We have made it available so that JSpecify project members can experiment with it, collaborate on it, and discuss the easiest way to incorporate changes into the Checker Framework itself. If all goes well, it will never be released for general use. Instead, existing tools (including the Checker Framework) will be modified to support JSpecify annotations directly, perhaps based on some of the code here.
Our main work is happening in repo https://github.com/jspecify/jspecify.
This is not an officially supported product of any of the participant organizations.
Usage
Again, this is not ready for general use. But for those in our group who are looking to try it out:
# Build the checker:
$ git clone https://github.com/jspecify/nullness-checker-for-checker-framework
$ cd nullness-checker-for-checker-framework
$ ./gradlew assemble
# Use it:
$ ../checker-framework/checker/bin/javac -processorpath ../jspecify/build/libs/jspecify-0.1.0-SNAPSHOT.jar:build/libs/nullness-checker-for-checker-framework.jar -processor com.google.jspecify.nullness.NullSpecChecker -AcheckImpl -cp ../jspecify/build/libs/jspecify-0.1.0-SNAPSHOT.jar:build/libs/nullness-checker-for-checker-framework.jar:... ...
# For example:
$ cat > SomeTest.java
import org.jspecify.annotations.DefaultNonNull;
import org.jspecify.annotations.Nullable;
@DefaultNonNull
class SomeTest {
Object passThrough(@Nullable Object o) {
return o;
}
}
$ ../checker-framework/checker/bin/javac -processorpath ../jspecify/build/libs/jspecify-0.1.0-SNAPSHOT.jar:build/libs/nullness-checker-for-checker-framework.jar -processor com.google.jspecify.nullness.NullSpecChecker -AcheckImpl -cp ../jspecify/build/libs/jspecify-0.1.0-SNAPSHOT.jar:build/libs/nullness-checker-for-checker-framework.jar SomeTest.java
SomeTest.java:7: error: [nullness] incompatible types in return.
return o;
^
type of expression: Object?
method return type: Object
1 error
# Run tests:
$ ./gradlew jspecifySamplesTest
# During development, you may wish to pass `-x ensureCheckerFrameworkBuilt` to
# `gradlew` for every build after your first. This will prevent the build
# process from also rebuilding some of our *dependencies* (which is slow).
# Also note: For some of the repos that the build process clones, it creates
# single-branch clones that use an https URL instead of a git URL. You may want
# to convert them into more "normal" GitHub clones:
$ perl -pi -e 's#https://github.com/#git\@github.com:#; s#fetch = \+refs/heads/(main|master):refs/remotes/origin/(main|master)#fetch = +refs/heads/*:refs/remotes/origin/*#;' ../*/.git/config
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