Predeclared dependencies (opt-in feature/restriction)

[nedtwigg]

We have a strange feature in the Spotless gradle plugin: googleJavaFormat('1.8') The exact chain by which that 1.8 becomes a dependency that gets declared to Gradle is this:

the stacktrace

spotless/plugin-gradle/src/main/java/com/diffplug/gradle/spotless/JavaExtension.java

Lines 168 to 171 in f9d66c4

	private FormatterStep createStep() {
	return GoogleJavaFormatStep.create(
	groupArtifact,
	version,

spotless/lib/src/main/java/com/diffplug/spotless/java/GoogleJavaFormatStep.java

Lines 137 to 139 in 2ca0db1

	State(String stepName, String groupArtifact, String version, String style, Provisioner provisioner, boolean reflowLongStrings) throws Exception {
	JVM_SUPPORT.assertFormatterSupported(version);
	this.jarState = JarState.from(groupArtifact + ":" + version, provisioner);

spotless/lib/src/main/java/com/diffplug/spotless/JarState.java

Lines 65 to 68 in 2ca0db1

	private static JarState provisionWithTransitives(boolean withTransitives, Collection<String> mavenCoordinates, Provisioner provisioner) throws IOException {
	Objects.requireNonNull(mavenCoordinates, "mavenCoordinates");
	Objects.requireNonNull(provisioner, "provisioner");
	Set<File> jars = provisioner.provisionWithTransitives(withTransitives, mavenCoordinates);

spotless/plugin-gradle/src/main/java/com/diffplug/gradle/spotless/GradleProvisioner.java

Lines 33 to 44 in 2ca0db1

	static Provisioner forProject(Project project) {
	Objects.requireNonNull(project);
	return (withTransitives, mavenCoords) -> {
	try {
	Configuration config = project.getConfigurations().create("spotless"
	+ new Request(withTransitives, mavenCoords).hashCode());
	mavenCoords.stream()
	.map(project.getDependencies()::create)
	.forEach(config.getDependencies()::add);
	config.setDescription(mavenCoords.toString());
	config.setTransitive(withTransitives);
	return config.resolve();

spotless/lib/src/main/java/com/diffplug/spotless/java/GoogleJavaFormatStep.java

Lines 147 to 148 in 2ca0db1

	FormatterFunc createFormat() throws Exception {
	ClassLoader classLoader = jarState.getClassLoader();

spotless/lib/src/main/java/com/diffplug/spotless/JarState.java

Lines 86 to 90 in 2ca0db1

	* The lifetime of the underlying cacheloader is controlled by {@link SpotlessCache}.
	*/
	public ClassLoader getClassLoader() {
	return SpotlessCache.instance().classloader(this);
	}

spotless/lib/src/main/java/com/diffplug/spotless/SpotlessCache.java

Lines 68 to 71 in 2ca0db1

	synchronized ClassLoader classloader(Serializable key, JarState state) {
	SerializedKey serializedKey = new SerializedKey(key);
	return cache
	.computeIfAbsent(serializedKey, k -> new FeatureClassLoader(state.jarUrls(), this.getClass().getClassLoader()));

In every Spotless before 6.0, we resolved all formatter dependencies against the buildscript repositories in the root project. That changed in 6.0 because of these two PRs:

• Resolve dependencies from "project" repositories, not buildscript #980 changed that to resolve against the normal project repositories in the root project
• Resolve dependencies per-project #983 changed that to resolve against the normal project repositories of each project where spotless was used

If you want the old behavior back, we're happy to take a PR which adds it as a feature like so.

// build.gradle (root project only)
spotless {
 predeclareDeps()
 // predeclareDepsFromBuildscript() to get pre-6.0 behavior
}
spotlessPredeclare {
 // now you have to declare every formatter (including version) that you plan to use
 // you don't need to set the target, that part doesn't matter
 java { googleJavaFormat('1.4') }
}

// works/build.gradle
spotless {
 java { googleJavaFormat('1.4') } // ok
}
// error/build.gradle
spotless {
 java { googleJavaFormat('1.3') } // throws error at configuration time
}

[nedtwigg]

Implemented in plugin-gradle 6.1.0.