feat: Supports P2 in predeclare

bric3 · bric3 · commit 57214bf3eacc · 2026-01-26T12:09:16.000+01:00
diff --git a/plugin-gradle/src/main/java/com/diffplug/gradle/spotless/GradleProvisioner.java b/plugin-gradle/src/main/java/com/diffplug/gradle/spotless/GradleProvisioner.java
@@ -51,15 +51,18 @@ enum Policy {
 		INDEPENDENT, ROOT_PROJECT, ROOT_BUILDSCRIPT;
 
 		public DedupingProvisioner dedupingProvisioner(Project project) {
-			switch (this) {
-			case ROOT_PROJECT:
-				return new DedupingProvisioner(forProject(project));
-			case ROOT_BUILDSCRIPT:
-				return new DedupingProvisioner(forRootProjectBuildscript(project));
-			case INDEPENDENT:
-			default:
-				throw Unhandled.enumException(this);
-			}
+			return switch (this) {
+				case ROOT_PROJECT -> new DedupingProvisioner(forProject(project));
+				case ROOT_BUILDSCRIPT -> new DedupingProvisioner(forRootProjectBuildscript(project));
+				default -> throw Unhandled.enumException(this);
+			};
+		}
+
+		public DedupingP2Provisioner dedupingP2Provisioner(Project project) {
+			return switch (this) {
+				case ROOT_PROJECT, ROOT_BUILDSCRIPT -> new DedupingP2Provisioner(P2Provisioner.createDefault());
+				default -> throw Unhandled.enumException(this);
+			};
 		}
 	}
 
@@ -222,6 +225,25 @@ public synchronized List<File> provisionP2Dependencies(
 			return result;
 		}
 
+		/** A child P2Provisioner which retrieves cached elements only. */
+		final P2Provisioner cachedOnly = (modelWrapper, mavenProvisioner, cacheDirectory) -> {
+			P2Request req = new P2Request(
+					List.copyOf(modelWrapper.getP2Repos()),
+					List.copyOf(modelWrapper.getInstallList()),
+					Set.copyOf(modelWrapper.getFilterNames()),
+					List.copyOf(modelWrapper.getPureMaven()),
+					modelWrapper.isUseMavenCentral(),
+					cacheDirectory);
+			List<File> result;
+			synchronized (cache) {
+				result = cache.get(req);
+			}
+			if (result != null) {
+				return result;
+			}
+			throw new GradleException("P2 dependencies not predeclared. Add Eclipse formatter configuration to the `spotlessPredeclare` block in the root project.");
+		};
+
 		/**
 		 * Cache key capturing all P2Model state that affects query results.
 		 * Based on P2Model fields from equo-ide:
diff --git a/plugin-gradle/src/main/java/com/diffplug/gradle/spotless/SpotlessExtensionPredeclare.java b/plugin-gradle/src/main/java/com/diffplug/gradle/spotless/SpotlessExtensionPredeclare.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2021-2025 DiffPlug
+ * Copyright 2021-2026 DiffPlug
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -29,6 +29,7 @@ public class SpotlessExtensionPredeclare extends SpotlessExtension {
 	public SpotlessExtensionPredeclare(Project project, GradleProvisioner.Policy policy) {
 		super(project);
 		getRegisterDependenciesTask().getTaskService().get().predeclaredProvisioner = policy.dedupingProvisioner(project);
+		getRegisterDependenciesTask().getTaskService().get().predeclaredP2Provisioner = policy.dedupingP2Provisioner(project);
 		project.afterEvaluate(unused -> toSetup.forEach((name, formatExtension) -> {
 			for (Action<FormatExtension> lazyAction : formatExtension.lazyActions) {
 				lazyAction.execute(formatExtension);
diff --git a/plugin-gradle/src/main/java/com/diffplug/gradle/spotless/SpotlessTaskService.java b/plugin-gradle/src/main/java/com/diffplug/gradle/spotless/SpotlessTaskService.java
@@ -80,7 +80,7 @@ P2Provisioner p2ProvisionerFor(SpotlessExtension spotless) {
 			return predeclaredP2Provisioner;
 		} else {
 			if (predeclaredP2Provisioner != null) {
-				return predeclaredP2Provisioner; // P2 doesn't have a cachedOnly variant
+				return predeclaredP2Provisioner.cachedOnly;
 			} else {
 				return p2Provisioner.computeIfAbsent(spotless.project.getPath(),
 						unused -> new GradleProvisioner.DedupingP2Provisioner(P2Provisioner.createDefault()));
diff --git a/plugin-gradle/src/test/java/com/diffplug/gradle/spotless/GradleProvisionerTest.java b/plugin-gradle/src/test/java/com/diffplug/gradle/spotless/GradleProvisionerTest.java
@@ -240,6 +240,47 @@ void identicalModelsDifferentInstancesUsesCache() throws IOException {
 			assertThat(callCount.get()).as("Only called once").isEqualTo(1);
 		}
 
+		@Test
+		void cachedOnlyCacheHitReturnsResult() throws IOException {
+			P2Provisioner underlying = mockP2Provisioner(new AtomicInteger(0));
+			GradleProvisioner.DedupingP2Provisioner deduping = new GradleProvisioner.DedupingP2Provisioner(underlying);
+
+			P2ModelWrapper model = createMockModel(
+					List.of("https://download.eclipse.org/eclipse/updates/4.26/"),
+					List.of("org.eclipse.jdt.core"),
+					Set.of(),
+					List.of(),
+					true,
+					null);
+
+			// Populate cache
+			deduping.provisionP2Dependencies(model, mockProvisioner(), null);
+
+			// cachedOnly should return cached result
+			List<File> result = deduping.cachedOnly.provisionP2Dependencies(model, mockProvisioner(), null);
+
+			assertThat(result).isNotEmpty();
+		}
+
+		@Test
+		void cachedOnlyCacheMissThrowsException() {
+			P2Provisioner underlying = mockP2Provisioner(new AtomicInteger(0));
+			GradleProvisioner.DedupingP2Provisioner deduping = new GradleProvisioner.DedupingP2Provisioner(underlying);
+
+			P2ModelWrapper model = createMockModel(
+					List.of("https://download.eclipse.org/eclipse/updates/4.26/"),
+					List.of("org.eclipse.jdt.core"),
+					Set.of(),
+					List.of(),
+					true,
+					null);
+
+			// cachedOnly should throw when not cached
+			assertThatThrownBy(() -> deduping.cachedOnly.provisionP2Dependencies(model, mockProvisioner(), null))
+					.isInstanceOf(GradleException.class)
+					.hasMessageContaining("spotlessPredeclare");
+		}
+
 		private P2Provisioner mockP2Provisioner(AtomicInteger callCount) {
 			return (modelWrapper, mavenProvisioner, cacheDirectory) -> {
 				callCount.incrementAndGet();
diff --git a/plugin-gradle/src/test/java/com/diffplug/gradle/spotless/SpotlessPredeclareIntegrationTest.java b/plugin-gradle/src/test/java/com/diffplug/gradle/spotless/SpotlessPredeclareIntegrationTest.java
