Prepare for SelfResolvingDependency's removal & Update to Gradle 8.6 (#1038)

* Prepare for SelfResolvingDependency's removal
Update to Gradle 8.6

* Update docker images

* ProjectDependency is also a SRD

* Throw if layered mappings are created too late.

.github/workflows/test-push.yml

@@ -10,7 +10,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        version: [8.3.0-jdk17]
+        version: [8.6.0-jdk17]
     runs-on: ubuntu-22.04
     container:
       image: gradle:${{ matrix.version }}
@@ -39,7 +39,7 @@ jobs:
 
     runs-on: ubuntu-22.04
     container:
-      image: gradle:8.3.0-jdk17
+      image: gradle:8.6.0-jdk17
       options: --user root
 
     steps:
@@ -58,7 +58,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        version: [8.3.0-jdk17]
+        version: [8.6.0-jdk17]
         test: ${{ fromJson(needs.prepare_test_matrix.outputs.matrix) }}
 
     runs-on: ubuntu-22.04

bootstrap/src/main/java/net/fabricmc/loom/bootstrap/LoomGradlePluginBootstrap.java

@@ -14,7 +14,7 @@ import org.gradle.util.GradleVersion;
  */
 @SuppressWarnings("unused")
 public class LoomGradlePluginBootstrap implements Plugin<PluginAware> {
-	private static final String MIN_SUPPORTED_GRADLE_VERSION = "8.3";
+	private static final String MIN_SUPPORTED_GRADLE_VERSION = "8.6";
 	private static final int MIN_SUPPORTED_MAJOR_JAVA_VERSION = 17;
 	private static final int MIN_SUPPORTED_MAJOR_IDEA_VERSION = 2021;
 

gradle/libs.versions.toml

@@ -1,5 +1,5 @@
 [versions]
-kotlin = "1.9.0"
+kotlin = "1.9.20"
 asm = "9.6"
 commons-io = "2.15.1"
 gson = "2.10.1"
@@ -11,7 +11,7 @@ access-widener = "2.1.0"
 mapping-io = "0.5.1"
 lorenz-tiny = "4.0.2"
 mercury = "0.4.1"
-kotlinx-metadata = "0.8.0"
+kotlinx-metadata = "0.9.0"
 
 # Plugins
 spotless = "6.20.0"

gradle/test.libs.versions.toml

@@ -6,7 +6,7 @@ mockito = "5.8.0"
 java-debug = "0.50.0"
 mixin = "0.11.4+mixin.0.8.5"
 
-gradle-nightly = "8.7-20240104001326+0000"
+gradle-nightly = "8.7-20240202001338+0000"
 fabric-loader = "0.15.3"
 fabric-installer = "1.0.0"
 

gradle/wrapper/gradle-wrapper.properties

@@ -1,6 +1,6 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-8.3-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.6-all.zip
 networkTimeout=10000
 validateDistributionUrl=true
 zipStoreBase=GRADLE_USER_HOME

src/main/java/net/fabricmc/loom/LoomGradleExtension.java

@@ -25,6 +25,7 @@
 package net.fabricmc.loom;
 
 import java.nio.file.Path;
+import java.util.Collection;
 import java.util.List;
 
 import org.gradle.api.Project;
@@ -38,12 +39,14 @@ import net.fabricmc.loom.api.mappings.layered.MappingsNamespace;
 import net.fabricmc.loom.configuration.InstallerData;
 import net.fabricmc.loom.configuration.LoomDependencyManager;
 import net.fabricmc.loom.configuration.accesswidener.AccessWidenerFile;
+import net.fabricmc.loom.configuration.providers.mappings.LayeredMappingsFactory;
 import net.fabricmc.loom.configuration.providers.mappings.MappingConfiguration;
 import net.fabricmc.loom.configuration.providers.minecraft.MinecraftProvider;
 import net.fabricmc.loom.configuration.providers.minecraft.library.LibraryProcessorManager;
 import net.fabricmc.loom.configuration.providers.minecraft.mapped.IntermediaryMinecraftProvider;
 import net.fabricmc.loom.configuration.providers.minecraft.mapped.NamedMinecraftProvider;
 import net.fabricmc.loom.extension.LoomFiles;
+import net.fabricmc.loom.extension.LoomProblemReporter;
 import net.fabricmc.loom.extension.MixinExtension;
 import net.fabricmc.loom.extension.RemapperExtensionHolder;
 import net.fabricmc.loom.util.download.DownloadBuilder;
@@ -118,4 +121,8 @@ public interface LoomGradleExtension extends LoomGradleExtensionAPI {
 	ListProperty<LibraryProcessorManager.LibraryProcessorFactory> getLibraryProcessors();
 
 	ListProperty<RemapperExtensionHolder> getRemapperExtensions();
+
+	Collection<LayeredMappingsFactory> getLayeredMappingFactories();
+
+	LoomProblemReporter getProblemReporter();
 }

src/main/java/net/fabricmc/loom/configuration/CompileConfiguration.java

@@ -53,6 +53,7 @@ import net.fabricmc.loom.configuration.accesswidener.AccessWidenerJarProcessor;
 import net.fabricmc.loom.configuration.ifaceinject.InterfaceInjectionProcessor;
 import net.fabricmc.loom.configuration.processors.MinecraftJarProcessorManager;
 import net.fabricmc.loom.configuration.processors.ModJavadocProcessor;
+import net.fabricmc.loom.configuration.providers.mappings.LayeredMappingsFactory;
 import net.fabricmc.loom.configuration.providers.mappings.MappingConfiguration;
 import net.fabricmc.loom.configuration.providers.minecraft.MinecraftJarConfiguration;
 import net.fabricmc.loom.configuration.providers.minecraft.MinecraftProvider;
@@ -148,6 +149,9 @@ public abstract class CompileConfiguration implements Runnable {
 		extension.setMinecraftProvider(minecraftProvider);
 		minecraftProvider.provide();
 
+		// Created any layered mapping files.
+		LayeredMappingsFactory.afterEvaluate(configContext);
+
 		final DependencyInfo mappingsDep = DependencyInfo.create(getProject(), Configurations.MAPPINGS);
 		final MappingConfiguration mappingConfiguration = MappingConfiguration.create(getProject(), configContext.serviceManager(), mappingsDep, minecraftProvider);
 		extension.setMappingConfiguration(mappingConfiguration);

src/main/java/net/fabricmc/loom/configuration/DependencyInfo.java

@@ -32,8 +32,11 @@ import org.gradle.api.Project;
 import org.gradle.api.artifacts.Configuration;
 import org.gradle.api.artifacts.Dependency;
 import org.gradle.api.artifacts.DependencySet;
+import org.gradle.api.artifacts.FileCollectionDependency;
 import org.gradle.api.artifacts.ResolvedDependency;
-import org.gradle.api.artifacts.SelfResolvingDependency;
+
+import net.fabricmc.loom.LoomGradleExtension;
+import net.fabricmc.loom.util.gradle.SelfResolvingDependencyUtils;
 
 public class DependencyInfo {
 	final Project project;
@@ -61,8 +64,11 @@ public class DependencyInfo {
 	}
 
 	public static DependencyInfo create(Project project, Dependency dependency, Configuration sourceConfiguration) {
-		if (dependency instanceof SelfResolvingDependency selfResolvingDependency) {
-			return new FileDependencyInfo(project, selfResolvingDependency, sourceConfiguration);
+		if (SelfResolvingDependencyUtils.isExplicitSRD(dependency)) {
+			LoomGradleExtension.get(project).getProblemReporter().reportSelfResolvingDependencyUsage();
+			return FileDependencyInfo.createForDeprecatedSRD(project, dependency, sourceConfiguration);
+		} else if (dependency instanceof FileCollectionDependency fileCollectionDependency) {
+			return new FileDependencyInfo(project, fileCollectionDependency, sourceConfiguration);
 		} else {
 			return new DependencyInfo(project, dependency, sourceConfiguration);
 		}
@@ -99,10 +105,6 @@ public class DependencyInfo {
 	}
 
 	public Set<File> resolve() {
-		if (dependency instanceof SelfResolvingDependency selfResolvingDependency) {
-			return selfResolvingDependency.resolve();
-		}
-
 		return sourceConfiguration.files(dependency);
 	}
 

src/main/java/net/fabricmc/loom/configuration/FileDependencyInfo.java

@@ -42,19 +42,24 @@ import org.apache.commons.io.FilenameUtils;
 import org.gradle.api.InvalidUserDataException;
 import org.gradle.api.Project;
 import org.gradle.api.artifacts.Configuration;
-import org.gradle.api.artifacts.SelfResolvingDependency;
+import org.gradle.api.artifacts.Dependency;
+import org.gradle.api.artifacts.FileCollectionDependency;
 
 import net.fabricmc.loom.util.ZipUtils;
+import net.fabricmc.loom.util.gradle.SelfResolvingDependencyUtils;
 
 public class FileDependencyInfo extends DependencyInfo {
 	protected final Map<String, File> classifierToFile = new HashMap<>();
 	protected final Set<File> resolvedFiles;
 	protected final String group, name, version;
 
-	FileDependencyInfo(Project project, SelfResolvingDependency dependency, Configuration configuration) {
+	FileDependencyInfo(Project project, FileCollectionDependency dependency, Configuration configuration) {
+		this(project, dependency, configuration, dependency.getFiles().getFiles());
+	}
+
+	private FileDependencyInfo(Project project, Dependency dependency, Configuration configuration, Set<File> files) {
 		super(project, dependency, configuration);
 
-		Set<File> files = dependency.resolve();
 		this.resolvedFiles = files;
 		switch (files.size()) {
 		case 0 -> //Don't think Gradle would ever let you do this
@@ -126,6 +131,15 @@ public class FileDependencyInfo extends DependencyInfo {
 		}
 	}
 
+	@Deprecated // Remove in Gradle 9
+	public static FileDependencyInfo createForDeprecatedSRD(Project project, Dependency dependency, Configuration configuration) {
+		if (!SelfResolvingDependencyUtils.isExplicitSRD(dependency)) {
+			throw new IllegalArgumentException("Dependency is a FileCollectionDependency");
+		}
+
+		return new FileDependencyInfo(project, dependency, configuration, SelfResolvingDependencyUtils.resolve(dependency));
+	}
+
 	@Override
 	public String getResolvedVersion() {
 		return version;

src/main/java/net/fabricmc/loom/configuration/mods/ArtifactRef.java

@@ -80,7 +80,7 @@ public interface ArtifactRef {
 		public void applyToConfiguration(Project project, Configuration configuration) {
 			final DependencyHandler dependencies = project.getDependencies();
 
-			Dependency dep = dependencies.module(artifact.getModuleVersion() + (artifact.getClassifier() == null ? "" : ':' + artifact.getClassifier())); // the owning module of the artifact
+			Dependency dep = dependencies.create(artifact.getModuleVersion() + (artifact.getClassifier() == null ? "" : ':' + artifact.getClassifier())); // the owning module of the artifact
 
 			if (dep instanceof ModuleDependency moduleDependency) {
 				moduleDependency.setTransitive(false);

src/main/java/net/fabricmc/loom/configuration/providers/mappings/LayeredMappingSpecBuilderImpl.java

@@ -85,4 +85,10 @@ public class LayeredMappingSpecBuilderImpl implements LayeredMappingSpecBuilder
 
 		return new LayeredMappingSpec(Collections.unmodifiableList(builtLayers));
 	}
+
+	public static LayeredMappingSpec buildOfficialMojangMappings() {
+		var builder = new LayeredMappingSpecBuilderImpl();
+		builder.officialMojangMappings();
+		return builder.build();
+	}
 }

src/main/java/net/fabricmc/loom/configuration/providers/mappings/LayeredMappingsFactory.java

@@ -24,9 +24,9 @@
 
 package net.fabricmc.loom.configuration.providers.mappings;
 
-import java.io.File;
 import java.io.IOException;
 import java.io.StringWriter;
+import java.io.UncheckedIOException;
 import java.io.Writer;
 import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
@@ -34,20 +34,18 @@ import java.nio.file.Path;
 import java.util.Collections;
 import java.util.List;
 import java.util.Map;
-import java.util.Objects;
-import java.util.Set;
 
 import org.gradle.api.Project;
 import org.gradle.api.artifacts.Dependency;
-import org.gradle.api.artifacts.FileCollectionDependency;
-import org.gradle.api.artifacts.SelfResolvingDependency;
-import org.gradle.api.file.FileCollection;
-import org.gradle.api.tasks.TaskDependency;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 import net.fabricmc.loom.LoomGradlePlugin;
 import net.fabricmc.loom.api.mappings.layered.MappingContext;
 import net.fabricmc.loom.api.mappings.layered.MappingLayer;
 import net.fabricmc.loom.api.mappings.layered.MappingsNamespace;
+import net.fabricmc.loom.configuration.ConfigContext;
+import net.fabricmc.loom.configuration.mods.dependency.LocalMavenHelper;
 import net.fabricmc.loom.configuration.providers.mappings.extras.unpick.UnpickLayer;
 import net.fabricmc.loom.configuration.providers.mappings.utils.AddConstructorMappingVisitor;
 import net.fabricmc.loom.util.ZipUtils;
@@ -56,43 +54,61 @@ import net.fabricmc.mappingio.adapter.MappingSourceNsSwitch;
 import net.fabricmc.mappingio.format.tiny.Tiny2FileWriter;
 import net.fabricmc.mappingio.tree.MemoryMappingTree;
 
-public class LayeredMappingsDependency implements SelfResolvingDependency, FileCollectionDependency {
+public record LayeredMappingsFactory(LayeredMappingSpec spec) {
 	private static final String GROUP = "loom";
 	private static final String MODULE = "mappings";
+	private static final Logger LOGGER = LoggerFactory.getLogger(LayeredMappingsFactory.class);
 
-	private final Project project;
-	private final MappingContext mappingContext;
-	private final LayeredMappingSpec layeredMappingSpec;
-	private final String version;
-
-	public LayeredMappingsDependency(Project project, MappingContext mappingContext, LayeredMappingSpec layeredMappingSpec, String version) {
-		this.project = project;
-		this.mappingContext = mappingContext;
-		this.layeredMappingSpec = layeredMappingSpec;
-		this.version = version;
-	}
-
-	@Override
-	public Set<File> resolve() {
-		Path mappingsDir = mappingContext.minecraftProvider().dir("layered").toPath();
-		Path mappingsFile = mappingsDir.resolve(String.format("%s.%s-%s.tiny", GROUP, MODULE, getVersion()));
-
-		if (!Files.exists(mappingsFile) || mappingContext.refreshDeps()) {
+	/*
+	As we no longer have SelfResolvingDependency we now always create the mappings file after evaluation.
+	This works in a similar way to how remapped mods are handled.
+	 */
+	public static void afterEvaluate(ConfigContext configContext) {
+		for (LayeredMappingsFactory layeredMappingFactory : configContext.extension().getLayeredMappingFactories()) {
 			try {
-				var processor = new LayeredMappingsProcessor(layeredMappingSpec);
-				List<MappingLayer> layers = processor.resolveLayers(mappingContext);
-
-				Files.deleteIfExists(mappingsFile);
-
-				writeMapping(processor, layers, mappingsFile);
-				writeSignatureFixes(processor, layers, mappingsFile);
-				writeUnpickData(processor, layers, mappingsFile);
+				layeredMappingFactory.evaluate(configContext);
 			} catch (IOException e) {
-				throw new RuntimeException("Failed to resolve layered mappings", e);
+				throw new UncheckedIOException("Failed to setup layered mappings: %s".formatted(layeredMappingFactory.mavenNotation()), e);
 			}
 		}
+	}
 
-		return Collections.singleton(mappingsFile.toFile());
+	private void evaluate(ConfigContext configContext) throws IOException {
+		LOGGER.info("Evaluating layer mapping: {}", mavenNotation());
+
+		final Path mavenRepoDir = configContext.extension().getFiles().getGlobalMinecraftRepo().toPath();
+		final LocalMavenHelper maven = new LocalMavenHelper(GROUP, MODULE, spec().getVersion(), null, mavenRepoDir);
+		final Path jar = resolve(configContext.project());
+		maven.copyToMaven(jar, null);
+	}
+
+	public Path resolve(Project project) throws IOException {
+		final MappingContext mappingContext = new GradleMappingContext(project, spec.getVersion().replace("+", "_").replace(".", "_"));
+		final Path mappingsDir = mappingContext.minecraftProvider().dir("layered").toPath();
+		final Path mappingsZip = mappingsDir.resolve(String.format("%s.%s-%s.jar", GROUP, MODULE, spec.getVersion()));
+
+		if (Files.exists(mappingsZip) && !mappingContext.refreshDeps()) {
+			return mappingsZip;
+		}
+
+		var processor = new LayeredMappingsProcessor(spec);
+		List<MappingLayer> layers = processor.resolveLayers(mappingContext);
+
+		Files.deleteIfExists(mappingsZip);
+
+		writeMapping(processor, layers, mappingsZip);
+		writeSignatureFixes(processor, layers, mappingsZip);
+		writeUnpickData(processor, layers, mappingsZip);
+
+		return mappingsZip;
+	}
+
+	public Dependency createDependency(Project project) {
+		return project.getDependencies().create(mavenNotation());
+	}
+
+	public String mavenNotation() {
+		return String.format("%s:%s:%s", GROUP, MODULE, spec.getVersion());
 	}
 
 	private void writeMapping(LayeredMappingsProcessor processor, List<MappingLayer> layers, Path mappingsFile) throws IOException {
@@ -133,57 +149,4 @@ public class LayeredMappingsDependency implements SelfResolvingDependency, FileC
 		ZipUtils.add(mappingsFile, "extras/definitions.unpick", unpickData.definitions());
 		ZipUtils.add(mappingsFile, "extras/unpick.json", unpickData.metadata().asJson());
 	}
-
-	@Override
-	public Set<File> resolve(boolean transitive) {
-		return resolve();
-	}
-
-	@Override
-	public TaskDependency getBuildDependencies() {
-		return task -> Collections.emptySet();
-	}
-
-	@Override
-	public String getGroup() {
-		return GROUP;
-	}
-
-	@Override
-	public String getName() {
-		return MODULE;
-	}
-
-	@Override
-	public String getVersion() {
-		return version;
-	}
-
-	@Override
-	public boolean contentEquals(Dependency dependency) {
-		if (dependency instanceof LayeredMappingsDependency layeredMappingsDependency) {
-			return Objects.equals(layeredMappingsDependency.getVersion(), this.getVersion());
-		}
-
-		return false;
-	}
-
-	@Override
-	public Dependency copy() {
-		return new LayeredMappingsDependency(project, mappingContext, layeredMappingSpec, version);
-	}
-
-	@Override
-	public String getReason() {
-		return null;
-	}
-
-	@Override
-	public void because(String s) {
-	}
-
-	@Override
-	public FileCollection getFiles() {
-		return project.files(resolve());
-	}
 }

src/main/java/net/fabricmc/loom/configuration/providers/mappings/utils/DependencyFileSpec.java

@@ -30,21 +30,37 @@ import java.util.Objects;
 import java.util.Set;
 
 import org.gradle.api.artifacts.Dependency;
-import org.gradle.api.artifacts.SelfResolvingDependency;
+import org.gradle.api.artifacts.FileCollectionDependency;
 
 import net.fabricmc.loom.api.mappings.layered.MappingContext;
 import net.fabricmc.loom.api.mappings.layered.spec.FileSpec;
+import net.fabricmc.loom.configuration.providers.mappings.GradleMappingContext;
+import net.fabricmc.loom.util.gradle.SelfResolvingDependencyUtils;
 
 public record DependencyFileSpec(Dependency dependency) implements FileSpec {
 	@Override
 	public Path get(MappingContext context) {
-		if (dependency instanceof SelfResolvingDependency selfResolvingDependency) {
-			Set<File> files = selfResolvingDependency.resolve();
+		if (SelfResolvingDependencyUtils.isExplicitSRD(dependency)) {
+			if (context instanceof GradleMappingContext gradleMappingContext) {
+				gradleMappingContext.getExtension().getProblemReporter().reportSelfResolvingDependencyUsage();
+			}
 
-			if (files.size() == 0) {
-				throw new RuntimeException("SelfResolvingDependency (%s) resolved no files".formatted(selfResolvingDependency.toString()));
+			Set<File> files = SelfResolvingDependencyUtils.resolve(dependency);
+
+			if (files.isEmpty()) {
+				throw new RuntimeException("SelfResolvingDependency (%s) resolved no files".formatted(dependency.toString()));
 			} else if (files.size() > 1) {
-				throw new RuntimeException("SelfResolvingDependency (%s) resolved too many files (%d) only 1 is expected".formatted(selfResolvingDependency.toString(), files.size()));
+				throw new RuntimeException("SelfResolvingDependency (%s) resolved too many files (%d) only 1 is expected".formatted(dependency.toString(), files.size()));
+			}
+
+			return files.iterator().next().toPath();
+		} else if (dependency instanceof FileCollectionDependency fileCollectionDependency) {
+			Set<File> files = fileCollectionDependency.getFiles().getFiles();
+
+			if (files.isEmpty()) {
+				throw new RuntimeException("FileCollectionDependency (%s) resolved no files".formatted(fileCollectionDependency.toString()));
+			} else if (files.size() > 1) {
+				throw new RuntimeException("FileCollectionDependency (%s) resolved too many files (%d) only 1 is expected".formatted(fileCollectionDependency.toString(), files.size()));
 			}
 
 			return files.iterator().next().toPath();

src/main/java/net/fabricmc/loom/extension/LoomGradleExtensionApiImpl.java

@@ -1,7 +1,7 @@
 /*
  * This file is part of fabric-loom, licensed under the MIT License (MIT).
  *
- * Copyright (c) 2021-2022 FabricMC
+ * Copyright (c) 2021-2024 FabricMC
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -26,6 +26,8 @@ package net.fabricmc.loom.extension;
 
 import java.io.File;
 import java.io.IOException;
+import java.util.HashMap;
+import java.util.Map;
 import java.util.Set;
 
 import org.gradle.api.Action;
@@ -59,10 +61,9 @@ import net.fabricmc.loom.api.remapping.RemapperParameters;
 import net.fabricmc.loom.configuration.RemapConfigurations;
 import net.fabricmc.loom.configuration.ide.RunConfigSettings;
 import net.fabricmc.loom.configuration.processors.JarProcessor;
-import net.fabricmc.loom.configuration.providers.mappings.GradleMappingContext;
 import net.fabricmc.loom.configuration.providers.mappings.LayeredMappingSpec;
 import net.fabricmc.loom.configuration.providers.mappings.LayeredMappingSpecBuilderImpl;
-import net.fabricmc.loom.configuration.providers.mappings.LayeredMappingsDependency;
+import net.fabricmc.loom.configuration.providers.mappings.LayeredMappingsFactory;
 import net.fabricmc.loom.configuration.providers.minecraft.MinecraftJarConfiguration;
 import net.fabricmc.loom.configuration.providers.minecraft.MinecraftSourceSets;
 import net.fabricmc.loom.task.GenerateSourcesTask;
@@ -102,6 +103,9 @@ public abstract class LoomGradleExtensionApiImpl implements LoomGradleExtensionA
 	// A common mistake with layered mappings is to call the wrong `officialMojangMappings` method, use this to keep track of when we are building a layered mapping spec.
 	protected final ThreadLocal<Boolean> layeredSpecBuilderScope = ThreadLocal.withInitial(() -> false);
 
+	protected boolean hasEvaluatedLayeredMappings = false;
+	protected final Map<LayeredMappingSpec, LayeredMappingsFactory> layeredMappingsDependencyMap = new HashMap<>();
+
 	protected LoomGradleExtensionApiImpl(Project project, LoomFiles directories) {
 		this.jarProcessors = project.getObjects().listProperty(JarProcessor.class)
 				.empty();
@@ -210,14 +214,19 @@ public abstract class LoomGradleExtensionApiImpl implements LoomGradleExtensionA
 
 	@Override
 	public Dependency layered(Action<LayeredMappingSpecBuilder> action) {
+		if (hasEvaluatedLayeredMappings) {
+			throw new IllegalStateException("Layered mappings have already been evaluated");
+		}
+
 		LayeredMappingSpecBuilderImpl builder = new LayeredMappingSpecBuilderImpl();
 
 		layeredSpecBuilderScope.set(true);
 		action.execute(builder);
 		layeredSpecBuilderScope.set(false);
 
-		LayeredMappingSpec builtSpec = builder.build();
-		return new LayeredMappingsDependency(getProject(), new GradleMappingContext(getProject(), builtSpec.getVersion().replace("+", "_").replace(".", "_")), builtSpec, builtSpec.getVersion());
+		final LayeredMappingSpec builtSpec = builder.build();
+		final LayeredMappingsFactory layeredMappingsFactory = layeredMappingsDependencyMap.computeIfAbsent(builtSpec, LayeredMappingsFactory::new);
+		return layeredMappingsFactory.createDependency(getProject());
 	}
 
 	@Override

src/main/java/net/fabricmc/loom/extension/LoomGradleExtensionImpl.java

@@ -1,7 +1,7 @@
 /*
  * This file is part of fabric-loom, licensed under the MIT License (MIT).
  *
- * Copyright (c) 2021 FabricMC
+ * Copyright (c) 2021-2024 FabricMC
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -27,6 +27,8 @@ package net.fabricmc.loom.extension;
 import java.net.URISyntaxException;
 import java.nio.file.Path;
 import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
 import java.util.List;
 import java.util.Objects;
 
@@ -43,6 +45,7 @@ import net.fabricmc.loom.configuration.InstallerData;
 import net.fabricmc.loom.configuration.LoomDependencyManager;
 import net.fabricmc.loom.configuration.accesswidener.AccessWidenerFile;
 import net.fabricmc.loom.configuration.providers.mappings.IntermediaryMappingsProvider;
+import net.fabricmc.loom.configuration.providers.mappings.LayeredMappingsFactory;
 import net.fabricmc.loom.configuration.providers.mappings.MappingConfiguration;
 import net.fabricmc.loom.configuration.providers.minecraft.MinecraftProvider;
 import net.fabricmc.loom.configuration.providers.minecraft.library.LibraryProcessorManager;
@@ -70,6 +73,7 @@ public class LoomGradleExtensionImpl extends LoomGradleExtensionApiImpl implemen
 	private boolean refreshDeps;
 	private Provider<Boolean> multiProjectOptimisation;
 	private final ListProperty<LibraryProcessorManager.LibraryProcessorFactory> libraryProcessorFactories;
+	private final LoomProblemReporter problemReporter;
 
 	public LoomGradleExtensionImpl(Project project, LoomFiles files) {
 		super(project, files);
@@ -97,6 +101,8 @@ public class LoomGradleExtensionImpl extends LoomGradleExtensionApiImpl implemen
 		if (refreshDeps) {
 			project.getLogger().lifecycle("Refresh dependencies is in use, loom will be significantly slower.");
 		}
+
+		problemReporter = project.getObjects().newInstance(LoomProblemReporter.class);
 	}
 
 	@Override
@@ -252,6 +258,12 @@ public class LoomGradleExtensionImpl extends LoomGradleExtensionApiImpl implemen
 		return remapperExtensions;
 	}
 
+	@Override
+	public Collection<LayeredMappingsFactory> getLayeredMappingFactories() {
+		hasEvaluatedLayeredMappings = true;
+		return Collections.unmodifiableCollection(layeredMappingsDependencyMap.values());
+	}
+
 	@Override
 	protected <T extends IntermediateMappingsProvider> void configureIntermediateMappingsProviderInternal(T provider) {
 		provider.getMinecraftVersion().set(getProject().provider(() -> getMinecraftProvider().minecraftVersion()));
@@ -260,4 +272,9 @@ public class LoomGradleExtensionImpl extends LoomGradleExtensionApiImpl implemen
 		provider.getDownloader().set(this::download);
 		provider.getDownloader().disallowChanges();
 	}
+
+	@Override
+	public LoomProblemReporter getProblemReporter() {
+		return problemReporter;
+	}
 }

src/main/java/net/fabricmc/loom/extension/LoomProblemReporter.java

@@ -0,0 +1,51 @@
+/*
+ * This file is part of fabric-loom, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) 2024 FabricMC
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package net.fabricmc.loom.extension;
+
+import javax.inject.Inject;
+
+import org.gradle.api.problems.ProblemReporter;
+import org.gradle.api.problems.Problems;
+import org.gradle.api.problems.Severity;
+
+public abstract class LoomProblemReporter {
+	private final ProblemReporter problemReporter;
+
+	@Inject
+	public LoomProblemReporter(Problems problems) {
+		this.problemReporter = problems.forNamespace("net.fabricmc.loom");
+	}
+
+	public void reportSelfResolvingDependencyUsage() {
+		problemReporter.reporting(spec -> spec
+				.label("SelfResolvingDependency is deprecated")
+				.details("SelfResolvingDependency has been deprecated for removal in Gradle 9")
+				.solution("Please replace usages of SelfResolvingDependency")
+				.documentedAt("https://github.com/gradle/gradle/pull/27420")
+				.severity(Severity.WARNING)
+				.stackLocation()
+		);
+	}
+}

src/main/java/net/fabricmc/loom/task/MigrateMappingsTask.java

@@ -26,8 +26,10 @@ package net.fabricmc.loom.task;
 
 import java.io.File;
 import java.io.IOException;
+import java.io.UncheckedIOException;
 import java.nio.file.Files;
 import java.nio.file.Path;
+import java.util.Collections;
 import java.util.Set;
 
 import com.google.common.collect.ImmutableMap;
@@ -50,8 +52,8 @@ import org.gradle.work.DisableCachingByDefault;
 
 import net.fabricmc.loom.LoomGradleExtension;
 import net.fabricmc.loom.api.mappings.layered.MappingsNamespace;
-import net.fabricmc.loom.api.mappings.layered.spec.LayeredMappingSpecBuilder;
-import net.fabricmc.loom.configuration.providers.mappings.LayeredMappingsDependency;
+import net.fabricmc.loom.configuration.providers.mappings.LayeredMappingSpecBuilderImpl;
+import net.fabricmc.loom.configuration.providers.mappings.LayeredMappingsFactory;
 import net.fabricmc.loom.configuration.providers.mappings.MappingConfiguration;
 import net.fabricmc.loom.util.FileSystemUtil;
 import net.fabricmc.loom.util.SourceRemapper;
@@ -133,8 +135,8 @@ public abstract class MigrateMappingsTask extends AbstractLoomTask {
 					throw new UnsupportedOperationException("Migrating Mojang mappings is currently only supported for the specified minecraft version");
 				}
 
-				LayeredMappingsDependency dep = (LayeredMappingsDependency) getExtension().layered(LayeredMappingSpecBuilder::officialMojangMappings);
-				files = dep.resolve();
+				LayeredMappingsFactory dep = new LayeredMappingsFactory(LayeredMappingSpecBuilderImpl.buildOfficialMojangMappings());
+				files = Collections.singleton(dep.resolve(getProject()).toFile());
 			} else {
 				Dependency dependency = project.getDependencies().create(mappings);
 				files = project.getConfigurations().detachedConfiguration(dependency).resolve();
@@ -143,11 +145,13 @@ public abstract class MigrateMappingsTask extends AbstractLoomTask {
 			project.getLogger().info("Could not locate mappings, presuming V2 Yarn");
 
 			try {
-				files = project.getConfigurations().detachedConfiguration(project.getDependencies().module(ImmutableMap.of("group", "net.fabricmc", "name", "yarn", "version", mappings, "classifier", "v2"))).resolve();
+				files = project.getConfigurations().detachedConfiguration(project.getDependencies().create(ImmutableMap.of("group", "net.fabricmc", "name", "yarn", "version", mappings, "classifier", "v2"))).resolve();
 			} catch (GradleException ignored2) {
 				project.getLogger().info("Could not locate mappings, presuming V1 Yarn");
-				files = project.getConfigurations().detachedConfiguration(project.getDependencies().module(ImmutableMap.of("group", "net.fabricmc", "name", "yarn", "version", mappings))).resolve();
+				files = project.getConfigurations().detachedConfiguration(project.getDependencies().create(ImmutableMap.of("group", "net.fabricmc", "name", "yarn", "version", mappings))).resolve();
 			}
+		} catch (IOException e) {
+			throw new UncheckedIOException("Failed to resolve mappings", e);
 		}
 
 		if (files.isEmpty()) {

src/main/java/net/fabricmc/loom/util/gradle/SelfResolvingDependencyUtils.java

@@ -0,0 +1,114 @@
+/*
+ * This file is part of fabric-loom, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) 2024 FabricMC
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package net.fabricmc.loom.util.gradle;
+
+import java.io.File;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+import java.util.Set;
+
+import javax.annotation.Nullable;
+
+import org.gradle.api.artifacts.Dependency;
+import org.gradle.api.artifacts.FileCollectionDependency;
+import org.gradle.api.artifacts.ProjectDependency;
+
+// SelfResolvingDependency is deprecated for removal, use reflection to ensure backwards compat.
+@Deprecated
+public class SelfResolvingDependencyUtils {
+	// Set this system prop to disable SRD support before Gradle does.
+	public static final boolean DISABLE_SRD_SUPPORT = System.getProperty("fabric.loom.disable.srd") != null;
+
+	private static final String SELF_RESOLVING_DEPENDENCY_CLASS_NAME = "org.gradle.api.artifacts.SelfResolvingDependency";
+	@Nullable
+	private static final Class<?> SELF_RESOLVING_DEPENDENCY_CLASS = getSelfResolvingDependencyOrNull();
+	@Nullable
+	private static final Method RESOLVE_METHOD = getResolveMethod(SELF_RESOLVING_DEPENDENCY_CLASS);
+
+	/**
+	 * @return true when dependency is a SelfResolvingDependency but NOT a FileCollectionDependency.
+	 */
+	public static boolean isExplicitSRD(Dependency dependency) {
+		// FileCollectionDependency is usually the replacement for SelfResolvingDependency
+		if (dependency instanceof FileCollectionDependency) {
+			return false;
+		} else if (dependency instanceof ProjectDependency) {
+			return false;
+		}
+
+		return isSRD(dependency);
+	}
+
+	private static boolean isSRD(Dependency dependency) {
+		if (SELF_RESOLVING_DEPENDENCY_CLASS == null) {
+			return false;
+		}
+
+		return dependency.getClass().isAssignableFrom(SELF_RESOLVING_DEPENDENCY_CLASS);
+	}
+
+	public static Set<File> resolve(Dependency dependency) {
+		if (!isSRD(dependency)) {
+			throw new IllegalStateException("dependency is not a SelfResolvingDependency");
+		}
+
+		try {
+			return (Set<File>) RESOLVE_METHOD.invoke(dependency);
+		} catch (IllegalAccessException | InvocationTargetException e) {
+			throw new RuntimeException("Failed to resolve SelfResolvingDependency", e);
+		}
+	}
+
+	@Nullable
+	private static Class<?> getSelfResolvingDependencyOrNull() {
+		if (DISABLE_SRD_SUPPORT) {
+			// Lets pretend SRD doesnt exist.
+			return null;
+		}
+
+		try {
+			return Class.forName(SELF_RESOLVING_DEPENDENCY_CLASS_NAME);
+		} catch (ClassNotFoundException e) {
+			// Gradle 9+
+			return null;
+		}
+	}
+
+	@Nullable
+	private static Method getResolveMethod(Class<?> clazz) {
+		if (clazz == null) {
+			// Gradle 9+
+			return null;
+		}
+
+		try {
+			var method = clazz.getDeclaredMethod("resolve");
+			method.setAccessible(true);
+			return method;
+		} catch (NoSuchMethodException e) {
+			throw new IllegalStateException("Failed to get SelfResolvingDependency.resolve() method", e);
+		}
+	}
+}

src/test/groovy/net/fabricmc/loom/test/integration/KotlinTest.groovy

@@ -40,7 +40,7 @@ class KotlinTest extends Specification implements GradleProjectTestTrait {
 		def gradle = gradleProject(project: "kotlin", version: version)
 		def server = ServerRunner.create(gradle.projectDir, "1.16.5")
 				.withMod(gradle.getOutputFile("fabric-example-mod-0.0.1.jar"))
-				.downloadMod(ServerRunner.FABRIC_LANG_KOTLIN, "fabric-language-kotlin-1.8.7+kotlin.1.7.22.jar")
+				.downloadMod(ServerRunner.FABRIC_LANG_KOTLIN, "fabric-language-kotlin-1.10.17+kotlin.1.9.22.jar")
 
 		when:
 		def result = gradle.run(tasks: [

src/test/resources/projects/kotlin/build.gradle.kts

@@ -1,8 +1,10 @@
 import java.util.Properties
+import org.jetbrains.kotlin.gradle.dsl.KotlinCompile
+import org.jetbrains.kotlin.gradle.dsl.KotlinJvmOptions
 
 plugins {
-	kotlin("jvm") version "1.7.22"
-	kotlin("plugin.serialization") version "1.7.22"
+	kotlin("jvm") version "1.9.22"
+	kotlin("plugin.serialization") version "1.9.22"
 	id("fabric-loom")
 	`maven-publish`
 }
@@ -12,6 +14,17 @@ java {
 	targetCompatibility = JavaVersion.VERSION_1_8
 }
 
+tasks {
+	withType<JavaCompile> {
+		options.release.set(8)
+	}
+	withType<KotlinCompile<KotlinJvmOptions>> {
+		kotlinOptions {
+			jvmTarget = "1.8"
+		}
+	}
+}
+
 group = "com.example"
 version = "0.0.1"
 
@@ -19,7 +32,7 @@ dependencies {
 	minecraft(group = "com.mojang", name = "minecraft", version = "1.16.5")
 	mappings(group = "net.fabricmc", name = "yarn", version = "1.16.5+build.5", classifier = "v2")
 	modImplementation("net.fabricmc:fabric-loader:0.12.12")
-	modImplementation(group = "net.fabricmc", name = "fabric-language-kotlin", version = "1.8.7+kotlin.1.7.22")
+	modImplementation(group = "net.fabricmc", name = "fabric-language-kotlin", version = "1.10.17+kotlin.1.9.22")
 }
 
 publishing {