Configure compile task mixin options lazily

src/main/java/net/fabricmc/loom/build/mixin/AnnotationProcessorInvoker.java

@@ -1,7 +1,7 @@
 /*
  * This file is part of fabric-loom, licensed under the MIT License (MIT).
  *
- * Copyright (c) 2020-2022 FabricMC
+ * Copyright (c) 2020-2025 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
@@ -40,6 +40,7 @@
 import org.gradle.api.artifacts.Configuration;
 import org.gradle.api.artifacts.ConfigurationContainer;
 import org.gradle.api.tasks.SourceSet;
+import org.gradle.api.tasks.TaskProvider;
 
 import net.fabricmc.loom.LoomGradleExtension;
 import net.fabricmc.loom.configuration.ide.idea.IdeaUtils;
@@ -64,13 +65,13 @@ public abstract class AnnotationProcessorInvoker<T extends Task> {
 	protected final Project project;
 	private final LoomGradleExtension loomExtension;
 	protected final MixinExtension mixinExtension;
-	protected final Map<SourceSet, T> invokerTasks;
+	protected final Map<SourceSet, TaskProvider<T>> invokerTasks;
 	private final String name;
 	private final Collection<Configuration> apConfigurations;
 
 	protected AnnotationProcessorInvoker(Project project,
 											Collection<Configuration> apConfigurations,
-											Map<SourceSet, T> invokerTasks, String name) {
+											Map<SourceSet, TaskProvider<T>> invokerTasks, String name) {
 		this.project = project;
 		this.loomExtension = LoomGradleExtension.get(project);
 		this.mixinExtension = loomExtension.getMixin();
@@ -146,8 +147,8 @@ public void configureMixin() {
 			}
 		}
 
-		for (Map.Entry<SourceSet, T> entry : invokerTasks.entrySet()) {
-			passMixinArguments(entry.getValue(), entry.getKey());
+		for (Map.Entry<SourceSet, TaskProvider<T>> entry : invokerTasks.entrySet()) {
+			entry.getValue().configure(t -> passMixinArguments(t, entry.getKey()));
 		}
 	}
 

src/main/java/net/fabricmc/loom/build/mixin/GroovyApInvoker.java

@@ -1,7 +1,7 @@
 /*
  * This file is part of fabric-loom, licensed under the MIT License (MIT).
  *
- * Copyright (c) 2022 FabricMC
+ * Copyright (c) 2022-2025 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
@@ -26,12 +26,12 @@
 
 import java.io.File;
 import java.util.Map;
-import java.util.Objects;
 import java.util.stream.Collectors;
 
 import com.google.common.collect.ImmutableList;
 import org.gradle.api.Project;
 import org.gradle.api.tasks.SourceSet;
+import org.gradle.api.tasks.TaskProvider;
 import org.gradle.api.tasks.compile.GroovyCompile;
 
 import net.fabricmc.loom.LoomGradleExtension;
@@ -46,11 +46,10 @@ public GroovyApInvoker(Project project) {
 				AnnotationProcessorInvoker.GROOVY);
 	}
 
-	private static Map<SourceSet, GroovyCompile> getInvokerTasks(Project project) {
+	private static Map<SourceSet, TaskProvider<GroovyCompile>> getInvokerTasks(Project project) {
 		MixinExtension mixin = LoomGradleExtension.get(project).getMixin();
-		return mixin.getInvokerTasksStream(AnnotationProcessorInvoker.GROOVY).collect(
-				Collectors.toMap(Map.Entry::getKey,
-						entry -> Objects.requireNonNull((GroovyCompile) entry.getValue())));
+		return mixin.getInvokerTasksStream(AnnotationProcessorInvoker.GROOVY, GroovyCompile.class).collect(
+				Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue));
 	}
 
 	@Override

src/main/java/net/fabricmc/loom/build/mixin/JavaApInvoker.java

@@ -1,7 +1,7 @@
 /*
  * This file is part of fabric-loom, licensed under the MIT License (MIT).
  *
- * Copyright (c) 2016-2022 FabricMC
+ * Copyright (c) 2016-2025 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
@@ -26,11 +26,11 @@
 
 import java.io.File;
 import java.util.Map;
-import java.util.Objects;
 import java.util.stream.Collectors;
 
 import org.gradle.api.Project;
 import org.gradle.api.tasks.SourceSet;
+import org.gradle.api.tasks.TaskProvider;
 import org.gradle.api.tasks.compile.JavaCompile;
 
 import net.fabricmc.loom.LoomGradleExtension;
@@ -45,10 +45,10 @@ public JavaApInvoker(Project project) {
 				AnnotationProcessorInvoker.JAVA);
 	}
 
-	private static Map<SourceSet, JavaCompile> getInvokerTasks(Project project) {
+	private static Map<SourceSet, TaskProvider<JavaCompile>> getInvokerTasks(Project project) {
 		MixinExtension mixin = LoomGradleExtension.get(project).getMixin();
-		return mixin.getInvokerTasksStream(AnnotationProcessorInvoker.JAVA)
-				.collect(Collectors.toMap(Map.Entry::getKey, entry -> Objects.requireNonNull((JavaCompile) entry.getValue())));
+		return mixin.getInvokerTasksStream(AnnotationProcessorInvoker.JAVA, JavaCompile.class)
+				.collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue));
 	}
 
 	@Override

src/main/java/net/fabricmc/loom/build/mixin/KaptApInvoker.java

@@ -1,7 +1,7 @@
 /*
  * This file is part of fabric-loom, licensed under the MIT License (MIT).
  *
- * Copyright (c) 2020-2022 FabricMC
+ * Copyright (c) 2020-2025 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
@@ -36,6 +36,7 @@
 import kotlin.Unit;
 import org.gradle.api.Project;
 import org.gradle.api.tasks.SourceSet;
+import org.gradle.api.tasks.TaskProvider;
 import org.gradle.api.tasks.compile.JavaCompile;
 import org.jetbrains.kotlin.gradle.plugin.KaptExtension;
 
@@ -66,35 +67,36 @@ public KaptApInvoker(Project project) {
 		kaptExtension.setIncludeCompileClasspath(false);
 	}
 
-	private static Map<SourceSet, JavaCompile> getInvokerTasks(Project project) {
+	private static Map<SourceSet, TaskProvider<JavaCompile>> getInvokerTasks(Project project) {
 		MixinExtension mixin = LoomGradleExtension.get(project).getMixin();
-		return mixin.getInvokerTasksStream(AnnotationProcessorInvoker.JAVA)
-				.collect(Collectors.toMap(Map.Entry::getKey, entry -> Objects.requireNonNull((JavaCompile) entry.getValue())));
+		return mixin.getInvokerTasksStream(AnnotationProcessorInvoker.JAVA, JavaCompile.class)
+				.collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue));
 	}
 
 	@Override
 	public void configureMixin() {
 		super.configureMixin();
 
-		for (Map.Entry<SourceSet, JavaCompile> entry : invokerTasks.entrySet()) {
+		for (Map.Entry<SourceSet, TaskProvider<JavaCompile>> entry : invokerTasks.entrySet()) {
 			// Kapt only allows specifying javac args to all annotation processors at once. So we need to specify some dummy
 			// target location for the refmap and then move it to the correct place for each sourceset
-			JavaCompile task = entry.getValue();
-			SourceSet sourceSet = entry.getKey();
-			task.doLast(t -> {
-				try {
-					String refmapName = Objects.requireNonNull(MixinExtension.getMixinInformationContainer(sourceSet)).refmapNameProvider().get();
-					Path src = Paths.get(getRefmapDestination(task, refmapName));
-					Path dest = Paths.get(task.getDestinationDirectory().get().getAsFile().toString(), refmapName);
-
-					// Possible that no mixin annotations exist
-					if (Files.exists(src)) {
-						project.getLogger().info("Copying refmap from " + src + " to " + dest);
-						Files.move(src, dest);
+			entry.getValue().configure(task -> {
+				SourceSet sourceSet = entry.getKey();
+				task.doLast(t -> {
+					try {
+						String refmapName = Objects.requireNonNull(MixinExtension.getMixinInformationContainer(sourceSet)).refmapNameProvider().get();
+						Path src = Paths.get(getRefmapDestination(task, refmapName));
+						Path dest = Paths.get(task.getDestinationDirectory().get().getAsFile().toString(), refmapName);
+
+						// Possible that no mixin annotations exist
+						if (Files.exists(src)) {
+							project.getLogger().info("Copying refmap from " + src + " to " + dest);
+							Files.move(src, dest);
+						}
+					} catch (IOException e) {
+						project.getLogger().warn("Could not move refmap generated by kapt for task " + task, e);
 					}
-				} catch (IOException e) {
-					project.getLogger().warn("Could not move refmap generated by kapt for task " + task, e);
-				}
+				});
 			});
 		}
 	}

src/main/java/net/fabricmc/loom/build/mixin/ScalaApInvoker.java

@@ -1,7 +1,7 @@
 /*
  * This file is part of fabric-loom, licensed under the MIT License (MIT).
  *
- * Copyright (c) 2016-2020 FabricMC
+ * Copyright (c) 2016-2025 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
@@ -26,12 +26,12 @@
 
 import java.io.File;
 import java.util.Map;
-import java.util.Objects;
 import java.util.stream.Collectors;
 
 import com.google.common.collect.ImmutableList;
 import org.gradle.api.Project;
 import org.gradle.api.tasks.SourceSet;
+import org.gradle.api.tasks.TaskProvider;
 import org.gradle.api.tasks.scala.ScalaCompile;
 
 import net.fabricmc.loom.LoomGradleExtension;
@@ -47,10 +47,10 @@ public ScalaApInvoker(Project project) {
 				AnnotationProcessorInvoker.SCALA);
 	}
 
-	private static Map<SourceSet, ScalaCompile> getInvokerTasks(Project project) {
+	private static Map<SourceSet, TaskProvider<ScalaCompile>> getInvokerTasks(Project project) {
 		MixinExtension mixin = LoomGradleExtension.get(project).getMixin();
-		return mixin.getInvokerTasksStream(AnnotationProcessorInvoker.SCALA)
-				.collect(Collectors.toMap(Map.Entry::getKey, entry -> Objects.requireNonNull((ScalaCompile) entry.getValue())));
+		return mixin.getInvokerTasksStream(AnnotationProcessorInvoker.SCALA, ScalaCompile.class)
+				.collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue));
 	}
 
 	@Override

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

@@ -1,7 +1,7 @@
 /*
  * This file is part of fabric-loom, licensed under the MIT License (MIT).
  *
- * Copyright (c) 2016-2012 FabricMC
+ * Copyright (c) 2016-2025 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
@@ -36,6 +36,7 @@
 import org.gradle.api.provider.Provider;
 import org.gradle.api.tasks.Input;
 import org.gradle.api.tasks.SourceSet;
+import org.gradle.api.tasks.TaskProvider;
 import org.gradle.api.tasks.util.PatternSet;
 import org.jetbrains.annotations.ApiStatus;
 import org.jetbrains.annotations.NotNull;
@@ -81,7 +82,7 @@ static void setMixinInformationContainer(SourceSet sourceSet, MixinInformationCo
 	Stream<Configuration> getApConfigurationsStream(Function<SourceSet, String> getApConfigNameFunc);
 
 	@NotNull
-	Stream<Map.Entry<SourceSet, Task>> getInvokerTasksStream(String compileTaskLanguage);
+	<T extends Task> Stream<Map.Entry<SourceSet, TaskProvider<T>>> getInvokerTasksStream(String compileTaskLanguage, Class<T> taskType);
 
 	@NotNull
 	@Input

src/main/java/net/fabricmc/loom/extension/MixinExtensionImpl.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) 2021-2025 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
@@ -44,6 +44,7 @@
 import org.gradle.api.provider.Provider;
 import org.gradle.api.tasks.Input;
 import org.gradle.api.tasks.SourceSet;
+import org.gradle.api.tasks.TaskProvider;
 import org.gradle.api.tasks.util.PatternSet;
 import org.jetbrains.annotations.NotNull;
 
@@ -57,6 +58,7 @@ public MixinExtensionImpl(Project project) {
 		this.isDefault = true;
 		this.defaultRefmapName = project.getObjects().property(String.class)
 				.convention(project.provider(this::getDefaultMixinRefmapName));
+		this.defaultRefmapName.finalizeValueOnRead();
 	}
 
 	@Override
@@ -100,11 +102,11 @@ public Stream<Configuration> getApConfigurationsStream(Function<SourceSet, Strin
 
 	@Override
 	@NotNull
-	public Stream<Map.Entry<SourceSet, Task>> getInvokerTasksStream(String compileTaskLanguage) {
+	public <T extends Task> Stream<Map.Entry<SourceSet, TaskProvider<T>>> getInvokerTasksStream(String compileTaskLanguage, Class<T> taskType) {
 		return getMixinSourceSetsStream()
 				.flatMap(sourceSet -> {
 					try {
-						Task task = project.getTasks().getByName(sourceSet.getCompileTaskName(compileTaskLanguage));
+						TaskProvider<T> task = project.getTasks().named(sourceSet.getCompileTaskName(compileTaskLanguage), taskType);
 						return Stream.of(new AbstractMap.SimpleEntry<>(sourceSet, task));
 					} catch (UnknownTaskException ignored) {
 						return Stream.empty();
@@ -133,7 +135,7 @@ private void initDefault() {
 			if (sourceSet.getName().equals("main")) {
 				add(sourceSet);
 			} else {
-				add(sourceSet, sourceSet.getName() + "-" + getDefaultRefmapName().get());
+				add(sourceSet, getDefaultRefmapName().map(defaultRefmapName -> "%s-%s".formatted(sourceSet.getName(), defaultRefmapName)), x -> { });
 			}
 		});
 	}

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

@@ -107,7 +107,7 @@ public RemapJarTask() {
 		getOptimizeFabricModJson().convention(false).finalizeValueOnRead();
 
 		TaskProvider<NestableJarGenerationTask> processIncludeJars = getProject().getTasks().named(Constants.Task.PROCESS_INCLUDE_JARS, NestableJarGenerationTask.class);
-		getNestedJars().from(getProject().fileTree(processIncludeJars.get().getOutputDirectory()));
+		getNestedJars().from(processIncludeJars.map(task -> getProject().fileTree(task.getOutputDirectory())));
 		getNestedJars().builtBy(processIncludeJars);
 
 		getUseMixinAP().set(LoomGradleExtension.get(getProject()).getMixin().getUseLegacyMixinAp());

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

@@ -79,7 +79,7 @@ public void run() {
 		});
 
 		Action<RemapJarTask> remapJarTaskAction = task -> {
-			final AbstractArchiveTask jarTask = getTasks().named(JavaPlugin.JAR_TASK_NAME, AbstractArchiveTask.class).get();
+			final TaskProvider<AbstractArchiveTask> jarTask = getTasks().named(JavaPlugin.JAR_TASK_NAME, AbstractArchiveTask.class);
 
 			// Basic task setup
 			task.dependsOn(jarTask);
@@ -89,7 +89,7 @@ public void run() {
 			getArtifacts().add(JavaPlugin.RUNTIME_ELEMENTS_CONFIGURATION_NAME, task);
 
 			// Setup the input file and the nested deps
-			task.getInputFile().convention(jarTask.getArchiveFile());
+			task.getInputFile().convention(jarTask.flatMap(AbstractArchiveTask::getArchiveFile));
 			task.dependsOn(getTasks().named(JavaPlugin.JAR_TASK_NAME));
 			task.getIncludesClientOnlyClasses().set(getProject().provider(extension::areEnvironmentSourceSetsSplit));
 		};

src/main/java/net/fabricmc/loom/task/service/SourceRemapperService.java

@@ -28,15 +28,19 @@
 import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Path;
+import java.util.concurrent.atomic.AtomicInteger;
 
 import org.cadixdev.mercury.Mercury;
 import org.cadixdev.mercury.remapper.MercuryRemapper;
+import org.gradle.api.JavaVersion;
+import org.gradle.api.Project;
 import org.gradle.api.file.ConfigurableFileCollection;
 import org.gradle.api.provider.Property;
 import org.gradle.api.provider.Provider;
 import org.gradle.api.tasks.Input;
 import org.gradle.api.tasks.InputFiles;
 import org.gradle.api.tasks.Nested;
+import org.gradle.api.tasks.compile.JavaCompile;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -69,7 +73,7 @@ public static Provider<Options> createOptions(RemapSourcesJarTask task) {
 					task.getSourceNamespace(),
 					task.getTargetNamespace()
 			));
-			o.getJavaCompileRelease().set(SourceRemapper.getJavaCompileRelease(task.getProject()));
+			o.getJavaCompileRelease().set(getJavaCompileRelease(task.getProject()));
 			o.getClasspath().from(task.getClasspath());
 		});
 	}
@@ -135,4 +139,28 @@ private Mercury createMercury() throws IOException {
 
 		return mercury;
 	}
+
+	public static int getJavaCompileRelease(Project project) {
+		AtomicInteger release = new AtomicInteger(-1);
+
+		project.getTasks().withType(JavaCompile.class, javaCompile -> {
+			Property<Integer> releaseProperty = javaCompile.getOptions().getRelease();
+
+			if (!releaseProperty.isPresent()) {
+				return;
+			}
+
+			int compileRelease = releaseProperty.get();
+			release.set(Math.max(release.get(), compileRelease));
+		});
+
+		final int i = release.get();
+
+		if (i < 0) {
+			// Unable to find the release used to compile with, default to the current version
+			return Integer.parseInt(JavaVersion.current().getMajorVersion());
+		}
+
+		return i;
+	}
 }