Clean up Javadocs a little

I've no motivation for modding right now, but always got time for build
system busywork!

CC:T (and CC before that) has always published its API docs. However,
they're not always the most helpful — they're useful if you know what
you're looking for, but aren't a good getting-started guide.

Part of the issue here is there's no examples, and everything is
described pretty abstractly. I have occasionally tried to improve this
(e.g. the peripheral docs in bdffabc08e),
but it's a long road.

This commit adds a new example mod, which registers peripherals, an API
and a turtle upgrade. While the mod itself isn't exported as part of the
docs, we reference blocks of it using Java's new {@snippet} tag.

 - Switch the Forge project to use NeoForge's new Legacy MDG plugin. We
   don't *need* to do this, but it means the build logic for Forge and
   NeoForge is more closely aligned.

 - Add a new SnippetTaglet, which is a partial backport of Java 18+'s
   {@snippet}.

 - Add an example mod. This is a working multi-loader mod, complete with
   datagen (albeit with no good multi-loader abstractions).

 - Move our existing <pre>{@code ...}</pre> blocks into the example mod,
   replacing them with {@snippet}s.

 - Add a new overview page to the docs, providing some getting-started
   information. We had this already in the dan200.computercraft.api
   package docs, but it's not especially visible there.

buildSrc/src/main/kotlin/cc-tweaked.forge.gradle.kts

@@ -10,21 +10,22 @@ import cc.tweaked.gradle.IdeaRunConfigurations
 import cc.tweaked.gradle.MinecraftConfigurations
 
 plugins {
-    id("net.minecraftforge.gradle")
-    // We must apply java-convention after Forge, as we need the fg extension to be present.
     id("cc-tweaked.java-convention")
-    id("org.parchmentmc.librarian.forgegradle")
+    id("net.neoforged.moddev.legacyforge")
 }
 
 plugins.apply(CCTweakedPlugin::class.java)
 
 val mcVersion: String by extra
 
-minecraft {
+legacyForge {
     val libs = project.extensions.getByType<VersionCatalogsExtension>().named("libs")
-    mappings("parchment", "${libs.findVersion("parchmentMc").get()}-${libs.findVersion("parchment").get()}-$mcVersion")
+    version = "${mcVersion}-${libs.findVersion("forge").get()}"
 
-    accessTransformer(project(":forge").file("src/main/resources/META-INF/accesstransformer.cfg"))
+    parchment {
+        minecraftVersion = libs.findVersion("parchmentMc").get().toString()
+        mappingsVersion = libs.findVersion("parchment").get().toString()
+    }
 }
 
 MinecraftConfigurations.setup(project)
@@ -32,13 +33,3 @@ MinecraftConfigurations.setup(project)
 extensions.configure(CCTweakedExtension::class.java) {
     linters(minecraft = true, loader = "forge")
 }
-
-dependencies {
-    val libs = project.extensions.getByType<VersionCatalogsExtension>().named("libs")
-    "minecraft"("net.minecraftforge:forge:$mcVersion-${libs.findVersion("forge").get()}")
-}
-
-tasks.configureEach {
-    // genIntellijRuns isn't registered until much later, so we need this silly hijinks.
-    if (name == "genIntellijRuns") doLast { IdeaRunConfigurations(project).patch() }
-}

buildSrc/src/main/kotlin/cc-tweaked.java-convention.gradle.kts

@@ -44,13 +44,6 @@ repositories {
 
     exclusiveContent {
         forRepositories(mainMaven)
-
-        // Include the ForgeGradle repository if present. This requires that ForgeGradle is already present, which we
-        // enforce in our Forge overlay.
-        val fg =
-            project.extensions.findByType(net.minecraftforge.gradle.userdev.DependencyManagementExtension::class.java)
-        if (fg != null) forRepositories(fg.repository)
-
         filter {
             includeGroup("cc.tweaked")
             // Things we mirror
@@ -99,6 +92,7 @@ sourceSets.all {
             check("OperatorPrecedence", CheckSeverity.OFF) // For now.
             check("NonOverridingEquals", CheckSeverity.OFF) // Peripheral.equals makes this hard to avoid
             check("FutureReturnValueIgnored", CheckSeverity.OFF) // Too many false positives with Netty
+            check("InvalidInlineTag", CheckSeverity.OFF) // Triggered by @snippet. Can be removed on Java 21.
 
             check("NullAway", CheckSeverity.ERROR)
             option(

buildSrc/src/main/kotlin/cc-tweaked.mod.gradle.kts

@@ -2,15 +2,16 @@
 //
 // SPDX-License-Identifier: MPL-2.0
 
-import cc.tweaked.gradle.clientClasses
-import cc.tweaked.gradle.commonClasses
-
 /**
  * Sets up the configurations for writing game tests.
  *
  * See notes in [cc.tweaked.gradle.MinecraftConfigurations] for the general design behind these cursed ideas.
  */
 
+import cc.tweaked.gradle.MinecraftConfigurations
+import cc.tweaked.gradle.clientClasses
+import cc.tweaked.gradle.commonClasses
+
 plugins {
     id("cc-tweaked.kotlin-convention")
     id("cc-tweaked.java-convention")
@@ -19,33 +20,16 @@ plugins {
 val main = sourceSets["main"]
 val client = sourceSets["client"]
 
-// datagen and testMod inherit from the main and client classpath, just so we have access to Minecraft classes.
-val datagen by sourceSets.creating {
-    compileClasspath += main.compileClasspath + client.compileClasspath
-    runtimeClasspath += main.runtimeClasspath + client.runtimeClasspath
-}
+MinecraftConfigurations.createDerivedConfiguration(project, MinecraftConfigurations.DATAGEN)
+MinecraftConfigurations.createDerivedConfiguration(project, MinecraftConfigurations.EXAMPLES)
+MinecraftConfigurations.createDerivedConfiguration(project, MinecraftConfigurations.TEST_MOD)
 
-val testMod by sourceSets.creating {
-    compileClasspath += main.compileClasspath + client.compileClasspath
-    runtimeClasspath += main.runtimeClasspath + client.runtimeClasspath
-}
+// Set up generated resources
+sourceSets.main { resources.srcDir("src/generated/resources") }
+sourceSets.named("examples") { resources.srcDir("src/examples/generatedResources") }
 
-val extraConfigurations = listOf(datagen, testMod)
-
-configurations {
-    for (config in extraConfigurations) {
-        named(config.compileClasspathConfigurationName) { shouldResolveConsistentlyWith(compileClasspath.get()) }
-        named(config.runtimeClasspathConfigurationName) { shouldResolveConsistentlyWith(runtimeClasspath.get()) }
-    }
-}
-
-// Like the main test configurations, we're safe to depend on source set outputs.
-dependencies {
-    for (config in extraConfigurations) {
-        add(config.implementationConfigurationName, main.output)
-        add(config.implementationConfigurationName, client.output)
-    }
-}
+// Make sure our examples compile.
+tasks.check { dependsOn(tasks.named("compileExamplesJava")) }
 
 // Similar to java-test-fixtures, but tries to avoid putting the obfuscated jar on the classpath.
 

buildSrc/src/main/kotlin/cc/tweaked/gradle/CCTweakedExtension.kt

@@ -113,7 +113,7 @@ abstract class CCTweakedExtension(
         // Pull in sources from the other project.
         extendSourceSet(otherProject, main)
         extendSourceSet(otherProject, client)
-        for (sourceSet in listOf("datagen", "testMod", "testFixtures")) {
+        for (sourceSet in listOf(MinecraftConfigurations.DATAGEN, MinecraftConfigurations.EXAMPLES, MinecraftConfigurations.TEST_MOD, "testFixtures")) {
             otherJava.sourceSets.findByName(sourceSet)?.let { extendSourceSet(otherProject, it) }
         }
 

buildSrc/src/main/kotlin/cc/tweaked/gradle/ForgeExtensions.kt

@@ -1,26 +0,0 @@
-// SPDX-FileCopyrightText: 2023 The CC: Tweaked Developers
-//
-// SPDX-License-Identifier: MPL-2.0
-
-package cc.tweaked.gradle
-
-import net.minecraftforge.gradle.common.util.RunConfig
-import net.minecraftforge.gradle.common.util.runs.setRunConfigInternal
-import org.gradle.api.plugins.JavaPluginExtension
-import org.gradle.api.tasks.JavaExec
-import org.gradle.jvm.toolchain.JavaToolchainService
-import java.nio.file.Files
-
-/**
- * Set [JavaExec] task to run a given [RunConfig].
- */
-fun JavaExec.setRunConfig(config: RunConfig) {
-    dependsOn("prepareRuns")
-    setRunConfigInternal(project, this, config)
-    doFirst("Create working directory") { Files.createDirectories(workingDir.toPath()) }
-
-    javaLauncher.set(
-        project.extensions.getByType(JavaToolchainService::class.java)
-            .launcherFor(project.extensions.getByType(JavaPluginExtension::class.java).toolchain),
-    )
-}

buildSrc/src/main/kotlin/cc/tweaked/gradle/MinecraftConfigurations.kt

@@ -24,7 +24,6 @@ class MinecraftConfigurations private constructor(private val project: Project)
     private val java = project.extensions.getByType(JavaPluginExtension::class.java)
     private val sourceSets = java.sourceSets
     private val configurations = project.configurations
-    private val objects = project.objects
 
     private val main = sourceSets[SourceSet.MAIN_SOURCE_SET_NAME]
     private val test = sourceSets[SourceSet.TEST_SOURCE_SET_NAME]
@@ -37,13 +36,7 @@ class MinecraftConfigurations private constructor(private val project: Project)
         val client = sourceSets.maybeCreate("client")
 
         // Ensure the client classpaths behave the same as the main ones.
-        configurations.named(client.compileClasspathConfigurationName) {
-            shouldResolveConsistentlyWith(configurations[main.compileClasspathConfigurationName])
-        }
-
-        configurations.named(client.runtimeClasspathConfigurationName) {
-            shouldResolveConsistentlyWith(configurations[main.runtimeClasspathConfigurationName])
-        }
+        consistentWithMain(client)
 
         // Set up an API configuration for clients (to ensure it's consistent with the main source set).
         val clientApi = configurations.maybeCreate(client.apiConfigurationName).apply {
@@ -85,6 +78,16 @@ class MinecraftConfigurations private constructor(private val project: Project)
         setupBasic()
     }
 
+    private fun consistentWithMain(sourceSet: SourceSet) {
+        configurations.named(sourceSet.compileClasspathConfigurationName) {
+            shouldResolveConsistentlyWith(configurations[main.compileClasspathConfigurationName])
+        }
+
+        configurations.named(sourceSet.runtimeClasspathConfigurationName) {
+            shouldResolveConsistentlyWith(configurations[main.runtimeClasspathConfigurationName])
+        }
+    }
+
     private fun setupBasic() {
         val client = sourceSets["client"]
 
@@ -102,7 +105,24 @@ class MinecraftConfigurations private constructor(private val project: Project)
         project.tasks.named("check") { dependsOn(checkDependencyConsistency) }
     }
 
+    /**
+     * Create a new configuration that pulls in the main and client classes from the mod.
+     */
+    private fun createDerivedConfiguration(name: String) {
+        val client = sourceSets["client"]
+        val sourceSet = sourceSets.create(name)
+        sourceSet.compileClasspath += main.compileClasspath + client.compileClasspath
+        sourceSet.runtimeClasspath += main.runtimeClasspath + client.runtimeClasspath
+        consistentWithMain(sourceSet)
+        project.dependencies.add(sourceSet.implementationConfigurationName, main.output)
+        project.dependencies.add(sourceSet.implementationConfigurationName, client.output)
+    }
+
     companion object {
+        const val DATAGEN = "datagen"
+        const val EXAMPLES = "examples"
+        const val TEST_MOD = "testMod"
+
         fun setupBasic(project: Project) {
             MinecraftConfigurations(project).setupBasic()
         }
@@ -110,6 +130,10 @@ class MinecraftConfigurations private constructor(private val project: Project)
         fun setup(project: Project) {
             MinecraftConfigurations(project).setup()
         }
+
+        fun createDerivedConfiguration(project: Project, name: String) {
+            MinecraftConfigurations(project).createDerivedConfiguration(name)
+        }
     }
 }
 

buildSrc/src/main/kotlin/cc/tweaked/gradle/MinecraftExec.kt

@@ -4,7 +4,7 @@
 
 package cc.tweaked.gradle
 
-import net.minecraftforge.gradle.common.util.RunConfig
+import net.neoforged.moddevgradle.internal.RunGameTask
 import org.gradle.api.GradleException
 import org.gradle.api.file.FileSystemOperations
 import org.gradle.api.invocation.Gradle
@@ -65,11 +65,19 @@ abstract class ClientJavaExec : JavaExec() {
         setTestProperties()
     }
 
+    fun copyFromForge(path: String) = copyFromForge(project.tasks.getByName(path, RunGameTask::class))
+
     /**
-     * Set this task to run a given [RunConfig].
+     * Set this task to run a given [RunGameTask].
      */
-    fun setRunConfig(config: RunConfig) {
-        (this as JavaExec).setRunConfig(config)
+    fun copyFromForge(task: RunGameTask) {
+        copyFrom(task)
+
+        // Eagerly evaluate the behaviour of RunGameTask.exec
+        environment.putAll(task.environmentProperty.get())
+        classpath(task.classpathProvider)
+        workingDir = task.gameDirectory.get().asFile
+
         setTestProperties() // setRunConfig may clobber some properties, ensure everything is set.
     }
 

buildSrc/src/main/kotlin/net/minecraftforge/gradle/common/util/runs/RunConfigSetup.kt

@@ -1,51 +0,0 @@
-// SPDX-FileCopyrightText: 2023 The CC: Tweaked Developers
-//
-// SPDX-License-Identifier: MPL-2.0
-
-package net.minecraftforge.gradle.common.util.runs
-
-import net.minecraftforge.gradle.common.util.RunConfig
-import org.gradle.api.Project
-import org.gradle.process.CommandLineArgumentProvider
-import org.gradle.process.JavaExecSpec
-import java.io.File
-import java.util.function.Supplier
-import java.util.stream.Collectors
-import java.util.stream.Stream
-
-/**
- * Set up a [JavaExecSpec] to execute a [RunConfig].
- *
- * [MinecraftRunTask] sets up all its properties when the task is executed, rather than when configured. As such, it's
- * not possible to use [cc.tweaked.gradle.copyToFull] like we do for Fabric. Instead, we set up the task manually.
- *
- * Unfortunately most of the functionality we need is package-private, and so we have to put our code into the package.
- */
-internal fun setRunConfigInternal(project: Project, spec: JavaExecSpec, config: RunConfig) {
-    spec.workingDir = File(config.workingDirectory)
-
-    spec.mainClass.set(config.main)
-    for (source in config.allSources) spec.classpath(source.runtimeClasspath)
-
-    val originalTask = project.tasks.named(config.taskName, MinecraftRunTask::class.java)
-
-    // Add argument and JVM argument via providers, to be as lazy as possible with fetching artifacts.
-    val lazyTokens = RunConfigGenerator.configureTokensLazy(
-        project, config, RunConfigGenerator.mapModClassesToGradle(project, config),
-        originalTask.get().minecraftArtifacts,
-        originalTask.get().runtimeClasspathArtifacts,
-    )
-    spec.argumentProviders.add(
-        CommandLineArgumentProvider {
-            RunConfigGenerator.getArgsStream(config, lazyTokens, false).toList()
-        },
-    )
-    spec.jvmArgumentProviders.add(
-        CommandLineArgumentProvider {
-            (if (config.isClient) config.jvmArgs + originalTask.get().additionalClientArgs.get() else config.jvmArgs).map { config.replace(lazyTokens, it) } +
-                config.properties.map { (k, v) -> "-D${k}=${config.replace(lazyTokens, v)}" }
-        },
-    )
-
-    for ((key, value) in config.environment) spec.environment(key, config.replace(lazyTokens, value))
-}