broken

build.gradle.kts

@@ -30,7 +30,7 @@ tasks.withType<KotlinCompile> {
 }
 
 gradlePlugin {
-    // we handle publications ourselves
+    // we handle publications manually
     isAutomatedPublishing = false
 }
 
@@ -79,6 +79,10 @@ dependencies {
     shade("net.fabricmc:lorenz-tiny:3.0.0")
 
     shade("io.sigpipe:jbsdiff:1.0")
+
+    val jgraphtVersion = "1.5.0"
+    shade("org.jgrapht:jgrapht-core:$jgraphtVersion")
+    shade("org.jgrapht:jgrapht-io:$jgraphtVersion")
 }
 
 ktlint {
@@ -124,13 +128,17 @@ tasks.shadowJar {
         "io.sigpipe",
         "me.jamiemansfield",
         "net.fabricmc",
+        "org.antlr",
         "org.apache.commons.codec",
         "org.apache.commons.compress",
         "org.apache.commons.logging",
+        "org.apache.commons.text",
         "org.apache.felix",
         "org.apache.http",
         "org.cadixdev",
         "org.eclipse",
+        "org.jgrapht",
+        "org.jheaps",
         "org.objectweb",
         "org.osgi",
         "org.tukaani"

gradle/wrapper/gradle-wrapper.properties

@@ -1,5 +1,5 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-6.7.1-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-6.8-bin.zip
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists

src/main/kotlin/Paperweight.kt

@@ -92,10 +92,12 @@ class Paperweight : Plugin<Project> {
 
         val tasks = target.createTasks()
 
+        val generatePaperclipPatch by target.tasks.registering<GeneratePaperclipPatch>()
+
         // Setup the server jar
         target.afterEvaluate {
             target.ext.serverProject.forUseAtConfigurationTime().orNull?.setupServerProject(target, tasks.spigotTasks)?.let { reobfJar ->
-                val generatePaperclipPatch by target.tasks.registering<GeneratePaperclipPatch> {
+                generatePaperclipPatch.configure {
                     originalJar.set(tasks.generalTasks.downloadServerJar.flatMap { it.outputJar })
                     patchedJar.set(reobfJar.flatMap { it.outputJar })
                     mcVersion.set(target.ext.minecraftVersion)
@@ -103,13 +105,13 @@ class Paperweight : Plugin<Project> {
 
                 target.tasks.named("jar", Jar::class) {
                     val paperclipConfig = target.configurations.named(Constants.PAPERCLIP_CONFIG)
-                    dependsOn(paperclipConfig)
+                    dependsOn(paperclipConfig, generatePaperclipPatch)
 
                     val paperclipZip = target.zipTree(paperclipConfig.map { it.singleFile })
                     from(paperclipZip) {
                         exclude("META-INF/MANIFEST.MF")
                     }
-                    from(target.zipTree(generatePaperclipPatch.flatMap { it.outputZip }.get()))
+                    from(target.zipTree(generatePaperclipPatch.flatMap { it.outputZip }))
 
                     manifest.from(paperclipZip.matching { include("META-INF/MANIFEST.MF") }.singleFile)
                 }
@@ -150,7 +152,7 @@ class Paperweight : Plugin<Project> {
         val initialTasks = createInitialTasks()
         val generalTasks = createGeneralTasks()
         val vanillaTasks = createVanillaTasks(initialTasks, generalTasks)
-        val spigotTasks = createSpigotTasks(initialTasks, generalTasks, vanillaTasks)
+        val spigotTasks = createSpigotTasks(generalTasks, vanillaTasks)
 
         val applyMergedAt by tasks.registering<ApplyAccessTransform> {
             inputJar.set(vanillaTasks.fixJar.flatMap { it.outputJar })
@@ -236,6 +238,7 @@ class Paperweight : Plugin<Project> {
     )
 
     data class VanillaTasks(
+        val inspectVanillaJar: TaskProvider<InspectVanillaJar>,
         val generateMappings: TaskProvider<GenerateMappings>,
         val fixJar: TaskProvider<FixJar>,
         val downloadMcLibraries: TaskProvider<DownloadMcLibraries>
@@ -334,11 +337,29 @@ class Paperweight : Plugin<Project> {
         val cache: File = layout.cache
         val downloadService = download
 
+        val downloadMcLibraries by tasks.registering<DownloadMcLibraries> {
+            mcLibrariesFile.set(initialTasks.setupMcLibraries.flatMap { it.outputFile })
+            mcRepo.set(Constants.MC_LIBRARY_URL)
+            outputDir.set(cache.resolve(Constants.MINECRAFT_JARS_PATH))
+            sourcesOutputDir.set(cache.resolve(Constants.MINECRAFT_SOURCES_PATH))
+
+            downloader.set(downloadService)
+        }
+
+        val inspectVanillaJar by tasks.registering<InspectVanillaJar> {
+            inputJar.set(generalTasks.downloadServerJar.flatMap { it.outputJar })
+            librariesDir.set(downloadMcLibraries.flatMap { it.outputDir })
+            mcLibraries.set(initialTasks.setupMcLibraries.flatMap { it.outputFile })
+
+            serverLibraries.set(cache.resolve(Constants.SERVER_LIBRARIES))
+        }
+
         val generateMappings by tasks.registering<GenerateMappings> {
             vanillaJar.set(generalTasks.filterVanillaJar.flatMap { it.outputJar })
 
             vanillaMappings.set(initialTasks.downloadMappings.flatMap { it.outputFile })
             paramMappings.fileProvider(configurations.named(Constants.PARAM_MAPPINGS_CONFIG).map { it.singleFile })
+            methodOverrides.set(inspectVanillaJar.flatMap { it.methodOverrides })
 
             outputMappings.set(cache.resolve(Constants.MOJANG_YARN_MAPPINGS))
         }
@@ -356,25 +377,16 @@ class Paperweight : Plugin<Project> {
             vanillaJar.set(generalTasks.downloadServerJar.flatMap { it.outputJar })
         }
 
-        val downloadMcLibraries by tasks.registering<DownloadMcLibraries> {
-            mcLibrariesFile.set(initialTasks.setupMcLibraries.flatMap { it.outputFile })
-            mcRepo.set(Constants.MC_LIBRARY_URL)
-            outputDir.set(cache.resolve(Constants.MINECRAFT_JARS_PATH))
-            sourcesOutputDir.set(cache.resolve(Constants.MINECRAFT_SOURCES_PATH))
-
-            downloader.set(downloadService)
+        return VanillaTasks(inspectVanillaJar, generateMappings, fixJar, downloadMcLibraries)
     }
 
-        return VanillaTasks(generateMappings, fixJar, downloadMcLibraries)
-    }
-
-    private fun Project.createSpigotTasks(initialTasks: InitialTasks, generalTasks: GeneralTasks, vanillaTasks: VanillaTasks): SpigotTasks {
+    private fun Project.createSpigotTasks(generalTasks: GeneralTasks, vanillaTasks: VanillaTasks): SpigotTasks {
         val cache: File = layout.cache
         val extension: PaperweightExtension = ext
         val downloadService = download
 
         val (buildDataInfo, downloadServerJar, filterVanillaJar) = generalTasks
-        val (generateMappings, _, _) = vanillaTasks
+        val (inspectVanillaJar, generateMappings, _, _) = vanillaTasks
 
         val addAdditionalSpigotMappings by tasks.registering<AddAdditionalSpigotMappings> {
             classSrg.set(extension.craftBukkit.mappingsDir.file(buildDataInfo.map { it.classMappings }))
@@ -383,14 +395,6 @@ class Paperweight : Plugin<Project> {
             additionalMemberEntriesSrg.set(extension.paper.additionalSpigotMemberMappings)
         }
 
-        val inspectVanillaJar by tasks.registering<InspectVanillaJar> {
-            inputJar.set(downloadServerJar.flatMap { it.outputJar })
-            librariesDir.set(vanillaTasks.downloadMcLibraries.flatMap { it.outputDir })
-            mcLibraries.set(initialTasks.setupMcLibraries.flatMap { it.outputFile })
-
-            serverLibraries.set(cache.resolve(Constants.SERVER_LIBRARIES))
-        }
-
         val generateSpigotMappings by tasks.registering<GenerateSpigotMappings> {
             classMappings.set(addAdditionalSpigotMappings.flatMap { it.outputClassSrg })
             memberMappings.set(addAdditionalSpigotMappings.flatMap { it.outputMemberSrg })
@@ -399,6 +403,7 @@ class Paperweight : Plugin<Project> {
             loggerFields.set(inspectVanillaJar.flatMap { it.loggerFile })
             paramIndexes.set(inspectVanillaJar.flatMap { it.paramIndexes })
             syntheticMethods.set(inspectVanillaJar.flatMap { it.syntheticMethods })
+            methodOverrides.set(inspectVanillaJar.flatMap { it.methodOverrides })
 
             sourceMappings.set(generateMappings.flatMap { it.outputMappings })
 

src/main/kotlin/tasks/FixJar.kt

@@ -23,6 +23,7 @@
 package io.papermc.paperweight.tasks
 
 import io.papermc.paperweight.util.AsmUtil
+import io.papermc.paperweight.util.ClassNodeCache
 import io.papermc.paperweight.util.SyntheticUtil
 import io.papermc.paperweight.util.defaultOutput
 import io.papermc.paperweight.util.file
@@ -33,7 +34,6 @@ import org.gradle.api.file.RegularFileProperty
 import org.gradle.api.tasks.InputFile
 import org.gradle.api.tasks.OutputFile
 import org.gradle.api.tasks.TaskAction
-import org.objectweb.asm.ClassReader
 import org.objectweb.asm.ClassWriter
 import org.objectweb.asm.Opcodes
 import org.objectweb.asm.Type
@@ -75,8 +75,7 @@ abstract class FixJar : BaseTask(), AsmUtil {
                         }
 
                         try {
-                            val node =
-                                classNodeCache.findClass(entry.name) ?: error("No ClassNode found for known entry")
+                            val node = classNodeCache.findClass(entry.name) ?: error("No ClassNode found for known entry")
 
                             ParameterAnnotationFixer(node).visitNode()
                             OverrideAnnotationAdder(node, classNodeCache).visitNode()
@@ -230,49 +229,3 @@ class OverrideAnnotationAdder(private val node: ClassNode, private val classNode
         return result
     }
 }
-
-class ClassNodeCache(private val jarFile: JarFile, private val fallbackJar: JarFile) {
-
-    private val classNodeMap = hashMapOf<String, ClassNode?>()
-
-    fun findClass(name: String): ClassNode? {
-        return classNodeMap.computeIfAbsent(normalize(name)) { fileName ->
-            val classData = findClassData(fileName) ?: return@computeIfAbsent null
-            val classReader = ClassReader(classData)
-            val node = ClassNode(Opcodes.ASM9)
-            classReader.accept(node, 0)
-            return@computeIfAbsent node
-        }
-    }
-
-    private fun findClassData(className: String): ByteArray? {
-        val entry = ZipEntry(className)
-        return (
-            jarFile.getInputStream(entry) // remapped class
-                ?: fallbackJar.getInputStream(entry) // library class
-                ?: ClassLoader.getSystemResourceAsStream(className)
-            )?.use { it.readBytes() } // JDK class
-    }
-
-    private fun normalize(name: String): String {
-        var workingName = name
-        if (workingName.endsWith(".class")) {
-            workingName = workingName.substring(0, workingName.length - 6)
-        }
-
-        var startIndex = 0
-        var endIndex = workingName.length
-        if (workingName.startsWith('L')) {
-            startIndex = 1
-        }
-        if (workingName.endsWith(';')) {
-            endIndex--
-        }
-
-        return workingName.substring(startIndex, endIndex).replace('.', '/') + ".class"
-    }
-
-    fun clear() {
-        classNodeMap.clear()
-    }
-}

src/main/kotlin/tasks/GenerateMappings.kt

@@ -30,6 +30,7 @@ import io.papermc.paperweight.util.file
 import io.papermc.paperweight.util.path
 import java.nio.file.FileSystems
 import java.nio.file.Files
+import java.util.zip.ZipFile
 import javax.inject.Inject
 import org.cadixdev.atlas.Atlas
 import org.cadixdev.bombe.asm.jar.JarEntryRemappingTransformer
@@ -41,6 +42,7 @@ import org.cadixdev.lorenz.merge.MappingSetMergerHandler
 import org.cadixdev.lorenz.merge.MergeConfig
 import org.cadixdev.lorenz.merge.MergeContext
 import org.cadixdev.lorenz.merge.MergeResult
+import org.cadixdev.lorenz.merge.MethodMergeStrategy
 import org.cadixdev.lorenz.model.ClassMapping
 import org.cadixdev.lorenz.model.FieldMapping
 import org.cadixdev.lorenz.model.InnerClassMapping
@@ -66,6 +68,8 @@ abstract class GenerateMappings : DefaultTask() {
     abstract val vanillaMappings: RegularFileProperty
     @get:InputFile
     abstract val paramMappings: RegularFileProperty
+    @get:InputFile
+    abstract val methodOverrides: RegularFileProperty
 
     @get:OutputFile
     abstract val outputMappings: RegularFileProperty
@@ -86,16 +90,17 @@ abstract class GenerateMappings : DefaultTask() {
             vanillaMappings,
             paramMappings,
             MergeConfig.builder()
+                .withMethodMergeStrategy(MethodMergeStrategy.STRICT)
                 .withFieldMergeStrategy(FieldMergeStrategy.STRICT)
                 .withMergeHandler(ParamsMergeHandler())
                 .build()
         ).merge()
 
+        ensureParentExists(outputMappings)
+
         // Fill out any missing inheritance info in the mappings
         val tempMappingsFile = Files.createTempFile("mappings", "tiny")
-        val tempMappingsOutputFile = Files.createTempFile("mappings-out", "tiny")
-
-        val filledMerged = try {
+        try {
             MappingFormats.TINY.write(merged, tempMappingsFile, Constants.OBF_NAMESPACE, Constants.DEOBF_NAMESPACE)
 
             val queue = workerExecutor.processIsolation {
@@ -105,20 +110,64 @@ abstract class GenerateMappings : DefaultTask() {
             queue.submit(AtlasAction::class) {
                 inputJar.set(vanillaJar.file)
                 mappingsFile.set(tempMappingsFile.toFile())
-                outputMappingsFile.set(tempMappingsOutputFile.toFile())
+                outputMappingsFile.set(outputMappings.file)
             }
 
             queue.await()
-
-            MappingFormats.TINY.read(tempMappingsOutputFile, Constants.OBF_NAMESPACE, Constants.DEOBF_NAMESPACE)
         } finally {
             Files.deleteIfExists(tempMappingsFile)
-            Files.deleteIfExists(tempMappingsOutputFile)
+        }
     }
 
-        ensureParentExists(outputMappings)
-        MappingFormats.TINY.write(filledMerged, outputMappings.path, Constants.OBF_NAMESPACE, Constants.DEOBF_NAMESPACE)
+    /*
+    private fun copyOverridenParamMappings(mappings: MappingSet) {
+        val methods = hashMapOf<String, String>()
+        methodOverrides.file.reader(Charsets.UTF_8).useLines { lines ->
+            lines.map { line ->
+                val (method, superMethod) = line.split("|")
+                methods[method] = superMethod
             }
+        }
+
+        for (classMapping in mappings.topLevelClassMappings) {
+            copyOverridenParamMappings(mappings, classMapping, methods)
+        }
+    }
+
+    private fun copyOverridenParamMappings(mappingSet: MappingSet, classMapping: ClassMapping<*, *>, methods: Map<String, String>) {
+        methodLoop@for (mapping in classMapping.methodMappings) {
+            if (mapping.parameterMappings.isNotEmpty()) {
+                continue
+            }
+
+            var baseClassName = classMapping.obfuscatedName
+            var baseMethod = mapping.obfuscatedName
+            var baseDesc = mapping.obfuscatedDescriptor
+
+            while (true) {
+                val superMethod = methods["$baseClassName,$baseMethod,$baseDesc"] ?: continue@methodLoop
+                val (className, methodName, methodDesc) = superMethod.split(",")
+
+                val superMethodMapping = mappingSet.getClassMapping(className).orNull?.getMethodMapping(methodName, methodDesc)?.orNull
+                if (superMethodMapping != null) {
+                    superMethodMapping.parameterMappings.forEach { it.copy(mapping) }
+                    break
+                }
+
+                // prevent possible infinite loops
+                if (baseClassName == className) {
+                    break
+                }
+
+                baseClassName = className
+                baseMethod = methodName
+                baseDesc = methodDesc
+            }
+        }
+
+        classMapping.innerClassMappings.forEach { copyOverridenParamMappings(mappingSet, it, methods) }
+    }
+     */
 
     abstract class AtlasAction : WorkAction<AtlasParameters> {
         override fun execute() {
@@ -237,7 +286,7 @@ class ParamsMergeHandler : MappingSetMergerHandler {
     ): MergeResult<MethodMapping?> {
         return MergeResult(
             target.createMethodMapping(left.signature, left.deobfuscatedName),
-            listOfNotNull(standardRightDuplicate, wiggledRightDuplicate)
+            listOfNotNull(standardRightDuplicate)
         )
     }
 

src/main/kotlin/tasks/GeneratePaperclipPatch.kt

@@ -36,11 +36,16 @@ import java.nio.file.StandardCopyOption
 import java.security.MessageDigest
 import java.security.NoSuchAlgorithmException
 import java.util.Properties
+import javax.inject.Inject
 import kotlin.experimental.and
 import org.gradle.api.file.RegularFileProperty
 import org.gradle.api.provider.Property
 import org.gradle.api.tasks.Input
 import org.gradle.api.tasks.InputFile
+import org.gradle.kotlin.dsl.submit
+import org.gradle.workers.WorkAction
+import org.gradle.workers.WorkParameters
+import org.gradle.workers.WorkerExecutor
 
 abstract class GeneratePaperclipPatch : ZippedTask() {
 
@@ -51,16 +56,39 @@ abstract class GeneratePaperclipPatch : ZippedTask() {
     @get:Input
     abstract val mcVersion: Property<String>
 
+    @get:Inject
+    abstract val workerExecutor: WorkerExecutor
+
     override fun run(rootDir: File) {
-        val patchFile = rootDir.resolve("paperMC.patch").toPath()
-        val propFile = rootDir.resolve("patch.properties").toPath()
-        val protocol = rootDir.resolve("META-INF/$PROTOCOL_FILE").toPath()
+        val queue = workerExecutor.processIsolation {
+            forkOptions.jvmArgs("-Xmx2G")
+        }
+
+        queue.submit(PaperclipAction::class) {
+            zipRootDir.set(rootDir)
+            originalJar.set(this@GeneratePaperclipPatch.originalJar.file)
+            patchedJar.set(this@GeneratePaperclipPatch.patchedJar.file)
+            mcVersion.set(this@GeneratePaperclipPatch.mcVersion.get())
+        }
+
+        queue.await()
+    }
+
+    abstract class PaperclipAction : WorkAction<PaperclipParameters> {
+        override fun execute() {
+            val rootDir = parameters.zipRootDir.path
+            val originalJarPath = parameters.originalJar.path
+            val patchedJarPath = parameters.patchedJar.path
+
+            val patchFile = rootDir.resolve("paperMC.patch")
+            val propFile = rootDir.resolve("patch.properties")
+            val protocol = rootDir.resolve("META-INF/$PROTOCOL_FILE")
 
             val zipUri = try {
-            val jarUri = patchedJar.file.toURI()
+                val jarUri = patchedJarPath.toUri()
                 URI("jar:${jarUri.scheme}", jarUri.path, null)
             } catch (e: URISyntaxException) {
-            throw PaperweightException("Failed to create jar URI for $patchedJar", e)
+                throw PaperweightException("Failed to create jar URI for $patchedJarPath", e)
             }
 
             try {
@@ -75,13 +103,13 @@ abstract class GeneratePaperclipPatch : ZippedTask() {
                     Files.copy(protocolPath, protocol, StandardCopyOption.REPLACE_EXISTING)
                 }
             } catch (e: IOException) {
-            throw PaperweightException("Failed to read $patchedJar contents", e)
+                throw PaperweightException("Failed to read $patchedJarPath contents", e)
             }
 
             // Read the files into memory
             println("Reading jars into memory")
-        val originalBytes = Files.readAllBytes(originalJar.path)
-        val patchedBytes = Files.readAllBytes(patchedJar.path)
+            val originalBytes = Files.readAllBytes(originalJarPath)
+            val patchedBytes = Files.readAllBytes(patchedJarPath)
 
             println("Creating Paperclip patch")
             try {
@@ -89,7 +117,7 @@ abstract class GeneratePaperclipPatch : ZippedTask() {
                     Diff.diff(originalBytes, patchedBytes, patchOutput)
                 }
             } catch (e: Exception) {
-            throw PaperweightException("Error creating patch between ${originalJar.path} and ${patchedJar.path}", e)
+                throw PaperweightException("Error creating patch between $originalJarPath and $patchedJarPath", e)
             }
 
             // Add the SHA-256 hashes for the files
@@ -116,11 +144,14 @@ abstract class GeneratePaperclipPatch : ZippedTask() {
             prop["patchedHash"] = toHex(patchedSha256)
             prop["patch"] = "paperMC.patch"
             prop["sourceUrl"] = "https://launcher.mojang.com/v1/objects/" + toHex(originalSha1).toLowerCase() + "/server.jar"
-        prop["version"] = mcVersion.get()
+            prop["version"] = parameters.mcVersion.get()
 
             println("Writing properties file")
             Files.newBufferedWriter(propFile).use { writer ->
-            prop.store(writer, "Default Paperclip launch values. Can be overridden by placing a paperclip.properties file in the server directory.")
+                prop.store(
+                    writer,
+                    "Default Paperclip launch values. Can be overridden by placing a paperclip.properties file in the server directory."
+                )
             }
         }
 
@@ -133,6 +164,14 @@ abstract class GeneratePaperclipPatch : ZippedTask() {
         }
 
         companion object {
-        const val PROTOCOL_FILE = "io.papermc.paper.daemon.protocol"
+            private const val PROTOCOL_FILE = "io.papermc.paper.daemon.protocol"
+        }
+    }
+
+    interface PaperclipParameters : WorkParameters {
+        val zipRootDir: RegularFileProperty
+        val originalJar: RegularFileProperty
+        val patchedJar: RegularFileProperty
+        val mcVersion: Property<String>
     }
 }

src/main/kotlin/tasks/GenerateSpigotMappings.kt

@@ -22,14 +22,16 @@
 
 package io.papermc.paperweight.tasks
 
-import io.papermc.paperweight.util.Constants
+import io.papermc.paperweight.util.Constants.DEOBF_NAMESPACE
+import io.papermc.paperweight.util.Constants.OBF_NAMESPACE
+import io.papermc.paperweight.util.Constants.SPIGOT_NAMESPACE
 import io.papermc.paperweight.util.MappingFormats
+import io.papermc.paperweight.util.MethodRef
 import io.papermc.paperweight.util.emptyMergeResult
 import io.papermc.paperweight.util.file
 import io.papermc.paperweight.util.orNull
-import io.papermc.paperweight.util.parentClass
+import io.papermc.paperweight.util.readOverrides
 import io.papermc.paperweight.util.path
-import org.cadixdev.bombe.type.signature.MethodSignature
 import org.cadixdev.lorenz.MappingSet
 import org.cadixdev.lorenz.merge.MappingSetMerger
 import org.cadixdev.lorenz.merge.MappingSetMergerHandler
@@ -46,6 +48,8 @@ import org.gradle.api.file.RegularFileProperty
 import org.gradle.api.tasks.InputFile
 import org.gradle.api.tasks.OutputFile
 import org.gradle.api.tasks.TaskAction
+import org.jgrapht.graph.SimpleDirectedGraph
+import org.jgrapht.traverse.DepthFirstIterator
 
 abstract class GenerateSpigotMappings : DefaultTask() {
 
@@ -62,6 +66,8 @@ abstract class GenerateSpigotMappings : DefaultTask() {
     abstract val paramIndexes: RegularFileProperty
     @get:InputFile
     abstract val syntheticMethods: RegularFileProperty
+    @get:InputFile
+    abstract val methodOverrides: RegularFileProperty
 
     @get:InputFile
     abstract val sourceMappings: RegularFileProperty
@@ -84,13 +90,10 @@ abstract class GenerateSpigotMappings : DefaultTask() {
         // Get the new package name
         val newPackage = packageMappings.asFile.get().readLines()[0].split(Regex("\\s+"))[1]
 
-        val sourceMappings = MappingFormats.TINY.read(
-            sourceMappings.path,
-            Constants.OBF_NAMESPACE,
-            Constants.DEOBF_NAMESPACE
-        )
+        val sourceMappings = MappingFormats.TINY.read(sourceMappings.path, OBF_NAMESPACE, DEOBF_NAMESPACE)
 
-        val synths = hashMapOf<String, MutableMap<String, MutableMap<String, String>>>()
+        /*
+        val synths = newSynths()
         syntheticMethods.file.useLines { lines ->
             for (line in lines) {
                 val (className, desc, synthName, baseName) = line.split(" ")
@@ -98,12 +101,15 @@ abstract class GenerateSpigotMappings : DefaultTask() {
                     .computeIfAbsent(desc) { hashMapOf() }[baseName] = synthName
             }
         }
+         */
+
+        val overrides = readOverrides(methodOverrides)
 
         val notchToSpigotSet = MappingSetMerger.create(
             mergedMappingSet,
             sourceMappings,
             MergeConfig.builder()
-                .withMergeHandler(SpigotMappingsMergerHandler(newPackage, synths))
+                .withMergeHandler(SpigotMappingsMergerHandler(newPackage, overrides))
                 .build()
         ).merge()
 
@@ -111,12 +117,7 @@ abstract class GenerateSpigotMappings : DefaultTask() {
         val cleanedSourceMappings = removeLambdaMappings(adjustedSourceMappings)
         val spigotToNamedSet = notchToSpigotSet.reverse().merge(cleanedSourceMappings)
 
-        MappingFormats.TINY.write(
-            spigotToNamedSet,
-            outputMappings.path,
-            Constants.SPIGOT_NAMESPACE,
-            Constants.DEOBF_NAMESPACE
-        )
+        MappingFormats.TINY.write(spigotToNamedSet, outputMappings.path, SPIGOT_NAMESPACE, DEOBF_NAMESPACE)
     }
 
     private fun adjustParamIndexes(mappings: MappingSet): MappingSet {
@@ -151,7 +152,7 @@ abstract class GenerateSpigotMappings : DefaultTask() {
         params: Map<String, Map<String, Map<Int, Int>>>
     ) {
         for (mapping in from.fieldMappings) {
-            to.createFieldMapping(mapping.signature, mapping.deobfuscatedName)
+            mapping.copy(to)
         }
         for (mapping in from.innerClassMappings) {
             val newMapping = to.createInnerClassMapping(mapping.obfuscatedName, mapping.deobfuscatedName)
@@ -169,7 +170,7 @@ abstract class GenerateSpigotMappings : DefaultTask() {
 
             val methodMap = classMap[mapping.signature.toJvmsIdentifier()] ?: continue
             for (paramMapping in paramMappings) {
-                val i = methodMap[paramMapping.index] ?: paramMapping.index
+                val i = methodMap[paramMapping.index] ?: continue
                 newMapping.createParameterMapping(i, paramMapping.deobfuscatedName)
             }
         }
@@ -210,11 +211,14 @@ abstract class GenerateSpigotMappings : DefaultTask() {
     }
 }
 
+/*
 typealias Synths = Map<String, Map<String, Map<String, String>>>
+fun newSynths() = hashMapOf<String, MutableMap<String, MutableMap<String, String>>>()
+ */
 
 class SpigotMappingsMergerHandler(
     private val newPackage: String,
-    private val synths: Synths
+    private val methodOverrides: SimpleDirectedGraph<MethodRef, *>
 ) : MappingSetMergerHandler {
 
     override fun mergeTopLevelClassMappings(
@@ -298,7 +302,7 @@ class SpigotMappingsMergerHandler(
         target: ClassMapping<*, *>,
         context: MergeContext
     ): MergeResult<InnerClassMapping?> {
-        // We want to get all of the inner classes from SRG, but not the SRG names
+        // We want to get all of the members from mojmap, but not the mojmap names
         return MergeResult(target.createInnerClassMapping(right.obfuscatedName, right.obfuscatedName), right)
     }
 
@@ -320,6 +324,8 @@ class SpigotMappingsMergerHandler(
         target: ClassMapping<*, *>,
         context: MergeContext
     ): FieldMapping {
+        // Spigot mappings don't include signature, so see if we can pull the signature out of the mojmap
+        // Regardless, still keep Spigot's name
         val right = strictRightDuplicate ?: looseRightDuplicate ?: strictRightContinuation ?: looseRightContinuation ?: left
         return target.createFieldMapping(right.signature, left.deobfuscatedName)
     }
@@ -342,33 +348,81 @@ class SpigotMappingsMergerHandler(
         target: ClassMapping<*, *>,
         context: MergeContext
     ): MergeResult<MethodMapping?> {
-        // Check if Spigot calls this mapping something else
-        val synthMethods = synths[left.parent.fullObfuscatedName]?.get(left.obfuscatedDescriptor)
-        val newName = synthMethods?.get(left.obfuscatedName)
-        return if (newName != null) {
-            val newLeftMapping = left.parentClass.getMethodMapping(MethodSignature(newName, left.descriptor)).orNull
-            val newMapping = if (newLeftMapping != null) {
-                target.getOrCreateMethodMapping(newLeftMapping.signature).also {
+        val ref = MethodRef.from(left.parent.obfuscatedName, left.signature)
+        val newMapping = if (methodOverrides.containsVertex(ref)) {
+            val methodRef = DepthFirstIterator(methodOverrides, ref).asSequence().firstOrNull() ?: ref
+            target.getOrCreateMethodMapping(methodRef.methodName, methodRef.methodDesc).also {
                 it.deobfuscatedName = left.deobfuscatedName
             }
         } else {
+            target.getOrCreateMethodMapping(left.signature).also {
+                it.deobfuscatedName = left.deobfuscatedName
+            }
+        }
+
+        return MergeResult(newMapping)
+        /*
+        val newMapping = target.getOrCreateMethodMapping(left.signature).also {
+            it.deobfuscatedName = left.deobfuscatedName
+        }
+
+        // Check if Spigot calls this mapping something else
+        val synthMethods = synths[left.parent.fullObfuscatedName]?.get(left.obfuscatedDescriptor)
+        val newName = synthMethods?.get(left.obfuscatedName)
+        return if (newName != null) {
+            // Spigot does call this mapping something else, we need to find it first
+            val newLeftMapping = left.parentClass.getMethodMapping(MethodSignature(newName, left.descriptor)).orNull
+            val newMapping = if (newLeftMapping != null) {
+                // We found it, use it for the left side instead
+                target.getOrCreateMethodMapping(newLeftMapping.signature).also {
+                    it.deobfuscatedName = left.deobfuscatedName
+                }
+            } else {
+                // Can't find the name spigot uses, check the hierarchy
+
+                val methodRef = MethodRef(newMapping.parent.obfuscatedName, newMapping.obfuscatedName, newMapping.descriptor.toString())
+
                 target.getOrCreateMethodMapping(left.signature).also {
                     it.deobfuscatedName = newName
                 }
             }
+
+            val methodRef = MethodRef(newMapping.parent.obfuscatedName, newMapping.obfuscatedName, newMapping.descriptor.toString())
+            if (methodOverrides.containsVertex(methodRef)) {
+                for ((superClass, superName, superDesc) in BreadthFirstIterator(methodOverrides, methodRef)) {
+
+                }
+            }
             MergeResult(newMapping)
         } else {
+            // normal mapping
             val newMapping = target.getOrCreateMethodMapping(left.signature).also {
                 it.deobfuscatedName = left.deobfuscatedName
             }
             return MergeResult(newMapping)
         }
+         */
     }
     override fun addLeftMethodMapping(
         left: MethodMapping,
         target: ClassMapping<*, *>,
         context: MergeContext
     ): MergeResult<MethodMapping?> {
+        val ref = MethodRef.from(left.parent.obfuscatedName, left.signature)
+        val newMapping = if (methodOverrides.containsVertex(ref)) {
+            val methodRef = DepthFirstIterator(methodOverrides, ref).asSequence().firstOrNull() ?: ref
+            target.getOrCreateMethodMapping(methodRef.methodName, methodRef.methodDesc).also {
+                it.deobfuscatedName = left.deobfuscatedName
+            }
+        } else {
+            target.getOrCreateMethodMapping(left.signature).also {
+                it.deobfuscatedName = left.deobfuscatedName
+            }
+        }
+
+        return MergeResult(newMapping)
+
+        /*
         // Check if Spigot maps this from a synthetic method name
         var obfName: String? = null
         val synthMethods = synths[left.parent.fullObfuscatedName]?.get(left.obfuscatedDescriptor)
@@ -383,12 +437,14 @@ class SpigotMappingsMergerHandler(
         }
 
         if (obfName == null) {
+            // This mapping doesn't actually exist, drop it
             return emptyMergeResult()
         }
 
         val newMapping = target.getOrCreateMethodMapping(obfName, left.descriptor)
         newMapping.deobfuscatedName = left.deobfuscatedName
         return MergeResult(newMapping)
+         */
     }
 
     override fun addLeftFieldMapping(left: FieldMapping, target: ClassMapping<*, *>, context: MergeContext): FieldMapping? {
@@ -410,6 +466,20 @@ class SpigotMappingsMergerHandler(
         target: ClassMapping<*, *>,
         context: MergeContext
     ): MergeResult<MethodMapping?> {
+        val ref = MethodRef.from(right.parent.obfuscatedName, right.signature)
+        if (methodOverrides.containsVertex(ref)) {
+            val methodRef = DepthFirstIterator(methodOverrides, ref).asSequence().firstOrNull() ?: ref
+            val originalMapping = context.left.getClassMapping(methodRef.className).orNull
+                ?.getMethodMapping(methodRef.methodName, methodRef.methodDesc)?.orNull ?: return emptyMergeResult()
+            val newMapping = target.getOrCreateMethodMapping(right.signature).also {
+                it.deobfuscatedName = originalMapping.deobfuscatedName
+            }
+            return MergeResult(newMapping)
+        } else {
+            return emptyMergeResult()
+        }
+
+        /*
         // Check if spigot changes this method automatically
         val synthMethods = synths[right.parentClass.fullObfuscatedName]?.get(right.obfuscatedDescriptor)
         val newName = synthMethods?.get(right.obfuscatedName) ?: return emptyMergeResult()
@@ -423,6 +493,7 @@ class SpigotMappingsMergerHandler(
             newMapping.deobfuscatedName = newName
         }
         return MergeResult(newMapping)
+         */
     }
 
     private fun prependPackage(name: String): String {

src/main/kotlin/tasks/InspectVanillaJar.kt

@@ -23,11 +23,16 @@
 package io.papermc.paperweight.tasks
 
 import io.papermc.paperweight.util.AsmUtil
+import io.papermc.paperweight.util.ClassNodeCache
 import io.papermc.paperweight.util.MavenArtifact
+import io.papermc.paperweight.util.MethodRef
 import io.papermc.paperweight.util.SyntheticUtil
 import io.papermc.paperweight.util.defaultOutput
 import io.papermc.paperweight.util.file
 import io.papermc.paperweight.util.isLibraryJar
+import io.papermc.paperweight.util.writeOverrides
+import java.util.concurrent.atomic.AtomicInteger
+import java.util.jar.JarFile
 import java.util.zip.ZipFile
 import org.gradle.api.file.DirectoryProperty
 import org.gradle.api.file.RegularFileProperty
@@ -35,13 +40,15 @@ import org.gradle.api.tasks.InputDirectory
 import org.gradle.api.tasks.InputFile
 import org.gradle.api.tasks.OutputFile
 import org.gradle.api.tasks.TaskAction
-import org.objectweb.asm.ClassReader
-import org.objectweb.asm.ClassVisitor
-import org.objectweb.asm.FieldVisitor
-import org.objectweb.asm.MethodVisitor
+import org.jgrapht.graph.DefaultEdge
+import org.jgrapht.graph.SimpleDirectedGraph
+import org.jgrapht.nio.Attribute
+import org.jgrapht.nio.DefaultAttribute
+import org.jgrapht.nio.dot.DOTExporter
+import org.jgrapht.nio.dot.DOTImporter
 import org.objectweb.asm.Opcodes
 import org.objectweb.asm.Type
-import org.objectweb.asm.tree.MethodNode
+import org.objectweb.asm.tree.ClassNode
 
 abstract class InspectVanillaJar : BaseTask() {
 
@@ -59,12 +66,15 @@ abstract class InspectVanillaJar : BaseTask() {
     @get:OutputFile
     abstract val syntheticMethods: RegularFileProperty
     @get:OutputFile
+    abstract val methodOverrides: RegularFileProperty
+    @get:OutputFile
     abstract val serverLibraries: RegularFileProperty
 
     override fun init() {
         loggerFile.convention(defaultOutput("$name-loggerFields", "txt"))
         paramIndexes.convention(defaultOutput("$name-paramIndexes", "txt"))
         syntheticMethods.convention(defaultOutput("$name-syntheticMethods", "txt"))
+        methodOverrides.convention(defaultOutput("$name-methodOverrides", "json"))
     }
 
     @TaskAction
@@ -72,28 +82,32 @@ abstract class InspectVanillaJar : BaseTask() {
         val loggers = mutableListOf<LoggerFields.Data>()
         val params = mutableListOf<ParamIndexes.Data>()
         val synthMethods = mutableListOf<SyntheticMethods.Data>()
+        val overrides = SimpleDirectedGraph<MethodRef, DefaultEdge>(DefaultEdge::class.java)
 
-        var visitor: ClassVisitor
-        visitor = LoggerFields.Visitor(null, loggers)
-        visitor = ParamIndexes.Visitor(visitor, params)
-        visitor = SyntheticMethods.Visitor(visitor, synthMethods)
+        JarFile(inputJar.file).use { jarFile ->
+            val classNodeCache = ClassNodeCache(jarFile)
 
-        archives.zipTree(inputJar.file).matching {
-            include("/*.class")
-            include("/net/minecraft/**/*.class")
-        }.forEach { file ->
-            if (file.isDirectory) {
-                return@forEach
+            for (entry in jarFile.entries()) {
+                if (!entry.name.endsWith(".class")) {
+                    continue
+                }
+                if (entry.name.count { it == '/' } > 0 && !entry.name.startsWith("net/minecraft/")) {
+                    continue
                 }
-            val classData = file.readBytes()
 
-            ClassReader(classData).accept(visitor, 0)
+                val node = classNodeCache.findClass(entry.name) ?: error("No ClassNode found for known entry")
+
+                LoggerFields.Visitor.visit(node, loggers)
+                ParamIndexes.Visitor.visit(node, params)
+                SyntheticMethods.Visitor.visit(node, synthMethods)
+                MethodOverrides.Visitor.visit(node, classNodeCache, overrides)
+            }
         }
 
         val serverLibs = checkLibraries()
 
-        loggerFile.file.bufferedWriter(Charsets.UTF_8).use { writer ->
         loggers.sort()
+        loggerFile.file.bufferedWriter().use { writer ->
             for (loggerField in loggers) {
                 writer.append(loggerField.className)
                 writer.append(' ')
@@ -102,8 +116,8 @@ abstract class InspectVanillaJar : BaseTask() {
             }
         }
 
-        paramIndexes.file.bufferedWriter(Charsets.UTF_8).use { writer ->
         params.sort()
+        paramIndexes.file.bufferedWriter().use { writer ->
             for (methodData in params) {
                 writer.append(methodData.className)
                 writer.append(' ')
@@ -120,8 +134,8 @@ abstract class InspectVanillaJar : BaseTask() {
             }
         }
 
-        syntheticMethods.file.bufferedWriter(Charsets.UTF_8).use { writer ->
         synthMethods.sort()
+        syntheticMethods.file.bufferedWriter().use { writer ->
             for ((className, desc, synthName, baseName) in synthMethods) {
                 writer.append(className)
                 writer.append(' ')
@@ -134,8 +148,11 @@ abstract class InspectVanillaJar : BaseTask() {
             }
         }
 
-        serverLibraries.file.bufferedWriter(Charsets.UTF_8).use { writer ->
-            serverLibs.map { it.toString() }.sorted().forEach { artifact ->
+        writeOverrides(overrides, methodOverrides)
+
+        val libs = serverLibs.map { it.toString() }.sorted()
+        serverLibraries.file.bufferedWriter().use { writer ->
+            libs.forEach { artifact ->
                 writer.appendln(artifact)
             }
         }
@@ -173,50 +190,22 @@ abstract class InspectVanillaJar : BaseTask() {
     }
 }
 
-abstract class BaseClassVisitor(classVisitor: ClassVisitor?) : ClassVisitor(Opcodes.ASM8, classVisitor), AsmUtil {
-    protected var currentClass: String? = null
-
-    override fun visit(
-        version: Int,
-        access: Int,
-        name: String,
-        signature: String?,
-        superName: String?,
-        interfaces: Array<out String>?
-    ) {
-        this.currentClass = name
-        super.visit(version, access, name, signature, superName, interfaces)
-    }
-}
-
 /*
  * SpecialSource2 automatically maps all Logger fields to the name LOGGER, without needing mappings defined, so we need
  * to make a note of all of those fields
  */
 object LoggerFields {
-    class Visitor(
-        classVisitor: ClassVisitor?,
-        private val fields: MutableList<Data>
-    ) : BaseClassVisitor(classVisitor) {
+    object Visitor : AsmUtil {
 
-        override fun visitField(
-            access: Int,
-            name: String,
-            descriptor: String,
-            signature: String?,
-            value: Any?
-        ): FieldVisitor? {
-            val ret = super.visitField(access, name, descriptor, signature, value)
-            val className = currentClass ?: return ret
-
-            if (Opcodes.ACC_STATIC !in access || Opcodes.ACC_FINAL !in access) {
-                return ret
+        fun visit(node: ClassNode, fields: MutableList<Data>) {
+            for (field in node.fields) {
+                if (Opcodes.ACC_STATIC !in field.access || Opcodes.ACC_FINAL !in field.access) {
+                    continue
+                }
+                if (field.desc == "Lorg/apache/logging/log4j/Logger;") {
+                    fields += Data(node.name, field.name)
                 }
-            if (descriptor != "Lorg/apache/logging/log4j/Logger;") {
-                return ret
             }
-            fields += Data(className, name)
-            return ret
         }
     }
 
@@ -235,31 +224,20 @@ object LoggerFields {
  * actual bytecode to translate the LVT-based indexes back to 0-based param indexes.
  */
 object ParamIndexes {
-    class Visitor(
-        classVisitor: ClassVisitor?,
-        private val methods: MutableList<Data>
-    ) : BaseClassVisitor(classVisitor) {
+    object Visitor : AsmUtil {
 
-        override fun visitMethod(
-            access: Int,
-            name: String,
-            descriptor: String,
-            signature: String?,
-            exceptions: Array<out String>?
-        ): MethodVisitor? {
-            val ret = super.visitMethod(access, name, descriptor, signature, exceptions)
-            val className = currentClass ?: return ret
-
-            val isStatic = access and Opcodes.ACC_STATIC != 0
+        fun visit(node: ClassNode, methods: MutableList<Data>) {
+            for (method in node.methods) {
+                val isStatic = Opcodes.ACC_STATIC in method.access
                 var currentIndex = if (isStatic) 0 else 1
 
-            val types = Type.getArgumentTypes(descriptor)
+                val types = Type.getArgumentTypes(method.desc)
                 if (types.isEmpty()) {
-                return ret
+                    continue
                 }
 
                 val params = ArrayList<ParamTarget>(types.size)
-            val data = Data(className, name, descriptor, params)
+                val data = Data(node.name, method.name, method.desc, params)
                 methods += data
 
                 for (i in types.indices) {
@@ -272,8 +250,7 @@ object ParamIndexes {
                         currentIndex++
                     }
                 }
-
-            return ret
+            }
         }
     }
 
@@ -303,45 +280,20 @@ object ParamIndexes {
  * can handle it in our generated mappings.
  */
 object SyntheticMethods {
-    class Visitor(
-        classVisitor: ClassVisitor?,
-        private val methods: MutableList<Data>
-    ) : BaseClassVisitor(classVisitor) {
+    object Visitor : AsmUtil {
 
-        override fun visitMethod(
-            access: Int,
-            name: String,
-            descriptor: String,
-            signature: String?,
-            exceptions: Array<out String>?
-        ): MethodVisitor? {
-            val ret = super.visitMethod(access, name, descriptor, signature, exceptions)
-            val className = currentClass ?: return ret
-
-            if (Opcodes.ACC_SYNTHETIC !in access || Opcodes.ACC_BRIDGE in access || name.contains('$')) {
-                return ret
+        fun visit(node: ClassNode, methods: MutableList<Data>) {
+            for (method in node.methods) {
+                if (Opcodes.ACC_SYNTHETIC !in method.access || Opcodes.ACC_BRIDGE in method.access || method.name.contains('$')) {
+                    continue
                 }
 
-            return SynthMethodVisitor(access, name, descriptor, signature, exceptions, className, methods)
-        }
-    }
+                val (baseName, baseDesc) = SyntheticUtil.findBaseMethod(method, node.name)
 
-    private class SynthMethodVisitor(
-        access: Int,
-        name: String,
-        descriptor: String,
-        signature: String?,
-        exceptions: Array<out String>?,
-        private val className: String,
-        private val methods: MutableList<Data>
-    ) : MethodNode(Opcodes.ASM9, access, name, descriptor, signature, exceptions) {
-
-        override fun visitEnd() {
-            val (baseName, baseDesc) = SyntheticUtil.findBaseMethod(this, className)
-
-            if (baseName != name || baseDesc != desc) {
+                if (baseName != method.name || baseDesc != method.desc) {
                     // Add this method as a synthetic for baseName
-                methods += Data(className, baseDesc, name, baseName)
+                    methods += Data(node.name, baseDesc, method.name, baseName)
+                }
             }
         }
     }
@@ -362,3 +314,68 @@ object SyntheticMethods {
         )
     }
 }
+
+/*
+ * There's no direct marker in bytecode to know if a
+ */
+object MethodOverrides {
+    object Visitor : AsmUtil {
+
+        fun visit(
+            node: ClassNode,
+            classNodeCache: ClassNodeCache,
+            methodOverrides: SimpleDirectedGraph<MethodRef, DefaultEdge>
+        ) {
+            val superMethods = collectSuperMethods(node, classNodeCache)
+
+            val disqualifiedMethods = Opcodes.ACC_STATIC or Opcodes.ACC_PRIVATE
+            for (method in node.methods) {
+                if (method.access in disqualifiedMethods) {
+                    continue
+                }
+
+                if (method.name == "<init>" || method.name == "<clinit>") {
+                    continue
+                }
+                val (name, desc) = SyntheticUtil.findBaseMethod(method, node.name)
+
+                superMethods[method.name + method.desc]?.let { className ->
+                    val targetMethod = node.methods.firstOrNull { it.name == name && it.desc == desc } ?: method
+
+                    val methodRef = MethodRef(node.name, method.name, method.desc)
+                    val targetMethodRef = MethodRef(className, targetMethod.name, targetMethod.desc)
+                    methodOverrides.addVertex(methodRef)
+                    methodOverrides.addVertex(targetMethodRef)
+                    methodOverrides.addEdge(methodRef, targetMethodRef)
+                }
+            }
+        }
+
+        private fun collectSuperMethods(node: ClassNode, classNodeCache: ClassNodeCache): Map<String, String> {
+            fun collectSuperMethods(node: ClassNode, superMethods: HashMap<String, String>) {
+                val supers = listOfNotNull(node.superName, *node.interfaces.toTypedArray())
+                if (supers.isEmpty()) {
+                    return
+                }
+
+                val disqualifiedMethods = Opcodes.ACC_STATIC or Opcodes.ACC_PRIVATE
+                val superNodes = supers.mapNotNull { classNodeCache.findClass(it) }
+                for (superNode in superNodes) {
+                    superNode.methods.asSequence()
+                        .filter { method -> method.access !in disqualifiedMethods }
+                        .filter { method -> method.name != "<init>" && method.name != "<clinit>" }
+                        .map { method -> method.name + method.desc to superNode.name }
+                        .toMap(superMethods)
+                }
+
+                for (superNode in superNodes) {
+                    collectSuperMethods(superNode, superMethods)
+                }
+            }
+
+            val result = hashMapOf<String, String>()
+            collectSuperMethods(node, result)
+            return result
+        }
+    }
+}

src/main/kotlin/util/ClassNodeCache.kt

@@ -0,0 +1,53 @@
+package io.papermc.paperweight.util
+
+import java.util.jar.JarFile
+import java.util.zip.ZipEntry
+import org.objectweb.asm.ClassReader
+import org.objectweb.asm.Opcodes
+import org.objectweb.asm.tree.ClassNode
+
+class ClassNodeCache(private val jarFile: JarFile, private val fallbackJar: JarFile? = null) {
+
+    private val classNodeMap = hashMapOf<String, ClassNode?>()
+
+    fun findClass(name: String): ClassNode? {
+        return classNodeMap.computeIfAbsent(normalize(name)) { fileName ->
+            val classData = findClassData(fileName) ?: return@computeIfAbsent null
+            val classReader = ClassReader(classData)
+            val node = ClassNode(Opcodes.ASM9)
+            classReader.accept(node, 0)
+            return@computeIfAbsent node
+        }
+    }
+
+    private fun findClassData(className: String): ByteArray? {
+        val entry = ZipEntry(className)
+        return (
+                jarFile.getInputStream(entry) // remapped class
+                    ?: fallbackJar?.getInputStream(entry) // library class
+                    ?: ClassLoader.getSystemResourceAsStream(className) // JDK class
+                )?.use { it.readBytes() }
+    }
+
+    private fun normalize(name: String): String {
+        var workingName = name
+        if (workingName.endsWith(".class")) {
+            workingName = workingName.substring(0, workingName.length - 6)
+        }
+
+        var startIndex = 0
+        var endIndex = workingName.length
+        if (workingName.startsWith('L')) {
+            startIndex = 1
+        }
+        if (workingName.endsWith(';')) {
+            endIndex--
+        }
+
+        return workingName.substring(startIndex, endIndex).replace('.', '/') + ".class"
+    }
+
+    fun clear() {
+        classNodeMap.clear()
+    }
+}

src/main/kotlin/util/Methodref.kt

@@ -0,0 +1,40 @@
+package io.papermc.paperweight.util
+
+import org.cadixdev.bombe.type.signature.MethodSignature
+import org.jgrapht.Graph
+import org.jgrapht.graph.DefaultEdge
+import org.jgrapht.graph.SimpleDirectedGraph
+import org.jgrapht.nio.dot.DOTImporter
+import org.jgrapht.nio.gml.GmlExporter
+import org.jgrapht.nio.gml.GmlImporter
+import org.jgrapht.nio.json.JSONExporter
+import org.jgrapht.nio.json.JSONImporter
+
+data class MethodRef(val className: String, val methodName: String, val methodDesc: String) {
+    companion object {
+        fun from(className: String, sig: MethodSignature): MethodRef {
+            return MethodRef(className, sig.name, sig.descriptor.toString())
+        }
+    }
+}
+
+fun writeOverrides(graph: Graph<MethodRef, DefaultEdge>, file: Any) {
+    val exporter = JSONExporter<MethodRef, DefaultEdge> { ref -> "${ref.className} ${ref.methodName} ${ref.methodDesc}" }
+    file.convertToFile().bufferedWriter().use { writer ->
+        exporter.exportGraph(graph, writer)
+    }
+}
+
+fun readOverrides(file: Any): SimpleDirectedGraph<MethodRef, *> {
+    val importer = JSONImporter<MethodRef, DefaultEdge>()
+    importer.setVertexFactory {
+        val (className, methodName, methodDesc) = it.split(" ")
+        MethodRef(className, methodName, methodDesc)
+    }
+    val overrides = SimpleDirectedGraph<MethodRef, DefaultEdge>(DefaultEdge::class.java)
+    file.convertToFile().bufferedReader().use { reader ->
+        importer.importGraph(overrides, reader)
+    }
+
+    return overrides
+}

src/main/kotlin/util/utils.kt

@@ -168,16 +168,21 @@ fun <T> emptyMergeResult(): MergeResult<T?> {
 }
 
 // We have to create our own task delegate because the ones Gradle provides don't work in plugin dev environments
-inline fun <reified T : Task> TaskContainer.registering(noinline configure: T.() -> Unit): TaskDelegateProvider<T> {
+inline fun <reified T : Task> TaskContainer.registering(noinline configure: (T.() -> Unit)? = null): TaskDelegateProvider<T> {
     return TaskDelegateProvider(this, T::class, configure)
 }
 class TaskDelegateProvider<T : Task>(
     private val container: TaskContainer,
     private val type: KClass<T>,
-    private val configure: T.() -> Unit
+    private val configure: (T.() -> Unit)?
 ) {
     operator fun provideDelegate(thisRef: Any?, property: KProperty<*>): TaskDelegate<T> {
-        val provider = container.register(property.name, type.java, configure)
+        val provider = if (configure != null) {
+            container.register(property.name, type.java, configure)
+        } else {
+            container.register(property.name, type.java) {
+            }
+        }
         return TaskDelegate(provider)
     }
 }