Add protection against large network channel lists

Better optimize the scanning for object holders by unrolling streams.

.gitattributes

@@ -3,6 +3,7 @@
 *.patch text eol=lf
 *.java text eol=lf
 *.gradle text eol=crlf
+**/MANIFEST.MF text eol=crlf
 *.png binary
 *.gif binary
 *.exe binary

.github/workflows/publish.yml

@@ -0,0 +1,28 @@
+name: Publish
+
+on:
+  push:
+    branches: [ '1.21.5' ]
+
+permissions:
+  contents: read
+
+jobs:
+  build:
+    uses: MinecraftForge/SharedActions/.github/workflows/gradle.yml@main
+    with:
+      java: 21
+      gradle_setup: './gradlew setup'
+      gradle_tasks: 'build publish'
+      artifact_name: 'forge'
+    secrets:
+      DISCORD_WEBHOOK: ${{ secrets.DISCORD_WEBHOOK }}
+      PROMOTE_ARTIFACT_WEBHOOK: ${{ secrets.PROMOTE_ARTIFACT_WEBHOOK }}
+      PROMOTE_ARTIFACT_USERNAME: ${{ secrets.PROMOTE_ARTIFACT_USERNAME }}
+      PROMOTE_ARTIFACT_PASSWORD: ${{ secrets.PROMOTE_ARTIFACT_PASSWORD }}
+      MAVEN_USER: ${{ secrets.MAVEN_USER }}
+      MAVEN_PASSWORD: ${{ secrets.MAVEN_PASSWORD }}
+      SIGN_KEY_ALIAS: ${{ secrets.SIGN_KEY_ALIAS }}
+      SIGN_KEY_PASSWORD: ${{ secrets.SIGN_KEY_PASSWORD }}
+      SIGN_KEYSTORE_PASSWORD: ${{ secrets.SIGN_KEYSTORE_PASSWORD }}
+      SIGN_KEYSTORE_DATA: ${{ secrets.SIGN_KEYSTORE_DATA }}

.github/workflows/pull_request_review.yml

@@ -7,7 +7,7 @@ jobs:
     name: Upload payload
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/upload-artifact@v3 # Payload artifact is consumed in Actionable
+      - uses: actions/upload-artifact@v4 # Payload artifact is consumed in Actionable
         with:
           name: payload
           path: ${{ github.event_path }}

.github/workflows/pull_request_review_comment.yml

@@ -7,7 +7,7 @@ jobs:
     name: Upload payload
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/upload-artifact@v3 # Payload artifact is consumed in Actionable
+      - uses: actions/upload-artifact@v4 # Payload artifact is consumed in Actionable
         with:
           name: payload
           path: ${{ github.event_path }}

.gitignore

@@ -26,7 +26,6 @@
 /projects/mcp/
 /projects/clean/
 /projects/forge/
-#/patches/*
 
 #occupational hazards
 /projects/**/build/
@@ -35,20 +34,15 @@
 /projects/**/*.launch
 /repo/
 src/*/generated/**/.cache/
+
 # Generated by gradle every import
 **/src/main/resources/META-INF/MANIFEST.MF
 /fmlloader/src/main/resources/forge_version.json
 
-#Patch rejects
-#/patches-/
-#*.patch.rej
-#/projects/*/rejects/
-
-# FML changelog
-changelog.txt
-*.py
-*.7z
-/logs/
-
 /ForgeRoot.ipr
 /ForgeRoot.iws
+
+# APT stuff
+/*/.gitignore
+/*/.factorypath
+/*/.apt_generated/

.teamcity/pom.xml

@@ -1,104 +0,0 @@
-<?xml version="1.0"?>
-<project>
-  <modelVersion>4.0.0</modelVersion>
-  <name>MinecraftForge_Forge Config DSL Script</name>
-  <groupId>MinecraftForge_Forge</groupId>
-  <artifactId>MinecraftForge_Forge_dsl</artifactId>
-  <version>1.0-SNAPSHOT</version>
-
-  <parent>
-    <groupId>org.jetbrains.teamcity</groupId>
-    <artifactId>configs-dsl-kotlin-parent</artifactId>
-    <version>1.0-SNAPSHOT</version>
-  </parent>
-
-  <repositories>
-    <repository>
-      <id>jetbrains-all</id>
-      <url>https://download.jetbrains.com/teamcity-repository</url>
-      <snapshots>
-        <enabled>true</enabled>
-      </snapshots>
-    </repository>
-    <repository>
-      <id>teamcity-server</id>
-      <url>https://teamcity.minecraftforge.net/app/dsl-plugins-repository</url>
-      <snapshots>
-        <enabled>true</enabled>
-      </snapshots>
-    </repository>
-  </repositories>
-
-  <pluginRepositories>
-    <pluginRepository>
-      <id>JetBrains</id>
-      <url>https://download.jetbrains.com/teamcity-repository</url>
-    </pluginRepository>
-  </pluginRepositories>
-
-  <build>
-    <sourceDirectory>${basedir}</sourceDirectory>
-    <plugins>
-      <plugin>
-        <artifactId>kotlin-maven-plugin</artifactId>
-        <groupId>org.jetbrains.kotlin</groupId>
-        <version>${kotlin.version}</version>
-
-        <configuration/>
-        <executions>
-          <execution>
-            <id>compile</id>
-            <phase>process-sources</phase>
-            <goals>
-              <goal>compile</goal>
-            </goals>
-          </execution>
-          <execution>
-            <id>test-compile</id>
-            <phase>process-test-sources</phase>
-            <goals>
-              <goal>test-compile</goal>
-            </goals>
-          </execution>
-        </executions>
-      </plugin>
-      <plugin>
-        <groupId>org.jetbrains.teamcity</groupId>
-        <artifactId>teamcity-configs-maven-plugin</artifactId>
-        <version>${teamcity.dsl.version}</version>
-        <configuration>
-          <format>kotlin</format>
-          <dstDir>target/generated-configs</dstDir>
-        </configuration>
-      </plugin>
-    </plugins>
-  </build>
-
-  <dependencies>
-    <dependency>
-      <groupId>org.jetbrains.teamcity</groupId>
-      <artifactId>configs-dsl-kotlin</artifactId>
-      <version>${teamcity.dsl.version}</version>
-      <scope>compile</scope>
-    </dependency>
-    <dependency>
-      <groupId>org.jetbrains.teamcity</groupId>
-      <artifactId>configs-dsl-kotlin-plugins</artifactId>
-      <version>1.0-SNAPSHOT</version>
-      <type>pom</type>
-      <scope>compile</scope>
-    </dependency>
-    <dependency>
-      <groupId>org.jetbrains.kotlin</groupId>
-      <artifactId>kotlin-stdlib-jdk8</artifactId>
-      <version>${kotlin.version}</version>
-      <scope>compile</scope>
-    </dependency>
-    <dependency>
-      <groupId>org.jetbrains.kotlin</groupId>
-      <artifactId>kotlin-script-runtime</artifactId>
-      <version>${kotlin.version}</version>
-      <scope>compile</scope>
-    </dependency>
-  </dependencies>
-</project>

.teamcity/settings.kts

@@ -1,193 +0,0 @@
-import jetbrains.buildServer.configs.kotlin.v2019_2.*
-import jetbrains.buildServer.configs.kotlin.v2019_2.projectFeatures.githubIssues
-import jetbrains.buildServer.configs.kotlin.*
-import jetbrains.buildServer.configs.kotlin.v2019_2.buildSteps.gradle
-
-/*
-The settings script is an entry point for defining a TeamCity
-project hierarchy. The script should contain a single call to the
-project() function with a Project instance or an init function as
-an argument.
-
-VcsRoots, BuildTypes, Templates, and subprojects can be
-registered inside the project using the vcsRoot(), buildType(),
-template(), and subProject() methods respectively.
-
-To debug settings scripts in command-line, run the
-
-    mvnDebug org.jetbrains.teamcity:teamcity-configs-maven-plugin:generate
-
-command and attach your debugger to the port 8000.
-
-To debug in IntelliJ Idea, open the 'Maven Projects' tool window (View
--> Tool Windows -> Maven Projects), find the generate task node
-(Plugins -> teamcity-configs -> teamcity-configs:generate), the
-'Debug' option is available in the context menu for the task.
-*/
-
-version = "2021.2"
-
-project {
-
-    buildType(Build)
-    buildType(BuildSecondaryBranches)
-    buildType(PullRequests)
-    buildType(PullRequestChecks)
-    buildType(PullRequestCompatibility)
-
-    params {
-        text("docker_jdk_version", "17", label = "Gradle version", description = "The version of the JDK to use during execution of tasks in a JDK.", display = ParameterDisplay.HIDDEN, allowEmpty = false)
-        text("docker_gradle_version", "7.5.1", label = "Gradle version", description = "The version of Gradle to use during execution of Gradle tasks.", display = ParameterDisplay.HIDDEN, allowEmpty = false)
-        text("git_main_branch", "1.20.x", label = "Git Main Branch", description = "The git main or default branch to use in VCS operations.", display = ParameterDisplay.HIDDEN, allowEmpty = false)
-        text("git_branch_spec", """
-                +:refs/heads/(main*)
-                +:refs/heads/(master*)
-                +:refs/heads/(develop|release|staging|main|master)
-                +:refs/heads/(1.*)
-            """.trimIndent(), label = "The branch specification of the repository", description = "By default all main branches are build by the configuration. Modify this value to adapt the branches build.", display = ParameterDisplay.HIDDEN, allowEmpty = true)
-        text("github_repository_name", "MinecraftForge", label = "The github repository name. Used to connect to it in VCS Roots.", description = "This is the repository slug on github. So for example `MinecraftForge` or `MinecraftForge`. It is interpolated into the global VCS Roots.", display = ParameterDisplay.HIDDEN, allowEmpty = false)
-        text("env.PUBLISHED_JAVA_ARTIFACT_ID", "forge", label = "Published artifact id", description = "The maven coordinate artifact id that has been published by this build. Can not be empty.", allowEmpty = false)
-        text("env.PUBLISHED_JAVA_GROUP", "net.minecraftforge", label = "Published group", description = "The maven coordinate group that has been published by this build. Can not be empty.", allowEmpty = false)
-        //These are references and not actually keys
-        password("env.CROWDIN_KEY", "credentialsJSON:a3102dbe-805d-4177-9f54-3d2c2eb08fd5", display = ParameterDisplay.HIDDEN)
-        password("env.KEYSTORE_URL", "credentialsJSON:a7ae1c82-8058-4061-8d12-7f6bc2618d2e", display = ParameterDisplay.HIDDEN)
-        password("env.KEYSTORE_PASSWORD", "credentialsJSON:d7b964e3-a1fd-47a8-b892-6f601fe47479", display = ParameterDisplay.HIDDEN)
-        text("additional_publishing_gradle_parameters", "-PcrowdinKey=%env.CROWDIN_KEY% -PkeystoreKeyPass=%env.KEYSTORE_PASSWORD% -PkeystoreStorePass=%env.KEYSTORE_PASSWORD% -Pkeystore=%env.KEYSTORE_URL%", label = "Additional gradle parameters for publish", description = "Contains the additional gradle parameters used during publishing.", display = ParameterDisplay.HIDDEN, allowEmpty = true)
-
-        checkbox("should_execute_build", "false", label = "Should build", description = "Indicates if the build task should be executed.", display = ParameterDisplay.HIDDEN,
-            checked = "true", unchecked = "false")
-        checkbox("should_execute_test", "false", label = "Should build", description = "Indicates if the build task should be executed.", display = ParameterDisplay.HIDDEN,
-            checked = "true", unchecked = "false")
-    }
-
-    features {
-        githubIssues {
-            id = "MinecraftForge_MinecraftForge__IssueTracker"
-            displayName = "MinecraftForge/MinecraftForge"
-            repositoryURL = "https://github.com/MinecraftForge/MinecraftForge"
-        }
-    }
-}
-
-object Build : BuildType({
-    templates(AbsoluteId("MinecraftForge_SetupGradleUtilsCiEnvironmen"), AbsoluteId("MinecraftForge_BuildWithDiscordNotifications"), AbsoluteId("MinecraftForge_BuildMainBranches"), AbsoluteId("MinecraftForge_SetupProjectUsingGradle"), AbsoluteId("MinecraftForge_BuildUsingGradle"), AbsoluteId("MinecraftForge_PublishProjectUsingGradle"), AbsoluteId("MinecraftForge_TriggersStaticFilesWebpageGenerator"))
-    id("MinecraftForge_MinecraftForge__Build")
-    name = "Build"
-    description = "Builds and Publishes the main branches of the project."
-})
-
-object BuildSecondaryBranches : BuildType({
-    templates(AbsoluteId("MinecraftForge_ExcludesBuildingDefaultBranch"), AbsoluteId("MinecraftForge_SetupGradleUtilsCiEnvironmen"), AbsoluteId("MinecraftForge_BuildWithDiscordNotifications"), AbsoluteId("MinecraftForge_BuildMainBranches"), AbsoluteId("MinecraftForge_SetupProjectUsingGradle"), AbsoluteId("MinecraftForge_BuildUsingGradle"))
-    id("MinecraftForge_MinecraftForge__BuildSecondaryBranches")
-    name = "Build - Secondary Branches"
-    description = "Builds and Publishes the secondary branches of the project."
-    params {
-        text("git_branch_spec", """
-                +:refs/heads/(*)
-                -:refs/heads/noci*
-            """.trimIndent(), label = "The branch specification of the repository", description = "By default all main branches are build by the configuration. Modify this value to adapt the branches build.", display = ParameterDisplay.HIDDEN, allowEmpty = true)
-    }
-    vcs {
-        branchFilter = """
-            +:*
-            -:1.*
-            -:<default>
-        """.trimIndent()
-    }
-})
-
-object PullRequests : BuildType({
-    templates(AbsoluteId("MinecraftForge_BuildPullRequests"), AbsoluteId("MinecraftForge_SetupGradleUtilsCiEnvironmen"), AbsoluteId("MinecraftForge_BuildWithDiscordNotifications"), AbsoluteId("MinecraftForge_SetupProjectUsingGradle"), AbsoluteId("MinecraftForge_BuildUsingGradle"))
-    id("MinecraftForge_MinecraftForge__PullRequests")
-    name = "Pull Requests"
-    description = "Builds pull requests for the project"
-
-    params {
-        checkbox("should_execute_build", "true", label = "Should build", description = "Indicates if the build task should be executed.", display = ParameterDisplay.HIDDEN,
-            checked = "true", unchecked = "false")
-        text(
-            "gradle_build_task",
-            "assemble",
-            label = "Gradle build task to execute during build",
-            description = "Determines the build task that is executed to build the project.",
-            display = ParameterDisplay.HIDDEN,
-            allowEmpty = false
-        )
-    }
-
-    vcs {
-        branchFilter = """
-            +:*
-            -:1.*
-            -:<default>
-        """.trimIndent()
-    }
-})
-
-object PullRequestChecks : BuildType({
-    templates(AbsoluteId("MinecraftForge_BuildPullRequests"), AbsoluteId("MinecraftForge_SetupGradleUtilsCiEnvironmen"), AbsoluteId("MinecraftForge_BuildWithDiscordNotifications"), AbsoluteId("MinecraftForge_SetupProjectUsingGradle"))
-    id("MinecraftForge_MinecraftForge__PullRequestChecks")
-    name = "Pull Requests (Checks)"
-    description = "Checks pull requests for the project"
-
-    steps {
-        gradle {
-            name = "Check"
-            id = "RUNNER_10_Check"
-
-            tasks = "checkAll"
-            gradleParams = "--continue %gradle_custom_args%"
-            enableStacktrace = true
-            dockerImage = "%docker_gradle_image%"
-            dockerRunParameters = """
-                -v "/opt/cache/agent/gradle:/home/gradle/.gradle"
-                -v "/opt/cache/shared/gradle:/home/gradle/rocache:ro"
-                --network=host
-                -u 1000:1000
-                %docker_additional_args%
-            """.trimIndent()
-        }
-    }
-
-    vcs {
-        branchFilter = """
-            +:*
-            -:1.*
-            -:<default>
-        """.trimIndent()
-    }
-})
-
-object PullRequestCompatibility : BuildType({
-    templates(AbsoluteId("MinecraftForge_BuildPullRequests"), AbsoluteId("MinecraftForge_SetupGradleUtilsCiEnvironmen"), AbsoluteId("MinecraftForge_BuildWithDiscordNotifications"), AbsoluteId("MinecraftForge_SetupProjectUsingGradle"))
-    id("MinecraftForge_MinecraftForge__PullRequestCompatibility")
-    name = "Pull Requests (Compatibility)"
-    description = "Validates binary compatibility for pull requests made to the project"
-
-    steps {
-        gradle {
-            name = "Validate"
-            id = "RUNNER_10_Compatibility"
-
-            tasks = "checkJarCompatibility"
-            gradleParams = "--continue %gradle_custom_args%"
-            enableStacktrace = true
-            dockerImage = "%docker_gradle_image%"
-            dockerRunParameters = """
-                -v "/opt/cache/agent/gradle:/home/gradle/.gradle"
-                -v "/opt/cache/shared/gradle:/home/gradle/rocache:ro"
-                --network=host
-                -u 1000:1000
-                %docker_additional_args%
-            """.trimIndent()
-        }
-    }
-
-    vcs {
-        branchFilter = """
-            +:*
-            -:1.*
-            -:<default>
-        """.trimIndent()
-    }
-})

CREDITS.txt

@@ -1,65 +0,0 @@
-Minecraft Forge: Credits/Thank You
-
-Forge is a set of tools and modifications to the Minecraft base game code to assist 
-mod developers in creating new and exciting content. It has been in development for 
-several years now, but I would like to take this time thank a few people who have 
-helped it along its way.
-
-First, the people who originally created the Forge projects way back in Minecraft 
-alpha. Eloraam of RedPower, and SpaceToad of Buildcraft, without their acceptiance 
-of me taking over the project, who knows what Minecraft modding would be today.
-
-Secondly, someone who has worked with me, and developed some of the core features
-that allow modding to be as functional, and as simple as it is, cpw. For developing
-FML, which stabilized the client and server modding ecosystem. As well as the base
-loading system that allows us to modify Minecraft's code as elegently as possible.
-
-Mezz, who has stepped up as the issue and pull request manager. Helping to keep me
-sane as well as guiding the community into creating better additions to Forge.
-
-Searge, Bspks, Fesh0r, ProfMobious, and all the rest over on the MCP team {of which 
-I am a part}. For creating some of the core tools needed to make Minecraft modding 
-both possible, and as stable as can be.
-  On that note, here is some specific information of the MCP data we use:
-    * Minecraft Coder Pack (MCP) *
-      Forge Mod Loader and Minecraft Forge have permission to distribute and automatically 
-      download components of MCP and distribute MCP data files. This permission is not 
-      transitive and others wishing to redistribute the Minecraft Forge source independently
-      should seek permission of MCP or remove the MCP data files and request their users 
-      to download MCP separately.
-      
-And lastly, the countless community members who have spent time submitting bug reports, 
-pull requests, and just helping out the community in general. Thank you.
-
---LexManos
-
-=========================================================================
-
-This is Forge Mod Loader.
-
-You can find the source code at all times at https://github.com/MinecraftForge/MinecraftForge/tree/1.12.x/src/main/java/net/minecraftforge/fml
-
-This minecraft mod is a clean open source implementation of a mod loader for minecraft servers
-and minecraft clients.
-
-The code is authored by cpw.
-
-It began by partially implementing an API defined by the client side ModLoader, authored by Risugami.
-https://www.minecraftforum.net/topic/75440-
-This support has been dropped as of Minecraft release 1.7, as Risugami no longer maintains ModLoader.
-
-It also contains suggestions and hints and generous helpings of code from LexManos, author of MinecraftForge.
-https://minecraftforge.net/
-
-Additionally, it contains an implementation of topological sort based on that 
-published at http://keithschwarz.com/interesting/code/?dir=topological-sort
-
-It also contains code from the Maven project for performing versioned dependency
-resolution. http://maven.apache.org/
-
-It also contains a partial repackaging of the javaxdelta library from http://sourceforge.net/projects/javaxdelta/
-with credit to it's authors.
-
-Forge Mod Loader downloads components from the Minecraft Coder Pack
-(http://mcp.ocean-labs.de/index.php/Main_Page) with kind permission from the MCP team.
-

build.gradle

@@ -7,8 +7,8 @@ plugins {
     id 'net.minecraftforge.gradleutils' version '[2.3.0,2.4.0)'
     id 'eclipse'
     id 'de.undercouch.download' version '5.4.0'
-    id 'net.minecraftforge.gradle.patcher' version '[6.0.16,6.2)' apply false
-    id 'net.minecraftforge.gradle.mcp' version '[6.0.16,6.2)' apply false
+    id 'net.minecraftforge.gradle.patcher' version '[6.0.22,6.2)' apply false
+    id 'net.minecraftforge.gradle.mcp' version '[6.0.22,6.2)' apply false
     id 'net.minecraftforge.gradlejarsigner' version '1.0.4'
     id 'org.barfuin.gradle.taskinfo' version '2.1.0'
 }

buildSrc/build.gradle

@@ -4,10 +4,10 @@ repositories {
 }
 
 dependencies {
-    implementation 'org.ow2.asm:asm:9.6'
-    implementation 'org.ow2.asm:asm-tree:9.6'
-    implementation 'net.minecraftforge:srgutils:0.5.+'
+    implementation 'org.ow2.asm:asm:9.9.1'
+    implementation 'org.ow2.asm:asm-tree:9.9.1'
+    implementation 'net.minecraftforge:srgutils:0.6.2'
     implementation 'commons-io:commons-io:2.13.0'
     implementation 'com.google.code.gson:gson:2.10.1'
-    implementation 'org.eclipse.jgit:org.eclipse.jgit:6.5.0.202303070854-r'
+    implementation 'org.eclipse.jgit:org.eclipse.jgit:6.7.0.202309050840-r'
 }

buildSrc/src/main/groovy/net/minecraftforge/forge/tasks/BundleList.groovy

@@ -10,15 +10,19 @@ import java.util.zip.ZipFile
 
 abstract class BundleList extends DefaultTask {
     @InputFiles abstract ConfigurableFileCollection getConfig()
+    @InputFiles abstract ConfigurableFileCollection getConfigExtra()
     @InputFile abstract RegularFileProperty getServerBundle()
     @OutputFile abstract RegularFileProperty getOutput()
 
     BundleList() {
         config.setFrom(project.configurations.installer)
+        configExtra.setFrom(project.configurations.installerextra)
         output.convention(project.layout.buildDirectory.file("$name/output.list"))
         configure {
             dependsOn(project.tasks.universalJar)
             inputs.file(project.tasks.universalJar.archiveFile)
+            dependsOn(project.tasks.applyServerBinPatches)
+            inputs.file(project.tasks.applyServerBinPatches.output)
         }
     }
     
@@ -32,6 +36,13 @@ abstract class BundleList extends DefaultTask {
             entries.put("$info.art.group:$info.art.name", "$dep.file.sha256\t$info.name\t$info.path")
         }
 
+        resolved = project.configurations.installerextra.resolvedConfiguration.resolvedArtifacts
+        for (def dep : resolved) {
+            def info = Util.getMavenInfoFromDep(dep)
+            //println("$dep.file.sha1\t$info.name\t$info.path")
+            entries.put("$info.art.group:$info.art.name", "$dep.file.sha256\t$info.name\t$info.path")
+        }
+
         var packed = (AbstractArchiveTask) project.tasks.universalJar
         var info = Util.getMavenInfoFromTask(packed)
         def file = packed.archiveFile.get().asFile

buildSrc/src/main/groovy/net/minecraftforge/forge/tasks/BytecodePredicateFinder.groovy

@@ -3,6 +3,7 @@ package net.minecraftforge.forge.tasks
 import groovy.transform.CompileStatic
 import org.gradle.api.provider.Property
 import org.gradle.api.tasks.Internal
+import org.objectweb.asm.Opcodes
 import org.objectweb.asm.tree.ClassNode
 import org.objectweb.asm.tree.MethodNode
 
@@ -12,13 +13,19 @@ abstract class BytecodePredicateFinder extends BytecodeFinder {
     @Internal
     abstract Property<Closure<Boolean>> getPredicate()
 
-    private final Set<String> matches = new HashSet<>()
+    private final Map<String, List<String>> matches = new TreeMap<>(Comparator.naturalOrder())
 
     @Override
     protected process(ClassNode parent, MethodNode node) {
         for (final current : node.instructions) {
             if (predicate.get().call(parent, node, current)) {
-                matches.add(parent.name)
+                var methods = matches.compute(parent.name, { k, v -> v ?: new ArrayList<>() })
+
+                // only add non-synthetic methods
+                if ((node.access & Opcodes.ACC_SYNTHETIC) == 0) {
+                    methods.add(node.name + node.desc)
+                }
+
                 return
             }
         }
@@ -27,6 +34,15 @@ abstract class BytecodePredicateFinder extends BytecodeFinder {
     @Internal
     @Override
     protected Object getData() {
-        return matches.toSorted(Comparator.naturalOrder()) ?: {throw new RuntimeException('Failed to find any targets, please ensure that method names and descriptors are correct.')}()
+        var array = new ArrayList<Object>()
+        matches.forEach { c, m ->
+            {
+                array.add(
+                        'class': c,
+                        'methods': m
+                )
+            }
+        }
+        return array ?: { throw new RuntimeException('Failed to find any targets, please ensure that method names and descriptors are correct.') }()
     }
 }

buildSrc/src/main/groovy/net/minecraftforge/forge/tasks/LauncherJson.groovy

@@ -24,6 +24,7 @@ abstract class LauncherJson extends DefaultTask {
         dependsOn(project.tasks.universalJar)
         input.from(project.tasks.universalJar.archiveFile)
         input.from(project.configurations.installer)
+        input.from(project.configurations.installerextra)
         configure {
             def mc    = project.rootProject.ext.MC_VERSION
             def forge = project.rootProject.ext.FORGE_VERSION
@@ -88,6 +89,7 @@ abstract class LauncherJson extends DefaultTask {
             ]
         ])
 
+        json.libraries.addAll(getArtifacts(project.configurations.installerextra).values())
         json.libraries.addAll(getArtifacts(project.configurations.installer).values())
         Files.writeString(output.get().asFile.toPath(), new JsonBuilder(json).toPrettyString())
     }

buildSrc/src/main/groovy/net/minecraftforge/forge/tasks/checks/CheckPatches.groovy

@@ -140,7 +140,7 @@ abstract class CheckPatches extends CheckTask {
                     final nextLineChange = i + 1 < lines.size() && lines[i + 1].startsWithAny('+','-')
 
                     if (!prevLineChange && !nextLineChange) {
-                        reporter.report("Patch contains white space change in valid hunk at line ${i + 1}, file: $patchPath", false)
+                        reporter.report("Patch contains white space change in valid hunk at line ${i + 1}, file: $patchPath \n$prevLine\n$line\n${lines[i+1]}", false)
                     }
                 }
 

build_clean.gradle

@@ -61,4 +61,13 @@ eclipse.classpath.file.whenMerged {
 	def src = entries.find { it.path == 'src/main/java' }
     if (src == null) throw new IllegalStateException("You must run `setup` task before importing")
     src.entryAttributes['ignore_optional_problems'] = 'true'
+}
+
+tasks.named('genPatches').configure {
+    onlyIf { false }
+}
+
+tasks.named('extractRangeMap').configure {
+    onlyIf { false }
+    tool = 'net.minecraftforge:Srg2Source:8.1.0:fatjar'
 }

build_forge.gradle

@@ -12,9 +12,9 @@ import net.minecraftforge.gradle.common.tasks.ApplyBinPatches
 import net.minecraftforge.gradle.common.tasks.CheckJarCompatibility
 import net.minecraftforge.gradle.common.tasks.DownloadMavenArtifact
 import net.minecraftforge.gradle.common.tasks.ExtractInheritance
+import net.minecraftforge.gradle.patcher.tasks.FilterNewJar
 import net.minecraftforge.gradle.patcher.tasks.GeneratePatches
 import net.minecraftforge.gradle.userdev.tasks.RenameJar
-import net.minecraftforge.gradleutils.PomUtils
 import org.apache.tools.ant.filters.ReplaceTokens
 import org.objectweb.asm.Opcodes
 
@@ -46,6 +46,8 @@ jarSigner.autoDetect('forge')
 
 applyPatches {
     level 'WARNING'
+    failOnError = UPDATING != 'true'
+    rejects = rootProject.layout.projectDirectory.dir('rejects').asFile
 }
 
 sourceSets {
@@ -77,7 +79,6 @@ final String SPEC_VERSION = gradleutils.gitInfo.tag
 final def MCP_ARTIFACT = project(':mcp').mcp.config.get()
 
 final List<File> EXTRA_TXTS = [
-        rootProject.file('CREDITS.txt'),
         rootProject.file('LICENSE.txt'),
         rootProject.tasks.createChangelog.outputFile
 ]
@@ -88,15 +89,20 @@ ext {
 final String MAVEN_PATH = ext.MAVEN_PATH
 
 final String BINPATCH_TOOL = 'net.minecraftforge:binarypatcher:1.2.0:fatjar'
-final String INSTALLER_TOOLS = 'net.minecraftforge:installertools:1.4.0'
+final String INSTALLER_TOOLS = 'net.minecraftforge:installertools:1.4.3'
 final String FART = 'net.minecraftforge:ForgeAutoRenamingTool:1.0.6'
+final String S2S_TOOL = 'net.minecraftforge:Srg2Source:8.1.1:fatjar'
 
 configurations {
     // Don't pull all libraries, if we're missing something, add it to the installer list so the installer knows to download it.
-    bootstrap  { transitive = false }        
-    installer { 
+    bootstrap  { transitive = false }
+    installer {
         extendsFrom(bootstrap)
-        transitive = false 
+        transitive = false
+    }
+    installerextra {
+        extendsFrom(bootstrap)
+        transitive = false
     }
     api.extendsFrom(installer)
 }
@@ -110,11 +116,12 @@ dependencies {
     bootstrap(libs.securemodules) // Has Union file system in it
     bootstrap(libs.unsafe)        // Needed by securemodules
     bootstrap(libs.bundles.asm)   // Needed by securemodules
-    
+
+    implementation(libs.jopt.simple)
+
     installer(libs.bootstrap)
     installer(libs.bootstrap.api) // Needed by securemodules
     installer(libs.accesstransformers)
-    installer(libs.antlr.runtime) // Dep of AccessTransformer
     installer(libs.eventbus)
     installer(libs.typetools) // Dep of EventBus
     installer(libs.forgespi)
@@ -135,10 +142,16 @@ dependencies {
     installer(project(':lowcodelanguage'))
     installer(project(':mclanguage'))
 
+    installerextra("${MCP_ARTIFACT.group}:${MCP_ARTIFACT.name}:${MCP_ARTIFACT.version}:srg2off")
+
     runtimeOnly(libs.bootstrap)
     runtimeOnly(libs.bootstrap.dev)
 }
 
+tasks.named('extractRangeMap').configure {
+    tool = S2S_TOOL
+}
+
 patcher {
     excs.from file("$rootDir/src/main/resources/forge.exc")
     parent = project(':mcp')
@@ -167,6 +180,7 @@ patcher {
 
         forge_client_test {
             parent runs.forge_client
+            source sourceSets.test
         }
 
         forge_server {
@@ -175,14 +189,17 @@ patcher {
 
         forge_server_test {
             parent runs.forge_server
+            source sourceSets.test
         }
 
         forge_server_gametest {
             args '--launchTarget', 'forge_dev_server_gametest'
+            args '--uniqueWorld' // Unique world is used so that the world regenerates, as well as the world config isn't influenced by other runs
         }
 
         forge_server_gametest_test {
             parent runs.forge_server_gametest
+            source sourceSets.test
         }
 
         forge_data {
@@ -191,13 +208,13 @@ patcher {
                  '--all',
                  '--validate',
                  '--output', rootProject.file('src/main/generated/'),
-                 '--validate',
                  '--existing', sourceSets.main.resources.srcDirs[0],
                  '--assetsDir', downloadAssets.output,
                  '--assetIndex', "{asset_index}"
         }
 
         forge_data_test {
+            source sourceSets.test
             args '--launchTarget', 'forge_dev_data',
                  '--mod', '.+',
                  '--all',
@@ -209,6 +226,29 @@ patcher {
                  '--assetIndex', "{asset_index}"
         }
 
+        forge_client_data {
+            args '--launchTarget', 'forge_dev_client_data',
+                 '--mod', 'forge',
+                 '--all',
+                 '--output', rootProject.file('src/main/generated/'),
+                 '--existing', sourceSets.main.resources.srcDirs[0],
+                 '--assetsDir', downloadAssets.output,
+                 '--assetIndex', "{asset_index}"
+        }
+
+        forge_client_data_test {
+            source sourceSets.test
+            args '--launchTarget', 'forge_dev',
+                 '--launchEntry', 'minecraft/net.minecraft.client.data.Main',
+                 '--launchData',
+                 '--mod', '.+',
+                 '--all',
+                 '--output', rootProject.file('src/test/generated/'),
+                 '--existing', sourceSets.main.resources.srcDirs[0],
+                 '--existing', sourceSets.test.resources.srcDirs[0],
+                 '--assetsDir', downloadAssets.output,
+                 '--assetIndex', "{asset_index}"
+        }
     }
 }
 
@@ -250,11 +290,11 @@ tasks.register('downloadCrowdin', Download) {
 tasks.userdevConfig.configure {
     configurations.installer.allDependencies.forEach {
         def dep = it.toString()
-        if (it instanceof ProjectDependency) 
+        if (it instanceof ProjectDependency)
             dep = "net.minecraftforge:$it.dependencyProject.name:$it.dependencyProject.version"
         libraries.add(dep)
     }
-    
+
     inject = '' // We don't have a userdev sourceset anymore. Empty as a gradle workaround...
     runs {
         client {
@@ -266,6 +306,13 @@ tasks.userdevConfig.configure {
             args '--assetsDir', '{assets_root}'
         }
 
+        clientData {
+            environment 'MCP_MAPPINGS', '{mcp_mappings}'
+            args '--launchTarget', "forge_userdev_client_data"
+            args '--assetIndex', '{asset_index}'
+            args '--assetsDir', '{assets_root}'
+        }
+
         server {
             environment 'MCP_MAPPINGS', '{mcp_mappings}'
             property 'forge.enableGameTest', 'true'
@@ -362,33 +409,15 @@ tasks.register('extractInheritance', ExtractInheritance) {
         Files.readAllLines(rf.asFile.toPath()).stream().map(File::new).toList()
     }
 }
-tasks.register("findFieldInstanceChecks", FieldCompareFinder) {
-    jar = createJoinedSRG.output
-    output = rootProject.file('src/main/resources/coremods/field_to_instanceof.json')
-    fields {
-        /* 1.17 changed most things to use Tags. So this isn't nessasary anymore so just make an empty list
-        bows {
-            cls = 'net/minecraft/world/item/Items'
-            name = 'f_42411_'
-            replacement = 'net/minecraft/world/item/BowItem'
-        }
-        crossbows {
-            cls = 'net/minecraft/world/item/Items'
-            name = 'f_42717_'
-            replacement = 'net/minecraft/world/item/CrossbowItem'
-        }
-        */
-    }
-}
 tasks.register("findFinalizeSpawnTargets", BytecodePredicateFinder) {
-    jar = createJoinedSRG.output
+    jar = createClientOfficial.output
     output = rootProject.file('src/main/resources/coremods/finalize_spawn_targets.json')
     predicate = {
         parent, node, insn ->
-            'net/minecraft/world/level/BaseSpawner' != parent.name // Ignore this class as we special case it.
-            && insn.getOpcode() === Opcodes.INVOKEVIRTUAL
-            && insn.name == 'm_6518_'
-            && insn.desc == '(Lnet/minecraft/world/level/ServerLevelAccessor;Lnet/minecraft/world/DifficultyInstance;Lnet/minecraft/world/entity/MobSpawnType;Lnet/minecraft/world/entity/SpawnGroupData;Lnet/minecraft/nbt/CompoundTag;)Lnet/minecraft/world/entity/SpawnGroupData;'
+            return 'net/minecraft/world/level/BaseSpawner' != parent.name // Ignore this class as we special case it.
+            && insn.getOpcode().equals(Opcodes.INVOKEVIRTUAL)
+            && insn.name == 'finalizeSpawn'
+            && insn.desc == '(Lnet/minecraft/world/level/ServerLevelAccessor;Lnet/minecraft/world/DifficultyInstance;Lnet/minecraft/world/entity/EntitySpawnReason;Lnet/minecraft/world/entity/SpawnGroupData;)Lnet/minecraft/world/entity/SpawnGroupData;';
     }
 }
 tasks.register('validateDeprecations', ValidateDeprecations) {
@@ -406,16 +435,6 @@ tasks.register("downloadServerShim", DownloadMavenArtifact) {
     artifact = libs.bootstrap.shim.get().toString()
     changing = true
 }
-tasks.register("downloadMCPConfig", DownloadMavenArtifact) {
-    artifact = MCP_ARTIFACT
-}
-tasks.register('extractMCPConfigMappings', net.minecraftforge.gradle.common.tasks.JarExec) {
-    ext.output = file('build/mcp_mappings.tsrg')
-    tool = INSTALLER_TOOLS + ':fatjar'
-    args = ['--task', 'MCP_DATA', '--key', 'mappings', '--input', downloadMCPConfig.output.get().asFile.absolutePath, '--output', output.absolutePath]
-    outputs.file(output)
-    inputs.file(downloadMCPConfig.output)
-}
 tasks.register('downloadClientMappings', net.minecraftforge.gradle.common.tasks.JarExec) {
     ext.output = file('build/client_mappings.tsrg')
     tool = INSTALLER_TOOLS + ':fatjar'
@@ -428,43 +447,34 @@ tasks.register('downloadServerMappings', net.minecraftforge.gradle.common.tasks.
     args = ['--task', 'DOWNLOAD_MOJMAPS', '--sanitize', '--version', MC_VERSION, '--side', 'server', '--output', output.absolutePath]
     outputs.file(output)
 }
-tasks.register('mergeClientMappings', net.minecraftforge.gradle.common.tasks.JarExec) {
-    ext.output = file('build/client_mappings_merged.tsrg')
-    tool = INSTALLER_TOOLS + ':fatjar'
-    args = ['--task', 'MERGE_MAPPING', '--classes', '--reverse-right', '--left', extractMCPConfigMappings.output.absolutePath, '--right', downloadClientMappings.output.absolutePath, '--output', output.absolutePath]
-    outputs.file(output)
-}
-tasks.register('mergeServerMappings', net.minecraftforge.gradle.common.tasks.JarExec) {
-    ext.output = file('build/server_mappings_merged.tsrg')
-    tool = INSTALLER_TOOLS + ':fatjar'
-    args = ['--task', 'MERGE_MAPPING', '--classes', '--reverse-right', '--left', extractMCPConfigMappings.output.absolutePath, '--right', downloadServerMappings.output.absolutePath, '--output', output.absolutePath]
-    outputs.file(output)
-}
 tasks.register("createJoinedSRG", DownloadMavenArtifact) {
     artifact = "net.minecraft:joined:${MC_VERSION}-${MCP_VERSION}:srg"
 }
-tasks.register("createClientSRG", RenameJar) {
+tasks.register("createClientOfficial", RenameJar) {
     tool = FART + ':all'
-    args = ['--input', '{input}', '--output', '{output}', '--names', '{mappings}', '--ann-fix', '--ids-fix', '--src-fix', '--record-fix', '--strip-sigs']
-    mappings = createMcp2Srg.srg
-    dependsOn(downloadClientRaw)
+    args = ['--input', '{input}', '--output', '{output}', '--names', '{mappings}', '--ann-fix', '--ids-fix', '--src-fix', '--record-fix', '--strip-sigs', '--reverse']
+    mappings = downloadClientMappings.output
+    dependsOn(downloadClientRaw, downloadClientMappings)
     input = downloadClientRaw.dest
-    output = file("build/createClientSRG/output.jar")
+    output = file("build/createClientOfficial/output.jar")
 }
-tasks.register("createServerSRG", RenameJar) {
+tasks.register("createServerOfficial", RenameJar) {
     tool = FART + ':all'
-    args = ['--input', '{input}', '--output', '{output}', '--names', '{mappings}', '--ann-fix', '--ids-fix', '--src-fix', '--record-fix', '--strip-sigs']
-    mappings = createMcp2Srg.srg
+    args = ['--input', '{input}', '--output', '{output}', '--names', '{mappings}', '--ann-fix', '--ids-fix', '--src-fix', '--record-fix', '--strip-sigs', '--reverse']
+    mappings = downloadServerMappings.output
+    dependsOn(downloadServerMappings)
     input = extractServer.output
-    output = file("build/createServerSRG/output.jar")
+    output = file("build/createServerOfficial/output.jar")
 }
 tasks.named('genClientBinPatches').configure {
     tool = BINPATCH_TOOL
-    cleanJar = createClientSRG.output
+    cleanJar = createClientOfficial.output
+    dirtyJar = jar.archiveFile
 }
 tasks.named('genServerBinPatches').configure {
     tool = BINPATCH_TOOL
-    cleanJar = createServerSRG.output
+    cleanJar = createServerOfficial.output
+    dirtyJar = jar.archiveFile
 }
 tasks.named('genJoinedBinPatches').configure {
     tool = BINPATCH_TOOL
@@ -472,13 +482,13 @@ tasks.named('genJoinedBinPatches').configure {
 }
 tasks.register('applyClientBinPatches', ApplyBinPatches) {
     tool = BINPATCH_TOOL
-    clean = createClientSRG.output
+    clean = createClientOfficial.output
     patch = genClientBinPatches.output
     args.addAll(['--data', '--unpatched'])
 }
 tasks.register('applyServerBinPatches', ApplyBinPatches) {
     tool = BINPATCH_TOOL
-    clean = createServerSRG.output
+    clean = createServerOfficial.output
     patch = genServerBinPatches.output
     args.addAll(['--data', '--unpatched'])
 }
@@ -494,10 +504,10 @@ tasks.register('createServerShimClasspath', BundleList) {
 tasks.register('createServerShimConfig') {
     ext.output = file('build/libs/bootstrap-shim.properties')
     doLast {
-        def cfg = new CleanProperties()
-        cfg."Main-Class" = 'net.minecraftforge.bootstrap.ForgeBootstrap'
-        cfg."Java-Version" = '17'
-        cfg."Arguments" = "--launchTarget forge_server"
+        var cfg = new CleanProperties()
+        cfg['Main-Class'] = 'net.minecraftforge.bootstrap.ForgeBootstrap'
+        cfg['Java-Version'] = '21'
+        cfg['Arguments'] = '--launchTarget forge_server'
         cfg.store(output)
     }
 }
@@ -512,7 +522,7 @@ tasks.register('serverShimJar', Jar) {
         from {
             zipTree(downloadServerShim.output).find { it.name == 'MANIFEST.MF' }
         }
-        
+
         attributes('Class-Path': configurations.bootstrap.resolvedConfiguration.resolvedArtifacts.collect { "libraries/${Util.getMavenInfoFromDep(it).path}" }.join(' '))
     }
     archiveClassifier = 'shim'
@@ -523,7 +533,7 @@ tasks.register('checkAll') {
     group = 'checks'
 }
 tasks.register('checkAllAndFix') {
-    dependsOn 'findFinalizeSpawnTargets', 'findFieldInstanceChecks', 'checkLicenses'
+    dependsOn 'findFinalizeSpawnTargets', 'checkLicenses'
     group = 'checks'
 }
 
@@ -605,7 +615,7 @@ tasks.register('checkJarCompatibility', CheckJarCompatibility) {
     baseLibraries.from(project.tasks.named('createJoinedSRG').flatMap { it.output })
 
     inputJar = project.tasks.named('reobfJar').flatMap { it.output }
-    
+
     commonLibraries.from(project.configurations.minecraftImplementation)
     commonLibraries.from(project.configurations.installer)
 }
@@ -626,26 +636,20 @@ tasks.register('launcherJson', LauncherJson).configure {
 
 tasks.register('installerJson', InstallerJson) {
     icon = rootProject.file('icon.ico')
-    
+
     // Json to install into the client's launcher
     dependsOn(launcherJson)
     input.from(launcherJson.output)
-    
-    // Extract MCP Mappings
-    dependsOn(extractMCPConfigMappings)
-    input.from(extractMCPConfigMappings.output)
+
     // Download Official Mappings
     dependsOn(downloadClientMappings, downloadServerMappings)
     input.from(downloadClientMappings.output, downloadServerMappings.output)
-    // Merge MCP and Official Mappings
-    dependsOn(mergeClientMappings, mergeServerMappings)
-    input.from(mergeClientMappings.output, mergeServerMappings.output)
     // Get 'base' MC jar, Client is straight download, server is extracted from the bundle
     dependsOn(downloadClientRaw, extractServer)
     input.from(downloadClientRaw.dest, extractServer.output)
     // Rename MC Jar
-    dependsOn(createClientSRG, createServerSRG)
-    input.from(createClientSRG.output, createServerSRG.output)
+    dependsOn(createClientOfficial, createServerOfficial)
+    input.from(createClientOfficial.output, createServerOfficial.output)
     // Apply Binary patches to vanilla jar
     dependsOn(applyClientBinPatches, applyServerBinPatches)
     input.from(applyClientBinPatches.output, applyServerBinPatches.output, genClientBinPatches.toolJar)
@@ -663,30 +667,14 @@ tasks.register('installerJson', InstallerJson) {
             minecraft: MC_VERSION,
             serverJarPath: '{LIBRARY_DIR}/net/minecraft/server/{MINECRAFT_VERSION}/server-{MINECRAFT_VERSION}-bundled.jar',
             data: [
-                MAPPINGS: [
-                    client: "[${MCP_ARTIFACT.group}:${MCP_ARTIFACT.name}:${MCP_ARTIFACT.version}:mappings@tsrg]",
-                    server: "[${MCP_ARTIFACT.group}:${MCP_ARTIFACT.name}:${MCP_ARTIFACT.version}:mappings@tsrg]"
-                ],
-                MAPPINGS_SHA: [
-                    client: "'${extractMCPConfigMappings.output.sha1}'",
-                    server: "'${extractMCPConfigMappings.output.sha1}'"
-                ],
                 MOJMAPS: [
-                    client: "[net.minecraft:client:${MC_VERSION}-${MCP_VERSION}:mappings@tsrg]",
-                    server: "[net.minecraft:server:${MC_VERSION}-${MCP_VERSION}:mappings@tsrg]"
+                    client: "[net.minecraft:client:${MC_VERSION}:mappings@tsrg]",
+                    server: "[net.minecraft:server:${MC_VERSION}:mappings@tsrg]"
                 ],
                 MOJMAPS_SHA: [
                     client: "'${downloadClientMappings.output.sha1}'",
                     server: "'${downloadServerMappings.output.sha1}'"
                 ],
-                MERGED_MAPPINGS: [
-                    client: "[${MCP_ARTIFACT.group}:${MCP_ARTIFACT.name}:${MCP_ARTIFACT.version}:mappings-merged@tsrg]",
-                    server: "[${MCP_ARTIFACT.group}:${MCP_ARTIFACT.name}:${MCP_ARTIFACT.version}:mappings-merged@tsrg]"
-                ],
-                MERGED_MAPPINGS_SHA: [
-                    client: "'${mergeClientMappings.output.sha1}'",
-                    server: "'${mergeServerMappings.output.sha1}'"
-                ],
                 MC_UNPACKED: [
                     client: "[net.minecraft:client:${MC_VERSION}]",
                     server: "[net.minecraft:server:${MC_VERSION}:unpacked]"
@@ -695,13 +683,13 @@ tasks.register('installerJson', InstallerJson) {
                     client: "'${downloadClientRaw.dest.sha1}'",
                     server: "'${extractServer.output.get().asFile.sha1}'"
                 ],
-                MC_SRG: [
-                    client: "[net.minecraft:client:${MC_VERSION}-${MCP_VERSION}:srg]",
-                    server: "[net.minecraft:server:${MC_VERSION}-${MCP_VERSION}:srg]"
+                MC_OFF: [
+                    client: "[net.minecraft:client:${MC_VERSION}:official]",
+                    server: "[net.minecraft:server:${MC_VERSION}:official]"
                 ],
-                MC_SRG_SHA: [
-                    client: "'${createClientSRG.output.get().asFile.sha1}'",
-                    server: "'${createServerSRG.output.get().asFile.sha1}'"
+                MC_OFF_SHA: [
+                    client: "'${createClientOfficial.output.get().asFile.sha1}'",
+                    server: "'${createServerOfficial.output.get().asFile.sha1}'"
                 ],
                 BINPATCH: [
                     client: '/data/client.lzma',
@@ -768,18 +756,6 @@ tasks.register('installerJson', InstallerJson) {
                     outputs: [
                         '{MC_UNPACKED}': '{MC_UNPACKED_SHA}'
                     ]
-                ], [
-                    jar: INSTALLER_TOOLS,
-                    classpath: INSTALLER_TOOLS_CLASSPATH,
-                    args: [
-                        '--task', 'MCP_DATA',
-                        '--input', "[${MCP_ARTIFACT.descriptor}]",
-                        '--output', '{MAPPINGS}',
-                        '--key', 'mappings'
-                    ],
-                    outputs: [
-                        '{MAPPINGS}': '{MAPPINGS_SHA}'
-                    ]
                 ], [
                     jar: INSTALLER_TOOLS,
                     classpath: INSTALLER_TOOLS_CLASSPATH,
@@ -793,31 +769,18 @@ tasks.register('installerJson', InstallerJson) {
                     outputs: [
                         '{MOJMAPS}': '{MOJMAPS_SHA}'
                     ]
-                ], [
-                    jar: INSTALLER_TOOLS,
-                    classpath: INSTALLER_TOOLS_CLASSPATH,
-                    args: [
-                        '--task', 'MERGE_MAPPING',
-                        '--left', '{MAPPINGS}',
-                        '--right', '{MOJMAPS}',
-                        '--output', '{MERGED_MAPPINGS}',
-                        '--classes', '--reverse-right'
-                    ],
-                    outputs: [
-                        '{MERGED_MAPPINGS}': '{MERGED_MAPPINGS_SHA}'
-                    ]
                 ], [
                     sides: ['server'],
                     jar: FART,
                     classpath: getClasspath(project, libs, FART),
                     args: [
                         '--input', '{MC_UNPACKED}',
-                        '--output', '{MC_SRG}',
-                        '--names', '{MERGED_MAPPINGS}',
-                        '--ann-fix', '--ids-fix', '--src-fix', '--record-fix', '--strip-sigs'
+                        '--output', '{MC_OFF}',
+                        '--names', '{MOJMAPS}',
+                        '--ann-fix', '--ids-fix', '--src-fix', '--record-fix', '--strip-sigs', '--reverse'
                     ],
                     outputs: [
-                        '{MC_SRG}': '{MC_SRG_SHA}'
+                        '{MC_OFF}': '{MC_OFF_SHA}'
                     ]
                 ], [
                     sides: ['client'],
@@ -825,18 +788,18 @@ tasks.register('installerJson', InstallerJson) {
                     classpath: getClasspath(project, libs, FART),
                     args: [
                         '--input', '{MINECRAFT_JAR}',
-                        '--output', '{MC_SRG}',
-                        '--names', '{MERGED_MAPPINGS}',
-                        '--ann-fix', '--ids-fix', '--src-fix', '--record-fix', '--strip-sigs'
+                        '--output', '{MC_OFF}',
+                        '--names', '{MOJMAPS}',
+                        '--ann-fix', '--ids-fix', '--src-fix', '--record-fix', '--strip-sigs', '--reverse'
                     ],
                     outputs: [
-                        '{MC_SRG}': '{MC_SRG_SHA}'
+                        '{MC_OFF}': '{MC_OFF_SHA}'
                     ]
                 ], [
                     jar: BINPATCH_TOOL.rsplit(':', 1)[0], // remove :fatjar
                     classpath: getClasspath(project, libs, BINPATCH_TOOL.rsplit(':', 1)[0]),
                     args: [
-                        '--clean', '{MC_SRG}',
+                        '--clean', '{MC_OFF}',
                         '--output', '{PATCHED}',
                         '--apply', '{BINPATCH}',
                         '--data', '--unpatched'
@@ -851,6 +814,27 @@ tasks.register('installerJson', InstallerJson) {
     }
 }
 
+tasks.register('officialClassesOnly', Zip).configure {
+    dependsOn(jar)
+    destinationDirectory = file('build/libs')
+    archiveClassifier = 'official-classes'
+    from zipTree(jar.archiveFile).matching {
+        include '**/*.class'
+        exclude 'mcp/**'
+    }
+}
+
+tasks.named('filterJarNew').configure {
+    dependsOn('officialClassesOnly')
+    input = officialClassesOnly.archiveFile
+}
+
+tasks.register('filterJarNewSRG', FilterNewJar).configure {
+    input = reobfJar.output
+    srg = filterJarNew.srg
+    blacklist = filterJarNew.blacklist
+}
+
 tasks.named('universalJar').configure {
     dependsOn downloadCrowdin
     from zipTree(downloadCrowdin.dest).matching {
@@ -862,6 +846,9 @@ tasks.named('universalJar').configure {
     exclude '.cache'
 
     manifest {
+        attributes([
+            'Automatic-Module-Name': 'net.minecraftforge.forge'
+        ] as LinkedHashMap)
         attributes([
             'Specification-Title':   'Forge',
             'Specification-Vendor':  'Forge Development LLC',
@@ -882,6 +869,20 @@ tasks.named('universalJar').configure {
     jarSigner.sign(it)
 }
 
+tasks.register('universalJarSrg', Jar).configure {
+    from zipTree(filterJarNewSRG.output)
+    duplicatesStrategy = DuplicatesStrategy.EXCLUDE
+    from zipTree(universalJar.archiveFile)
+    destinationDirectory = file('build/libs')
+    archiveClassifier = 'universal-srg'
+    manifest.from(universalJar.manifest)
+    jarSigner.sign(it)
+}
+
+tasks.named('userdevConfig').configure {
+    universal = "$project.group:$project.name:$project.version:universal-srg@jar"
+}
+
 tasks.register('installerJar', InstallerJar) {
     fat = !System.env.TEAMCITY_VERSION
     //offline = true
@@ -921,23 +922,31 @@ tasks.register('installerJar', InstallerJar) {
     jarSigner.sign(it)
 }
 
+final mdkGradleWrapper = tasks.register('mdkGradleWrapper', Wrapper) {
+    gradleVersion = '9.3.1'
+}
+
 tasks.register('mdkZip', Zip) {
+    dependsOn mdkGradleWrapper
+
     archiveBaseName = project.name
     archiveClassifier = 'mdk'
     archiveVersion = project.version
     destinationDirectory = file('build/libs')
 
-    from rootProject.file('gradlew')
-    from rootProject.file('gradlew.bat')
+    from mdkGradleWrapper.map(Wrapper.&getScriptFile)
+    from mdkGradleWrapper.map(Wrapper.&getBatchScript)
     from(EXTRA_TXTS)
-    from(rootProject.file('gradle/')){
-        into('gradle/')
+    into('gradle/wrapper/') {
+        from mdkGradleWrapper.map(Wrapper.&getJarFile)
+        from mdkGradleWrapper.map(Wrapper.&getPropertiesFile)
     }
     from(rootProject.file('mdk/')){
-        rootProject.file('mdk/gitignore.txt').eachLine{
+        rootProject.file('mdk/gitignore.txt').eachLine {
             if (!it.trim().isEmpty() && !it.trim().startsWith('#'))
                 exclude it
         }
+
         filter(ReplaceTokens, tokens: [
             FORGE_VERSION: FORGE_VERSION,
             FORGE_GROUP: project.group,
@@ -951,6 +960,9 @@ tasks.register('mdkZip', Zip) {
         rename 'gitignore\\.txt', '.gitignore'
         rename 'gitattributes\\.txt', '.gitattributes'
     }
+    from(rootProject.file('src/test/java/com/example/examplemod/')) {
+        into('src/main/java/com/example/examplemod/')
+    }
     from(rootProject.file('src/test/generated/mdk_datagen/')) {
         into('src/main/resources/')
         exclude '**/.cache/'
@@ -1068,6 +1080,7 @@ tasks.named('javadoc', Javadoc).configure {
 publishing {
     publications.register('mavenJava', MavenPublication).configure {
         artifact universalJar
+        artifact universalJarSrg
         artifact installerJar
         artifact mdkZip
         artifact userdevJar
@@ -1079,16 +1092,16 @@ publishing {
             name = project.name
             description = 'Modifactions to Minecraft to enable mod developers.'
             url = 'https://github.com/MinecraftForge/MinecraftForge'
-            PomUtils.setGitHubDetails(pom, 'MinecraftForge')
-            license PomUtils.Licenses.LGPLv2_1
+            gradleutils.pom.setGitHubDetails(pom, 'MinecraftForge')
+            license gradleutils.pom.Licenses.LGPLv2_1
         }
     }
-    
+
     repositories {
         maven gradleutils.publishingForgeMaven
     }
 }
 
 // Make sure we run bin compat checking during local testing.
-if (!System.env.MAVEN_USER || !System.env.MAVEN_PASSWORD)
+if ((!System.env.MAVEN_USER || !System.env.MAVEN_PASSWORD) && CHECK_COMPATIBILITY == "true")
     tasks.named('publish').configure { dependsOn(':forge:checkJarCompatibility') }

build_shared.gradle

@@ -44,6 +44,7 @@ tasks.withType(JavaCompile).configureEach {
     dependsOn 'processResources' // Needed because we merge the output of this with the output of the compile task. And gradle detects downstream tasks using the output without a hard dep
     options.encoding = 'UTF-8' // Use the UTF-8 charset for Java compilation
     options.warnings = false // Shutup deprecated for removal warnings
+    options.forkOptions.jvmArgs += '-Xmx6G' // Needed to make compiling faster, and not run out of heap space in some cases.
 }
 
 // Merge the resources and classes into the same directory. We'll need to split them at runtime because
@@ -74,3 +75,11 @@ eclipse {
     // Run when importing the project
     synchronizationTasks generateResources, copyEclipseSettings, eclipseClasspath, eclipseProject
 }
+
+idea {
+    module {
+        // IntelliJ IDEA does not do this by itself anymore...
+        downloadJavadoc = true
+        downloadSources = true
+    }
+}

docs/README.md

@@ -2,16 +2,15 @@
 
 MinecraftForge
 =============
-[![Stable Release](https://img.shields.io/badge/dynamic/json?url=https://files.minecraftforge.net/net/minecraftforge/forge/promotions_slim.json&label=Stable&prefix=1.20.2-&query=$.promos["1.20.2-recommended"]&color=brightgreen&logo=data:image/svg+xml;base64,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)][Download]
-[![Latest Release](https://img.shields.io/badge/dynamic/json?url=https://files.minecraftforge.net/net/minecraftforge/forge/promotions_slim.json&label=Latest&prefix=1.20.3-&query=$.promos["1.20.3-latest"]&color=blue&logo=data:image/svg+xml;base64,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
+[![Stable Release](https://img.shields.io/badge/dynamic/json?url=https://files.minecraftforge.net/net/minecraftforge/forge/promotions_slim.json&label=Stable&prefix=1.21.5-&query=$.promos["1.21.5-recommended"]&color=brightgreen&logo=data:image/svg+xml;base64,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)][Download]
+[![Latest Release](https://img.shields.io/badge/dynamic/json?url=https://files.minecraftforge.net/net/minecraftforge/forge/promotions_slim.json&label=Latest&prefix=1.21.5-&query=$.promos["1.21.5-latest"]&color=blue&logo=data:image/svg+xml;base64,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
 )][Download] [![Discord](https://img.shields.io/discord/313125603924639766.svg?color=%237289da&label=Discord&logo=discord&logoColor=%237289da)][Discord] [![Support](https://img.shields.io/badge/Patreon-Support-orange.svg?logo=Patreon)][Patreon]
 
 Forge is a free, open-source modding API all of your favourite mods use!
 
-| Version |    Support    |
-|---------| ------------- |
-| 1.20.x  |    Active     |
-| 1.19.x  |    Legacy     |
+| Version      | Support                     |
+|--------------|-----------------------------|
+| All versions | [Supported][Support-Policy] |
 
 * [Download]
 * [Forum]
@@ -31,6 +30,19 @@ You can download the installer for the *Recommended Build* or the
  
 For support and questions, visit [the Support Forum][Support-Forum] or [the Forge Discord server][Discord].
 
+## Required Java Versions
+
+We require the version of Java that Minecraft requires, which is currently:
+
+| Minecraft     | Java              |
+|---------------|-------------------|
+| 1.20.6+       | [21][Adoptium-21] |
+| 1.18 - 1.20.4 | [17][Adoptium-17] |
+| 1.17.1        | [16][Adoptium-16] |
+| 1.16.5-       | [8][Adoptium-8]   |
+
+**If you are on Windows and have difficulty using Java to launch JAR files, consider using [Jarfix by Johann Löfflmann][Jarfix].**
+
 # Creating Mods
 
 [See the "Getting Started" section in the Forge Documentation][Getting-Started].
@@ -58,13 +70,25 @@ Please ensure you have a valid email address associated with your GitHub account
  to use and modify. However, it costs money to run such a large project as this, so please consider 
  [becoming a patron][Patreon].*
 
+### Thanks
+[![YourKit](https://www.yourkit.com/images/yklogo.png)](https://www.yourkit.com/)
+
+YourKit for providing us accesss to their [YourKit Java Profiler] which helps identify bottlenecks and places for improvment.
+
 [Contributing]: ./CONTRIBUTING.md
 [CLA]: https://cla-assistant.io/MinecraftForge/MinecraftForge
 
 [Download]: https://files.minecraftforge.net/
 
+[Adoptium-21]: https://adoptium.net/temurin/releases/?version=21
+[Adoptium-17]: https://adoptium.net/temurin/releases/?version=17
+[Adoptium-16]: https://adoptium.net/temurin/releases/?version=16
+[Adoptium-8]: https://adoptium.net/temurin/releases/?version=8
+[Jarfix]: https://johann.loefflmann.net/en/software/jarfix/index.html
+
 [Forum]: https://forums.minecraftforge.net/
 [Support-Forum]: https://forums.minecraftforge.net/forum/18-support-bug-reports/
+[Support-Policy]: https://forums.minecraftforge.net/topic/144690-new-tiered-support-policy
 
 [Discord]: https://discord.minecraftforge.net/
 
@@ -74,3 +98,4 @@ Please ensure you have a valid email address associated with your GitHub account
 [Pull-Requests]: https://docs.minecraftforge.net/en/latest/forgedev/#making-changes-and-pull-requests
 
 [Patreon]: https://www.patreon.com/LexManos
+[YourKit Java Profiler]: https://www.yourkit.com/java/profiler/

dump.sh

@@ -0,0 +1,24 @@
+#!/usr/bin/env bash
+
+for file in $(find repo | grep --invert-match -e md5 -e sha | grep -e .jar -e .zip); do
+    file_path=$(realpath $file)
+    file_name=$(basename $file)
+    
+    echo "$file_name"
+    files=$(unzip -l $file | awk '{print $4}')
+    for f in $files; do
+        out="_actual/$file_name/$f"
+        parent=$(dirname "$out")
+        echo $out
+        
+        if [ ! -d "$parent" ]; then
+            mkdir -p "$parent"
+        fi
+            
+        if [[ $f == *.class ]]; then
+            javap -v -p jar:file://$file_path!/$f | tail -n +4 >$out.txt
+        elif [[ $f != */ && $f != "Name" && $f != "----" ]]; then
+            unzip -o -q $file $f -d _actual/$file_name
+        fi
+    done
+done

fmlcore/src/main/java/net/minecraftforge/fml/Bindings.java

@@ -9,41 +9,35 @@ import net.minecraftforge.eventbus.api.IEventBus;
 import net.minecraftforge.fml.config.IConfigEvent;
 import net.minecraftforge.fml.loading.FMLLoader;
 
-import java.util.ArrayList;
 import java.util.ServiceConfigurationError;
 import java.util.ServiceLoader;
 import java.util.function.Supplier;
 
+/**
+ * Used to allow access to certain things from the game layer
+ */
 public class Bindings {
-    private static final Bindings INSTANCE = new Bindings();
+    private Bindings() {}
 
-    private final IBindingsProvider provider;
-
-    private Bindings() {
-        var providers = new ArrayList<IBindingsProvider>(1);
-        for (var itr = ServiceLoader.load(FMLLoader.getGameLayer(), IBindingsProvider.class).iterator(); itr.hasNext(); ) {
-            try {
-                providers.add(itr.next());
-            } catch (ServiceConfigurationError sce) {
-                sce.printStackTrace();
-            }
-        }
-
-        if (providers.size() != 1)
-            throw new IllegalStateException("Could not find bindings provider: " + providers);
-
-        this.provider = providers.get(0);
-    }
+    /**
+     * The provider of the bindings
+     * @implNote May also throw a {@link ServiceConfigurationError}
+     */
+    private static final IBindingsProvider PROVIDER = ServiceLoader.load(FMLLoader.getGameLayer(), IBindingsProvider.class)
+            .findFirst().orElseThrow(() -> new IllegalStateException("Could not find bindings provider"));
 
+    /**
+     * @return A supplier of net.minecraftforge.common.MinecraftForge#EVENT_BUS
+     */
     public static Supplier<IEventBus> getForgeBus() {
-        return INSTANCE.provider.getForgeBusSupplier();
+        return PROVIDER.getForgeBusSupplier();
     }
 
     public static Supplier<I18NParser> getMessageParser() {
-        return INSTANCE.provider.getMessageParser();
+        return PROVIDER.getMessageParser();
     }
 
     public static Supplier<IConfigEvent.ConfigConfig> getConfigConfiguration() {
-        return INSTANCE.provider.getConfigConfiguration();
+        return PROVIDER.getConfigConfiguration();
     }
 }

fmlcore/src/main/java/net/minecraftforge/fml/DeferredWorkQueue.java

@@ -57,7 +57,9 @@ public class DeferredWorkQueue
         LOGGER.debug(LOADING, "Dispatching synchronous work for work queue {}: {} jobs", modLoadingStage, tasks.size());
         RuntimeException aggregate = new RuntimeException();
         Stopwatch timer = Stopwatch.createStarted();
-        tasks.forEach(t -> makeRunnable(t, Runnable::run, aggregate));
+        for (TaskInfo t : tasks) {
+            makeRunnable(t, Runnable::run, aggregate);
+        }
         timer.stop();
         if (aggregate.getSuppressed().length > 0) {
             LOGGER.fatal(
@@ -114,7 +116,7 @@ public class DeferredWorkQueue
         return future;
     }
 
-    private static class TaskInfo {
+    private static final class TaskInfo {
         private final ModContainer owner;
         private Runnable task;
         private CompletableFuture<?> future;

fmlcore/src/main/java/net/minecraftforge/fml/DistExecutor.java

@@ -25,7 +25,18 @@ import java.util.function.Supplier;
  * <li>When you want to call one thing on one side, another thing on the other and return a result {@link #safeRunForDist(Supplier, Supplier)}</li>
  * <li>When you want to run something on one side {@link #safeRunWhenOn(Dist, Supplier)}</li>
  * </ul>
+ *
+ * @deprecated Historically, this allowed for safe execution of code on the correct side by exploiting a low-level
+ * detail in Java 8, but in newer versions a simple if check is enough.
+ * <br>
+ * For example:
+ * <pre>{@code
+ * if (FMLEnvironment.dist.isClient()) {
+ *     // client code here
+ * }
+ * }</pre>
  */
+@Deprecated(since = "1.21.5", forRemoval = true)
 public final class DistExecutor
 {
     private static final Logger LOGGER = LogManager.getLogger();

fmlcore/src/main/java/net/minecraftforge/fml/IModLoadingState.java

@@ -68,13 +68,15 @@ public interface IModLoadingState {
      * @return a transition task for this state
      * @see #buildTransition(Executor, Executor, ProgressMeter, Function, Function)
      */
-    default <T extends Event & IModBusEvent>
-    Optional<CompletableFuture<Void>> buildTransition(final Executor syncExecutor,
-                                                      final Executor parallelExecutor,
-                                                      final ProgressMeter progressBar) {
+    default <T extends Event & IModBusEvent> Optional<CompletableFuture<Void>> buildTransition(
+        final Executor syncExecutor,
+        final Executor parallelExecutor,
+        final ProgressMeter progressBar
+    ) {
         return buildTransition(syncExecutor, parallelExecutor, progressBar,
-                e -> CompletableFuture.runAsync(() -> {}, e),
-                e -> CompletableFuture.runAsync(() -> {}, e));
+            e -> CompletableFuture.completedFuture(null),
+            e -> CompletableFuture.completedFuture(null)
+        );
     }
 
     /**

fmlcore/src/main/java/net/minecraftforge/fml/IModStateTransition.java

@@ -9,8 +9,6 @@ import net.minecraftforge.eventbus.api.Event;
 import net.minecraftforge.fml.event.IModBusEvent;
 import net.minecraftforge.fml.loading.progress.ProgressMeter;
 
-import java.util.ArrayList;
-import java.util.List;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.Executor;
 import java.util.function.BiFunction;
@@ -18,103 +16,67 @@ import java.util.function.Function;
 import java.util.function.Supplier;
 import java.util.stream.Stream;
 
-@SuppressWarnings("unchecked")
+import org.jetbrains.annotations.Nullable;
+
 public interface IModStateTransition {
+    /** Magic value to allow me to optimize the futures list by ignoring the default value without making old methods nullable. */
+    public static final BiFunction<Executor, ? extends EventGenerator<?>, CompletableFuture<Void>> NULL_HOOK = (e, g) -> CompletableFuture.completedFuture(null);
+
     static IModStateTransition buildNoopTransition() {
-        return new NoopTransition();
+        return ModStateTransitionHelper.NOOP;
     }
 
-    default <T extends Event & IModBusEvent>
-    CompletableFuture<Void> build(final String name,
-                                  final Executor syncExecutor,
-                                  final Executor parallelExecutor,
-                                  final ProgressMeter progressBar,
-                                  final Function<Executor, CompletableFuture<Void>> preSyncTask,
-                                  final Function<Executor, CompletableFuture<Void>> postSyncTask) {
-        List<CompletableFuture<Void>> futures = new ArrayList<>();
-
-        this.eventFunctionStream().get()
-                .map(f -> (EventGenerator<T>) f)
-                .reduce((head, tail) -> addCompletableFutureTaskForModDispatch(syncExecutor, parallelExecutor, futures, progressBar, head, ModLoadingStage::currentState, tail))
-                .ifPresent(last -> addCompletableFutureTaskForModDispatch(syncExecutor, parallelExecutor, futures, progressBar, last, nextModLoadingStage(), null));
-
-        final CompletableFuture<Void> preSyncTaskCF = preSyncTask.apply(syncExecutor);
-        final CompletableFuture<Void> eventDispatchCF = ModList.gather(futures).thenCompose(ModList::completableFutureFromExceptionList);
-        final CompletableFuture<Void> postEventDispatchCF = preSyncTaskCF
-                .thenApplyAsync(n -> {
-                    progressBar.label(progressBar.name() + ": dispatching "+name);
-                    return null;
-                }, parallelExecutor)
-                .thenComposeAsync(n -> eventDispatchCF, parallelExecutor)
-                .thenApply(r -> {
-                    postSyncTask.apply(syncExecutor);
-                    return null;
-                });
-        return this.finalActivityGenerator().apply(syncExecutor, postEventDispatchCF);
+    default CompletableFuture<Void> build(
+        final String name,
+        final Executor syncExecutor,
+        final Executor parallelExecutor,
+        final ProgressMeter progressBar,
+        final Function<Executor, CompletableFuture<Void>> preSyncTask,
+        final Function<Executor, CompletableFuture<Void>> postSyncTask
+    ) {
+        return ModStateTransitionHelper.build(this, name, syncExecutor, parallelExecutor, progressBar, preSyncTask, postSyncTask);
     }
 
     default BiFunction<ModLoadingStage, Throwable, ModLoadingStage> nextModLoadingStage() {
         return ModLoadingStage::nextState;
     }
 
-    private <T extends Event & IModBusEvent>
-    EventGenerator<T> addCompletableFutureTaskForModDispatch(final Executor syncExecutor,
-                                                             final Executor parallelExecutor,
-                                                             final List<CompletableFuture<Void>> completableFutures,
-                                                             final ProgressMeter progressBar,
-                                                             final EventGenerator<T> eventGenerator,
-                                                             final BiFunction<ModLoadingStage, Throwable, ModLoadingStage> nextState,
-                                                             final EventGenerator<T> nextGenerator) {
-        final Executor selectedExecutor = threadSelector().apply(syncExecutor, parallelExecutor);
-
-        var preDispatchHook = (BiFunction<Executor, EventGenerator<T>, CompletableFuture<Void>>) preDispatchHook();
-        completableFutures.add(preDispatchHook.apply(selectedExecutor, eventGenerator));
-
-        completableFutures.add(ModList.get().futureVisitor(eventGenerator, progressBar, nextState).apply(threadSelector().apply(syncExecutor, parallelExecutor)));
-
-        var postDispatchHook = (BiFunction<Executor, EventGenerator<T>, CompletableFuture<Void>>) postDispatchHook();
-        completableFutures.add(postDispatchHook.apply(selectedExecutor, eventGenerator));
-
-        return nextGenerator;
+    /**
+     * This used to allow you to fire multiple events during the transition. However, in doing so it would cause issues with the default
+     * ModContainer's event handlers causing issues such as mod classes being constructed multiple times.
+     */
+    @Deprecated(since = "1.21.3", forRemoval = true)
+    default Supplier<Stream<EventGenerator<?>>> eventFunctionStream() {
+        return () -> Stream.ofNullable(eventFunction());
+    }
+
+    @Nullable
+    default <T extends Event & IModBusEvent> EventGenerator<T> eventFunction() {
+        return null;
     }
 
-    Supplier<Stream<EventGenerator<?>>> eventFunctionStream();
     ThreadSelector threadSelector();
     BiFunction<Executor, CompletableFuture<Void>, CompletableFuture<Void>> finalActivityGenerator();
-    BiFunction<Executor, ? extends EventGenerator<?>, CompletableFuture<Void>> preDispatchHook();
-    BiFunction<Executor, ? extends EventGenerator<?>, CompletableFuture<Void>> postDispatchHook();
+
+    /**
+     * I think this was meant as a way to do some things for each mod container beforge/after the transition had been sent to the container.
+     * However, the Future returned by this was never linked to the main transition future in any way.  Which means that it was run
+     * in parallel and couldn't guarantee the state of the ModContainer.
+     * <p>
+     * Plus all existing code that I could find returned a completedFuture, so I don't think anyone ever used this.
+     * <p>
+     * If I were to add this back it would be a CompletableFuture wrap(ModContainer, CompletableFuture)
+     * <p>
+     * Added magic value NULL_HOOK to allow me to optimize the futures list by ignoring the default value without making this method nullable.
+     */
+    @Deprecated(since = "1.21.3", forRemoval = true)
+    default BiFunction<Executor, ? extends EventGenerator<?>, CompletableFuture<Void>> preDispatchHook() { return NULL_HOOK; }
+    @Deprecated(since = "1.21.3", forRemoval = true)
+    default BiFunction<Executor, ? extends EventGenerator<?>, CompletableFuture<Void>> postDispatchHook() { return NULL_HOOK; }
 
     interface EventGenerator<T extends Event & IModBusEvent> extends Function<ModContainer, T> {
         static <FN extends Event & IModBusEvent> EventGenerator<FN> fromFunction(Function<ModContainer, FN> fn) {
             return fn::apply;
         }
     }
-}
-
-record NoopTransition() implements IModStateTransition {
-
-    @Override
-    public Supplier<Stream<EventGenerator<?>>> eventFunctionStream() {
-        return Stream::of;
-    }
-
-    @Override
-    public ThreadSelector threadSelector() {
-        return ThreadSelector.SYNC;
-    }
-
-    @Override
-    public BiFunction<Executor, CompletableFuture<Void>, CompletableFuture<Void>> finalActivityGenerator() {
-        return (e, t) -> t.thenApplyAsync(Function.identity(), e);
-    }
-
-    @Override
-    public BiFunction<Executor, ? extends EventGenerator<?>, CompletableFuture<Void>> preDispatchHook() {
-        return (t, f)-> CompletableFuture.completedFuture(null);
-    }
-
-    @Override
-    public BiFunction<Executor, ? extends EventGenerator<?>, CompletableFuture<Void>> postDispatchHook() {
-        return (t, f)-> CompletableFuture.completedFuture(null);
-    }
 }

fmlcore/src/main/java/net/minecraftforge/fml/InterModComms.java

@@ -61,7 +61,7 @@ public class InterModComms
         }
     }
 
-    private static ConcurrentMap<String, ConcurrentLinkedQueue<IMCMessage>> containerQueues = new ConcurrentHashMap<>();
+    private static final ConcurrentMap<String, ConcurrentLinkedQueue<IMCMessage>> containerQueues = new ConcurrentHashMap<>();
 
     /**
      * Send IMC to remote. Sender will default to the active modcontainer, or minecraft if not.
@@ -115,16 +115,14 @@ public class InterModComms
         return getMessages(modId, s->Boolean.TRUE);
     }
 
-    private static class QueueFilteringSpliterator implements Spliterator<IMCMessage>
-    {
-        private final ConcurrentLinkedQueue<IMCMessage> queue;
-        private final Predicate<String> methodFilter;
-        private final Iterator<IMCMessage> iterator;
+    private record QueueFilteringSpliterator(
+            ConcurrentLinkedQueue<IMCMessage> queue,
+            Predicate<String> methodFilter,
+            Iterator<IMCMessage> iterator
+    ) implements Spliterator<IMCMessage> {
 
         public QueueFilteringSpliterator(final ConcurrentLinkedQueue<IMCMessage> queue, final Predicate<String> methodFilter) {
-            this.queue = queue;
-            this.iterator = queue.iterator();
-            this.methodFilter = methodFilter;
+            this(queue, methodFilter, queue.iterator());
         }
 
         @Override

fmlcore/src/main/java/net/minecraftforge/fml/LogicalSide.java

@@ -16,8 +16,7 @@ import net.minecraftforge.api.distmarker.Dist;
  *
  * @see Dist
  */
-public enum LogicalSide
-{
+public enum LogicalSide {
     /**
      * The logical client of the Minecraft game, which interfaces with the player's inputs and renders the player's
      * viewpoint.
@@ -27,6 +26,7 @@ public enum LogicalSide
      * @see Dist#CLIENT
      */
     CLIENT,
+
     /**
      * The logical server of the Minecraft game, responsible for connecting to clients and running the simulation logic
      * on the level.
@@ -41,16 +41,14 @@ public enum LogicalSide
     /**
      * {@return if this logical side is the server}
      */
-    public boolean isServer()
-    {
+    public boolean isServer() {
         return !isClient();
     }
 
     /**
      * {@return if the logical side is the client}
      */
-    public boolean isClient()
-    {
+    public boolean isClient() {
         return this == CLIENT;
     }
 }

fmlcore/src/main/java/net/minecraftforge/fml/ModContainer.java

@@ -9,18 +9,15 @@ import net.minecraftforge.eventbus.api.Event;
 import net.minecraftforge.fml.config.IConfigEvent;
 import net.minecraftforge.fml.config.ModConfig;
 import net.minecraftforge.fml.event.IModBusEvent;
-import net.minecraftforge.fml.loading.progress.ProgressMeter;
 import net.minecraftforge.forgespi.language.IModInfo;
 
 import java.util.EnumMap;
-import java.util.HashMap;
+import java.util.HashSet;
 import java.util.IdentityHashMap;
 import java.util.Map;
 import java.util.Objects;
 import java.util.Optional;
-import java.util.concurrent.CompletableFuture;
-import java.util.concurrent.Executor;
-import java.util.function.BiFunction;
+import java.util.Set;
 import java.util.function.BiPredicate;
 import java.util.function.Consumer;
 import java.util.function.Supplier;
@@ -33,26 +30,24 @@ import java.util.function.Supplier;
  * a mechanism by which we can wrap actual mod code so that the loader and other
  * facilities can treat mods at arms length.
  * </p>
- *
- * @author cpw
- *
  */
-
-public abstract class ModContainer
-{
+public abstract class ModContainer {
     protected final String modId;
     protected final String namespace;
     protected final IModInfo modInfo;
     protected ModLoadingStage modLoadingStage;
     protected Supplier<?> contextExtension;
-    protected final Map<ModLoadingStage, Runnable> activityMap = new HashMap<>();
+    protected final Map<ModLoadingStage, Runnable> activityMap = new EnumMap<>(ModLoadingStage.class);
     protected final Map<Class<? extends IExtensionPoint<?>>, Supplier<?>> extensionPoints = new IdentityHashMap<>();
     protected final EnumMap<ModConfig.Type, ModConfig> configs = new EnumMap<>(ModConfig.Type.class);
-    @SuppressWarnings("OptionalUsedAsFieldOrParameterType")
+    final Set<ModContainer> dependencies = new HashSet<>();
+    /**
+     * If you want to handle the event, override {@link #dispatchConfigEvent(IConfigEvent)}
+     */
+    @Deprecated(since = "1.21.3", forRemoval = true)
     protected Optional<Consumer<IConfigEvent>> configHandler = Optional.empty();
 
-    public ModContainer(IModInfo info)
-    {
+    public ModContainer(IModInfo info) {
         this.modId = info.getModId();
         // TODO: Currently not reading namespace from configuration..
         this.namespace = this.modId;
@@ -82,58 +77,35 @@ public abstract class ModContainer
     /**
      * Errored container state, used for filtering. Does nothing.
      */
-    ModContainer()
-    {
+    ModContainer() {
         this.modLoadingStage = ModLoadingStage.ERROR;
         modId = "BROKEN";
         namespace = "BROKEN";
         modInfo = null;
     }
+
     /**
      * @return the modid for this mod
      */
-    public final String getModId()
-    {
+    public final String getModId() {
         return modId;
     }
 
     /**
      * @return the resource prefix for the mod
      */
-    public final String getNamespace()
-    {
+    public final String getNamespace() {
         return namespace;
     }
 
     /**
      * @return The current loading stage for this mod
      */
-    public ModLoadingStage getCurrentState()
-    {
+    public ModLoadingStage getCurrentState() {
         return modLoadingStage;
     }
 
-    public static <T extends Event & IModBusEvent> CompletableFuture<Void> buildTransitionHandler(
-            final ModContainer target,
-            final IModStateTransition.EventGenerator<T> eventGenerator,
-            final ProgressMeter progressBar,
-            final BiFunction<ModLoadingStage, Throwable, ModLoadingStage> stateChangeHandler,
-            final Executor executor) {
-        return CompletableFuture
-                .runAsync(() -> {
-                    ModLoadingContext.get().setActiveContainer(target);
-                    target.activityMap.getOrDefault(target.modLoadingStage, ()->{}).run();
-                    target.acceptEvent(eventGenerator.apply(target));
-                }, executor)
-                .whenComplete((mc, exception) -> {
-                    target.modLoadingStage = stateChangeHandler.apply(target.modLoadingStage, exception);
-                    progressBar.increment();
-                    ModLoadingContext.get().setActiveContainer(null);
-                });
-    }
-
-    public IModInfo getModInfo()
-    {
+    public IModInfo getModInfo() {
         return modInfo;
     }
 
@@ -142,8 +114,7 @@ public abstract class ModContainer
         return Optional.ofNullable((T)extensionPoints.getOrDefault(point,()-> null).get());
     }
 
-    public <T extends Record & IExtensionPoint<T>> void registerExtensionPoint(Class<? extends IExtensionPoint<T>> point, Supplier<T> extension)
-    {
+    public <T extends Record & IExtensionPoint<T>> void registerExtensionPoint(Class<? extends IExtensionPoint<T>> point, Supplier<T> extension) {
         extensionPoints.put(point, extension);
     }
 
@@ -168,7 +139,10 @@ public abstract class ModContainer
     }
 
     public void dispatchConfigEvent(IConfigEvent event) {
-        configHandler.ifPresent(configHandler->configHandler.accept(event));
+        var handler = configHandler.orElse(null);
+        if (handler != null) {
+            handler.accept(event);
+        }
     }
 
     /**

fmlcore/src/main/java/net/minecraftforge/fml/ModList.java

@@ -5,9 +5,6 @@
 
 package net.minecraftforge.fml;
 
-import net.minecraftforge.eventbus.api.Event;
-import net.minecraftforge.fml.event.IModBusEvent;
-import net.minecraftforge.fml.loading.progress.ProgressMeter;
 import net.minecraftforge.forgespi.language.IModFileInfo;
 import net.minecraftforge.forgespi.language.IModInfo;
 import net.minecraftforge.forgespi.language.ModFileScanData;
@@ -15,27 +12,15 @@ import net.minecraftforge.fml.loading.moddiscovery.ModFile;
 import net.minecraftforge.fml.loading.moddiscovery.ModFileInfo;
 import net.minecraftforge.fml.loading.moddiscovery.ModInfo;
 import net.minecraftforge.forgespi.locating.IModFile;
-import org.apache.logging.log4j.LogManager;
-import org.apache.logging.log4j.Logger;
-
-import java.util.AbstractMap;
-import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.Collection;
+import java.util.Collections;
 import java.util.Comparator;
+import java.util.HashMap;
 import java.util.List;
 import java.util.Locale;
 import java.util.Map;
 import java.util.Objects;
 import java.util.Optional;
-import java.util.concurrent.CompletableFuture;
-import java.util.concurrent.CompletionException;
-import java.util.concurrent.CompletionStage;
-import java.util.concurrent.Executor;
-import java.util.concurrent.ForkJoinPool;
-import java.util.concurrent.ForkJoinWorkerThread;
 import java.util.function.BiConsumer;
-import java.util.function.BiFunction;
 import java.util.function.Consumer;
 import java.util.function.Function;
 import java.util.stream.Collectors;
@@ -45,27 +30,25 @@ import java.util.stream.Stream;
  * Master list of all mods - game-side version. This is classloaded in the game scope and
  * can dispatch game level events as a result.
  */
-public class ModList
-{
-    //private static final Logger LOGGER = LogManager.getLogger();
+public class ModList {
     private static ModList INSTANCE;
     private final List<IModFileInfo> modFiles;
     private final List<IModInfo> sortedList;
-    private final Map<String, ModFileInfo> fileById;
+    private final Map<String, IModFileInfo> fileById;
     private List<ModContainer> mods;
     private Map<String, ModContainer> indexedMods;
     private List<ModFileScanData> modFileScanData;
     private List<ModContainer> sortedContainers;
 
-    private ModList(final List<ModFile> modFiles, final List<ModInfo> sortedList)
-    {
-        this.modFiles = modFiles.stream().map(ModFile::getModFileInfo).map(ModFileInfo.class::cast).collect(Collectors.toList());
-        this.sortedList = sortedList.stream().
-                map(ModInfo.class::cast).
-                collect(Collectors.toList());
-        this.fileById = this.modFiles.stream().map(IModFileInfo::getMods).flatMap(Collection::stream).
-                map(ModInfo.class::cast).
-                collect(Collectors.toMap(ModInfo::getModId, ModInfo::getOwningFile));
+    private ModList(final List<ModFile> modFiles, final List<ModInfo> sortedList) {
+        this.modFiles = modFiles.stream().map(ModFile::getModFileInfo).toList();
+        this.sortedList = sortedList.stream().map(IModInfo.class::cast).toList();
+        var byId = new HashMap<String, IModFileInfo>();
+        for (var file : this.modFiles) {
+            for (var mod : file.getMods())
+                byId.put(mod.getModId(), mod.getOwningFile());
+        }
+        this.fileById = Collections.unmodifiableMap(byId);
         CrashReportCallables.registerCrashCallable("Mod List", this::crashReport);
     }
 
@@ -74,19 +57,20 @@ public class ModList
     }
 
     private String fileToLine(IModFile mf) {
+        var mainMod = mf.getModInfos().getFirst();
         return String.format(Locale.ENGLISH, "%-50.50s|%-30.30s|%-30.30s|%-20.20s|%-10.10s|Manifest: %s", mf.getFileName(),
-                mf.getModInfos().get(0).getDisplayName(),
-                mf.getModInfos().get(0).getModId(),
-                mf.getModInfos().get(0).getVersion(),
-                getModContainerState(mf.getModInfos().get(0).getModId()),
+                mainMod.getDisplayName(),
+                mainMod.getModId(),
+                mainMod.getVersion(),
+                getModContainerState(mainMod.getModId()),
                 ((ModFileInfo)mf.getModFileInfo()).getCodeSigningFingerprint().orElse("NOSIGNATURE"));
     }
+
     private String crashReport() {
         return "\n"+applyForEachModFile(this::fileToLine).collect(Collectors.joining("\n\t\t", "\t\t", ""));
     }
 
-    public static ModList of(List<ModFile> modFiles, List<ModInfo> sortedList)
-    {
+    public static ModList of(List<ModFile> modFiles, List<ModInfo> sortedList) {
         INSTANCE = new ModList(modFiles, sortedList);
         return INSTANCE;
     }
@@ -95,109 +79,47 @@ public class ModList
         return INSTANCE;
     }
 
-    private static ForkJoinWorkerThread newForkJoinWorkerThread(ForkJoinPool pool) {
-        ForkJoinWorkerThread thread = ForkJoinPool.defaultForkJoinWorkerThreadFactory.newThread(pool);
-        thread.setName("modloading-worker-" + thread.getPoolIndex());
-        // The default sets it to the SystemClassloader, so copy the current one.
-        thread.setContextClassLoader(Thread.currentThread().getContextClassLoader());
-        return thread;
-    }
-
-    public List<IModFileInfo> getModFiles()
-    {
+    public List<IModFileInfo> getModFiles() {
         return modFiles;
     }
 
-    public IModFileInfo getModFileById(String modid)
-    {
+    public IModFileInfo getModFileById(String modid) {
         return this.fileById.get(modid);
     }
 
-    <T extends Event & IModBusEvent> Function<Executor, CompletableFuture<Void>> futureVisitor(
-            final IModStateTransition.EventGenerator<T> eventGenerator,
-            final ProgressMeter progressBar,
-            final BiFunction<ModLoadingStage, Throwable, ModLoadingStage> stateChange) {
-        return executor -> gather(
-                this.mods.stream()
-                .map(mod -> ModContainer.buildTransitionHandler(mod, eventGenerator, progressBar, stateChange, executor))
-                .toList()
-        ).thenComposeAsync(ModList::completableFutureFromExceptionList, executor);
-    }
-    static CompletionStage<Void> completableFutureFromExceptionList(List<? extends Map.Entry<?, Throwable>> t) {
-        if (t.stream().noneMatch(e->e.getValue()!=null)) {
-            return CompletableFuture.completedFuture(null);
-        } else {
-            final List<Throwable> throwables = t.stream().filter(e -> e.getValue() != null).map(Map.Entry::getValue).toList();
-            CompletableFuture<Void> cf = new CompletableFuture<>();
-            final RuntimeException accumulator = new RuntimeException();
-            cf.completeExceptionally(accumulator);
-            throwables.forEach(exception -> {
-                if (exception instanceof CompletionException) {
-                    exception = exception.getCause();
-                }
-                if (exception.getSuppressed().length!=0) {
-                    Arrays.stream(exception.getSuppressed()).forEach(accumulator::addSuppressed);
-                } else {
-                    accumulator.addSuppressed(exception);
-                }
-            });
-            return cf;
-        }
-    }
-
-    static <V> CompletableFuture<List<Map.Entry<V, Throwable>>> gather(List<? extends CompletableFuture<? extends V>> futures) {
-        List<Map.Entry<V, Throwable>> list = new ArrayList<>(futures.size());
-        CompletableFuture<?>[] results = new CompletableFuture[futures.size()];
-        futures.forEach(future -> {
-            int i = list.size();
-            list.add(null);
-            results[i] = future.whenComplete((result, exception) -> list.set(i, new AbstractMap.SimpleImmutableEntry<>(result, exception)));
-        });
-        return CompletableFuture.allOf(results).handle((r, th)->null).thenApply(res -> list);
-    }
-
-    void setLoadedMods(final List<ModContainer> modContainers)
-    {
+    void setLoadedMods(final List<ModContainer> modContainers) {
         this.mods = modContainers;
-        this.sortedContainers = modContainers.stream().sorted(Comparator.comparingInt(c->sortedList.indexOf(c.getModInfo()))).toList();
+        this.sortedContainers = modContainers.stream().sorted(Comparator.comparingInt(c -> sortedList.indexOf(c.getModInfo()))).toList();
         this.indexedMods = modContainers.stream().collect(Collectors.toMap(ModContainer::getModId, Function.identity()));
     }
 
     @SuppressWarnings("unchecked")
-    public <T> Optional<T> getModObjectById(String modId)
-    {
+    public <T> Optional<T> getModObjectById(String modId) {
         return getModContainerById(modId).map(ModContainer::getMod).map(o -> (T) o);
     }
 
-    public Optional<? extends ModContainer> getModContainerById(String modId)
-    {
+    public Optional<? extends ModContainer> getModContainerById(String modId) {
         return Optional.ofNullable(this.indexedMods.get(modId));
     }
 
-    public Optional<? extends ModContainer> getModContainerByObject(Object obj)
-    {
+    public Optional<? extends ModContainer> getModContainerByObject(Object obj) {
         return mods.stream().filter(mc -> mc.getMod() == obj).findFirst();
     }
 
-    public List<IModInfo> getMods()
-    {
+    public List<IModInfo> getMods() {
         return this.sortedList;
     }
 
-    public boolean isLoaded(String modTarget)
-    {
+    public boolean isLoaded(String modTarget) {
         return this.indexedMods.containsKey(modTarget);
     }
 
-    public int size()
-    {
+    public int size() {
         return mods.size();
     }
 
-    public List<ModFileScanData> getAllScanData()
-    {
-        if (modFileScanData == null)
-        {
+    public List<ModFileScanData> getAllScanData() {
+        if (modFileScanData == null) {
             modFileScanData = this.sortedList.stream().
                     map(IModInfo::getOwningFile).
                     filter(Objects::nonNull).
@@ -210,8 +132,7 @@ public class ModList
 
     }
 
-    public void forEachModFile(Consumer<IModFile> fileConsumer)
-    {
+    public void forEachModFile(Consumer<IModFile> fileConsumer) {
         modFiles.stream().map(IModFileInfo::getFile).forEach(fileConsumer);
     }
 
@@ -227,13 +148,11 @@ public class ModList
         this.sortedContainers.forEach(containerConsumer);
     }
 
+    public List<ModContainer> getLoadedMods() {
+        return this.sortedContainers;
+    }
+
     public <T> Stream<T> applyForEachModContainer(Function<ModContainer, T> function) {
         return indexedMods.values().stream().map(function);
     }
-
-    private static class UncaughtModLoadingException extends ModLoadingException {
-        public UncaughtModLoadingException(ModLoadingStage stage, Throwable originalException) {
-            super(null, stage, "fml.modloading.uncaughterror", originalException);
-        }
-    }
 }

fmlcore/src/main/java/net/minecraftforge/fml/ModLoader.java

@@ -6,7 +6,6 @@
 package net.minecraftforge.fml;
 
 import com.google.common.collect.ImmutableList;
-import com.google.common.collect.Streams;
 import net.minecraftforge.eventbus.api.Event;
 import net.minecraftforge.fml.event.IModBusEvent;
 import net.minecraftforge.fml.loading.FMLEnvironment;
@@ -33,8 +32,6 @@ import java.util.function.BiConsumer;
 import java.util.function.Consumer;
 import java.util.function.Function;
 import java.util.stream.Collectors;
-import java.util.stream.Stream;
-
 import static net.minecraftforge.fml.Logging.CORE;
 import static net.minecraftforge.fml.Logging.LOADING;
 
@@ -74,49 +71,53 @@ import static net.minecraftforge.fml.Logging.LOADING;
  *     and completes the mod loading sequence.</dd>
  * </dl>
  */
-public class ModLoader
-{
+public class ModLoader {
     private static final Logger LOGGER = LogManager.getLogger();
-    private static ModLoader INSTANCE;
     private final LoadingModList loadingModList;
 
     private final List<ModLoadingException> loadingExceptions;
+    private final Set<IModInfo> erroredModInfos;
     private final List<ModLoadingWarning> loadingWarnings;
     private final ModStateManager stateManager;
-    private boolean loadingStateValid;
-    @SuppressWarnings("OptionalUsedAsFieldOrParameterType")
-    private final Optional<Consumer<String>> statusConsumer = StartupNotificationManager.modLoaderConsumer();
+    private static boolean loadingStateValid;
+    private final Consumer<String> statusConsumer = StartupNotificationManager.modLoaderConsumer().orElse(msg -> {});
     private final Set<IModLoadingState> completedStates = new HashSet<>();
     private ModList modList;
 
-    private ModLoader()
-    {
-        INSTANCE = this;
+    private ModLoader() {
         this.loadingModList = FMLLoader.getLoadingModList();
         this.loadingExceptions = this.loadingModList.getErrors().stream()
                 .flatMap(ModLoadingException::fromEarlyException)
-                .collect(Collectors.toList());
+                .toList();
         this.loadingWarnings = this.loadingModList.getBrokenFiles().stream()
                 .map(file -> new ModLoadingWarning(null, ModLoadingStage.VALIDATE, InvalidModIdentifier.identifyJarProblem(file.getFilePath()).orElse("fml.modloading.brokenfile"), file.getFileName()))
                 .collect(Collectors.toList());
+        if (this.loadingExceptions.isEmpty()) {
+            this.erroredModInfos = Collections.emptySet();
+        } else {
+            this.erroredModInfos = Collections.newSetFromMap(new IdentityHashMap<>());
+            this.erroredModInfos.addAll(this.loadingExceptions.stream().map(ModLoadingException::getModInfo).toList());
+        }
         this.loadingModList.getModFiles().stream()
                 .filter(ModFileInfo::missingLicense)
-                .filter(modFileInfo -> modFileInfo.getMods().stream().noneMatch(thisModInfo -> this.loadingExceptions.stream().map(ModLoadingException::getModInfo).anyMatch(otherInfo -> otherInfo == thisModInfo))) //Ignore files where any other mod already encountered an error
+                .filter(modFileInfo -> modFileInfo.getMods().stream().noneMatch(this.erroredModInfos::contains)) //Ignore files where any other mod already encountered an error
                 .map(modFileInfo -> new ModLoadingException(null, ModLoadingStage.VALIDATE, "fml.modloading.missinglicense", null, modFileInfo.getFile()))
                 .forEach(this.loadingExceptions::add);
         this.stateManager = new ModStateManager();
         CrashReportCallables.registerCrashCallable("ModLauncher", FMLLoader::getLauncherInfo);
         CrashReportCallables.registerCrashCallable("ModLauncher launch target", FMLLoader::launcherHandlerName);
         CrashReportCallables.registerCrashCallable("ModLauncher naming", FMLLoader::getNaming);
-        CrashReportCallables.registerCrashCallable("ModLauncher services", this::computeModLauncherServiceList);
-        CrashReportCallables.registerCrashCallable("FML Language Providers", this::computeLanguageList);
+        CrashReportCallables.registerCrashCallable("ModLauncher services", ModLoader::computeModLauncherServiceList);
+        CrashReportCallables.registerCrashCallable("FML Language Providers", ModLoader::computeLanguageList);
     }
 
-    private String computeLanguageList() {
-        return "\n"+FMLLoader.getLanguageLoadingProvider().applyForEach(lp->lp.name() +"@"+ lp.getClass().getPackage().getImplementationVersion()).collect(Collectors.joining("\n\t\t", "\t\t", ""));
+    private static String computeLanguageList() {
+        return "\n" + FMLLoader.getLanguageLoadingProvider()
+                .applyForEach(lp -> lp.name() + "@" + lp.getClass().getPackage().getImplementationVersion())
+                .collect(Collectors.joining("\n\t\t", "\t\t", ""));
     }
 
-    private String computeModLauncherServiceList() {
+    private static String computeModLauncherServiceList() {
         final List<Map<String, String>> mods = FMLLoader.modLauncherModList();
         return "\n"+mods.stream().map(mod->mod.getOrDefault("file","nofile")+
                 " "+mod.getOrDefault("name", "missing")+
@@ -125,9 +126,13 @@ public class ModLoader
                 collect(Collectors.joining("\n\t\t","\t\t",""));
     }
 
-    public static ModLoader get()
-    {
-        return INSTANCE == null ? INSTANCE = new ModLoader() : INSTANCE;
+    public static ModLoader get() {
+        return LazyInit.INSTANCE;
+    }
+
+    private static final class LazyInit {
+        private static final ModLoader INSTANCE = new ModLoader();
+        private LazyInit() {}
     }
 
     /**
@@ -144,21 +149,21 @@ public class ModLoader
         final ModList modList = ModList.of(loadingModList.getModFiles().stream().map(ModFileInfo::getFile).toList(),
                 loadingModList.getMods());
         if (!this.loadingExceptions.isEmpty()) {
-            LOGGER.fatal(CORE, "Error during pre-loading phase", loadingExceptions.get(0));
-            statusConsumer.ifPresent(c->c.accept("ERROR DURING MOD LOADING"));
+            LOGGER.fatal(CORE, "Error during pre-loading phase", loadingExceptions.getFirst());
+            statusConsumer.accept("ERROR DURING MOD LOADING");
             modList.setLoadedMods(Collections.emptyList());
             loadingStateValid = false;
             throw new LoadingFailedException(loadingExceptions);
         }
         List<? extends ForgeFeature.Bound> failedBounds = loadingModList.getMods().stream()
                 .map(ModInfo::getForgeFeatures)
-                .flatMap(Collection::stream)
+                .flatMap(List::stream)
                 .filter(bound -> !ForgeFeature.testFeature(FMLEnvironment.dist, bound))
                 .toList();
 
         if (!failedBounds.isEmpty()) {
             LOGGER.fatal(CORE, "Failed to validate feature bounds for mods: {}", failedBounds);
-            statusConsumer.ifPresent(c->c.accept("ERROR DURING MOD LOADING"));
+            statusConsumer.accept("ERROR DURING MOD LOADING");
             modList.setLoadedMods(Collections.emptyList());
             loadingStateValid = false;
             throw new LoadingFailedException(failedBounds.stream()
@@ -166,38 +171,67 @@ public class ModLoader
                     .toList());
         }
 
-        final List<ModContainer> modContainers = loadingModList.getModFiles().stream()
-                .map(ModFileInfo::getFile)
-                .map(this::buildMods)
-                .<ModContainer>mapMulti(Iterable::forEach)
-                .toList();
+        final var modContainers = new HashMap<String, ModContainer>();
+        for (var file : loadingModList.getModFiles()) {
+            var containers = this.buildMods(file.getFile());
+            for (var container : containers)
+                modContainers.put(container.getModId(), container);
+        }
+
         if (!loadingExceptions.isEmpty()) {
-            LOGGER.fatal(CORE, "Failed to initialize mod containers", loadingExceptions.get(0));
-            statusConsumer.ifPresent(c->c.accept("ERROR DURING MOD LOADING"));
+            LOGGER.fatal(CORE, "Failed to initialize mod containers", loadingExceptions.getFirst());
+            statusConsumer.accept("ERROR DURING MOD LOADING");
             modList.setLoadedMods(Collections.emptyList());
             loadingStateValid = false;
             throw new LoadingFailedException(loadingExceptions);
         }
-        modList.setLoadedMods(modContainers);
+
+        // Gather all dependencies, so we can make sure they have finished their transition events before we fire ours
+        for (var mod : modContainers.values()) {
+            for (var dep : mod.getModInfo().getDependencies()) {
+                var target = modContainers.get(dep.getModId());
+                if (target == null)
+                    continue;
+
+                switch (dep.getOrdering()) {
+                    case AFTER:
+                        mod.dependencies.add(target);
+                        break;
+                    case BEFORE:
+                        target.dependencies.add(mod);
+                        break;
+                    default:
+                        break;
+                }
+            }
+        }
+
+        modList.setLoadedMods(modContainers.values().stream().toList());
         this.modList = modList;
         var stateList = stateManager.getStates(ModLoadingPhase.GATHER);
-        var progress = StartupMessageManager.addProgressBar("Mod Gather", stateList.stream().mapToInt(mls -> mls.size().applyAsInt(modList)).sum());
-        stateList.forEach(mls->dispatchAndHandleError(mls, syncExecutor, parallelExecutor, periodicTask, progress));
+        var progress = StartupMessageManager.addProgressBar("Mod Gather", stateList.stream().mapToInt(mls -> mls.size().applyAsInt(this.modList)).sum());
+        for (IModLoadingState mls : stateList) {
+            dispatchAndHandleError(mls, syncExecutor, parallelExecutor, periodicTask, progress);
+        }
         progress.complete();
     }
 
     public void loadMods(final ModWorkManager.DrivenExecutor syncExecutor, final Executor parallelExecutor, final Runnable periodicTask) {
         var stateList = stateManager.getStates(ModLoadingPhase.LOAD);
         var progress = StartupMessageManager.addProgressBar("Mod Loading", stateList.stream().mapToInt(mls -> mls.size().applyAsInt(modList)).sum());
-        stateList.forEach(mls->dispatchAndHandleError(mls, syncExecutor, parallelExecutor, periodicTask, progress));
+        for (IModLoadingState mls : stateList) {
+            dispatchAndHandleError(mls, syncExecutor, parallelExecutor, periodicTask, progress);
+        }
         progress.complete();
     }
 
     public void finishMods(final ModWorkManager.DrivenExecutor syncExecutor, final Executor parallelExecutor, final Runnable periodicTask) {
         var stateList = stateManager.getStates(ModLoadingPhase.COMPLETE);
         var progress = StartupMessageManager.addProgressBar("Mod Complete", stateList.stream().mapToInt(mls -> mls.size().applyAsInt(modList)).sum());
-        stateList.forEach(mls->dispatchAndHandleError(mls, syncExecutor, parallelExecutor, periodicTask, progress));
-        statusConsumer.ifPresent(c->c.accept(String.format("Mod loading complete - %d mods loaded", this.modList.size())));
+        for (IModLoadingState mls : stateList) {
+            dispatchAndHandleError(mls, syncExecutor, parallelExecutor, periodicTask, progress);
+        }
+        statusConsumer.accept(String.format("Mod loading complete - %d mods loaded", this.modList.size()));
         progress.complete();
     }
 
@@ -206,10 +240,15 @@ public class ModLoader
             LOGGER.error("Cowardly refusing to process mod state change request from {}", state);
             return;
         }
-        progressBar.label(progressBar.name()+ " working");
+        progressBar.label(progressBar.name() + " working");
         syncExecutor.drive(ticker);
-        state.inlineRunnable().ifPresent(a->this.handleInlineTransition(a, state, syncExecutor, ticker));
-        state.buildTransition(syncExecutor, parallelExecutor, progressBar).ifPresent(t->waitForTransition(state, syncExecutor, ticker, t));
+
+        var inlineRunnable = state.inlineRunnable().orElse(null);
+        if (inlineRunnable != null) handleInlineTransition(inlineRunnable, state, syncExecutor, ticker);
+
+        var transition = state.buildTransition(syncExecutor, parallelExecutor, progressBar).orElse(null);
+        if (transition != null) waitForTransition(state, syncExecutor, ticker, transition);
+
         completedStates.add(state);
     }
 
@@ -221,10 +260,12 @@ public class ModLoader
         pb.complete();
         syncExecutor.drive(ticker);
     }
+
     private void waitForTransition(final IModLoadingState state, final ModWorkManager.DrivenExecutor syncExecutor, final Runnable ticker, final CompletableFuture<Void> transition) {
         while (!transition.isDone()) {
             syncExecutor.drive(ticker);
         }
+
         try {
             transition.join();
         } catch (CompletionException e) {
@@ -234,36 +275,38 @@ public class ModLoader
                     .anyMatch(obj -> !(obj instanceof ModLoadingException));
             if (hasNotModLoadingEx) {
                 LOGGER.fatal("Encountered non-modloading exceptions!", e);
-                statusConsumer.ifPresent(c->c.accept("ERROR DURING MOD LOADING"));
+                statusConsumer.accept("ERROR DURING MOD LOADING");
                 throw e;
             }
 
             final List<ModLoadingException> modLoadingExceptions = Arrays.stream(t.getSuppressed())
                     .filter(ModLoadingException.class::isInstance)
                     .map(ModLoadingException.class::cast)
-                    .collect(Collectors.toList());
+                    .toList();
             LOGGER.fatal(LOADING,"Failed to complete lifecycle event {}, {} errors found", state.name(), modLoadingExceptions.size());
-            statusConsumer.ifPresent(c->c.accept("ERROR DURING MOD LOADING"));
+            statusConsumer.accept("ERROR DURING MOD LOADING");
             throw new LoadingFailedException(modLoadingExceptions);
         }
     }
 
-    private List<ModContainer> buildMods(final IModFile modFile)
-    {
-        final Map<String, IModInfo> modInfoMap = modFile.getModFileInfo().getMods().stream().collect(Collectors.toMap(IModInfo::getModId, Function.identity()));
+    private List<ModContainer> buildMods(final IModFile modFile) {
+        final Map<String, IModInfo> modInfoMap = new HashMap<>();
+        for (var mod : modFile.getModFileInfo().getMods())
+            modInfoMap.put(mod.getModId(), mod);
 
         LOGGER.trace(LOADING, "ModContainer is {}", ModContainer.class.getClassLoader());
-        final List<ModContainer> containers = modFile.getScanResult().getTargets()
-                .entrySet()
-                .stream()
-                .map(e -> buildModContainerFromTOML(modFile, modInfoMap, e))
-                .filter(Objects::nonNull)
-                .toList();
+        final List<ModContainer> containers = new ArrayList<>();
+        for (var entry : modFile.getScanResult().getTargets().entrySet()) {
+            var container = buildModContainerFromTOML(modFile, modInfoMap, entry.getKey(), entry.getValue());
+            if (container != null)
+                containers.add(container);
+        }
+
         if (containers.size() != modInfoMap.size()) {
             var modIds = modInfoMap.values().stream().map(IModInfo::getModId).sorted().toList();
             var containerIds = containers.stream().map(c -> c != null ? c.getModId() : "(null)").sorted().toList();
 
-            LOGGER.fatal(LOADING,"File {} constructed {} mods: {}, but had {} mods specified: {}",
+            LOGGER.fatal(LOADING, "File {} constructed {} mods: {}, but had {} mods specified: {}",
                     modFile.getFilePath(),
                     containers.size(), containerIds,
                     modInfoMap.size(), modIds);
@@ -278,17 +321,20 @@ public class ModLoader
 
             loadingExceptions.add(new ModLoadingException(null, ModLoadingStage.CONSTRUCT, "fml.modloading.missingclasses", null, modFile.getFilePath()));
         }
+
         // remove errored mod containers
         return containers.stream().filter(mc -> mc.modLoadingStage != ModLoadingStage.ERROR).toList();
     }
 
-    private ModContainer buildModContainerFromTOML(final IModFile modFile, final Map<String, IModInfo> modInfoMap, final Map.Entry<String, ? extends IModLanguageProvider.IModLanguageLoader> idToProviderEntry) {
+    private ModContainer buildModContainerFromTOML(final IModFile modFile, final Map<String, IModInfo> modInfoMap,
+        final String modId, final IModLanguageProvider.IModLanguageLoader languageLoader
+    ) {
         try {
-            final String modId = idToProviderEntry.getKey();
-            final IModLanguageProvider.IModLanguageLoader languageLoader = idToProviderEntry.getValue();
-            IModInfo info = Optional.ofNullable(modInfoMap.get(modId)).
-                    // throw a missing metadata error if there is no matching modid in the modInfoMap from the mods.toml file
-                    orElseThrow(()->new ModLoadingException(null, ModLoadingStage.CONSTRUCT, "fml.modloading.missingmetadata", null, modId));
+            IModInfo info = modInfoMap.get(modId);
+            // throw a missing metadata error if there is no matching modid in the modInfoMap from the mods.toml file
+            if (info == null)
+                throw new ModLoadingException(null, ModLoadingStage.CONSTRUCT, "fml.modloading.missingmetadata", null, modId);
+
             return languageLoader.loadMod(info, modFile.getScanResult(), FMLLoader.getGameLayer());
         } catch (ModLoadingException mle) {
             // exceptions are caught and added to the error list for later handling
@@ -303,7 +349,7 @@ public class ModLoader
      * and don't want to cause extraneous crashes due to trying to do things that aren't possible in a "broken load"
      */
     public static boolean isLoadingStateValid() {
-        return get().loadingStateValid;
+        return loadingStateValid;
     }
 
     public boolean hasCompletedState(final String stateName) {
@@ -326,6 +372,7 @@ public class ModLoader
         }
         ModList.get().forEachModInOrder(mc -> mc.acceptEvent(e));
     }
+
     public <T extends Event & IModBusEvent> T postEventWithReturn(T e) {
         if (!loadingStateValid) {
             LOGGER.error("Cowardly refusing to send event {} to a broken mod state", e.getClass().getName());
@@ -334,9 +381,15 @@ public class ModLoader
         ModList.get().forEachModInOrder(mc -> mc.acceptEvent(e));
         return e;
     }
+
+    @SuppressWarnings("removal")
     public <T extends Event & IModBusEvent> void postEventWrapContainerInModOrder(T event) {
-        postEventWithWrapInModOrder(event, (mc, e) -> ModLoadingContext.get().setActiveContainer(mc), (mc, e) -> ModLoadingContext.get().setActiveContainer(null));
+        postEventWithWrapInModOrder(event,
+            (mc, e) -> ModLoadingContext.get().setActiveContainer(mc),
+            (mc, e) -> ModLoadingContext.get().setActiveContainer(null)
+        );
     }
+
     public <T extends Event & IModBusEvent> void postEventWithWrapInModOrder(T e, BiConsumer<ModContainer, T> pre, BiConsumer<ModContainer, T> post) {
         if (!loadingStateValid) {
             LOGGER.error("Cowardly refusing to send event {} to a broken mod state", e.getClass().getName());
@@ -349,13 +402,11 @@ public class ModLoader
         });
     }
 
-    public List<ModLoadingWarning> getWarnings()
-    {
+    public List<ModLoadingWarning> getWarnings() {
         return ImmutableList.copyOf(this.loadingWarnings);
     }
 
-    public void addWarning(ModLoadingWarning warning)
-    {
+    public void addWarning(ModLoadingWarning warning) {
         this.loadingWarnings.add(warning);
     }
 

fmlcore/src/main/java/net/minecraftforge/fml/ModLoadingContext.java

@@ -8,39 +8,57 @@ package net.minecraftforge.fml;
 import com.mojang.logging.LogUtils;
 import net.minecraftforge.fml.config.IConfigSpec;
 import net.minecraftforge.fml.config.ModConfig;
-import net.minecraftforge.fml.loading.FMLLoader;
 import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
 import java.util.function.BiPredicate;
 import java.util.function.Supplier;
 
-public class ModLoadingContext
-{
+public class ModLoadingContext {
     private static final Logger LOGGER = LogUtils.getLogger();
     private static final ThreadLocal<ModLoadingContext> context = ThreadLocal.withInitial(ModLoadingContext::new);
+    private ModContainer activeContainer;
     private Object languageExtension;
-    private ModLoadingStage stage;
 
+    /**
+     * @deprecated Use the context provided by your language loader in your mod's constructor
+     */
+    @Deprecated(forRemoval = true, since="1.21.1")
     public static ModLoadingContext get() {
         return context.get();
     }
 
-    private ModContainer activeContainer;
-
+    /**
+     * @deprecated Going to be moved to ForgeHooks for Internal use.
+     */
+    @Deprecated(forRemoval = true, since="1.21.1")
     public void setActiveContainer(final ModContainer container) {
         this.activeContainer = container;
         this.languageExtension = container == null ? null : container.contextExtension.get();
     }
 
+    /**
+     * Going to be moved to ForgeHooks for Internal use.
+     * @deprecated Override/Use {@link ModLoadingContext#getContainer()}
+     */
+    @Deprecated(forRemoval = true, since="1.21.1")
     public ModContainer getActiveContainer() {
         return activeContainer == null ? ModList.get().getModContainerById("minecraft").orElseThrow(()->new RuntimeException("Where is minecraft???!")) : activeContainer;
     }
 
+    /**
+     * @deprecated Going to be moved to ForgeHooks for Internal use.
+     */
+    @Deprecated(forRemoval = true, since="1.21.1")
     public String getActiveNamespace() {
         return activeContainer == null ? "minecraft" : activeContainer.getNamespace();
     }
 
+    /**
+     * @return {@link ModLoadingContext#getActiveContainer()} by default.
+     */
+    public ModContainer getContainer() {
+        return getActiveContainer();
+    }
+
     /**
      * Register an {@link IExtensionPoint} with the mod container.
      * @param point The extension point to register
@@ -48,7 +66,7 @@ public class ModLoadingContext
      * @param <T> The type signature of the extension operator
      */
     public <T extends Record & IExtensionPoint<T>> void registerExtensionPoint(Class<? extends IExtensionPoint<T>> point, Supplier<T> extension) {
-        getActiveContainer().registerExtensionPoint(point, extension);
+        getContainer().registerExtensionPoint(point, extension);
     }
 
     /**
@@ -57,7 +75,7 @@ public class ModLoadingContext
      * @param displayTest The {@link IExtensionPoint.DisplayTest} to register
      */
     public void registerDisplayTest(IExtensionPoint.DisplayTest displayTest) {
-        getActiveContainer().registerDisplayTest(() -> displayTest);
+        getContainer().registerDisplayTest(() -> displayTest);
     }
 
     /**
@@ -66,7 +84,7 @@ public class ModLoadingContext
      * @param displayTest The {@link Supplier<IExtensionPoint.DisplayTest>} to register
      */
     public void registerDisplayTest(Supplier<IExtensionPoint.DisplayTest> displayTest) {
-        getActiveContainer().registerDisplayTest(displayTest);
+        getContainer().registerDisplayTest(displayTest);
     }
 
     /**
@@ -76,7 +94,7 @@ public class ModLoadingContext
      * @see IExtensionPoint.DisplayTest#DisplayTest(String, BiPredicate)
      */
     public void registerDisplayTest(String version, BiPredicate<String, Boolean> remoteVersionTest) {
-        getActiveContainer().registerDisplayTest(new IExtensionPoint.DisplayTest(version, remoteVersionTest));
+        getContainer().registerDisplayTest(new IExtensionPoint.DisplayTest(version, remoteVersionTest));
     }
 
     /**
@@ -86,29 +104,29 @@ public class ModLoadingContext
      * @see IExtensionPoint.DisplayTest#DisplayTest(Supplier, BiPredicate)
      */
     public void registerDisplayTest(Supplier<String> suppliedVersion, BiPredicate<String, Boolean> remoteVersionTest) {
-        getActiveContainer().registerDisplayTest(new IExtensionPoint.DisplayTest(suppliedVersion, remoteVersionTest));
+        getContainer().registerDisplayTest(new IExtensionPoint.DisplayTest(suppliedVersion, remoteVersionTest));
     }
 
     public void registerConfig(ModConfig.Type type, IConfigSpec<?> spec) {
         if (spec.isEmpty())
         {
             // This handles the case where a mod tries to register a config, without any options configured inside it.
-            LOGGER.debug("Attempted to register an empty config for type {} on mod {}", type, getActiveContainer().getModId());
+            LOGGER.debug("Attempted to register an empty config for type {} on mod {}", type, getContainer().getModId());
             return;
         }
 
-        getActiveContainer().addConfig(new ModConfig(type, spec, getActiveContainer()));
+        getContainer().addConfig(new ModConfig(type, spec, getContainer()));
     }
 
     public void registerConfig(ModConfig.Type type, IConfigSpec<?> spec, String fileName) {
         if (spec.isEmpty())
         {
             // This handles the case where a mod tries to register a config, without any options configured inside it.
-            LOGGER.debug("Attempted to register an empty config for type {} on mod {} using file name {}", type, getActiveContainer().getModId(), fileName);
+            LOGGER.debug("Attempted to register an empty config for type {} on mod {} using file name {}", type, getContainer().getModId(), fileName);
             return;
         }
 
-        getActiveContainer().addConfig(new ModConfig(type, spec, getActiveContainer(), fileName));
+        getContainer().addConfig(new ModConfig(type, spec, getContainer(), fileName));
     }
 
 

fmlcore/src/main/java/net/minecraftforge/fml/ModLoadingState.java

@@ -26,20 +26,27 @@ import java.util.function.ToIntFunction;
  * @param inlineRunnable an optional runnable, which runs before starting the transition from this state to the next
  * @param transition     optional state transition information
  */
-public record ModLoadingState(String name, String previous,
-                              Function<ModList, String> message,
-                              ToIntFunction<ModList> size,
-                              ModLoadingPhase phase,
-                              Optional<Consumer<ModList>> inlineRunnable,
-                              Optional<IModStateTransition> transition) implements IModLoadingState {
+public record ModLoadingState(
+    String name,
+    String previous,
+    Function<ModList, String> message,
+    ToIntFunction<ModList> size,
+    ModLoadingPhase phase,
+    Optional<Consumer<ModList>> inlineRunnable,
+    Optional<IModStateTransition> transition
+) implements IModLoadingState {
     @Override
-    public <T extends Event & IModBusEvent>
-    Optional<CompletableFuture<Void>> buildTransition(final Executor syncExecutor,
-                                                      final Executor parallelExecutor,
-                                                      final ProgressMeter progressBar,
-                                                      final Function<Executor, CompletableFuture<Void>> preSyncTask,
-                                                      final Function<Executor, CompletableFuture<Void>> postSyncTask) {
-        return transition.map(t -> t.build(name, syncExecutor, parallelExecutor, progressBar, preSyncTask, postSyncTask));
+    public <T extends Event & IModBusEvent> Optional<CompletableFuture<Void>> buildTransition(
+        final Executor syncExecutor,
+        final Executor parallelExecutor,
+        final ProgressMeter progressBar,
+        final Function<Executor, CompletableFuture<Void>> preSyncTask,
+        final Function<Executor, CompletableFuture<Void>> postSyncTask
+    ) {
+        var transition = this.transition.orElse(null);
+        return transition == null
+                ? Optional.empty()
+                : Optional.ofNullable(transition.build(name, syncExecutor, parallelExecutor, progressBar, preSyncTask, postSyncTask));
     }
 
     /**
@@ -49,9 +56,12 @@ public record ModLoadingState(String name, String previous,
      * @param name     the name of the state
      * @param previous the name of the immediately previous state to this state
      * @param phase    the mod loading phase the state belongs to
+     *
+     * @deprecated Use the builder
      */
+    @Deprecated(since = "1.21.3", forRemoval = true)
     public static ModLoadingState empty(final String name, final String previous, final ModLoadingPhase phase) {
-        return new ModLoadingState(name, previous, ml -> "", f->0, phase, Optional.empty(), Optional.empty());
+        return of(name, phase).after(previous).empty();
     }
 
     /**
@@ -62,11 +72,13 @@ public record ModLoadingState(String name, String previous,
      * @param previous   the name of the immediately previous state to this state
      * @param phase      the mod loading phase the state belongs to
      * @param transition the state transition information
-     * @return a mod loading state with state transition information and a default message
+     *
+     * @deprecated Use the builder
      */
+    @Deprecated(since = "1.21.3", forRemoval = true)
     public static ModLoadingState withTransition(final String name, final String previous, final ModLoadingPhase phase,
                                                  final IModStateTransition transition) {
-        return new ModLoadingState(name, previous, ml -> "Processing transition " + name, ModList::size, phase, Optional.empty(), Optional.of(transition));
+        return of(name, phase).after(previous).withTransition(transition);
     }
 
     /**
@@ -78,11 +90,14 @@ public record ModLoadingState(String name, String previous,
      * @param phase      the mod loading phase the state belongs to
      * @param transition the state transition information
      * @return a mod loading state with state transition information and a custom message
+     *
+     * @deprecated Use the builder
      */
+    @Deprecated(since = "1.21.3", forRemoval = true)
     public static ModLoadingState withTransition(final String name, final String previous,
                                                  final Function<ModList, String> message, final ModLoadingPhase phase,
                                                  final IModStateTransition transition) {
-        return new ModLoadingState(name, previous, message, ModList::size, phase, Optional.empty(), Optional.of(transition));
+        return of(name, phase).after(previous).message(message).withTransition(transition);
     }
 
     /**
@@ -94,9 +109,59 @@ public record ModLoadingState(String name, String previous,
      * @param phase    the mod loading phase the state belongs to
      * @param inline   an optional runnable, which runs before starting the transition from this state to the next
      * @return a mod loading state with an inline runnable and default message
+     *
+     * @deprecated Use the builder
      */
+    @Deprecated(since = "1.21.3", forRemoval = true)
     public static ModLoadingState withInline(final String name, final String previous, final ModLoadingPhase phase,
                                              final Consumer<ModList> inline) {
-        return new ModLoadingState(name, previous, ml -> "Processing work " + name, ml->0, phase, Optional.of(inline), Optional.empty());
+        return of(name, phase).after(previous).withInline(inline);
+    }
+
+    public static Builder of(final String name, final ModLoadingPhase phase) {
+        return new Builder(name, phase);
+    }
+
+    public static class Builder {
+        private final String name;
+        private final ModLoadingPhase phase;
+        private String after;
+        private Function<ModList, String> message = null;
+        private ToIntFunction<ModList> size = null;
+
+        private Builder(final String name, final ModLoadingPhase phase) {
+            this.name = name;
+            this.phase = phase;
+        }
+
+        public Builder after(final ModLoadingState value) { return after(value.name()); }
+        public Builder after(final String value) {
+            this.after = value;
+            return this;
+        }
+
+        public Builder message(final String value) { return message(ml -> value); }
+        public Builder message(final Function<ModList, String> value) {
+            this.message = value;
+            return this;
+        }
+
+        public Builder size(final int value) { return size(ml -> value); }
+        public Builder size(final ToIntFunction<ModList> value) {
+            this.size = value;
+            return this;
+        }
+
+        public ModLoadingState empty() {
+            return new ModLoadingState(name, after, message != null ? message : ml -> "", size != null ? size : ml -> 0, phase, Optional.empty(), Optional.empty());
+        }
+
+        public ModLoadingState withTransition(final IModStateTransition transition) {
+            return new ModLoadingState(name, after, message != null ? message : ml -> "Processing transition " + name, size != null ? size : ModList::size, phase, Optional.empty(), Optional.of(transition));
+        }
+
+        public ModLoadingState withInline(final Consumer<ModList> inline) {
+            return new ModLoadingState(name, after, message != null ? message : ml -> "Processing work " + name, size != null ? size : ml -> 0, phase, Optional.of(inline), Optional.empty());
+        }
     }
 }

fmlcore/src/main/java/net/minecraftforge/fml/ModStateManager.java

@@ -16,15 +16,13 @@ import java.util.stream.Collectors;
 
 @SuppressWarnings("UnstableApiUsage")
 public class ModStateManager {
-    static ModStateManager INSTANCE;
     private final EnumMap<ModLoadingPhase, List<IModLoadingState>> stateMap;
 
     public ModStateManager() {
-        INSTANCE = this;
         final var sp = ServiceLoader.load(FMLLoader.getGameLayer(), IModStateProvider.class);
         this.stateMap = ServiceLoaderUtils.streamWithErrorHandling(sp, sce->{})
                 .map(IModStateProvider::getAllStates)
-                .<IModLoadingState>mapMulti(Iterable::forEach)
+                .flatMap(List::stream)
                 .collect(Collectors.groupingBy(IModLoadingState::phase, ()->new EnumMap<>(ModLoadingPhase.class), Collectors.toUnmodifiableList()));
     }
 
@@ -36,14 +34,16 @@ public class ModStateManager {
         var dummy = ModLoadingState.empty("", "", phase);
         nodes.forEach(graph::addNode);
         graph.addNode(dummy);
-        nodes.forEach(n->graph.putEdge(lookup.getOrDefault(n.previous(), dummy), n));
+        for (IModLoadingState node : nodes) {
+            graph.putEdge(lookup.getOrDefault(node.previous(), dummy), node);
+        }
         return TopologicalSort.topologicalSort(graph, Comparator.comparingInt(nodes::indexOf)).stream().filter(st->st!=dummy).toList();
     }
 
     public IModLoadingState findState(final String stateName) {
         return stateMap.values()
                 .stream()
-                .flatMap(Collection::stream)
+                .flatMap(List::stream)
                 .filter(mls -> mls.name().equals(stateName))
                 .findFirst()
                 .orElseThrow(() -> new IllegalArgumentException("Unknown IModLoadingState: " + stateName));

fmlcore/src/main/java/net/minecraftforge/fml/ModStateTransitionHelper.java

@@ -0,0 +1,181 @@
+/*
+ * Copyright (c) Forge Development LLC and contributors
+ * SPDX-License-Identifier: LGPL-2.1-only
+ */
+
+package net.minecraftforge.fml;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.CompletionException;
+import java.util.concurrent.CompletionStage;
+import java.util.concurrent.Executor;
+import java.util.function.BiFunction;
+import java.util.function.Function;
+import org.jetbrains.annotations.ApiStatus;
+
+import net.minecraftforge.eventbus.api.Event;
+import net.minecraftforge.fml.IModStateTransition.EventGenerator;
+import net.minecraftforge.fml.event.IModBusEvent;
+import net.minecraftforge.fml.loading.progress.ProgressMeter;
+
+@ApiStatus.Internal
+class ModStateTransitionHelper {
+    static final IModStateTransition NOOP = new NoopTransition();
+    record NoopTransition() implements IModStateTransition {
+        @Override
+        public ThreadSelector threadSelector() {
+            return ThreadSelector.SYNC;
+        }
+
+        @Override
+        public BiFunction<Executor, CompletableFuture<Void>, CompletableFuture<Void>> finalActivityGenerator() {
+            return (e, t) -> t.thenApplyAsync(Function.identity(), e);
+        }
+    }
+
+    static <V> CompletionStage<Void> completableFutureFromExceptionList(List<FutureResult<V>> t) {
+        if (t.stream().noneMatch(e -> e.exception() != null)) {
+            return CompletableFuture.completedFuture(null);
+        } else {
+            final var throwables = t.stream().map(FutureResult::exception).filter(e -> e != null).toList();
+            CompletableFuture<Void> cf = new CompletableFuture<>();
+            final RuntimeException accumulator = new RuntimeException();
+            cf.completeExceptionally(accumulator);
+            for (Throwable exception : throwables) {
+                if (exception instanceof CompletionException) {
+                    exception = exception.getCause();
+                }
+                if (exception.getSuppressed().length != 0) {
+                    for (Throwable throwable : exception.getSuppressed()) {
+                        accumulator.addSuppressed(throwable);
+                    }
+                } else {
+                    accumulator.addSuppressed(exception);
+                }
+            }
+            return cf;
+        }
+    }
+
+    record FutureResult<V>(V value, Throwable exception){}
+
+    static <V> CompletableFuture<List<FutureResult<V>>> gather(Collection<? extends CompletableFuture<? extends V>> futures) {
+        var list = new ArrayList<FutureResult<V>>(futures.size());
+        var results = new CompletableFuture[futures.size()];
+
+        for (var future : futures) {
+            int i = list.size();
+            list.add(null);
+            results[i] = future.whenComplete((result, exception) -> list.set(i, new FutureResult<>(result, exception)));
+        }
+
+        return CompletableFuture.allOf(results).handle((r, th)->null).thenApply(res -> list);
+    }
+
+    private static <T extends Event & IModBusEvent> void addCompletableFutureTaskForModDispatch(
+        final IModStateTransition transition,
+        final Executor executor,
+        final List<CompletableFuture<Void>> completableFutures,
+        final ProgressMeter progressBar,
+        final EventGenerator<T> eventGenerator,
+        final BiFunction<ModLoadingStage, Throwable, ModLoadingStage> nextState
+     ) {
+
+        @SuppressWarnings("removal")
+        var preDispatchHook = getHook(transition.preDispatchHook(), executor, eventGenerator);
+        if (preDispatchHook != null)
+            completableFutures.add(preDispatchHook);
+
+        var modFutures = new LinkedHashMap<String, CompletableFuture<Void>>();
+        for (var mod : ModList.get().getLoadedMods()) {
+
+            CompletableFuture<Void> parent = null;
+            if (mod.dependencies.isEmpty()) {
+                parent = CompletableFuture.allOf();
+            } else {
+                var deps = new CompletableFuture[mod.dependencies.size()];
+                int idx = 0;
+                for (var depContainer : mod.dependencies) {
+                    var future = modFutures.get(depContainer.getModId());
+                    if (future == null)
+                        throw new IllegalStateException("Could not find dependency future " + depContainer.getModId() + " for " + mod.getModId());
+                    deps[idx++] = future;
+                }
+                parent = CompletableFuture.allOf(deps);
+            }
+
+            @SuppressWarnings("removal")
+            var dispatch = parent
+                .thenRunAsync(() -> {
+                    ModLoadingContext.get().setActiveContainer(mod);
+                    var handler = mod.activityMap.get(mod.modLoadingStage);
+                    if (handler != null)
+                        handler.run();
+                    mod.acceptEvent(eventGenerator.apply(mod));
+                }, executor)
+                .whenComplete((mc, exception) -> {
+                    mod.modLoadingStage = nextState.apply(mod.modLoadingStage, exception);
+                    progressBar.increment();
+                    ModLoadingContext.get().setActiveContainer(null);
+                });
+
+            modFutures.put(mod.getModId(), dispatch);
+        }
+
+        var dispatch = gather(modFutures.values()).thenComposeAsync(ModStateTransitionHelper::completableFutureFromExceptionList, executor);
+        completableFutures.add(dispatch);
+
+        @SuppressWarnings("removal")
+        var postDispatchHook = getHook(transition.preDispatchHook(), executor, eventGenerator);
+        if (postDispatchHook != null)
+            completableFutures.add(postDispatchHook);
+    }
+
+    private static <T extends Event & IModBusEvent> CompletableFuture<Void> getHook(BiFunction<Executor, ? extends EventGenerator<?>, CompletableFuture<Void>> hook, Executor executor, EventGenerator<T> eventGenerator) {
+        if (hook == null || hook == IModStateTransition.NULL_HOOK) return null;
+        @SuppressWarnings("unchecked")
+        var hookTyped = (BiFunction<Executor, EventGenerator<T>, CompletableFuture<Void>>)hook;
+        return hookTyped.apply(executor, eventGenerator);
+    }
+
+    static <T extends Event & IModBusEvent> CompletableFuture<Void> build(
+        final IModStateTransition transition,
+        final String name,
+        final Executor syncExecutor,
+        final Executor parallelExecutor,
+        final ProgressMeter progressBar,
+        final Function<Executor, CompletableFuture<Void>> preSyncTask,
+        final Function<Executor, CompletableFuture<Void>> postSyncTask
+    ) {
+        List<CompletableFuture<Void>> futures = new ArrayList<>();
+        final var executor = transition.threadSelector().apply(syncExecutor, parallelExecutor);
+
+        @SuppressWarnings({ "removal", "unchecked" })
+        var events = transition.eventFunctionStream().get().map(f -> (EventGenerator<T>)f).toList();
+        for (int x = 0; x < events.size(); x++) {
+            var gen = events.get(x);
+            BiFunction<ModLoadingStage, Throwable, ModLoadingStage> state = x == events.size() - 1
+                ? transition.nextModLoadingStage()
+                : ModLoadingStage::currentState;
+            addCompletableFutureTaskForModDispatch(transition, executor, futures, progressBar, gen, state);
+        }
+
+        final CompletableFuture<Void> preSyncTaskCF = preSyncTask.apply(syncExecutor);
+        final CompletableFuture<Void> eventDispatchCF = gather(futures).thenCompose(ModStateTransitionHelper::completableFutureFromExceptionList);
+        final CompletableFuture<Void> postEventDispatchCF = preSyncTaskCF
+            .thenApplyAsync(n -> {
+                progressBar.label(progressBar.name() + ": dispatching " + name);
+                return null;
+            }, parallelExecutor)
+            .thenComposeAsync(n -> eventDispatchCF, parallelExecutor)
+            .thenApply(r -> {
+                postSyncTask.apply(syncExecutor);
+                return null;
+            });
+        return transition.finalActivityGenerator().apply(syncExecutor, postEventDispatchCF);
+    }
+}

fmlcore/src/main/java/net/minecraftforge/fml/ModWorkManager.java

@@ -17,6 +17,7 @@ import static net.minecraftforge.fml.Logging.LOADING;
 public class ModWorkManager {
     private static final Logger LOGGER = LogManager.getLogger();
     private static final long PARK_TIME = TimeUnit.MILLISECONDS.toNanos(1);
+
     public interface DrivenExecutor extends Executor {
         boolean selfDriven();
         boolean driveOne();
@@ -33,8 +34,11 @@ public class ModWorkManager {
             }
         }
     }
-    private static class SyncExecutor implements DrivenExecutor {
-        private ConcurrentLinkedDeque<Runnable> tasks = new ConcurrentLinkedDeque<>();
+
+    private record SyncExecutor(ConcurrentLinkedDeque<Runnable> tasks) implements DrivenExecutor {
+        public SyncExecutor() {
+            this(new ConcurrentLinkedDeque<>());
+        }
 
         @Override
         public boolean driveOne() {
@@ -56,13 +60,7 @@ public class ModWorkManager {
         }
     }
 
-    private static class WrappingExecutor implements DrivenExecutor {
-        private final Executor wrapped;
-
-        public WrappingExecutor(final Executor executor) {
-            this.wrapped = executor;
-        }
-
+    private record WrappingExecutor(Executor wrapped) implements DrivenExecutor {
         @Override
         public boolean selfDriven() {
             return true;
@@ -79,11 +77,9 @@ public class ModWorkManager {
         }
     }
 
-    private static SyncExecutor syncExecutor;
+    private static final SyncExecutor syncExecutor = new SyncExecutor();
 
     public static DrivenExecutor syncExecutor() {
-        if (syncExecutor == null)
-            syncExecutor = new SyncExecutor();
         return syncExecutor;
     }
 
@@ -91,14 +87,8 @@ public class ModWorkManager {
         return new WrappingExecutor(executor);
     }
 
-    private static ForkJoinPool parallelThreadPool;
     public static Executor parallelExecutor() {
-        if (parallelThreadPool == null) {
-            final int loadingThreadCount = FMLConfig.getIntConfigValue(FMLConfig.ConfigValue.MAX_THREADS);
-            LOGGER.debug(LOADING, "Using {} threads for parallel mod-loading", loadingThreadCount);
-            parallelThreadPool = new ForkJoinPool(loadingThreadCount, ModWorkManager::newForkJoinWorkerThread, null, false);
-        }
-        return parallelThreadPool;
+        return LazyInit.PARALLEL_EXECUTOR;
     }
 
     private static ForkJoinWorkerThread newForkJoinWorkerThread(ForkJoinPool pool) {
@@ -109,4 +99,14 @@ public class ModWorkManager {
         return thread;
     }
 
+    private static final class LazyInit {
+        private LazyInit() {}
+        private static final ForkJoinPool PARALLEL_EXECUTOR;
+
+        static {
+            final int loadingThreadCount = FMLConfig.getIntConfigValue(FMLConfig.ConfigValue.MAX_THREADS);
+            LOGGER.debug(LOADING, "Using {} threads for parallel mod-loading", loadingThreadCount);
+            PARALLEL_EXECUTOR = new ForkJoinPool(loadingThreadCount, ModWorkManager::newForkJoinWorkerThread, null, false);
+        }
+    }
 }

fmlcore/src/main/java/net/minecraftforge/fml/OptionalMod.java

@@ -23,7 +23,7 @@ public final class OptionalMod<T>
         return new OptionalMod<>(modId);
     }
 
-    private static OptionalMod<?> EMPTY = new OptionalMod<>(true);
+    private static final OptionalMod<?> EMPTY = new OptionalMod<>(true);
     private static <T> OptionalMod<T> empty() {
         @SuppressWarnings("unchecked")
         OptionalMod<T> t = (OptionalMod<T>) EMPTY;
@@ -213,8 +213,8 @@ public final class OptionalMod<T>
     public boolean equals(Object obj)
     {
         if (this == obj) return true;
-        if (obj instanceof OptionalMod) {
-            return Objects.equals(((OptionalMod)obj).modId, modId);
+        if (obj instanceof OptionalMod<?> optionalMod) {
+            return Objects.equals(optionalMod.modId, modId);
         }
         return false;
     }

fmlcore/src/main/java/net/minecraftforge/fml/VersionChecker.java

@@ -48,8 +48,8 @@ public class VersionChecker {
         BETA(),
         BETA_OUTDATED(6, true, true);
 
-        final int sheetOffset;
-        final boolean draw, animated;
+        private final int sheetOffset;
+        private final boolean draw, animated;
 
         Status() {
             this(0, false, false);
@@ -72,6 +72,10 @@ public class VersionChecker {
         public boolean isAnimated() {
             return animated;
         }
+
+        public boolean isOutdated() {
+            return this == OUTDATED || this == BETA_OUTDATED;
+        }
     }
 
     public record CheckResult(VersionChecker.Status status, ComparableVersion target, Map<ComparableVersion, String> changes, String url) {}
@@ -211,7 +215,7 @@ public class VersionChecker {
                     LOGGER.warn("Failed to process update information", e);
                     status = FAILED;
                 }
-                results.put(mod, new CheckResult(status, target, changes, display_url));
+                RESULTS.put(mod, new CheckResult(status, target, changes, display_url));
             }
         }.start();
     }
@@ -226,10 +230,10 @@ public class VersionChecker {
         return ret;
     }
 
-    private static Map<IModInfo, CheckResult> results = new ConcurrentHashMap<>();
+    private static final Map<IModInfo, CheckResult> RESULTS = new ConcurrentHashMap<>();
     private static final CheckResult PENDING_CHECK = new CheckResult(PENDING, null, null, null);
 
     public static CheckResult getResult(IModInfo mod) {
-        return results.getOrDefault(mod, PENDING_CHECK);
+        return RESULTS.getOrDefault(mod, PENDING_CHECK);
     }
 }

fmlcore/src/main/java/net/minecraftforge/fml/config/ConfigFileTypeHandler.java

@@ -14,6 +14,7 @@ import com.mojang.logging.LogUtils;
 import net.minecraftforge.fml.loading.FMLConfig;
 import net.minecraftforge.fml.loading.FMLPaths;
 import org.apache.commons.io.FilenameUtils;
+import org.jetbrains.annotations.Nullable;
 import org.slf4j.Logger;
 
 import java.io.IOException;
@@ -25,9 +26,66 @@ import static net.minecraftforge.fml.config.ConfigTracker.CONFIG;
 
 public class ConfigFileTypeHandler {
     private static final Logger LOGGER = LogUtils.getLogger();
-    static ConfigFileTypeHandler TOML = new ConfigFileTypeHandler();
     private static final Path defaultConfigPath = FMLPaths.GAMEDIR.get().resolve(FMLConfig.getConfigValue(FMLConfig.ConfigValue.DEFAULT_CONFIG_PATH));
 
+    private static final ConfigFileTypeHandler CLIENT = new ConfigFileTypeHandler(ModConfig.Type.CLIENT);
+    private static final ConfigFileTypeHandler COMMON = new ConfigFileTypeHandler(ModConfig.Type.COMMON);
+    private static final ConfigFileTypeHandler SERVER = new ConfigFileTypeHandler(ModConfig.Type.SERVER);
+
+    private final @Nullable ModConfig.Type type;
+    private @Nullable FileWatcher watcher;
+
+    // exists for bin compat
+    public ConfigFileTypeHandler() {
+        this(null);
+    }
+
+    private ConfigFileTypeHandler(@Nullable ModConfig.Type type) {
+        this.type = type;
+    }
+
+    /**
+     * Gets the handler for the given {@link ModConfig.Type}.
+     *
+     * @param type The type to get the handler for
+     * @return The handler
+     */
+    static ConfigFileTypeHandler get(ModConfig.Type type) {
+        return switch (type) {
+            case CLIENT -> CLIENT;
+            case COMMON -> COMMON;
+            case SERVER -> SERVER;
+        };
+    }
+
+    /**
+     * Gets the {@link FileWatcher} for this handler, creating it if it doesn't exist and/or has been stopped.
+     *
+     * @return The watcher
+     *
+     * @apiNote This is package-private so modders can't just call {@link FileWatcher#stop()} and fuck up everything.
+     */
+    FileWatcher getWatcher() {
+        if (this.watcher == null) {
+            LOGGER.debug(CONFIG, "Starting watcher for handler: {}", this);
+            this.watcher = new FileWatcher();
+        }
+
+        return this.watcher;
+    }
+
+    /**
+     * Stops the {@link FileWatcher} for this handler, and sets it to null afterward. Use this instead of
+     * {@link FileWatcher#stop()}.
+     */
+    void stopWatcher() {
+        if (this.watcher == null) return;
+
+        LOGGER.debug(CONFIG, "Stopping watcher for hander: {}", this);
+        this.watcher.stop();
+        this.watcher = null;
+    }
+
     public Function<ModConfig, CommentedFileConfig> reader(Path configBasePath) {
         return (c) -> {
             final Path configPath = configBasePath.resolve(c.getFileName());
@@ -37,7 +95,7 @@ public class ConfigFileTypeHandler {
                     onFileNotFound((newfile, configFormat)-> setupConfigFile(c, newfile, configFormat)).
                     writingMode(WritingMode.REPLACE).
                     build();
-            LOGGER.debug(CONFIG, "Built TOML config for {}", configPath.toString());
+            LOGGER.debug(CONFIG, "Built TOML config for {}", configPath);
             try
             {
                 configData.load();
@@ -46,13 +104,9 @@ public class ConfigFileTypeHandler {
             {
                 throw new ConfigLoadingException(c, ex);
             }
-            LOGGER.debug(CONFIG, "Loaded TOML config file {}", configPath.toString());
-            try {
-                FileWatcher.defaultInstance().addWatch(configPath, new ConfigWatcher(c, configData, Thread.currentThread().getContextClassLoader()));
-                LOGGER.debug(CONFIG, "Watching TOML config file {} for changes", configPath.toString());
-            } catch (IOException e) {
-                throw new RuntimeException("Couldn't watch config file", e);
-            }
+            LOGGER.debug(CONFIG, "Loaded TOML config file {}", configPath);
+            this.getWatcher().addWatch(configPath, new ConfigWatcher(c, configData, Thread.currentThread().getContextClassLoader()));
+            LOGGER.debug(CONFIG, "Watching TOML config file {} for changes", configPath);
             return configData;
         };
     }
@@ -60,14 +114,16 @@ public class ConfigFileTypeHandler {
     public void unload(Path configBasePath, ModConfig config) {
         Path configPath = configBasePath.resolve(config.getFileName());
         try {
-            FileWatcher.defaultInstance().removeWatch(configBasePath.resolve(config.getFileName()));
+            this.getWatcher().removeWatch(configPath);
         } catch (RuntimeException e) {
-            LOGGER.error("Failed to remove config {} from tracker!", configPath.toString(), e);
+            LOGGER.error("Failed to remove config {} from tracker!", configPath, e);
         }
     }
 
-    private boolean setupConfigFile(final ModConfig modConfig, final Path file, final ConfigFormat<?> conf) throws IOException {
-        Files.createDirectories(file.getParent());
+    private static boolean setupConfigFile(final ModConfig modConfig, final Path file, final ConfigFormat<?> conf) throws IOException {
+        if (!Files.isDirectory(file.getParent())) {
+            Files.createDirectories(file.getParent());
+        }
         Path p = defaultConfigPath.resolve(modConfig.getFileName());
         if (Files.exists(p)) {
             LOGGER.info(CONFIG, "Loading default config file from path {}", p);
@@ -111,17 +167,16 @@ public class ConfigFileTypeHandler {
         }
     }
 
-    private static class ConfigWatcher implements Runnable {
-        private final ModConfig modConfig;
-        private final CommentedFileConfig commentedFileConfig;
-        private final ClassLoader realClassLoader;
-
-        ConfigWatcher(final ModConfig modConfig, final CommentedFileConfig commentedFileConfig, final ClassLoader classLoader) {
-            this.modConfig = modConfig;
-            this.commentedFileConfig = commentedFileConfig;
-            this.realClassLoader = classLoader;
-        }
+    @Override
+    public String toString() {
+        return "ConfigFileTypeHandler[" + (type != null ? type : "UNKNOWN") + "]";
+    }
 
+    private record ConfigWatcher(
+            ModConfig modConfig,
+            CommentedFileConfig commentedFileConfig,
+            ClassLoader realClassLoader
+    ) implements Runnable {
         @Override
         public void run() {
             // Force the regular classloader onto the special thread

fmlcore/src/main/java/net/minecraftforge/fml/config/ConfigTracker.java

@@ -8,6 +8,9 @@ package net.minecraftforge.fml.config;
 import com.electronwill.nightconfig.core.CommentedConfig;
 import com.electronwill.nightconfig.core.file.CommentedFileConfig;
 import com.mojang.logging.LogUtils;
+import net.minecraftforge.api.distmarker.Dist;
+import net.minecraftforge.fml.DistExecutor;
+import net.minecraftforge.fml.loading.FMLPaths;
 import org.slf4j.Logger;
 import org.slf4j.Marker;
 import org.slf4j.MarkerFactory;
@@ -47,15 +50,32 @@ public class ConfigTracker {
 
     public void loadConfigs(ModConfig.Type type, Path configBasePath) {
         LOGGER.debug(CONFIG, "Loading configs type {}", type);
-        this.configSets.get(type).forEach(config -> openConfig(config, configBasePath));
+        for (ModConfig config : this.configSets.get(type)) {
+            openConfig(config, configBasePath);
+        }
     }
 
+    // TODO: [FML] This is only called for the server (outside of forceUnload)
+    // rethink config implementation for eventual FML rewrite
     public void unloadConfigs(ModConfig.Type type, Path configBasePath) {
         LOGGER.debug(CONFIG, "Unloading configs type {}", type);
-        this.configSets.get(type).forEach(config -> closeConfig(config, configBasePath));
+        for (ModConfig config : this.configSets.get(type)) {
+            closeConfig(config, configBasePath);
+        }
+        ConfigFileTypeHandler.get(type).stopWatcher();
     }
 
-    private void openConfig(final ModConfig config, final Path configBasePath) {
+    // If there is a better way to do this, please tell me. Because this is FUCKED
+    public void forceUnload() {
+        // This is how ModStateProvider handles loading configs. So we're doing the same but with unloadConfigs instead
+        DistExecutor.unsafeRunWhenOn(Dist.CLIENT, () -> () -> this.unloadConfigs(ModConfig.Type.CLIENT, FMLPaths.CONFIGDIR.get()));
+        this.unloadConfigs(ModConfig.Type.COMMON, FMLPaths.CONFIGDIR.get());
+
+        // just in case server watcher is still alive somehow...
+        ConfigFileTypeHandler.get(ModConfig.Type.SERVER).stopWatcher();
+    }
+
+    private static void openConfig(final ModConfig config, final Path configBasePath) {
         LOGGER.trace(CONFIG, "Loading config file type {} at {} for {}", config.getType(), config.getFileName(), config.getModId());
         final CommentedFileConfig configData = config.getHandler().reader(configBasePath).apply(config);
         config.setConfigData(configData);
@@ -63,7 +83,7 @@ public class ConfigTracker {
         config.save();
     }
 
-    private void closeConfig(final ModConfig config, final Path configBasePath) {
+    private static void closeConfig(final ModConfig config, final Path configBasePath) {
         if (config.getConfigData() != null) {
             LOGGER.trace(CONFIG, "Closing config file type {} at {} for {}", config.getType(), config.getFileName(), config.getModId());
             // stop the filewatcher before we save the file and close it, so reload doesn't fire

fmlcore/src/main/java/net/minecraftforge/fml/config/ModConfig.java

@@ -24,14 +24,13 @@ public class ModConfig
     private final ModContainer container;
     private final ConfigFileTypeHandler configHandler;
     private CommentedConfig configData;
-    private Callable<Void> saveHandler;
 
     public ModConfig(final Type type, final IConfigSpec<?> spec, final ModContainer container, final String fileName) {
         this.type = type;
         this.spec = spec;
         this.fileName = fileName;
         this.container = container;
-        this.configHandler = ConfigFileTypeHandler.TOML;
+        this.configHandler = ConfigFileTypeHandler.get(type);
         ConfigTracker.INSTANCE.trackConfig(this);
     }
 

fmlearlydisplay/src/main/java/net/minecraftforge/fml/earlydisplay/DisplayWindow.java

@@ -22,9 +22,7 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 import java.awt.Desktop;
-import java.io.BufferedReader;
 import java.io.IOException;
-import java.io.InputStreamReader;
 import java.lang.reflect.Method;
 import java.lang.reflect.Modifier;
 import java.net.URI;
@@ -87,11 +85,17 @@ public class DisplayWindow implements ImmediateWindowProvider {
     private ScheduledFuture<?> initializationFuture;
 
     private PerformanceInfo performanceInfo;
+    @SuppressWarnings("unused")
     private ScheduledFuture<?> performanceTick;
     // The GL ID of the window. Used for all operations
     private long window;
     // The thread that contains and ticks the window while Forge is loading mods
-    private ScheduledExecutorService renderScheduler;
+    private static final ScheduledExecutorService renderScheduler = Executors.newSingleThreadScheduledExecutor(r -> {
+        final var thread = Executors.defaultThreadFactory().newThread(r);
+        thread.setName("EarlyDisplay");
+        thread.setDaemon(true);
+        return thread;
+    });
     private int fbWidth;
     private int fbHeight;
     private int fbScale;
@@ -150,7 +154,7 @@ public class DisplayWindow implements ImmediateWindowProvider {
         }
         this.maximized = parsed.has(maximizedopt) || FMLConfig.getBoolConfigValue(FMLConfig.ConfigValue.EARLY_WINDOW_MAXIMIZED);
 
-        StartupNotificationManager.modLoaderConsumer().ifPresent(c->c.accept("Forge loading " + forgeVersion));
+        StartupNotificationManager.modLoaderConsumer().ifPresent(c->c.accept("Forge loading " + FMLLoader.versionInfo().forgeVersion()));
         performanceInfo = new PerformanceInfo();
         return start(mcVersion, forgeVersion);
     }
@@ -239,7 +243,7 @@ public class DisplayWindow implements ImmediateWindowProvider {
 
         var date = Calendar.getInstance();
         if (FMLConfig.getBoolConfigValue(FMLConfig.ConfigValue.EARLY_WINDOW_SQUIR) || (date.get(Calendar.MONTH) == Calendar.APRIL && date.get(Calendar.DAY_OF_MONTH) == 1))
-            this.elements.add(0, RenderElement.squir());
+            this.elements.addFirst(RenderElement.squir());
 
         glEnable(GL_BLEND);
         glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
@@ -259,7 +263,11 @@ public class DisplayWindow implements ImmediateWindowProvider {
         glEnable(GL_BLEND);
         glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
 
-        this.elements.removeIf(element -> !element.render(context, framecount));
+        for (var itr = this.elements.iterator(); itr.hasNext(); ) {
+            var element = itr.next();
+            if (!element.render(context, framecount))
+                itr.remove();
+        }
         if (animationTimerTrigger.compareAndSet(true, false)) // we only increment the framecount on a periodic basis
             framecount++;
     }
@@ -284,12 +292,6 @@ public class DisplayWindow implements ImmediateWindowProvider {
      * Start the window and Render Thread; we're ready to go.
      */
     public Runnable start(@Nullable String mcVersion, final String forgeVersion) {
-        renderScheduler = Executors.newSingleThreadScheduledExecutor(r -> {
-            final var thread = Executors.defaultThreadFactory().newThread(r);
-            thread.setName("EarlyDisplay");
-            thread.setDaemon(true);
-            return thread;
-        });
         initWindow(mcVersion);
         this.initializationFuture = renderScheduler.schedule(() -> initRender(mcVersion, forgeVersion), 1, TimeUnit.MILLISECONDS);
         return this::periodicTick;
@@ -301,14 +303,7 @@ public class DisplayWindow implements ImmediateWindowProvider {
         return this.glVersion;
     }
 
-    private void crashElegantly(String errorDetails) {
-        String qrText;
-        try (var is = new BufferedReader(new InputStreamReader(getClass().getResourceAsStream("/glfailure.txt")))) {
-            qrText = is.lines().collect(Collectors.joining("\n"));
-        } catch (IOException ioe) {
-            qrText = "";
-        }
-
+    private static void crashElegantly(String errorDetails) {
         StringBuilder msgBuilder = new StringBuilder(2000);
         msgBuilder.append("Failed to initialize graphics window with current settings.\n");
         msgBuilder.append("\n\n");
@@ -407,13 +402,13 @@ public class DisplayWindow implements ImmediateWindowProvider {
             if (showHelpLog && versidx == 0) {
                 LOGGER.info("""
                 If this message is the only thing at the bottom of your log before a crash, you probably have a driver issue.
-                
+
                 Possible solutions:
                 A) Make sure Minecraft is set to prefer high performance graphics in the OS and/or driver control panel
                 B) Check for driver updates on the graphics brand's website
                 C) Try reinstalling your graphics drivers
                 D) If still not working after trying all of the above, ask for further help on the Forge forums or Discord
-                
+
                 You can safely ignore this message if the game starts up successfully.""");
             }
             glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, GL_VERSIONS[versidx][0]); // we try our versions one at a time
@@ -497,10 +492,6 @@ public class DisplayWindow implements ImmediateWindowProvider {
         glfwPollEvents();
     }
 
-    private void badWindowHandler(final int code, final long desc) {
-        LOGGER.error("Got error from GLFW window init: "+code+ " "+MemoryUtil.memUTF8(desc));
-    }
-
     private void winResize(long window, int width, int height) {
         if (window == this.window && width != 0 && height != 0) {
             this.winWidth = width;
@@ -520,7 +511,7 @@ public class DisplayWindow implements ImmediateWindowProvider {
             this.winY = y;
         }
     }
-    private void handleLastGLFWError(BiConsumer<Integer, String> handler) {
+    private static void handleLastGLFWError(BiConsumer<Integer, String> handler) {
         try (MemoryStack memorystack = MemoryStack.stackPush()) {
             PointerBuffer pointerbuffer = memorystack.mallocPointer(1);
             int error = glfwGetError(pointerbuffer);
@@ -612,10 +603,25 @@ public class DisplayWindow implements ImmediateWindowProvider {
 
     @Override
     public void updateModuleReads(final ModuleLayer layer) {
-        var fm = layer.findModule("forge").orElseThrow();
-        getClass().getModule().addReads(fm);
-        var clz = FMLLoader.getGameLayer().findModule("forge").map(l->Class.forName(l, "net.minecraftforge.client.loading.ForgeLoadingOverlay")).orElseThrow();
-        loadingOverlay = Arrays.stream(clz.getDeclaredMethods()).filter(m-> Modifier.isStatic(m.getModifiers()) && m.getName().equals("newInstance")).findFirst().orElseThrow();
+        final var FORGE_MODULE = "net.minecraftforge.forge";
+        var forge_module = layer.findModule(FORGE_MODULE).orElse(null);
+        if (forge_module == null)
+            throw new IllegalStateException("Could not find " + FORGE_MODULE + " in " + layer);
+
+        getClass().getModule().addReads(forge_module);
+
+
+        var clz = Class.forName(forge_module, "net.minecraftforge.client.loading.ForgeLoadingOverlay");
+
+        for (var mtd : clz.getDeclaredMethods()) {
+            if (Modifier.isStatic(mtd.getModifiers()) && "newInstance".equals(mtd.getName())) {
+                this.loadingOverlay = mtd;
+                break;
+            }
+        }
+
+        if (loadingOverlay == null)
+            throw new IllegalStateException("Could not find static newInstace method in " + clz.getName());
     }
 
     public int getFramebufferTextureId() {
@@ -633,8 +639,7 @@ public class DisplayWindow implements ImmediateWindowProvider {
     }
 
     public void addMojangTexture(final int textureId) {
-        this.elements.add(0, RenderElement.mojang(textureId, framecount));
-//        this.elements.get(0).retire(framecount + 1);
+        this.elements.addFirst(RenderElement.mojang(textureId, framecount));
     }
 
     public void close() {

fmlearlydisplay/src/main/java/net/minecraftforge/fml/earlydisplay/PerformanceInfo.java

@@ -13,10 +13,10 @@ import java.lang.management.MemoryMXBean;
 import java.lang.management.MemoryUsage;
 
 public class PerformanceInfo {
+    private static final MemoryMXBean MEMORY_BEAN = ManagementFactory.getMemoryMXBean();
 
     private final boolean showCPUUsage;
     private final OperatingSystemMXBean osBean;
-    private final MemoryMXBean memoryBean;
 
     private float memory;
     private String text;
@@ -24,15 +24,14 @@ public class PerformanceInfo {
     PerformanceInfo() {
         showCPUUsage = FMLConfig.getBoolConfigValue(FMLConfig.ConfigValue.EARLY_WINDOW_SHOW_CPU);
         osBean = showCPUUsage ? ManagementFactory.getPlatformMXBean(OperatingSystemMXBean.class) : null;
-        memoryBean = ManagementFactory.getMemoryMXBean();
     }
 
     void update() {
-        final MemoryUsage heapusage = memoryBean.getHeapMemoryUsage();
+        final MemoryUsage heapusage = MEMORY_BEAN.getHeapMemoryUsage();
         memory = (float) heapusage.getUsed() / heapusage.getMax();
 
         if (!showCPUUsage) {
-            text = "Heap: %d/%d MB (%.1f%%) OffHeap: %d MB".formatted(heapusage.getUsed() >> 20, heapusage.getMax() >> 20, memory * 100.0, memoryBean.getNonHeapMemoryUsage().getUsed() >> 20);
+            text = "Memory: %d/%dMB (%.1f%%)".formatted(heapusage.getUsed() >>> 20, heapusage.getMax() >>> 20, memory * 100f);
             return;
         }
 
@@ -44,7 +43,7 @@ public class PerformanceInfo {
             cpuText = "CPU: %.1f%%".formatted(cpuLoad * 100f);
         }
 
-        text = "Heap: %d/%d MB (%.1f%%) OffHeap: %d MB  %s".formatted(heapusage.getUsed() >> 20, heapusage.getMax() >> 20, memory * 100.0, memoryBean.getNonHeapMemoryUsage().getUsed() >> 20, cpuText);
+        text = "Memory: %d/%dMB (%.1f%%)  %s".formatted(heapusage.getUsed() >>> 20, heapusage.getMax() >>> 20, memory * 100f, cpuText);
     }
 
     String text() {

fmlearlydisplay/src/main/java/net/minecraftforge/fml/earlydisplay/RenderElement.java

@@ -22,8 +22,8 @@ public class RenderElement {
     static int globalAlpha = 255;
     private int retireCount;
 
+    @FunctionalInterface
     interface Renderer {
-
         void accept(SimpleBufferBuilder bb, DisplayContext context, int frame);
 
         default Renderer then(Renderer r) {
@@ -38,6 +38,9 @@ public class RenderElement {
     interface TextureRenderer {
         void accept(SimpleBufferBuilder bb, DisplayContext context, int[] size, int frame);
     }
+
+    /** @deprecated Use {@link Renderer} directly. This was always eagerly resolved, making it an unnecessary wrapper. */
+    @Deprecated(since = "1.21.5", forRemoval = true)
     @FunctionalInterface
     interface Initializer extends Supplier<Renderer> {}
 
@@ -56,11 +59,18 @@ public class RenderElement {
         }
     }
 
+    /** @deprecated Use {@link RenderElement#RenderElement(Renderer)} instead */
+    @Deprecated(since = "1.21.5", forRemoval = true)
     public RenderElement(final Initializer rendererInitializer) {
         this.bb = new SimpleBufferBuilder(1);
         this.renderer = rendererInitializer.get();
     }
 
+    public RenderElement(Renderer renderer) {
+        this.bb = new SimpleBufferBuilder(1);
+        this.renderer = renderer;
+    }
+
     public boolean render(DisplayContext ctx, int count) {
         this.renderer.accept(bb, ctx, count);
         return this.retireCount == 0 || this.retireCount < count;
@@ -75,7 +85,7 @@ public class RenderElement {
         List<SimpleFont.DisplayText> texts = new ArrayList<>();
         for (int i = messages.size() - 1; i >= 0; i--) {
             final StartupNotificationManager.AgeMessage pair = messages.get(i);
-            final float fade = clamp((4000.0f - (float) pair.age() - ( i - 4 ) * 1000.0f) / 5000.0f, 0.0f, 1.0f);
+            final float fade = Math.clamp((4000.0f - (float) pair.age() - ( i - 4 ) * 1000.0f) / 5000.0f, 0.0f, 1.0f);
             if (fade <0.01f) continue;
             Message msg = pair.message();
             int colour = Math.min((int)(fade * 255f), globalAlpha) << 24 | 0xFFFFFF;
@@ -84,19 +94,9 @@ public class RenderElement {
 
         font.generateVerticesForTexts(10, context.scaledHeight() -  texts.size() * font.lineSpacing() + font.descent() - 10, bb, texts.toArray(SimpleFont.DisplayText[]::new));
     }
-    public static RenderElement monag() {
-        return new RenderElement(RenderElement.initializeTexture("monagstudios.png", 45000, 4, (bb, ctx, sz, frame) -> {
-            var size = 256;
-            var x0 = (ctx.width() - 2 * size) / 2;
-            var y0 = 64;
-            QuadHelper.loadQuad(bb, x0, x0+size, y0, y0+size/2f, 0f, 1f, 0f, 0.5f, 0xFFFFFFFF);
-            QuadHelper.loadQuad(bb, x0+size, x0+2*size, y0, y0+size/2f, 0f, 1f, 0.5f, 1f, 0xFFFFFFFF);
-        }));
-
-    }
 
     public static RenderElement mojang(final int textureId, final int frameStart) {
-        return new RenderElement(()->(bb, ctx, frame) -> {
+        return new RenderElement((bb, ctx, frame) -> {
             var size = 256 * ctx.scale();
             var x0 = (ctx.scaledWidth() - 2 * size) / 2;
             var y0 = 64 * ctx.scale() + 32;
@@ -148,11 +148,11 @@ public class RenderElement {
         }));
     }
     public static RenderElement progressBars(SimpleFont font) {
-        return new RenderElement(() -> (bb, ctx, frame) -> RenderElement.startupProgressBars(font, bb, ctx, frame));
+        return new RenderElement((bb, ctx, frame) -> RenderElement.startupProgressBars(font, bb, ctx, frame));
     }
 
     public static RenderElement performanceBar(SimpleFont font) {
-        return new RenderElement(() -> (bb, ctx, frame) -> RenderElement.memoryInfo(font, bb, ctx, frame));
+        return new RenderElement((bb, ctx, frame) -> RenderElement.memoryInfo(font, bb, ctx, frame));
     }
 
     public static void startupProgressBars(SimpleFont font, final SimpleBufferBuilder buffer, final DisplayContext context, final int frameNumber) {
@@ -187,10 +187,10 @@ public class RenderElement {
     }
     private static float[] indeterminateBar(int frame, boolean isActive) {
         if (RenderElement.globalAlpha != 0xFF || !isActive) {
-            return new float[] {0f,1f};
+            return new float[] { 0f, 1f };
         } else {
-            var progress = frame % 100;
-            return new float[]{clamp((progress - 2) / 100f, 0f, 1f), clamp((progress + 2) / 100f, 0f, 1f)};
+            int progress = frame % 100;
+            return new float[] { Math.clamp((progress - 2) / 100f, 0f, 1f), Math.clamp((progress + 2) / 100f, 0f, 1f) };
         }
     }
 
@@ -249,8 +249,8 @@ public class RenderElement {
         };
     }
 
-    private static Initializer initializeText(SimpleFont font, TextGenerator textGenerator) {
-        return () -> (bb, context, frame) -> renderText(font, textGenerator, bb, context);
+    private static Renderer initializeText(SimpleFont font, TextGenerator textGenerator) {
+        return (bb, context, frame) -> renderText(font, textGenerator, bb, context);
     }
 
     private static void renderText(final SimpleFont font, final TextGenerator textGenerator, final SimpleBufferBuilder bb, final DisplayContext context) {
@@ -264,14 +264,13 @@ public class RenderElement {
     private static TextGenerator text(int x, int y, String text, int colour) {
         return (bb, font, context) -> font.generateVerticesForTexts(x, y, bb, new SimpleFont.DisplayText(text, colour));
     }
-    private static Initializer initializeTexture(final String textureFileName, int size, int textureNumber, TextureRenderer positionAndColour) {
-        return ()->{
-            int[] imgSize = STBHelper.loadTextureFromClasspath(textureFileName, size, GL_TEXTURE0 + textureNumber + INDEX_TEXTURE_OFFSET);
-            return (bb, ctx, frame) -> {
-                ctx.elementShader().updateTextureUniform(textureNumber + INDEX_TEXTURE_OFFSET);
-                ctx.elementShader().updateRenderTypeUniform(ElementShader.RenderType.TEXTURE);
-                renderTexture(bb, ctx, frame, imgSize, positionAndColour);
-            };
+
+    private static Renderer initializeTexture(final String textureFileName, int size, int textureNumber, TextureRenderer positionAndColour) {
+        int[] imgSize = STBHelper.loadTextureFromClasspath(textureFileName, size, GL_TEXTURE0 + textureNumber + INDEX_TEXTURE_OFFSET);
+        return (bb, ctx, frame) -> {
+            ctx.elementShader().updateTextureUniform(textureNumber + INDEX_TEXTURE_OFFSET);
+            ctx.elementShader().updateRenderTypeUniform(ElementShader.RenderType.TEXTURE);
+            renderTexture(bb, ctx, frame, imgSize, positionAndColour);
         };
     }
 
@@ -281,21 +280,13 @@ public class RenderElement {
         bb.draw();
     }
 
-
+    @Deprecated(since = "1.21.5", forRemoval = true)
     public static float clamp(float num, float min, float max) {
-        if (num < min) {
-            return min;
-        } else {
-            return Math.min(num, max);
-        }
+        return Math.clamp(num, min, max);
     }
 
     public static int clamp(int num, int min, int max) {
-        if (num < min) {
-            return min;
-        } else {
-            return Math.min(num, max);
-        }
+        return Math.min(max, Math.max(num, min));
     }
 
     public static int hsvToRGB(float hue, float saturation, float value) {

fmlearlydisplay/src/main/java/net/minecraftforge/fml/earlydisplay/SimpleFont.java

@@ -11,8 +11,6 @@ import org.lwjgl.stb.STBTTFontinfo;
 import org.lwjgl.stb.STBTTPackContext;
 import org.lwjgl.stb.STBTTPackRange;
 import org.lwjgl.stb.STBTTPackedchar;
-import org.lwjgl.system.MemoryStack;
-
 import java.nio.ByteBuffer;
 import java.nio.charset.StandardCharsets;
 
@@ -24,8 +22,8 @@ public class SimpleFont {
     private final int textureNumber;
     private final int lineSpacing;
     private final int descent;
-    private final int GLYPH_COUNT = 127-32;
-    private Glyph[] glyphs;
+    private static final int GLYPH_COUNT = 127 - 32;
+    private final Glyph[] glyphs;
 
     private record Glyph(char c, int charwidth, int[] pos, float[] uv) {
         Pos loadQuad(Pos pos, int colour, SimpleBufferBuilder bb) {
@@ -122,7 +120,7 @@ public class SimpleFont {
                 case '\n', '\t' -> 0;
                 case ' ' -> glyphs[0].charwidth();
                 default -> {
-                    if (c - 32 < this.GLYPH_COUNT && c > 32) {
+                    if (c - 32 < GLYPH_COUNT && c > 32) {
                         yield this.glyphs[c - 32].charwidth();
                     } else {
                         yield 0;
@@ -153,7 +151,7 @@ public class SimpleFont {
                     case '\t' -> new Pos(pos.x()+font.glyphs[0].charwidth() * 4, pos.y(), pos.minx());
                     case ' ' -> new Pos(pos.x()+font.glyphs[0].charwidth(), pos.y(), pos.minx());
                     default -> {
-                        if (c-32 < font.GLYPH_COUNT && c > 32) {
+                        if (c-32 < GLYPH_COUNT && c > 32) {
                             pos = font.glyphs[c - 32].loadQuad(pos, colour(), bb);
                         }
                         yield pos;

fmlloader/build.gradle

@@ -5,6 +5,7 @@ plugins {
     id 'maven-publish'
     id 'net.minecraftforge.licenser'
     id 'net.minecraftforge.gradleutils'
+    alias(libs.plugins.apt)
 }
 
 apply from: rootProject.file('build_shared.gradle')
@@ -36,8 +37,9 @@ dependencies {
     implementation(libs.terminalconsoleappender)
     implementation(libs.jimfs)
 
+    // Needed because we have a custom log4j plugin, and they removed package scanning and require a data file to be generated
     implementation(libs.log4j.core)
-    annotationProcessor(libs.log4j.core)
+    annotationProcessor(libs.bundles.log4j)
 
     testCompileOnly(libs.nulls)
     testRuntimeOnly(libs.bootstrap)
@@ -85,7 +87,7 @@ publishing {
             license PomUtils.Licenses.LGPLv2_1
         }
     }
-    
+
     repositories {
         maven gradleutils.publishingForgeMaven
     }
@@ -102,5 +104,23 @@ tasks.register('writeForgeVersionJson') {
 }
 
 tasks.named('generateResources').configure {
+    dependsOn('eclipseJdt')
+    dependsOn('eclipseJdtApt')
+    dependsOn('eclipseFactorypath')
     dependsOn('writeForgeVersionJson')
 }
+
+eclipse {
+    classpath {
+       // We need to set the default output directory for the log4j annotation processor
+       // Ideally we'd just set the value, but the eclipse plugin deduplicates the output directories
+       // So we have to do a hacky whenMerged
+       //defaultOutputDir = file('bin/main')
+       file.whenMerged {
+           entries.each { entry ->
+               if (entry.kind == 'output' && entry.hasProperty('path'))
+                   entry.path = 'bin/main'
+           }
+       }
+    }
+}

fmlloader/src/main/java/net/minecraftforge/fml/common/asm/CapabilityTokenSubclass.java

@@ -36,9 +36,9 @@ import cpw.mods.modlauncher.serviceapi.ILaunchPluginService;
  */
 public class CapabilityTokenSubclass implements ILaunchPluginService {
 
-    private final String FUNC_NAME = "getType";
-    private final String FUNC_DESC = "()Ljava/lang/String;";
-    private final String CAP_INJECT = "net/minecraftforge/common/capabilities/CapabilityToken"; //Don't directly reference this to prevent class loading.
+    private static final String FUNC_NAME = "getType";
+    private static final String FUNC_DESC = "()Ljava/lang/String;";
+    private static final String CAP_INJECT = "net/minecraftforge/common/capabilities/CapabilityToken"; //Don't directly reference this to prevent class loading.
 
     @Override
     public String name() {
@@ -49,49 +49,45 @@ public class CapabilityTokenSubclass implements ILaunchPluginService {
     private static final EnumSet<Phase> NAY = EnumSet.noneOf(Phase.class);
 
     @Override
-    public EnumSet<Phase> handlesClass(Type classType, boolean isEmpty)
-    {
-        return isEmpty ? NAY : YAY;
+    public EnumSet<Phase> handlesClass(Type classType, boolean isEmpty) {
+        if (isEmpty)
+            return NAY;
+
+        String internalName = classType.getInternalName();
+        if (internalName.startsWith("net/minecraft/") || internalName.startsWith("com/mojang/"))
+            return NAY;
+        
+        return YAY;
     }
 
     @Override
-    public int processClassWithFlags(final Phase phase, final ClassNode classNode, final Type classType, final String reason)
-    {
-        if (CAP_INJECT.equals(classNode.name))
-        {
-            for (MethodNode mtd : classNode.methods)
-            {
-                if (FUNC_NAME.equals(mtd.name) && FUNC_DESC.equals(mtd.desc))
-                {
+    public int processClassWithFlags(final Phase phase, final ClassNode classNode, final Type classType, final String reason) {
+        if (CAP_INJECT.equals(classNode.name)) {
+            for (MethodNode mtd : classNode.methods) {
+                if (FUNC_NAME.equals(mtd.name) && FUNC_DESC.equals(mtd.desc)) {
                     mtd.access &= ~Opcodes.ACC_FINAL; // We have it final in code so people don't override it, cuz that'd be stupid, and make our transformer more complicated.
                 }
             }
             return ComputeFlags.SIMPLE_REWRITE;
-        }
-        else if (CAP_INJECT.equals(classNode.superName))
-        {
+        } else if (CAP_INJECT.equals(classNode.superName)) {
             Holder cls = new Holder();
 
             SignatureReader reader = new SignatureReader(classNode.signature); // Having a node version of this would probably be useful.
-            reader.accept(new SignatureVisitor(Opcodes.ASM9)
-            {
-                Deque<String> stack = new ArrayDeque<>();
+            reader.accept(new SignatureVisitor(Opcodes.ASM9) {
+                final Deque<String> stack = new ArrayDeque<>();
 
                 @Override
-                public void visitClassType(final String name)
-                {
+                public void visitClassType(final String name) {
                     stack.push(name);
                 }
 
                 @Override
-                public void visitInnerClassType(final String name)
-                {
+                public void visitInnerClassType(final String name) {
                     stack.push(stack.pop() + '$' + name);
                 }
 
                 @Override
-                public void visitEnd()
-                {
+                public void visitEnd() {
                     var val = stack.pop();
                     if (!stack.isEmpty() && CAP_INJECT.equals(stack.peek()))
                         cls.value = val;
@@ -106,15 +102,12 @@ public class CapabilityTokenSubclass implements ILaunchPluginService {
             mtd.visitInsn(Opcodes.ARETURN);
             mtd.visitEnd();
             return ComputeFlags.COMPUTE_MAXS;
-        }
-        else
-        {
+        } else {
             return ComputeFlags.NO_REWRITE;
         }
     }
 
-    private static class Holder {
+    private static final class Holder {
         String value;
     }
-
 }

fmlloader/src/main/java/net/minecraftforge/fml/common/asm/ObjectHolderDefinalize.java

@@ -8,6 +8,7 @@ package net.minecraftforge.fml.common.asm;
 import java.util.EnumSet;
 import java.util.List;
 import java.util.Map;
+import java.util.Set;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.function.Function;
 import java.util.stream.Collectors;
@@ -34,8 +35,12 @@ public class ObjectHolderDefinalize implements ILaunchPluginService {
             new VanillaObjectHolderData("net.minecraft.world.effect.MobEffects", "mob_effect", "net.minecraft.world.effect.MobEffect"),
             new VanillaObjectHolderData("net.minecraft.core.particles.ParticleTypes", "particle_type", "net.minecraft.core.particles.ParticleType"),
             new VanillaObjectHolderData("net.minecraft.sounds.SoundEvents", "sound_event", "net.minecraft.sounds.SoundEvent")
-    ).collect(Collectors.toMap(VanillaObjectHolderData::holderClass, Function.identity()));
-    private final String OBJECT_HOLDER = "Lnet/minecraftforge/registries/ObjectHolder;"; //Don't directly reference this to prevent class loading.
+    ).collect(Collectors.toUnmodifiableMap(VanillaObjectHolderData::holderClass, Function.identity()));
+    private static final Set<String> VANILLA_OBJECT_HOLDER_CLASSES = VANILLA_OBJECT_HOLDERS.keySet().stream()
+            .map(it -> it.replace('.', '/'))
+            .collect(Collectors.toUnmodifiableSet());
+    private static final String OBJECT_HOLDER = "Lnet/minecraftforge/registries/ObjectHolder;"; //Don't directly reference this to prevent class loading.
+    private static final int PUBLIC_STATIC_FINAL_FLAGS = Opcodes.ACC_PUBLIC | Opcodes.ACC_STATIC | Opcodes.ACC_FINAL;
 
     @Override
     public String name() {
@@ -46,13 +51,29 @@ public class ObjectHolderDefinalize implements ILaunchPluginService {
     private static final EnumSet<Phase> NAY = EnumSet.noneOf(Phase.class);
 
     @Override
-    public EnumSet<Phase> handlesClass(Type classType, boolean isEmpty)
-    {
-        return isEmpty ? NAY : YAY;
+    public EnumSet<Phase> handlesClass(Type classType, boolean isEmpty) {
+        if (isEmpty)
+            return NAY;
+
+        // Let's skip processing classes that definitely don't have object holders
+        String internalName = classType.getInternalName();
+
+        // Forge classes that aren't in the debug package (that package is used for tests)
+        if (internalName.startsWith("net/minecraftforge/") && !internalName.substring(18).contains("debug"))
+            return NAY;
+
+        // Vanilla classes that don't have object holders
+        if (internalName.startsWith("com/mojang/"))
+            return NAY;
+
+        // ...except specific ones we added to the VANILLA_OBJECT_HOLDERS map
+        if (internalName.startsWith("net/minecraft/") && !VANILLA_OBJECT_HOLDER_CLASSES.contains(internalName))
+            return NAY;
+
+        return YAY;
     }
 
-    private boolean hasHolder(List<AnnotationNode> lst)
-    {
+    private static boolean hasHolder(List<AnnotationNode> lst) {
         return lst != null && lst.stream().anyMatch(n -> n.desc.equals(OBJECT_HOLDER));
     }
 
@@ -76,10 +97,9 @@ public class ObjectHolderDefinalize implements ILaunchPluginService {
     {
         final AtomicBoolean changes = new AtomicBoolean();
         //Must be public static finals, and non-array objects
-        final int flags = Opcodes.ACC_PUBLIC | Opcodes.ACC_STATIC | Opcodes.ACC_FINAL;
 
         //Fix Annotated Fields before injecting from class level
-        classNode.fields.stream().filter(f -> ((f.access & flags) == flags) && f.desc.startsWith("L") && hasHolder(f.visibleAnnotations)).forEach(f ->
+        classNode.fields.stream().filter(f -> ((f.access & PUBLIC_STATIC_FINAL_FLAGS) == PUBLIC_STATIC_FINAL_FLAGS) && f.desc.startsWith("L") && hasHolder(f.visibleAnnotations)).forEach(f ->
         {
             int prev = f.access;
             f.access &= ~Opcodes.ACC_FINAL; //Strip final
@@ -89,7 +109,7 @@ public class ObjectHolderDefinalize implements ILaunchPluginService {
 
         if (VANILLA_OBJECT_HOLDERS.containsKey(classType.getClassName())) //Class level, de-finalize all fields and add @ObjectHolder to them!
         {
-            classNode.fields.stream().filter(f -> ((f.access & flags) == flags) && f.desc.startsWith("L")).forEach(f ->
+            classNode.fields.stream().filter(f -> ((f.access & PUBLIC_STATIC_FINAL_FLAGS) == PUBLIC_STATIC_FINAL_FLAGS) && f.desc.startsWith("L")).forEach(f ->
             {
                 int prev = f.access;
                 f.access &= ~Opcodes.ACC_FINAL;

fmlloader/src/main/java/net/minecraftforge/fml/common/asm/RuntimeEnumExtender.java

@@ -28,15 +28,16 @@ import org.slf4j.Logger;
 public class RuntimeEnumExtender implements ILaunchPluginService {
 
     private static final Logger LOGGER = LogUtils.getLogger();
-    private final Type STRING = Type.getType(String.class);
-    private final Type ENUM = Type.getType(Enum.class);
-    private final Type MARKER_IFACE = Type.getType("Lnet/minecraftforge/common/IExtensibleEnum;");
-    private final Type ARRAY_UTILS = Type.getType("Lorg/apache/commons/lang3/ArrayUtils;"); //Don't directly reference this to prevent class loading.
-    private final String ADD_DESC = Type.getMethodDescriptor(Type.getType(Object[].class), Type.getType(Object[].class), Type.getType(Object.class));
-    private final Type UNSAFE_HACKS = Type.getType("Lnet/minecraftforge/fml/unsafe/UnsafeHacks;"); //Again, not direct reference to prevent class loading.
-    private final String CLEAN_DESC = Type.getMethodDescriptor(Type.VOID_TYPE, Type.getType(Class.class));
-    private final String NAME_DESC = Type.getMethodDescriptor(STRING);
-    private final String EQUALS_DESC = Type.getMethodDescriptor(Type.BOOLEAN_TYPE, STRING);
+    private static final Type STRING = Type.getType(String.class);
+    private static final Type ENUM = Type.getType(Enum.class);
+    private static final Type MARKER_IFACE = Type.getType("Lnet/minecraftforge/common/IExtensibleEnum;");
+    private static final Type ARRAY_UTILS = Type.getType("Lorg/apache/commons/lang3/ArrayUtils;"); //Don't directly reference this to prevent class loading.
+    private static final String ADD_DESC = Type.getMethodDescriptor(Type.getType(Object[].class), Type.getType(Object[].class), Type.getType(Object.class));
+    private static final Type UNSAFE_HACKS = Type.getType("Lnet/minecraftforge/fml/unsafe/UnsafeHacks;"); //Again, not direct reference to prevent class loading.
+    private static final String CLEAN_DESC = Type.getMethodDescriptor(Type.VOID_TYPE, Type.getType(Class.class));
+    private static final String NAME_DESC = Type.getMethodDescriptor(STRING);
+    private static final String EQUALS_DESC = Type.getMethodDescriptor(Type.BOOLEAN_TYPE, STRING);
+    private static final int FLAGS = Opcodes.ACC_PRIVATE | Opcodes.ACC_STATIC | Opcodes.ACC_FINAL | Opcodes.ACC_SYNTHETIC;
 
     @Override
     public String name() {
@@ -47,9 +48,15 @@ public class RuntimeEnumExtender implements ILaunchPluginService {
     private static final EnumSet<Phase> NAY = EnumSet.noneOf(Phase.class);
 
     @Override
-    public EnumSet<Phase> handlesClass(Type classType, boolean isEmpty)
-    {
-        return isEmpty ? NAY : YAY;
+    public EnumSet<Phase> handlesClass(Type classType, boolean isEmpty) {
+        if (isEmpty)
+            return NAY;
+
+        String internalName = classType.getInternalName();
+        if (internalName.startsWith("net/minecraftforge/") || internalName.startsWith("com/mojang/"))
+            return NAY;
+
+        return YAY;
     }
 
     @Override
@@ -58,25 +65,24 @@ public class RuntimeEnumExtender implements ILaunchPluginService {
         if ((classNode.access & Opcodes.ACC_ENUM) == 0)
             return ComputeFlags.NO_REWRITE;
 
-        Type array = Type.getType("[" + classType.getDescriptor());
-        final int flags = Opcodes.ACC_PRIVATE | Opcodes.ACC_STATIC | Opcodes.ACC_FINAL | Opcodes.ACC_SYNTHETIC;
-
-        FieldNode values = classNode.fields.stream().filter(f -> f.desc.contentEquals(array.getDescriptor()) && ((f.access & flags) == flags)).findFirst().orElse(null);
-
-        if (!classNode.interfaces.contains(MARKER_IFACE.getInternalName())) {
+        if (!classNode.interfaces.contains(MARKER_IFACE.getInternalName()))
             return ComputeFlags.NO_REWRITE;
-        }
+
+        Type array = Type.getType("[" + classType.getDescriptor());
+        String arrayDesc = array.getDescriptor();
+
+        FieldNode values = classNode.fields.stream().filter(f -> f.desc.equals(arrayDesc) && ((f.access & FLAGS) == FLAGS)).findFirst().orElse(null);
 
         //Static methods named "create" with first argument as a string
         List<MethodNode> candidates = classNode.methods.stream()
                 .filter(m -> ((m.access & Opcodes.ACC_STATIC) != 0) && m.name.equals("create"))
-                .collect(Collectors.toList());
+                .toList();
 
         if (candidates.isEmpty()) {
             throw new IllegalStateException("IExtensibleEnum has no candidate factory methods: " + classType.getClassName());
         }
 
-        candidates.forEach(mtd ->
+        for (var mtd : candidates)
         {
             Type[] args = Type.getArgumentTypes(mtd.desc);
             if (args.length == 0 || !args[0].equals(STRING)) {
@@ -108,8 +114,7 @@ public class RuntimeEnumExtender implements ILaunchPluginService {
             Type[] ctrArgs = new Type[args.length + 1];
             ctrArgs[0] = STRING;
             ctrArgs[1] = Type.INT_TYPE;
-            for (int x = 1; x < args.length; x++)
-                ctrArgs[1 + x] = args[x];
+            System.arraycopy(args, 1, ctrArgs, 2, args.length - 1);
 
             String desc = Type.getMethodDescriptor(Type.VOID_TYPE, ctrArgs);
 
@@ -231,7 +236,7 @@ public class RuntimeEnumExtender implements ILaunchPluginService {
                 ins.load(vars, classType);
                 ins.areturn(classType);
             }
-        });
+        }
         return ComputeFlags.COMPUTE_FRAMES;
     }
 

fmlloader/src/main/java/net/minecraftforge/fml/loading/BackgroundWaiter.java

@@ -6,14 +6,13 @@
 package net.minecraftforge.fml.loading;
 
 import java.util.concurrent.ExecutionException;
-import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 import java.util.concurrent.Future;
 
 public class BackgroundWaiter {
-    private static final ExecutorService runner = Executors.newSingleThreadExecutor();
 
     public static void runAndTick(Runnable r, Runnable tick) {
+        var runner = Executors.newSingleThreadExecutor();
         ImmediateWindowHandler.updateProgress("Loading bootstrap resources");
         final Future<?> work = runner.submit(r);
         do {

fmlloader/src/main/java/net/minecraftforge/fml/loading/FMLLoader.java

@@ -17,11 +17,9 @@ import net.minecraftforge.api.distmarker.Dist;
 import net.minecraftforge.fml.loading.targets.CommonLaunchHandler;
 import net.minecraftforge.forgespi.Environment;
 import net.minecraftforge.forgespi.coremod.ICoreModProvider;
-import org.apache.commons.lang3.tuple.Pair;
 import org.slf4j.Logger;
 
 import java.nio.file.Path;
-import java.nio.file.Paths;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
@@ -36,7 +34,6 @@ import static net.minecraftforge.fml.loading.LogMarkers.SCAN;
 public class FMLLoader {
     private static final Logger LOGGER = LogUtils.getLogger();
     private static AccessTransformerService accessTransformer;
-    private static ModDiscoverer modDiscoverer;
     private static ICoreModProvider coreModProvider;
     private static LanguageLoadingProvider languageLoadingProvider;
     private static Dist dist;
@@ -62,7 +59,7 @@ public class FMLLoader {
         /*eventBus       =*/ getPlugin(env, "eventbus",           "1.0", "EventBus");
         runtimeDistCleaner = getPlugin(env, "runtimedistcleaner", "1.0", "RuntimeDistCleaner");
         coreModProvider = getSingleService(ICoreModProvider.class, "CoreMod");
-        LOGGER.debug(CORE,"FML found CoreMod version : {}", JarVersionLookupHandler.getInfo(coreModProvider.getClass()).impl().version().orElse("MISSING"));
+        LOGGER.debug(CORE, "FML found CoreMod version : {}", JarVersionLookupHandler.getInfo(coreModProvider.getClass()).impl().version().orElse("MISSING"));
         checkPackage(Environment.class, "2.0", "ForgeSPI");
 
         try {
@@ -74,14 +71,15 @@ public class FMLLoader {
         }
     }
 
+    @SuppressWarnings("unchecked")
     private static <T> T getPlugin(IEnvironment env, String id, String version, String name) throws IncompatibleEnvironmentException {
-        @SuppressWarnings("unchecked")
-        var plugin = (T)env.findLaunchPlugin(id).orElseThrow(() -> {
+        var plugin = env.findLaunchPlugin(id).orElse(null);
+        if (plugin == null) {
             LOGGER.error(CORE, "{} library is missing, we need this to run", name);
-            return new IncompatibleEnvironmentException("Missing " + name + ", cannot run");
-        });
+            throw new IncompatibleEnvironmentException("Missing " + name + ", cannot run");
+        }
         checkPackage(plugin.getClass(), version, name);
-        return plugin;
+        return (T) plugin;
     }
 
     private static void checkPackage(Class<?> cls, String version, String name) throws IncompatibleEnvironmentException {
@@ -137,20 +135,20 @@ public class FMLLoader {
         }
         commonLaunchHandler = (CommonLaunchHandler)launchHandler.get();
         launchHandlerName = launchHandler.get().name();
-        gamePath = environment.getProperty(IEnvironment.Keys.GAMEDIR.get()).orElse(Paths.get(".").toAbsolutePath());
+        gamePath = environment.getProperty(IEnvironment.Keys.GAMEDIR.get()).orElse(Path.of(".").toAbsolutePath());
 
         naming = commonLaunchHandler.getNaming();
         dist = commonLaunchHandler.getDist();
         production = commonLaunchHandler.isProduction();
 
-        accessTransformer.getExtension().accept(Pair.of(naming, "srg"));
+        accessTransformer.getExtension().accept(Map.entry(naming, "srg"));
 
         runtimeDistCleaner.getExtension().accept(dist);
     }
 
     public static List<ITransformationService.Resource> beginModScan(final Map<String,?> arguments) {
         LOGGER.debug(SCAN,"Scanning for Mod Locators");
-        modDiscoverer = new ModDiscoverer(arguments);
+        var modDiscoverer = new ModDiscoverer(arguments);
         modValidator = modDiscoverer.discoverMods();
         var pluginResources = modValidator.getPluginResources();
         return List.of(pluginResources);
@@ -172,16 +170,12 @@ public class FMLLoader {
         return languageLoadingProvider;
     }
 
-    static ModDiscoverer getModDiscoverer() {
-        return modDiscoverer;
-    }
-
     public static CommonLaunchHandler getLaunchHandler() {
         return commonLaunchHandler;
     }
 
     public static void addAccessTransformer(Path atPath, ModFile modName) {
-        LOGGER.debug(SCAN, "Adding Access Transformer in {}", modName.getFilePath());
+        LOGGER.debug(SCAN, "Adding Access Transformer {} in {}", atPath, modName.getFilePath());
         accessTransformer.offerResource(atPath, modName.getFileName());
     }
 

fmlloader/src/main/java/net/minecraftforge/fml/loading/FMLServiceProvider.java

@@ -7,7 +7,6 @@ package net.minecraftforge.fml.loading;
 
 import com.mojang.logging.LogUtils;
 import cpw.mods.modlauncher.api.*;
-import joptsimple.OptionSpecBuilder;
 import net.minecraftforge.fml.loading.moddiscovery.ModFile;
 import net.minecraftforge.forgespi.Environment;
 import org.jetbrains.annotations.NotNull;
@@ -19,12 +18,11 @@ import java.util.List;
 import java.util.Locale;
 import java.util.Map;
 import java.util.Set;
-import java.util.function.BiFunction;
 import static net.minecraftforge.fml.loading.LogMarkers.CORE;
 
 public class FMLServiceProvider implements ITransformationService {
     private static final Logger LOGGER = LogUtils.getLogger();
-    private Map<String, Object> arguments;
+    private final Map<String, Object> arguments = new HashMap<>();
 
     public FMLServiceProvider() {
         var markers = System.getProperty("forge.logging.markers", "").split(",");
@@ -45,7 +43,6 @@ public class FMLServiceProvider implements ITransformationService {
         FMLConfig.load();
         LOGGER.debug(CORE, "Preparing ModFile");
         environment.computePropertyIfAbsent(Environment.Keys.MODFILEFACTORY.get(), k->ModFile::new);
-        arguments = new HashMap<>();
         LOGGER.debug(CORE, "Preparing launch handler");
         FMLLoader.setupLaunchHandler(environment, arguments);
         FMLEnvironment.setupInteropEnvironment(environment);
@@ -68,14 +65,6 @@ public class FMLServiceProvider implements ITransformationService {
         FMLLoader.onInitialLoad(environment, otherServices);
     }
 
-    @Override
-    public void arguments(BiFunction<String, String, OptionSpecBuilder> argumentBuilder) {
-    }
-
-    @Override
-    public void argumentValues(OptionResult option) {
-    }
-
     @SuppressWarnings("rawtypes")
     @Override
     public @NotNull List<ITransformer> transformers() {

fmlloader/src/main/java/net/minecraftforge/fml/loading/ImmediateWindowHandler.java

@@ -140,7 +140,7 @@ public class ImmediateWindowHandler {
 
         @Override
         public void updateModuleReads(final ModuleLayer layer) {
-            var fm = layer.findModule("forge");
+            var fm = layer.findModule("net.minecraftforge.forge");
             if (fm.isPresent()) {
                 getClass().getModule().addReads(fm.get());
                 var clz = fm.map(l -> Class.forName(l, "net.minecraftforge.client.loading.NoVizFallback")).orElseThrow();

fmlloader/src/main/java/net/minecraftforge/fml/loading/LoadingModList.java

@@ -5,31 +5,28 @@
 
 package net.minecraftforge.fml.loading;
 
-import cpw.mods.modlauncher.api.LamdbaExceptionUtils;
+import com.mojang.logging.LogUtils;
 import net.minecraftforge.fml.loading.moddiscovery.BackgroundScanHandler;
 import net.minecraftforge.fml.loading.moddiscovery.ModFile;
 import net.minecraftforge.fml.loading.moddiscovery.ModFileInfo;
 import net.minecraftforge.fml.loading.moddiscovery.ModInfo;
 import net.minecraftforge.forgespi.locating.IModFile;
+import org.slf4j.Logger;
 
-import java.net.URL;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.ArrayList;
 import java.util.Collection;
-import java.util.Enumeration;
-import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
-import java.util.NoSuchElementException;
 import java.util.stream.Collectors;
 
 /**
  * Master list of all mods <em>in the loading context. This class cannot refer outside the
  * loading package</em>
  */
-public class LoadingModList
-{
+public class LoadingModList {
+    private static final Logger LOGGER = LogUtils.getLogger();
     private static LoadingModList INSTANCE;
     private final List<ModFileInfo> modFiles;
     private final List<ModInfo> sortedList;
@@ -37,15 +34,14 @@ public class LoadingModList
     private final List<EarlyLoadingException> preLoadErrors;
     private List<IModFile> brokenFiles;
 
-    private LoadingModList(final List<ModFile> modFiles, final List<ModInfo> sortedList)
-    {
+    private LoadingModList(final List<ModFile> modFiles, final List<ModInfo> sortedList) {
         this.modFiles = modFiles.stream()
                 .map(ModFile::getModFileInfo)
                 .map(ModFileInfo.class::cast)
-                .collect(Collectors.toList());
+                .toList();
         this.sortedList = sortedList.stream()
                 .map(ModInfo.class::cast)
-                .collect(Collectors.toList());
+                .toList();
         this.fileById = this.modFiles.stream()
                 .map(ModFileInfo::getMods)
                 .flatMap(Collection::stream)
@@ -54,21 +50,18 @@ public class LoadingModList
         this.preLoadErrors = new ArrayList<>();
     }
 
-    public static LoadingModList of(List<ModFile> modFiles, List<ModInfo> sortedList, final EarlyLoadingException earlyLoadingException)
-    {
+    public static LoadingModList of(List<ModFile> modFiles, List<ModInfo> sortedList, final EarlyLoadingException earlyLoadingException) {
         INSTANCE = new LoadingModList(modFiles, sortedList);
         if (earlyLoadingException != null)
-        {
             INSTANCE.preLoadErrors.add(earlyLoadingException);
-        }
         return INSTANCE;
     }
 
     public static LoadingModList get() {
         return INSTANCE;
     }
-    public void addCoreMods()
-    {
+
+    public void addCoreMods() {
         modFiles.stream()
                 .map(ModFileInfo::getFile)
                 .map(ModFile::getCoreMods)
@@ -76,28 +69,37 @@ public class LoadingModList
                 .forEach(FMLLoader.getCoreModProvider()::addCoreMod);
     }
 
-    public void addAccessTransformers()
-    {
-        modFiles.stream()
-                .map(ModFileInfo::getFile)
-                .forEach(mod -> mod.getAccessTransformer().ifPresent(path -> FMLLoader.addAccessTransformer(path, mod)));
+    public void addAccessTransformers() {
+        var errors = new ArrayList<EarlyLoadingException.ExceptionData>();
+        for (ModFileInfo modFile : modFiles) {
+            ModFile mod = modFile.getFile();
+            for (Path at : mod.getAccessTransformers()) {
+                if (!Files.exists(at)) {
+                    var message = "Invalid mod file: " + modFile.getFile().getFileName() + ". Missing Access Transformer: " + at;
+                    errors.add(new EarlyLoadingException.ExceptionData(message));
+                    LOGGER.error(message);
+                } else {
+                    FMLLoader.addAccessTransformer(at, mod);
+                }
+            }
+        }
+        if (!errors.isEmpty()) {
+            preLoadErrors.add(new EarlyLoadingException("Invalid Access Transformers", null, errors));
+        }
     }
 
-    public void addForScanning(BackgroundScanHandler backgroundScanHandler)
-    {
+    public void addForScanning(BackgroundScanHandler backgroundScanHandler) {
         backgroundScanHandler.setLoadingModList(this);
         modFiles.stream()
                 .map(ModFileInfo::getFile)
                 .forEach(backgroundScanHandler::submitForScanning);
     }
 
-    public List<ModFileInfo> getModFiles()
-    {
+    public List<ModFileInfo> getModFiles() {
         return modFiles;
     }
 
-    public Path findResource(final String className)
-    {
+    public Path findResource(final String className) {
         for (ModFileInfo mf : modFiles) {
             final Path resource = mf.getFile().findResource(className);
             if (Files.exists(resource)) return resource;
@@ -105,55 +107,11 @@ public class LoadingModList
         return null;
     }
 
-    public Enumeration<URL> findAllURLsForResource(final String resName) {
-        final String resourceName;
-        // strip a leading slash
-        if (resName.startsWith("/")) {
-            resourceName = resName.substring(1);
-        } else {
-            resourceName = resName;
-        }
-        return new Enumeration<URL>() {
-            private final Iterator<ModFileInfo> modFileIterator = modFiles.iterator();
-            private URL next;
-            @Override
-            public boolean hasMoreElements() {
-                if (next!=null) return true;
-                next = findNextURL();
-                return next != null;
-            }
-
-            @Override
-            public URL nextElement() {
-                if (next == null) {
-                    next = findNextURL();
-                    if (next == null) throw new NoSuchElementException();
-                }
-                URL result = next;
-                next = null;
-                return result;
-            }
-
-            private URL findNextURL() {
-                while (modFileIterator.hasNext()) {
-                    final ModFileInfo next = modFileIterator.next();
-                    final Path resource = next.getFile().findResource(resourceName);
-                    if (Files.exists(resource)) {
-                        return LamdbaExceptionUtils.uncheck(()->new URL("modjar://" + next.getMods().get(0).getModId() + "/" + resourceName));
-                    }
-                }
-                return null;
-            }
-        };
-    }
-
-    public ModFileInfo getModFileById(String modid)
-    {
+    public ModFileInfo getModFileById(String modid) {
         return this.fileById.get(modid);
     }
 
-    public List<ModInfo> getMods()
-    {
+    public List<ModInfo> getMods() {
         return this.sortedList;
     }
 

fmlloader/src/main/java/net/minecraftforge/fml/loading/MCPNamingService.java

@@ -36,7 +36,7 @@ public class MCPNamingService implements INameMappingService {
 
     @Override
     public Map.Entry<String, String> understanding() {
-        return Pair.of("srg", "mcp");
+        return Map.entry("srg", "mcp");
     }
 
     @Override
@@ -77,7 +77,7 @@ public class MCPNamingService implements INameMappingService {
     }
 
     private static void loadMappings(final String mappingFileName, BiConsumer<String, String> mapStore) {
-        URL path = ClassLoader.getSystemResource(mappingFileName); //We EXPLICITLY go through the SystemClassLoader here because this is dev-time only. And will be on the root classpath.
+        URL path = MCPNamingService.class.getClassLoader().getResource(mappingFileName);
         if (path == null)
             return;
 

fmlloader/src/main/java/net/minecraftforge/fml/loading/MavenCoordinateResolver.java

@@ -34,7 +34,7 @@ public class MavenCoordinateResolver {
                 (!extension.isEmpty() ? "." + extension : ".jar");
 
         String[] groups = groupId.split("\\.");
-        Path result = Paths.get(groups[0]);
+        Path result = Path.of(groups[0]);
         for (int i = 1; i < groups.length; i++) {
             result = result.resolve(groups[i]);
         }

fmlloader/src/main/java/net/minecraftforge/fml/loading/ModDirTransformerDiscoverer.java

@@ -10,6 +10,8 @@ import cpw.mods.jarhandling.SecureJar;
 import cpw.mods.modlauncher.api.LamdbaExceptionUtils;
 import cpw.mods.modlauncher.api.NamedPath;
 import cpw.mods.modlauncher.serviceapi.ITransformerDiscoveryService;
+
+import org.jetbrains.annotations.ApiStatus;
 import org.slf4j.Logger;
 
 import java.io.IOException;
@@ -20,6 +22,7 @@ import java.util.ArrayList;
 import java.util.List;
 import java.util.Set;
 
+@ApiStatus.Internal
 public class ModDirTransformerDiscoverer implements ITransformerDiscoveryService {
     private static final Logger LOGGER = LogUtils.getLogger();
     private static final Set<String> SERVICES = Set.of(
@@ -76,4 +79,15 @@ public class ModDirTransformerDiscoverer implements ITransformerDiscoveryService
             .filter(SERVICES::contains)
             .forEach(s -> found.add(new NamedPath(s, path)));
     }
+
+    public static boolean isServiceProvider(Path path) {
+        var jar = SecureJar.from(path);
+
+        for (var providers : jar.moduleDataProvider().descriptor().provides()) {
+            if (SERVICES.contains(providers.service()))
+                return true;
+        }
+
+        return false;
+    }
 }

fmlloader/src/main/java/net/minecraftforge/fml/loading/ModSorter.java

@@ -8,7 +8,7 @@ package net.minecraftforge.fml.loading;
 import com.google.common.graph.GraphBuilder;
 import com.google.common.graph.MutableGraph;
 import com.mojang.logging.LogUtils;
-import net.minecraftforge.forgespi.language.IModInfo;
+import net.minecraftforge.forgespi.language.IModInfo.ModVersion;
 import net.minecraftforge.fml.loading.EarlyLoadingException.ExceptionData;
 import net.minecraftforge.fml.loading.moddiscovery.ModFile;
 import net.minecraftforge.fml.loading.moddiscovery.ModFileInfo;
@@ -20,229 +20,250 @@ import org.apache.maven.artifact.versioning.DefaultArtifactVersion;
 import org.slf4j.Logger;
 
 import java.util.ArrayList;
-import java.util.Collections;
+import java.util.Collection;
 import java.util.Comparator;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
-import java.util.concurrent.atomic.AtomicInteger;
-import java.util.function.Function;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
-import static java.util.stream.Collectors.*;
 import static net.minecraftforge.fml.loading.LogMarkers.LOADING;
 
-public class ModSorter
-{
+public class ModSorter {
     private static final Logger LOGGER = LogUtils.getLogger();
-    private final UniqueModListBuilder uniqueModListBuilder;
-    private List<ModFile> modFiles;
-    private List<ModInfo> sortedList;
-    private Map<String, IModInfo> modIdNameLookup;
-    private List<ModFile> systemMods;
 
-    private ModSorter(final List<ModFile> modFiles)
-    {
-        this.uniqueModListBuilder = new UniqueModListBuilder(modFiles);
-    }
+    private record State(List<ModFile> files, List<ModInfo> mods) {}
+
+    private ModSorter() {}
+
+    @SuppressWarnings("removal")
+    public static LoadingModList sort(List<ModFile> mods, final List<ExceptionData> errors) {
+        State systemMods = detectSystemMods(mods);
+        List<ModFile> modFiles;
 
-    public static LoadingModList sort(List<ModFile> mods, final List<ExceptionData> errors)
-    {
-        final ModSorter ms = new ModSorter(mods);
         try {
-            ms.buildUniqueList();
+            modFiles = new UniqueModListBuilder(mods).buildUniqueList().modFiles();
         } catch (EarlyLoadingException e) {
             // We cannot build any list with duped mods. We have to abort immediately and report it
             // Note this will never actually throw an error because the duplicate checks are done in ModDiscovererer before we get to this phase
             // So all this is really doing is wasting time.
             // But i'm leaving it here until I rewrite all of cpw's mod loading code because its such a clusterfuck.
-            return LoadingModList.of(ms.systemMods, ms.systemMods.stream().map(mf->(ModInfo)mf.getModInfos().get(0)).collect(toList()), e);
+            return LoadingModList.of(systemMods.files(), systemMods.mods(), e);
         }
+
+        var named = new HashMap<String, ModInfo>();
+        for (var file : modFiles) {
+            for (var info : file.getModInfos())
+                named.put(info.getModId(), (ModInfo)info);
+        }
+
         // try and validate dependencies
-        final List<ExceptionData> failedList = Stream.concat(ms.verifyDependencyVersions().stream(), errors.stream()).toList();
+        final List<ExceptionData> failedList = Stream.concat(verifyDependencyVersions(modFiles).stream(), errors.stream()).toList();
+
         // if we miss one or the other, we abort now
         if (!failedList.isEmpty()) {
-            return LoadingModList.of(ms.systemMods, ms.systemMods.stream().map(mf->(ModInfo)mf.getModInfos().get(0)).collect(toList()), new EarlyLoadingException("failure to validate mod list", null, failedList));
+            return LoadingModList.of(systemMods.files(), systemMods.mods(), new EarlyLoadingException("failure to validate mod list", null, failedList));
         } else {
             // Otherwise, lets try and sort the modlist and proceed
-            EarlyLoadingException earlyLoadingException = null;
             try {
-                ms.sort();
+                var sorted = sort(modFiles, named);
+                return LoadingModList.of(sorted.files(), sorted.mods(), null);
             } catch (EarlyLoadingException e) {
-                earlyLoadingException = e;
+                // The only exception that can happen here is a cyclic exception, but fall back to system mods so we can display the nice screen.
+                return LoadingModList.of(systemMods.files(), systemMods.mods(), e);
             }
-            return LoadingModList.of(ms.modFiles, ms.sortedList, earlyLoadingException);
         }
     }
 
-    private void sort()
-    {
-        // lambdas are identity based, so sorting them is impossible unless you hold reference to them
-        final MutableGraph<ModFileInfo> graph = GraphBuilder.directed().build();
-        AtomicInteger counter = new AtomicInteger();
-        Map<ModFileInfo, Integer> infos = modFiles.stream()
-                .map(ModFile::getModFileInfo)
-                .filter(ModFileInfo.class::isInstance)
-                .map(ModFileInfo.class::cast)
-                .collect(toMap(Function.identity(), e -> counter.incrementAndGet()));
-        infos.keySet().forEach(graph::addNode);
-        modFiles.stream()
-                .map(ModFile::getModInfos)
-                .<IModInfo>mapMulti(Iterable::forEach)
-                .map(IModInfo::getDependencies)
-                .<IModInfo.ModVersion>mapMulti(Iterable::forEach)
-                .forEach(dep -> addDependency(graph, dep));
+    private static State sort(final List<ModFile> modFiles, final Map<String, ModInfo> named) {
+        final MutableGraph<ModInfo> graph = GraphBuilder.directed().build();
 
-        final List<ModFileInfo> sorted;
-        try
-        {
-            sorted = TopologicalSort.topologicalSort(graph, Comparator.comparing(infos::get));
-        }
-        catch (CyclePresentException e)
-        {
-            Set<Set<ModFileInfo>> cycles = e.getCycles();
-            if (LOGGER.isErrorEnabled(LOADING))
-            {
-                LOGGER.error(LOADING, "Mod Sorting failed.\nDetected Cycles: {}\n", cycles);
+        int counter = 0;
+        var infos = new HashMap<ModInfo, Integer>();
+        for (var file : modFiles) {
+            if (file.getModFileInfo() instanceof ModFileInfo info) {
+                for (var imod : info.getMods()) {
+                    var mod = (ModInfo)imod;
+                    infos.put(mod, counter++);
+                    graph.addNode(mod);
+                }
             }
-            var dataList = cycles.stream()
-                    .<ModFileInfo>mapMulti(Iterable::forEach)
-                    .<IModInfo>mapMulti((mf,c)->mf.getMods().forEach(c))
-                    .map(IModInfo::getModId)
-                    .map(list -> new ExceptionData("fml.modloading.cycle", list))
-                    .toList();
+        }
+
+        for (var file : modFiles) {
+            for (var info : file.getModInfos()) {
+                for (var dep : info.getDependencies()) {
+                    // Ordering isn't effected by sides, should it be?
+                    //if (!dep.getSide().isCorrectSide())
+                    //    continue;
+
+                    var target = named.get(dep.getModId());
+
+                    // soft dep that doesn't exist. No edge required.
+                    if (target == null)
+                        continue;
+
+                    var self = (ModInfo)dep.getOwner();
+
+                    switch (dep.getOrdering()) {
+                        case BEFORE -> graph.putEdge(self, target);
+                        case AFTER -> graph.putEdge(target, self);
+                        default -> {}
+                    }
+                }
+            }
+        }
+
+        final List<ModInfo> sorted;
+        try {
+            sorted = TopologicalSort.topologicalSort(graph, Comparator.comparing(infos::get));
+        } catch (CyclePresentException e) {
+            Set<Set<ModInfo>> cycles = e.getCycles();
+            var buf = new StringBuilder();
+            buf.append("Mod Sorting failed - Detected Cycles: \n");
+
+            var dataList = new ArrayList<ExceptionData>();
+            for (var cycle : cycles) {
+                buf.append("\tCycle:\n");
+                for (var mod : cycle) {
+                    var modDeps = new StringBuilder()
+                        .append(mod.getModId())
+                        .append(' ')
+                        .append(mod.getDependencies().stream()
+                            .filter(v -> cycle.stream().anyMatch(m -> m.getModId().equals(v.getModId())))
+                            .map(dep -> dep.getOrdering().name() + " " + dep.getModId())
+                            .collect(Collectors.joining(", "))
+                        );
+                    dataList.add(new ExceptionData("fml.modloading.cycle", modDeps.toString()));
+                    buf.append("\t\tMod: ").append(modDeps.toString()).append('\n');
+                }
+            }
+
+            LOGGER.error(LOADING, buf.toString());
+
             throw new EarlyLoadingException("Sorting error", e, dataList);
         }
-        this.sortedList = sorted.stream()
-                .map(ModFileInfo::getMods)
-                .<IModInfo>mapMulti(Iterable::forEach)
-                .map(ModInfo.class::cast)
-                .collect(toList());
-        this.modFiles = sorted.stream()
-                .map(ModFileInfo::getFile)
-                .collect(toList());
-    }
 
-    private void addDependency(MutableGraph<ModFileInfo> topoGraph, IModInfo.ModVersion dep)
-    {
-        final ModFileInfo self = (ModFileInfo)dep.getOwner().getOwningFile();
-        final IModInfo targetModInfo = modIdNameLookup.get(dep.getModId());
-        // soft dep that doesn't exist. Just return. No edge required.
-        if (targetModInfo == null || !(targetModInfo.getOwningFile() instanceof final ModFileInfo target)) return;
-        if (self == target)
-            return; // in case a jar has two mods that have dependencies between
-        switch (dep.getOrdering()) {
-            case BEFORE -> topoGraph.putEdge(self, target);
-            case AFTER -> topoGraph.putEdge(target, self);
-            default -> {}
+        var files = new LinkedHashSet<ModFile>();
+        var list = new ArrayList<ModInfo>();
+
+        for (var mod : sorted) {
+            files.add(mod.getOwningFile().getFile());
+            list.add(mod);
         }
+
+        return new State(files.stream().toList(), list);
     }
 
-    private void buildUniqueList()
-    {
-        final UniqueModListBuilder.UniqueModListData uniqueModListData = uniqueModListBuilder.buildUniqueList();
-
-        this.modFiles = uniqueModListData.modFiles();
-
-        detectSystemMods(uniqueModListData.modFilesByFirstId());
-
-        modIdNameLookup = uniqueModListData.modFilesByFirstId().entrySet().stream()
-                .filter(e -> !e.getValue().get(0).getModInfos().isEmpty())
-                .collect(Collectors.toMap(
-                    Map.Entry::getKey,
-                    e -> e.getValue().get(0).getModInfos().get(0)
-                  ));
-    }
-
-    private void detectSystemMods(final Map<String, List<ModFile>> modFilesByFirstId) {
+    private static State detectSystemMods(final List<ModFile> modFiles) {
         // Capture system mods (ex. MC, Forge) here, so we can keep them for later
         var systemMods = List.of("minecraft", "forge");
         LOGGER.debug("Configured system mods: {}", systemMods);
 
-        this.systemMods = new ArrayList<>();
+        var mods = new ArrayList<ModInfo>();
+        var files = new ArrayList<ModFile>();
         for (var systemMod : systemMods) {
-            var container = modFilesByFirstId.get(systemMod);
-            if (container != null && !container.isEmpty()) {
-                LOGGER.debug("Found system mod: {}", systemMod);
-                this.systemMods.add((ModFile) container.get(0));
-            } else {
+            var mod = findMod(modFiles, systemMod);
+            if (mod == null)
                 throw new IllegalStateException("Failed to find system mod: " + systemMod);
-            }
+
+            LOGGER.debug("Found system mod: {}", systemMod);
+            mods.add(mod.info());
+            files.add(mod.file());
         }
+
+        return new State(files, mods);
     }
 
-    private List<EarlyLoadingException.ExceptionData> verifyDependencyVersions()
-    {
-        final var modVersions = modFiles.stream()
-                .map(ModFile::getModInfos)
-                .<IModInfo>mapMulti(Iterable::forEach)
-                .collect(toMap(IModInfo::getModId, IModInfo::getVersion));
+    private record ModPair(ModFile file, ModInfo info) {}
+    private static ModPair findMod(final List<ModFile> modFiles, String name) {
+        for (var file : modFiles) {
+            for (var mod : file.getModFileInfo().getMods()) {
+                if (name.equals(mod.getModId()))
+                    return new ModPair(file, (ModInfo)mod);
+            }
+        }
+        return null;
+    }
 
-        final var modVersionDependencies = modFiles.stream()
-                .map(ModFile::getModInfos)
-                .<IModInfo>mapMulti(Iterable::forEach)
-                .collect(groupingBy(Function.identity(), flatMapping(e -> e.getDependencies().stream(), toList())));
+    private static List<ExceptionData> verifyDependencyVersions(final List<ModFile> files) {
+        final var modVersions = new HashMap<String, ArtifactVersion>();
+        final var modRequirements = new HashSet<ModVersion>();
+        int mandatoryRequired = 0;
 
-        final var modRequirements = modVersionDependencies.values().stream()
-                .<IModInfo.ModVersion>mapMulti(Iterable::forEach)
-                .filter(mv -> mv.getSide().isCorrectSide())
-                .collect(toSet());
+        for (var file : files) {
+            for (var info : file.getModInfos()) {
+                modVersions.put(info.getModId(), info.getVersion());
+                for (var dep : info.getDependencies()) {
+                    if (dep.getSide().isCorrectSide()) {
+                        if (modRequirements.add(dep) && dep.isMandatory())
+                            mandatoryRequired++;
+                    }
+                }
+            }
+        }
 
-        final long mandatoryRequired = modRequirements.stream().filter(IModInfo.ModVersion::isMandatory).count();
         LOGGER.debug(LOADING, "Found {} mod requirements ({} mandatory, {} optional)", modRequirements.size(), mandatoryRequired, modRequirements.size() - mandatoryRequired);
-        final var missingVersions = modRequirements.stream()
-                .filter(mv -> (mv.isMandatory() || modVersions.containsKey(mv.getModId())) && this.modVersionNotContained(mv, modVersions))
-                .collect(toSet());
-        final long mandatoryMissing = missingVersions.stream().filter(IModInfo.ModVersion::isMandatory).count();
-        LOGGER.debug(LOADING, "Found {} mod requirements missing ({} mandatory, {} optional)", missingVersions.size(), mandatoryMissing, missingVersions.size() - mandatoryMissing);
 
-        if (!missingVersions.isEmpty()) {
-            if (mandatoryMissing > 0) {
-                LOGGER.error(
-                        LOADING,
-                        "Missing or unsupported mandatory dependencies:\n{}",
-                        missingVersions.stream()
-                                .filter(IModInfo.ModVersion::isMandatory)
-                                .map(ver -> formatDependencyError(ver, modVersions))
-                                .collect(Collectors.joining("\n"))
-                );
-            }
-            if (missingVersions.size() - mandatoryMissing > 0) {
-                LOGGER.error(
-                        LOADING,
-                        "Unsupported installed optional dependencies:\n{}",
-                        missingVersions.stream()
-                                .filter(ver -> !ver.isMandatory())
-                                .map(ver -> formatDependencyError(ver, modVersions))
-                                .collect(Collectors.joining("\n"))
-                );
-            }
+        final var missingMandatory = new HashSet<ModVersion>();
+        final var missingOptional = new HashSet<ModVersion>();
 
-            return missingVersions.stream()
-                    .map(mv -> new ExceptionData(mv.isMandatory() ? "fml.modloading.missingdependency" : "fml.modloading.missingdependency.optional",
-                            mv.getOwner(), mv.getModId(), mv.getOwner().getModId(), mv.getVersionRange(),
-                            modVersions.getOrDefault(mv.getModId(), new DefaultArtifactVersion("null"))))
-                    .toList();
+        for (var dep : modRequirements) {
+            var modId = dep.getModId();
+            var existing = modVersions.get(modId);
+
+            if (!dep.isMandatory() && existing == null)
+                continue;
+
+            var range = dep.getVersionRange();
+            if (existing != null && (range.containsVersion(existing) || "0.0NONE".equals(existing.toString())))
+                continue;
+
+            if (!VersionSupportMatrix.testVersionSupportMatrix(range, modId, "mod"))
+                (dep.isMandatory() ? missingMandatory : missingOptional).add(dep);
         }
-        return Collections.emptyList();
+
+
+        LOGGER.debug(LOADING, "Found {} mod requirements missing ({} mandatory, {} optional)", missingMandatory.size() + missingOptional.size(), missingMandatory.size(), missingOptional.size());
+
+        var ret = new ArrayList<ExceptionData>();
+
+        if (!missingMandatory.isEmpty()) {
+            LOGGER.error(LOADING, "Missing or unsupported mandatory dependencies:\n{}", formatDependencyError(missingMandatory, modVersions));
+            for (var mv : missingMandatory)
+                ret.add(data(mv, modVersions, "fml.modloading.missingdependency"));
+        }
+
+        if (!missingOptional.isEmpty()) {
+            LOGGER.error(LOADING, "Unsupported installed optional dependencies:\n{}", formatDependencyError(missingMandatory, modVersions));
+            for (var mv : missingMandatory)
+                ret.add(data(mv, modVersions, "fml.modloading.missingdependency.optional"));
+        }
+
+        return ret;
     }
 
-    private static String formatDependencyError(IModInfo.ModVersion dependency, Map<String, ArtifactVersion> modVersions)
-    {
-        ArtifactVersion installed = modVersions.get(dependency.getModId());
-        return String.format(
+    private static String formatDependencyError(Collection<ModVersion> missing, Map<String, ArtifactVersion> modVersions) {
+        var ret = new ArrayList<String>();
+        for (var dep : missing) {
+            var installed = modVersions.get(dep.getModId());
+            ret.add(String.format(
                 "\tMod ID: '%s', Requested by: '%s', Expected range: '%s', Actual version: '%s'",
-                dependency.getModId(),
-                dependency.getOwner().getModId(),
-                dependency.getVersionRange(),
+                dep.getModId(),
+                dep.getOwner().getModId(),
+                dep.getVersionRange(),
                 installed != null ? installed.toString() : "[MISSING]"
-        );
+            ));
+        }
+        return String.join("\n", ret);
     }
 
-    private boolean modVersionNotContained(final IModInfo.ModVersion mv, final Map<String, ArtifactVersion> modVersions)
-    {
-        return !(VersionSupportMatrix.testVersionSupportMatrix(mv.getVersionRange(), mv.getModId(), "mod", (modId, range) -> modVersions.containsKey(modId) &&
-                (range.containsVersion(modVersions.get(modId)) || modVersions.get(modId).toString().equals("0.0NONE"))));
+    private static final ArtifactVersion NULL_VERSION = new DefaultArtifactVersion("null");
+    private static ExceptionData data(ModVersion mv, Map<String, ArtifactVersion> modVersions, String key) {
+        return new ExceptionData(key, mv.getOwner(), mv.getModId(), mv.getOwner().getModId(), mv.getVersionRange(), modVersions.getOrDefault(mv.getModId(), NULL_VERSION));
     }
 }

fmlloader/src/main/java/net/minecraftforge/fml/loading/RuntimeDistCleaner.java

@@ -8,14 +8,8 @@ package net.minecraftforge.fml.loading;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.EnumSet;
-import java.util.Iterator;
 import java.util.List;
-import java.util.Objects;
-import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.function.Consumer;
-import java.util.stream.Collectors;
-
-import com.google.common.collect.Streams;
 import com.mojang.logging.LogUtils;
 import cpw.mods.modlauncher.serviceapi.ILaunchPluginService;
 import net.minecraftforge.api.distmarker.Dist;
@@ -28,150 +22,199 @@ import org.objectweb.asm.Type;
 import org.objectweb.asm.tree.AbstractInsnNode;
 import org.objectweb.asm.tree.AnnotationNode;
 import org.objectweb.asm.tree.ClassNode;
-import org.objectweb.asm.tree.FieldNode;
 import org.objectweb.asm.tree.MethodNode;
 import org.slf4j.Logger;
 import org.slf4j.Marker;
 import org.slf4j.MarkerFactory;
 
-public class RuntimeDistCleaner implements ILaunchPluginService
-{
+public final class RuntimeDistCleaner implements ILaunchPluginService {
     private static final Logger LOGGER = LogUtils.getLogger();
     private static final Marker DISTXFORM = MarkerFactory.getMarker("DISTXFORM");
     private static String DIST;
     private static final String ONLYIN = Type.getDescriptor(OnlyIn.class);
     private static final String ONLYINS = Type.getDescriptor(OnlyIns.class);
+    private static final String MOD = "Lnet/minecraftforge/fml/common/Mod;";
+
     @Override
-    public String name()
-    {
+    public String name() {
         return "runtimedistcleaner";
     }
 
-    @Override
-    public int processClassWithFlags(final Phase phase, final ClassNode classNode, final Type classType, final String reason)
-    {
-        AtomicBoolean changes = new AtomicBoolean();
-        if (remove(classNode.visibleAnnotations, DIST))
-        {
-            LOGGER.error(DISTXFORM, "Attempted to load class {} for invalid dist {}", classNode.name, DIST);
-            throw new RuntimeException("Attempted to load class "+ classNode.name  + " for invalid dist "+ DIST);
-        }
-
-        if (classNode.interfaces != null )
-        {
-            unpack(classNode.visibleAnnotations).stream()
-                .filter(ann->Objects.equals(ann.desc, ONLYIN))
-                .filter(ann->ann.values.indexOf("_interface") != -1)
-                .filter(ann->!Objects.equals(((String[])ann.values.get(ann.values.indexOf("value") + 1))[1], DIST))
-                .map(ann -> ((Type)ann.values.get(ann.values.indexOf("_interface") + 1)).getInternalName())
-                .forEach(intf -> {
-                    if (classNode.interfaces.remove(intf)) {
-                        LOGGER.debug(DISTXFORM,"Removing Interface: {} implements {}", classNode.name, intf);
-                        changes.compareAndSet(false, true);
-                    }
-                });
-
-            //Remove Class level @OnlyIn/@OnlyIns annotations, this is important if anyone gets ambitious and tries to reflect an annotation with _interface set.
-            if (classNode.visibleAnnotations != null) {
-                Iterator<AnnotationNode> itr = classNode.visibleAnnotations.iterator();
-                while (itr.hasNext()) {
-                    AnnotationNode ann = itr.next();
-                    if (Objects.equals(ann.desc, ONLYIN) || Objects.equals(ann.desc, ONLYINS)) {
-                        LOGGER.debug(DISTXFORM,"Removing Class Annotation: {} @{}", classNode.name, ann.desc);
-                        itr.remove();
-                        changes.compareAndSet(false, true);
-                    }
-                }
-            }
-        }
-
-        Iterator<FieldNode> fields = classNode.fields.iterator();
-        while(fields.hasNext())
-        {
-            FieldNode field = fields.next();
-            if (remove(field.visibleAnnotations, DIST))
-            {
-                LOGGER.debug(DISTXFORM,"Removing field: {}.{}", classNode.name, field.name);
-                fields.remove();
-                changes.compareAndSet(false, true);
-            }
-        }
-
-        LambdaGatherer lambdaGatherer = new LambdaGatherer();
-        Iterator<MethodNode> methods = classNode.methods.iterator();
-        while(methods.hasNext())
-        {
-            MethodNode method = methods.next();
-            if (remove(method.visibleAnnotations, DIST))
-            {
-                LOGGER.debug(DISTXFORM,"Removing method: {}.{}{}", classNode.name, method.name, method.desc);
-                methods.remove();
-                lambdaGatherer.accept(method);
-                changes.compareAndSet(false, true);
-            }
-        }
-
-        // remove dynamic synthetic lambda methods that are inside of removed methods
-        for (List<Handle> dynamicLambdaHandles = lambdaGatherer.getDynamicLambdaHandles();
-            !dynamicLambdaHandles.isEmpty(); dynamicLambdaHandles = lambdaGatherer.getDynamicLambdaHandles())
-        {
-            lambdaGatherer = new LambdaGatherer();
-            methods = classNode.methods.iterator();
-            while (methods.hasNext())
-            {
-                MethodNode method = methods.next();
-                if ((method.access & Opcodes.ACC_SYNTHETIC) == 0) continue;
-                for (Handle dynamicLambdaHandle : dynamicLambdaHandles)
-                {
-                    if (method.name.equals(dynamicLambdaHandle.getName()) && method.desc.equals(dynamicLambdaHandle.getDesc()))
-                    {
-                        LOGGER.debug(DISTXFORM,"Removing lambda method: {}.{}{}", classNode.name, method.name, method.desc);
-                        methods.remove();
-                        lambdaGatherer.accept(method);
-                        changes.compareAndSet(false, true);
-                    }
-                }
-            }
-        }
-        return changes.get() ? ComputeFlags.SIMPLE_REWRITE : ComputeFlags.NO_REWRITE;
-    }
-
-    @SuppressWarnings("unchecked")
-    private static List<AnnotationNode> unpack(final List<AnnotationNode> anns) {
-        if (anns == null) return Collections.emptyList();
-        List<AnnotationNode> ret = anns.stream().filter(ann->Objects.equals(ann.desc, ONLYIN)).collect(Collectors.toList());
-        anns.stream().filter(ann->Objects.equals(ann.desc, ONLYINS) && ann.values != null)
-            .map( ann -> (List<AnnotationNode>)ann.values.get(ann.values.indexOf("value") + 1))
-            .filter(v -> v != null)
-            .forEach(v -> v.forEach(ret::add));
-        return ret;
-    }
-
-    private boolean remove(final List<AnnotationNode> anns, final String side)
-    {
-        return unpack(anns).stream().
-                filter(ann->Objects.equals(ann.desc, ONLYIN)).
-                filter(ann->ann.values.indexOf("_interface") == -1).
-                anyMatch(ann -> !Objects.equals(((String[])ann.values.get(ann.values.indexOf("value")+1))[1], side));
-    }
-
-    @SuppressWarnings("unchecked")
-    @Override
-    public Consumer<Dist> getExtension()
-    {
-        return (s)-> {
-            DIST = s.name();
-            LOGGER.debug(DISTXFORM, "Configuring for Dist {}", DIST);
-        };
-    }
-
     private static final EnumSet<Phase> YAY = EnumSet.of(Phase.AFTER);
     private static final EnumSet<Phase> NAY = EnumSet.noneOf(Phase.class);
 
     @Override
-    public EnumSet<Phase> handlesClass(Type classType, boolean isEmpty)
-    {
-        return isEmpty ? NAY : YAY;
+    public EnumSet<Phase> handlesClass(Type classType, boolean isEmpty) {
+        if (isEmpty)
+            return NAY;
+
+        String internalName = classType.getInternalName();
+        if (internalName.startsWith("net/minecraftforge/"))
+            return NAY;
+
+        // No Vanilla classes use @OnlyIn(Dist.SERVER), so we can skip them entirely when we're running on a client
+        if (FMLEnvironment.dist.isClient() && (internalName.startsWith("net/minecraft/") || internalName.startsWith("com/mojang/")))
+            return NAY;
+
+        return YAY;
+    }
+
+    @Override
+    public int processClassWithFlags(final Phase phase, final ClassNode classNode, final Type classType, final String reason) {
+        var changed = false;
+
+        var annotations = unpack(classNode.visibleAnnotations);
+
+        if (remove(annotations, DIST)) {
+            LOGGER.error(DISTXFORM, "Attempted to load class {} for invalid dist {}", classNode.name, DIST);
+            throw new RuntimeException("Attempted to load class "+ classNode.name  + " for invalid dist "+ DIST);
+        }
+
+        if (!FMLEnvironment.production && !annotations.isEmpty() && hasModAnnotation(classNode.visibleAnnotations)) {
+            LOGGER.error(DISTXFORM, "Attempted to load class {} with @Mod and @OnlyIn/@OnlyIns annotations", classNode.name);
+            throw new RuntimeException("Found @OnlyIn on @Mod class "+ classNode.name  + " - this is not allowed as it causes crashes. Remove the OnlyIn and consider setting clientSideOnly=true in the root of your mods.toml instead");
+        }
+
+        if (classNode.interfaces != null && !classNode.interfaces.isEmpty()) {
+            for (var ann : annotations) {
+                if (ann.intf == null || DIST.equals(ann.side))
+                    continue;
+
+                if (classNode.interfaces.remove(ann.intf)) {
+                    LOGGER.debug(DISTXFORM,"Removing Interface: {} implements {}", classNode.name, ann.intf);
+                    changed = true;
+                }
+            }
+
+            //Remove Class level @OnlyIn/@OnlyIns annotations, this is important if anyone gets ambitious and tries to reflect an annotation with _interface set.
+            if (classNode.visibleAnnotations != null) {
+                for (var itr = classNode.visibleAnnotations.iterator(); itr.hasNext(); ) {
+                    var ann = itr.next();
+                    if (ONLYIN.equals(ann.desc) || ONLYINS.equals(ann.desc)) {
+                        LOGGER.debug(DISTXFORM, "Removing Class Annotation: {} @{}", classNode.name, ann.desc);
+                        itr.remove();
+                        changed = true;
+                    }
+                }
+            }
+        }
+
+        for (var itr = classNode.fields.iterator(); itr.hasNext(); ) {
+            var field = itr.next();
+            if (remove(unpack(field.visibleAnnotations), DIST)) {
+                LOGGER.debug(DISTXFORM, "Removing field: {}.{}", classNode.name, field.name);
+                itr.remove();
+                changed = true;
+            }
+        }
+
+        var lambdaGatherer = new LambdaGatherer();
+        for (var itr = classNode.methods.iterator(); itr.hasNext(); ) {
+            var method = itr.next();
+            if (remove(unpack(method.visibleAnnotations), DIST)) {
+                LOGGER.debug(DISTXFORM, "Removing method: {}.{}{}", classNode.name, method.name, method.desc);
+                itr.remove();
+                lambdaGatherer.accept(method);
+                changed = true;
+            }
+        }
+
+        // remove dynamic synthetic lambda methods that are inside of removed methods
+        for (List<Handle> handles = lambdaGatherer.getDynamicLambdaHandles();
+            !handles.isEmpty(); handles = lambdaGatherer.getDynamicLambdaHandles()) {
+            lambdaGatherer = new LambdaGatherer();
+            for (var itr = classNode.methods.iterator(); itr.hasNext(); ) {
+                MethodNode method = itr.next();
+                if ((method.access & Opcodes.ACC_SYNTHETIC) == 0)
+                    continue;
+
+                for (var handle : handles) {
+                    if (method.name.equals(handle.getName()) && method.desc.equals(handle.getDesc())) {
+                        LOGGER.debug(DISTXFORM, "Removing lambda method: {}.{}{}", classNode.name, method.name, method.desc);
+                        itr.remove();
+                        lambdaGatherer.accept(method);
+                        changed = true;
+                    }
+                }
+            }
+        }
+
+        return changed ? ComputeFlags.SIMPLE_REWRITE : ComputeFlags.NO_REWRITE;
+    }
+
+    private static record Target(String side, String intf) {
+        static Target from(final AnnotationNode node) {
+            var idx = node.values.indexOf("value");
+            var value = (String[])node.values.get(idx + 1); // Enums are stored as [Type, Value]
+
+            idx = node.values.indexOf("_interface");
+            if (idx == -1)
+                return new Target(value[1], null);
+
+            var intf = (Type)node.values.get(idx + 1);
+            return new Target(value[1], intf.getInternalName());
+        }
+    }
+
+    /**
+     * Unpack any OnlyIn or OnlyIns annotations to Target objects.
+     */
+    @SuppressWarnings("unchecked")
+    private static List<Target> unpack(final List<AnnotationNode> anns) {
+        if (anns == null || anns.isEmpty())
+            return Collections.emptyList();
+
+        var ret = new ArrayList<Target>();
+        for (var node : anns) {
+            if (ONLYIN.equals(node.desc))
+                ret.add(Target.from(node));
+            else if (ONLYINS.equals(node.desc)) {
+                if (node.values == null || node.values.isEmpty())
+                    continue;
+
+                int idx = node.values.indexOf("value");
+                if (idx == -1)
+                    continue;
+
+                var subNodes = (List<AnnotationNode>)node.values.get(idx + 1);
+                if (subNodes != null) {
+                    for (var sub : subNodes)
+                        ret.add(Target.from(sub));
+                }
+            }
+        }
+
+        return ret;
+    }
+
+    private static boolean remove(final List<Target> targets, final String side) {
+        for (var target : targets) {
+            if (target.intf == null && !side.equals(target.side))
+                return true;
+        }
+
+        return false;
+    }
+
+    private static boolean hasModAnnotation(final List<AnnotationNode> anns) {
+        if (anns == null || anns.isEmpty())
+            return false;
+
+        for (var ann : anns) {
+            if (ann.desc.equals(MOD))
+                return true;
+        }
+
+        return false;
+    }
+
+    @SuppressWarnings("unchecked")
+    @Override
+    public Consumer<Dist> getExtension() {
+        return s -> {
+            DIST = s.name();
+            LOGGER.debug(DISTXFORM, "Configuring for Dist {}", DIST);
+        };
     }
 
     private static class LambdaGatherer extends MethodVisitor {
@@ -186,23 +229,21 @@ public class RuntimeDistCleaner implements ILaunchPluginService
         }
 
         public void accept(MethodNode method) {
-            Streams.stream(method.instructions.iterator()).
-                    filter(insnNode->insnNode.getType() == AbstractInsnNode.INVOKE_DYNAMIC_INSN).
-                    forEach(insnNode->insnNode.accept(this));
-        }
-
-        @Override
-        public void visitInvokeDynamicInsn(String name, String desc, Handle bsm, Object... bsmArgs)
-        {
-            if (META_FACTORY.equals(bsm))
-            {
-                Handle dynamicLambdaHandle = (Handle) bsmArgs[1];
-                dynamicLambdaHandles.add(dynamicLambdaHandle);
+            for (var insn : method.instructions) {
+                if (insn.getType() == AbstractInsnNode.INVOKE_DYNAMIC_INSN)
+                    insn.accept(this);
             }
         }
 
-        public List<Handle> getDynamicLambdaHandles()
-        {
+        @Override
+        public void visitInvokeDynamicInsn(String name, String desc, Handle bsm, Object... bsmArgs) {
+            if (META_FACTORY.equals(bsm)) {
+                var handle = (Handle)bsmArgs[1];
+                dynamicLambdaHandles.add(handle);
+            }
+        }
+
+        public List<Handle> getDynamicLambdaHandles() {
             return dynamicLambdaHandles;
         }
     }

fmlloader/src/main/java/net/minecraftforge/fml/loading/StringSubstitutor.java

@@ -14,16 +14,17 @@ import org.apache.commons.lang3.text.StrSubstitutor;
 
 @SuppressWarnings("deprecation")
 public class StringSubstitutor {
+    private static final Map<String, String> GLOBALS = Map.of(
+        "mcVersion", FMLLoader.versionInfo().mcVersion(),
+        "forgeVersion", FMLLoader.versionInfo().forgeVersion()
+    );
+
     public static String replace(final String in, final ModFile file) {
         return new StrSubstitutor(getStringLookup(file)).replace(in);
     }
 
     private static StrLookup<String> getStringLookup(final ModFile file) {
-        var globals = Map.of(
-            "mcVersion", FMLLoader.versionInfo().mcVersion(),
-            "forgeVersion", FMLLoader.versionInfo().forgeVersion()
-        );
-        return new StrLookup<String>() {
+        return new StrLookup<>() {
             @Override
             public String lookup(String key) {
                 var parts = key.split("\\.");
@@ -32,7 +33,7 @@ public class StringSubstitutor {
                 var pfx = parts[0];
 
                 if ("global".equals(pfx))
-                    return globals.get(parts[1]);
+                    return GLOBALS.get(parts[1]);
                 else if ("file".equals(pfx) && file != null)
                     return String.valueOf(file.getSubstitutionMap().get().get(parts[1]));
 

fmlloader/src/main/java/net/minecraftforge/fml/loading/UniqueModListBuilder.java

@@ -9,6 +9,7 @@ import com.mojang.logging.LogUtils;
 import net.minecraftforge.fml.loading.moddiscovery.ModFile;
 import net.minecraftforge.forgespi.language.IModInfo;
 import org.apache.maven.artifact.versioning.ArtifactVersion;
+import org.jetbrains.annotations.ApiStatus;
 import org.slf4j.Logger;
 
 import java.util.ArrayList;
@@ -23,16 +24,18 @@ import static java.util.stream.Collectors.groupingBy;
 import static java.util.stream.Collectors.joining;
 import static net.minecraftforge.fml.loading.LogMarkers.LOADING;
 
-public class UniqueModListBuilder
-{
+@ApiStatus.Internal
+@Deprecated(since = "1.21.3", forRemoval = true) // TODO: [FML][Loading] Convert to package private in 1.22
+public class UniqueModListBuilder {
     private final static Logger LOGGER = LogUtils.getLogger();
 
     private final List<ModFile> modFiles;
 
-    public UniqueModListBuilder(final List<ModFile> modFiles) {this.modFiles = modFiles;}
+    public UniqueModListBuilder(final List<ModFile> modFiles) {
+        this.modFiles = modFiles;
+    }
 
-    public UniqueModListData buildUniqueList()
-    {
+    public UniqueModListData buildUniqueList() {
         List<ModFile> uniqueModList;
         List<ModFile> uniqueLibListWithVersion;
 
@@ -47,12 +50,12 @@ public class UniqueModListBuilder
 
         // Select the newest by artifact version sorting of non-unique files thus identified
         uniqueModList = modFilesByFirstId.entrySet().stream()
-                .map(this::selectNewestModInfo)
+                .map(UniqueModListBuilder::selectNewestModInfo)
                 .toList();
 
         // Select the newest by artifact version sorting of non-unique files thus identified
         uniqueLibListWithVersion = libFilesWithVersionByModuleName.entrySet().stream()
-                .map(this::selectNewestModInfo)
+                .map(UniqueModListBuilder::selectNewestModInfo)
                 .toList();
 
         // Transform to the full mod id list
@@ -75,7 +78,7 @@ public class UniqueModListBuilder
         final List<String> dupedModErrors = modIds.values().stream()
                 .filter(modInfos -> modInfos.size() > 1)
                 .map(mods -> String.format("\tMod ID: '%s' from mod files: %s",
-                        mods.get(0).getModId(),
+                        mods.getFirst().getModId(),
                         mods.stream()
                                 .map(modInfo -> modInfo.getOwningFile().getFile().getFileName()).collect(joining(", "))
                 )).toList();
@@ -91,9 +94,8 @@ public class UniqueModListBuilder
         final List<String> dupedLibErrors = versionedLibIds.values().stream()
                 .filter(modFiles -> modFiles.size() > 1)
                 .map(mods -> String.format("\tLibrary: '%s' from files: %s",
-                        getModId(mods.get(0)),
-                        mods.stream()
-                                .map(modFile -> modFile.getFileName()).collect(joining(", "))
+                        getModId(mods.getFirst()),
+                        mods.stream().map(ModFile::getFileName).collect(joining(", "))
                 )).toList();
 
         if (!dupedLibErrors.isEmpty()) {
@@ -107,25 +109,23 @@ public class UniqueModListBuilder
         final Map<String, List<ModFile>> uniqueModFilesByFirstId = uniqueModList.stream()
                 .collect(groupingBy(UniqueModListBuilder::getModId));
 
-        final List<ModFile> loadedList = new ArrayList<>();
-        loadedList.addAll(uniqueModList);
+        final List<ModFile> loadedList = new ArrayList<>(uniqueModList);
         loadedList.addAll(uniqueLibListWithVersion);
 
         return new UniqueModListData(loadedList, uniqueModFilesByFirstId);
     }
 
-    private ModFile selectNewestModInfo(Map.Entry<String, List<ModFile>> fullList) {
+    private static ModFile selectNewestModInfo(Map.Entry<String, List<ModFile>> fullList) {
         List<ModFile> modInfoList = fullList.getValue();
         if (modInfoList.size() > 1) {
             LOGGER.debug("Found {} mods for first modid {}, selecting most recent based on version data", modInfoList.size(), fullList.getKey());
-            modInfoList.sort(Comparator.comparing(this::getVersion).reversed());
-            LOGGER.debug("Selected file {} for modid {} with version {}", modInfoList.get(0).getFileName(), fullList.getKey(), this.getVersion(modInfoList.get(0)));
+            modInfoList.sort(Comparator.comparing(UniqueModListBuilder::getVersion).reversed());
+            LOGGER.debug("Selected file {} for modid {} with version {}", modInfoList.getFirst().getFileName(), fullList.getKey(), getVersion(modInfoList.getFirst()));
         }
         return modInfoList.get(0);
     }
 
-    private ArtifactVersion getVersion(final ModFile mf)
-    {
+    private static ArtifactVersion getVersion(final ModFile mf) {
         if (mf.getModFileInfo() == null || mf.getModInfos() == null || mf.getModInfos().isEmpty()) {
             return mf.getJarVersion();
         }
@@ -138,9 +138,8 @@ public class UniqueModListBuilder
             return modFile.getSecureJar().name();
         }
 
-        return modFile.getModFileInfo().moduleName();
+        return modFile.getModFileInfo().getMods().get(0).getModId();
     }
 
     public record UniqueModListData(List<ModFile> modFiles, Map<String, List<ModFile>> modFilesByFirstId) {}
-
 }

fmlloader/src/main/java/net/minecraftforge/fml/loading/VersionSupportMatrix.java

@@ -5,33 +5,53 @@
 
 package net.minecraftforge.fml.loading;
 
-import net.minecraftforge.forgespi.language.MavenVersionAdapter;
 import org.apache.maven.artifact.versioning.ArtifactVersion;
 import org.apache.maven.artifact.versioning.DefaultArtifactVersion;
 import org.apache.maven.artifact.versioning.VersionRange;
+import org.jetbrains.annotations.ApiStatus;
 
-import java.util.ArrayList;
-import java.util.HashMap;
+import java.util.Collections;
 import java.util.List;
+import java.util.Map;
 import java.util.function.BiPredicate;
 
+@ApiStatus.Internal // since 1.21.1, will be made non-public in a later MC version
 public class VersionSupportMatrix {
-    private static final HashMap<String, List<ArtifactVersion>> overrideVersions = new HashMap<>();
+    private static final Map<String, List<ArtifactVersion>> OVERRIDE_VERSIONS;
+
     static {
-         final ArtifactVersion version = new DefaultArtifactVersion(FMLLoader.versionInfo().mcVersion());
-         if (MavenVersionAdapter.createFromVersionSpec("[1.19.2]").containsVersion(version)) {
-             // 1.19.2 is Compatible with 1.19.1
-             add("languageloader.javafml", "42");
-             add("mod.minecraft",          "1.19.1");
-             add("mod.forge",              "42.0.9");
+        if ("1.21.1".equals(FMLLoader.versionInfo().mcVersion())) {
+            OVERRIDE_VERSIONS = Map.ofEntries(
+                    // 1.21.1 is compatible with 1.21
+                    entry("languageloader.javafml", "51"),
+                    entry("mod.minecraft",          "1.21"),
+                    entry("mod.forge",              "51.0.33")
+            );
+        } else {
+            OVERRIDE_VERSIONS = Collections.emptyMap();
         }
     }
-    private static void add(String key, String value) {
-        overrideVersions.computeIfAbsent(key, k -> new ArrayList<>()).add(new DefaultArtifactVersion(value));
-    }
-    public static <T> boolean testVersionSupportMatrix(VersionRange declaredRange, String lookupId, String type, BiPredicate<String, VersionRange> standardLookup) {
+
+    /**
+     * @deprecated Use {@link #testVersionSupportMatrix(VersionRange, String, String)} instead, unwrapping your BiPredicate.
+     */
+    @Deprecated(forRemoval = true, since = "1.21.1")
+    public static boolean testVersionSupportMatrix(VersionRange declaredRange, String lookupId, String type, BiPredicate<String, VersionRange> standardLookup) {
         if (standardLookup.test(lookupId, declaredRange)) return true;
-        List<ArtifactVersion> custom = overrideVersions.get(type + "." + lookupId);
-        return custom == null ? false  : custom.stream().anyMatch(declaredRange::containsVersion);
+        return testVersionSupportMatrix(declaredRange, lookupId, type);
+    }
+
+    public static boolean testVersionSupportMatrix(VersionRange declaredRange, String lookupId, String type) {
+        if (OVERRIDE_VERSIONS.isEmpty()) return false;
+        List<ArtifactVersion> custom = OVERRIDE_VERSIONS.get(type + "." + lookupId);
+        return custom != null && custom.stream().anyMatch(declaredRange::containsVersion);
+    }
+
+    private static Map.Entry<String, List<ArtifactVersion>> entry(String typeAndLookupId, String declaredRange) {
+        return Map.entry(typeAndLookupId, List.of(new DefaultArtifactVersion(declaredRange)));
+    }
+
+    private static Map.Entry<String, List<ArtifactVersion>> entry(String typeAndLookupId, List<String> declaredRanges) {
+        return Map.entry(typeAndLookupId, declaredRanges.stream().map(DefaultArtifactVersion::new).map(it -> (ArtifactVersion) it).toList());
     }
 }

fmlloader/src/main/java/net/minecraftforge/fml/loading/log4j/ForgeHighlight.java

@@ -18,9 +18,7 @@ import org.apache.logging.log4j.util.PerformanceSensitive;
 import org.jetbrains.annotations.Nullable;
 
 import java.lang.reflect.Method;
-import java.util.ArrayList;
 import java.util.Arrays;
-import java.util.List;
 
 /**
  * A wrapper for {@link HighlightConverter} that auto-disables ANSI when the terminal doesn't support it.
@@ -49,10 +47,7 @@ public class ForgeHighlight {
             LOGGER.warn("Failed to invoke initializeTerminal on TCA", e);
         }
         if (!TerminalConsoleAppender.isAnsiSupported() && Arrays.stream(options).noneMatch(s -> s.equals("disableAnsi=true"))) {
-            List<String> optionList = new ArrayList<>();
-            optionList.add(options[0]);
-            optionList.add("disableAnsi=true");
-            options = optionList.toArray(new String[0]);
+            options = new String[] { options[0], "disableAnsi=true" };
         }
         return HighlightConverter.newInstance(config, options);
     }

fmlloader/src/main/java/net/minecraftforge/fml/loading/moddiscovery/AbstractModProvider.java

@@ -6,9 +6,9 @@
 package net.minecraftforge.fml.loading.moddiscovery;
 
 import com.mojang.logging.LogUtils;
+
 import cpw.mods.jarhandling.JarMetadata;
 import cpw.mods.jarhandling.SecureJar;
-import net.minecraftforge.fml.loading.EarlyLoadingException;
 import net.minecraftforge.fml.loading.LogMarkers;
 import net.minecraftforge.forgespi.language.IConfigurable;
 import net.minecraftforge.forgespi.language.IModFileInfo;
@@ -19,38 +19,59 @@ import net.minecraftforge.forgespi.locating.IModProvider;
 import net.minecraftforge.forgespi.locating.ModFileLoadingException;
 
 import org.jetbrains.annotations.ApiStatus;
+import org.jetbrains.annotations.Nullable;
 import org.slf4j.Logger;
 
 import java.io.IOException;
+import java.lang.module.InvalidModuleDescriptorException;
+import java.lang.module.ModuleDescriptor;
+import java.lang.module.ModuleDescriptor.Version;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.Collections;
+import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
 import java.util.function.Consumer;
 import java.util.jar.JarFile;
+import java.util.stream.Collectors;
 
 @ApiStatus.Internal
 public abstract class AbstractModProvider implements IModProvider {
-    private static final   Logger LOGGER    = LogUtils.getLogger();
-    protected static final String MODS_TOML = "META-INF/mods.toml";
+    private static final   Logger LOGGER      = LogUtils.getLogger();
+    protected static final String MODS_TOML   = "META-INF/mods.toml";
+    protected static final String MODULE_INFO = "module-info.class";
 
     protected IModLocator.ModFileOrException createMod(Path path) {
+        return createMod(path, false);
+    }
+
+    @Nullable
+    protected IModLocator.ModFileOrException createMod(Path path, boolean ignoreUnknown) {
+        return createMod(path, ignoreUnknown, getDefaultJarModType());
+    }
+
+    @Nullable
+    protected IModLocator.ModFileOrException createMod(Path path, boolean ignoreUnknown, String defaultType) {
         var mjm = new ModJarMetadata();
-        var sj = SecureJar.from(
-            jar -> jar.moduleDataProvider().findFile(MODS_TOML).isPresent() ? mjm : JarMetadata.from(jar, path),
-            path
-        );
+        SecureJar sj = null;
+        try {
+            sj = SecureJar.from(jar -> loadMetaFromJar(jar, mjm), path);
+        } catch (Throwable t) {
+            return new IModLocator.ModFileOrException(null, new ModFileLoadingException("Failed to create secure jar for \"" + path + "\" - " + t.getMessage()));
+        }
 
         IModFile mod;
         var type = sj.moduleDataProvider().getManifest().getMainAttributes().getValue(ModFile.TYPE);
         if (type == null)
-            type = getDefaultJarModType();
+            type = defaultType;
 
         if (sj.moduleDataProvider().findFile(MODS_TOML).isPresent()) {
             LOGGER.debug(LogMarkers.SCAN, "Found {} mod of type {}: {}", MODS_TOML, type, path);
             mod = new ModFile(sj, this, ModFileParser::modsTomlParser);
+            // ModJarMetadata is only used when loading mods.toml mods as ModJarMetadata
+            mjm.setModFile(mod);
             if (mod.getModFileInfo().getFileProperties().containsKey(ModFileInfo.NOT_A_FORGE_MOD_PROP)) {
                 LOGGER.error(LogMarkers.SCAN, "Unable to load file \"{}\" because its mods.toml is requesting an invalid javafml loaderVersion (use \"*\" if you want to allow all versions) and is missing a forge modId dependency declaration (see the sample mods.toml in the MDK).", path);
                 return new IModLocator.ModFileOrException(null, new ModFileLoadingException("File \"%s\" is not a Forge mod and cannot be loaded. Look for a Forge version of this mod or consider alternative mods.".formatted(mod.getFileName())));
@@ -58,17 +79,68 @@ public abstract class AbstractModProvider implements IModProvider {
         } else if (type != null) {
             LOGGER.debug(LogMarkers.SCAN, "Found {} mod of type {}: {}", JarFile.MANIFEST_NAME, type, path);
             mod = new ModFile(sj, this, this::manifestParser, type);
+        } else if (ignoreUnknown) {
+            return null;
         } else
             return new IModLocator.ModFileOrException(null, new ModFileLoadingException("Invalid mod file found " + path));
 
-        mjm.setModFile(mod);
         return new IModLocator.ModFileOrException(mod, null);
     }
 
+    private static JarMetadata loadMetaFromJar(SecureJar jar, ModJarMetadata mjm) {
+        var info = jar.moduleDataProvider().open(MODULE_INFO).orElse(null);
+        if (info != null) {
+            try {
+                var desc = ModuleDescriptor.read(info, jar::getPackages);
+                var all = new HashSet<>(jar.getPackages());
+                all.removeAll(desc.packages());
+                if (!all.isEmpty()) {
+                    var missing = all.stream().sorted().collect(Collectors.joining(", "));
+                    LOGGER.error("Invalid module-info, missing packages " + missing);
+                    throw new ModFileLoadingException("Invalid module-info, missing packages " + missing);
+                } else {
+                    return new JarMetadata() {
+                        @Override
+                        public String name() {
+                            return desc.name();
+                        }
+
+                        @Override
+                        public String version() {
+                            return desc.version().map(Version::toString).or(desc::rawVersion).orElse(null);
+                        }
+
+                        @Override
+                        public ModuleDescriptor descriptor() {
+                            return desc;
+                        }
+                    };
+                }
+            } catch (InvalidModuleDescriptorException | IOException e) {
+                LOGGER.error("Failed to parse " + jar.getPrimaryPath() + " module-info", e);
+                throw new ModFileLoadingException("Invalid module-info: " + e.getMessage());
+            } finally {
+                try {
+                    info.close();
+                } catch (IOException e) {}
+            }
+        }
+
+        if (jar.moduleDataProvider().findFile(MODS_TOML).isEmpty())
+            return JarMetadata.from(jar, jar.getPrimaryPath());
+
+        return mjm;
+    }
+
     protected IModFileInfo manifestParser(final IModFile mod) {
         var mf = mod.getSecureJar().moduleDataProvider().getManifest().getMainAttributes();
         var license = mf.getValue("LICENSE");
         var dummy = new IConfigurable() {
+            @Override
+            public <T> Optional<T> getConfigElement(String key) {
+                return Optional.empty();
+            }
+
             @Override
             public <T> Optional<T> getConfigElement(String... key) {
                 return Optional.empty();
@@ -128,10 +200,11 @@ public abstract class AbstractModProvider implements IModProvider {
     }
 
     private static final class Holder<T> {
-        T value;
+        private T value;
     }
 
     private record DefaultModFileInfo(IModFile mod, String license, IConfigurable configurable) implements IModFileInfo, IConfigurable {
+        @Override public <T> Optional<T> getConfigElement(final String string) { return Optional.empty(); }
         @Override public <T> Optional<T> getConfigElement(final String... strings) { return Optional.empty(); }
         @Override public List<? extends IConfigurable> getConfigList(final String... strings) { return null; }
         @Override public List<IModInfo> getMods() { return Collections.emptyList(); }

fmlloader/src/main/java/net/minecraftforge/fml/loading/moddiscovery/BackgroundScanHandler.java

@@ -29,6 +29,7 @@ public class BackgroundScanHandler
     }
 
     private static final Logger LOGGER = LogUtils.getLogger();
+    private static final boolean DEBUG = LOGGER.isErrorEnabled(LogMarkers.SCAN);
     private final ExecutorService modContentScanner;
     private final List<ModFile> modFiles;
     private ScanStatus status;
@@ -55,16 +56,16 @@ public class BackgroundScanHandler
         }
         status = ScanStatus.RUNNING;
         ImmediateWindowHandler.updateProgress("Scanning mod candidates");
-        final CompletableFuture<ModFileScanData> future = CompletableFuture.supplyAsync(file::compileContent, modContentScanner)
-                .whenComplete(file::setScanResult)
-                .whenComplete((r,t)-> this.addCompletedFile(file,r,t));
+        CompletableFuture<ModFileScanData> future = CompletableFuture.supplyAsync(file::compileContent, modContentScanner)
+                .whenComplete(file::setScanResult);
+        if (DEBUG) future = future.whenComplete((r, t) -> addCompletedFile(file, t));
         file.setFutureScanResult(future);
     }
 
-    private void addCompletedFile(final ModFile file, final ModFileScanData modFileScanData, final Throwable throwable) {
+    private void addCompletedFile(final ModFile file, final Throwable throwable) {
         if (throwable != null) {
             status = ScanStatus.ERRORED;
-            LOGGER.error(LogMarkers.SCAN,"An error occurred scanning file {}", file, throwable);
+            LOGGER.error(LogMarkers.SCAN, "An error occurred scanning file {}", file, throwable);
         }
     }
 

fmlloader/src/main/java/net/minecraftforge/fml/loading/moddiscovery/ClasspathLocator.java

@@ -8,6 +8,7 @@ package net.minecraftforge.fml.loading.moddiscovery;
 import com.mojang.logging.LogUtils;
 
 import net.minecraftforge.fml.loading.LogMarkers;
+import net.minecraftforge.fml.loading.ModDirTransformerDiscoverer;
 import net.minecraftforge.forgespi.locating.IModLocator;
 
 import org.jetbrains.annotations.ApiStatus;
@@ -17,9 +18,9 @@ import java.io.IOException;
 import java.net.URI;
 import java.net.URL;
 import java.nio.file.Path;
-import java.nio.file.Paths;
 import java.util.ArrayList;
 import java.util.Collections;
+import java.util.Comparator;
 import java.util.HashSet;
 import java.util.List;
 import java.util.jar.Attributes;
@@ -27,7 +28,7 @@ import java.util.jar.JarFile;
 import java.util.jar.Manifest;
 
 @ApiStatus.Internal
-public class ClasspathLocator extends AbstractModProvider implements IModLocator {
+public final class ClasspathLocator extends AbstractModProvider implements IModLocator {
     private static final Logger LOGGER = LogUtils.getLogger();
     private static final Attributes.Name MOD_TYPE = new Attributes.Name("FMLModType");
 
@@ -71,16 +72,19 @@ public class ClasspathLocator extends AbstractModProvider implements IModLocator
         }
 
         var ret = new ArrayList<ModFileOrException>();
-        for (var path : claimed)
-            ret.add(createMod(path));
+        for (var path : claimed) {
+            // Filter out anything found by the ServiceLoader
+            if (!ModDirTransformerDiscoverer.isServiceProvider(path))
+                ret.add(createMod(path));
+        }
         return ret;
     }
 
-    private List<URL> getUrls(ClassLoader cl, String resource) {
+    private static List<URL> getUrls(ClassLoader cl, String resource) {
         try {
             var lst = Collections.list(cl.getResources(resource));
             if (LOGGER.isDebugEnabled(LogMarkers.SCAN)) {
-                Collections.sort(lst, (a, b) -> a.toString().compareTo(b.toString()));
+                lst.sort(Comparator.comparing(URL::toString));
                 LOGGER.debug(LogMarkers.SCAN, "Scanning Classloader: {} for {}", cl, resource);
                 for (var url : lst)
                     LOGGER.debug(LogMarkers.SCAN, "\t{}", url);
@@ -100,8 +104,7 @@ public class ClasspathLocator extends AbstractModProvider implements IModLocator
             len += 2;
         }
         str = str.substring(0, str.length() - len);
-        var path = Paths.get(URI.create(str));
-        return path;
+        return Path.of(URI.create(str));
     }
 
     private static Path getPathFromResource(ClassLoader cl, String resource) {

fmlloader/src/main/java/net/minecraftforge/fml/loading/moddiscovery/CoreModFile.java

@@ -15,7 +15,7 @@ import java.nio.file.Path;
 import org.jetbrains.annotations.ApiStatus;
 
 @ApiStatus.Internal
-public class CoreModFile implements ICoreModFile {
+public final class CoreModFile implements ICoreModFile {
     private final Path internalPath;
     private final ModFile file;
     private final String name;

fmlloader/src/main/java/net/minecraftforge/fml/loading/moddiscovery/InvalidModIdentifier.java

@@ -9,7 +9,6 @@ import cpw.mods.modlauncher.api.LamdbaExceptionUtils.Supplier_WithExceptions;
 import net.minecraftforge.fml.loading.StringUtils;
 
 import java.nio.file.Path;
-import java.util.Arrays;
 import java.util.Optional;
 import java.util.function.BiPredicate;
 import java.util.stream.Stream;

fmlloader/src/main/java/net/minecraftforge/fml/loading/moddiscovery/JarInJarDependencyLocator.java

@@ -6,7 +6,6 @@
 package net.minecraftforge.fml.loading.moddiscovery;
 
 import com.google.common.collect.ImmutableMap;
-import com.google.common.collect.Lists;
 import com.mojang.logging.LogUtils;
 import net.minecraftforge.fml.loading.EarlyLoadingException;
 import net.minecraftforge.forgespi.language.IModInfo;
@@ -26,6 +25,7 @@ import java.nio.file.FileSystem;
 import java.nio.file.FileSystems;
 import java.nio.file.Files;
 import java.nio.file.Path;
+import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
@@ -51,7 +51,7 @@ public class JarInJarDependencyLocator extends AbstractModProvider implements ID
 
     @Override
     public List<IModFile> scanMods(Iterable<IModFile> loadedMods) {
-        final List<IModFile> sources = Lists.newArrayList();
+        final List<IModFile> sources = new ArrayList<>();
         loadedMods.forEach(sources::add);
 
         var dependenciesToLoad = JarSelector.detectAndSelect(
@@ -83,7 +83,14 @@ public class JarInJarDependencyLocator extends AbstractModProvider implements ID
             final Map<String, ?> outerFsArgs = ImmutableMap.of("packagePath", pathInModFile);
             final FileSystem zipFS = FileSystems.newFileSystem(filePathUri, outerFsArgs);
             final Path pathInFS = zipFS.getPath("/");
-            return Optional.of(createMod(pathInFS).file());
+            final IModFile.Type parentType = file.getType();
+            final String modType;
+            if (parentType == IModFile.Type.LIBRARY || parentType == IModFile.Type.LANGPROVIDER) {
+                modType = IModFile.Type.LIBRARY.name();
+            } else {
+                modType = IModFile.Type.GAMELIBRARY.name();
+            }
+            return Optional.of(createMod(pathInFS, false, modType).file());
         } catch (Exception e) {
             LOGGER.error("Failed to load mod file {} from {}", path, file.getFileName());
             final RuntimeException exception = new ModFileLoadingException("Failed to load mod file " + file.getFileName());
@@ -95,34 +102,34 @@ public class JarInJarDependencyLocator extends AbstractModProvider implements ID
     protected EarlyLoadingException exception(Collection<JarSelector.ResolutionFailureInformation<IModFile>> failedDependencies) {
         final List<EarlyLoadingException.ExceptionData> errors = failedDependencies.stream()
                .filter(entry -> !entry.sources().isEmpty()) //Should never be the case, but just to be sure
-               .map(this::buildExceptionData)
+               .map(JarInJarDependencyLocator::buildExceptionData)
                .toList();
 
         return new EarlyLoadingException(failedDependencies.size() + " Dependency restrictions were not met.", null, errors);
     }
 
     @NotNull
-    private EarlyLoadingException.ExceptionData buildExceptionData(JarSelector.ResolutionFailureInformation<IModFile> entry) {
+    private static EarlyLoadingException.ExceptionData buildExceptionData(JarSelector.ResolutionFailureInformation<IModFile> entry) {
         return new EarlyLoadingException.ExceptionData(
                 getErrorTranslationKey(entry),
                 entry.identifier().group() + ":" + entry.identifier().artifact(),
                 entry.sources()
                      .stream()
-                     .flatMap(this::getModWithVersionRangeStream)
-                     .map(this::formatError)
+                     .flatMap(JarInJarDependencyLocator::getModWithVersionRangeStream)
+                     .map(JarInJarDependencyLocator::formatError)
                      .collect(Collectors.joining(", "))
         );
     }
 
     @NotNull
-    private String getErrorTranslationKey(JarSelector.ResolutionFailureInformation<IModFile> entry) {
+    private static String getErrorTranslationKey(JarSelector.ResolutionFailureInformation<IModFile> entry) {
         return entry.failureReason() == JarSelector.FailureReason.VERSION_RESOLUTION_FAILED ?
                        "fml.dependencyloading.conflictingdependencies" :
                        "fml.dependencyloading.mismatchedcontaineddependencies";
     }
 
     @NotNull
-    private Stream<ModWithVersionRange> getModWithVersionRangeStream(JarSelector.SourceWithRequestedVersionRange<IModFile> file) {
+    private static Stream<ModWithVersionRange> getModWithVersionRangeStream(JarSelector.SourceWithRequestedVersionRange<IModFile> file) {
         return file.sources()
                    .stream()
                    .map(IModFile::getModFileInfo)
@@ -145,7 +152,7 @@ public class JarInJarDependencyLocator extends AbstractModProvider implements ID
     }
 
     @NotNull
-    private String formatError(ModWithVersionRange modWithVersionRange){
+    private static String formatError(ModWithVersionRange modWithVersionRange){
         return YELLOW + modWithVersionRange.modInfo().getModId() + RESET + " - " +
                RED + modWithVersionRange.versionRange().toString() + RESET + " - " +
                GREEN + modWithVersionRange.artifactVersion().toString() + RESET;

fmlloader/src/main/java/net/minecraftforge/fml/loading/moddiscovery/MinecraftLocator.java

@@ -18,24 +18,22 @@ import java.util.List;
 import org.jetbrains.annotations.ApiStatus;
 
 @ApiStatus.Internal
-public class MinecraftLocator extends AbstractModProvider implements IModLocator {
+public final class MinecraftLocator extends AbstractModProvider implements IModLocator {
     @Override
     public List<IModLocator.ModFileOrException> scanMods() {
         var minecraft = FMLLoader.getLaunchHandler().getMinecraftPaths();
+        var paths = minecraft.toArray(Path[]::new);
 
         // Minecraft itself.
         var meta = new ModJarMetadata();
-        var mcjar = SecureJar.from(
-            jar -> meta,
-            minecraft.toArray(Path[]::new)
-        );
-        var mc = ModFileFactory.FACTORY.build(mcjar, this, this::buildMinecraftTOML);
+        var mcjar = SecureJar.from(jar -> meta, paths);
+        var mc = ModFileFactory.FACTORY.build(mcjar, this, MinecraftLocator::buildMinecraftTOML);
         meta.setModFile(mc);
 
         return List.of(new ModFileOrException(mc, null));
     }
 
-    private IModFileInfo buildMinecraftTOML(final IModFile iModFile) {
+    private static IModFileInfo buildMinecraftTOML(final IModFile iModFile) {
         // We haven't changed this in years, and I can't be asked right now to special case this one file in the path.
         final var conf = Config.inMemory();
         conf.set("modLoader", "minecraft");
@@ -52,7 +50,7 @@ public class MinecraftLocator extends AbstractModProvider implements IModLocator
         conf.set("mods", List.of(mods));
 
         var configWrapper = new NightConfigWrapper(conf);
-        return new ModFileInfo((ModFile)iModFile, configWrapper, configWrapper::setFile, List.of());
+        return new ModFileInfo((ModFile) iModFile, configWrapper, configWrapper::setFile);
     }
 
     @Override

fmlloader/src/main/java/net/minecraftforge/fml/loading/moddiscovery/ModDiscoverer.java

@@ -6,7 +6,6 @@
 package net.minecraftforge.fml.loading.moddiscovery;
 
 import com.google.common.collect.ImmutableList;
-import com.google.common.collect.Maps;
 import com.mojang.logging.LogUtils;
 import cpw.mods.modlauncher.Launcher;
 import cpw.mods.modlauncher.api.IModuleLayerManager;
@@ -28,6 +27,7 @@ import org.jetbrains.annotations.ApiStatus;
 import org.slf4j.Logger;
 
 import java.util.ArrayList;
+import java.util.EnumMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Objects;
@@ -49,23 +49,26 @@ public class ModDiscoverer {
         modLocators = ServiceLoader.load(moduleLayerManager.getLayer(IModuleLayerManager.Layer.SERVICE).orElseThrow(), IModLocator.class);
         dependencyLocators = ServiceLoader.load(moduleLayerManager.getLayer(IModuleLayerManager.Layer.SERVICE).orElseThrow(), IDependencyLocator.class);
         modLocatorList = ServiceLoaderUtils.streamServiceLoader(()-> modLocators, sce->LOGGER.error("Failed to load mod locator list", sce)).collect(Collectors.toList());
-        modLocatorList.forEach(l->l.initArguments(arguments));
+        for (IModLocator iModLocator : modLocatorList) {
+            iModLocator.initArguments(arguments);
+        }
         dependencyLocatorList = ServiceLoaderUtils.streamServiceLoader(()-> dependencyLocators, sce->LOGGER.error("Failed to load dependency locator list", sce)).collect(Collectors.toList());
-        dependencyLocatorList.forEach(l->l.initArguments(arguments));
+        for (IDependencyLocator l : dependencyLocatorList) {
+            l.initArguments(arguments);
+        }
         if (LOGGER.isDebugEnabled(LogMarkers.CORE))
         {
             LOGGER.debug(LogMarkers.CORE, "Found Mod Locators : {}", modLocatorList.stream()
                                                                        .map(modLocator -> "(%s:%s)".formatted(modLocator.name(),
                                                                          modLocator.getClass().getPackage().getImplementationVersion())).collect(Collectors.joining(",")));
-        }
-        if (LOGGER.isDebugEnabled(LogMarkers.CORE))
-        {
+
             LOGGER.debug(LogMarkers.CORE, "Found Dependency Locators : {}", dependencyLocatorList.stream()
                                                                        .map(dependencyLocator -> "(%s:%s)".formatted(dependencyLocator.name(),
                                                                          dependencyLocator.getClass().getPackage().getImplementationVersion())).collect(Collectors.joining(",")));
         }
     }
 
+    @SuppressWarnings("removal")
     public ModValidator discoverMods() {
         LOGGER.debug(LogMarkers.SCAN,"Scanning for mods and other resources to load. We know {} ways to find mods", modLocatorList.size());
         List<ModFile> loadedFiles = new ArrayList<>();
@@ -126,7 +129,7 @@ public class ModDiscoverer {
         }
 
         //First processing run of the mod list. Any duplicates will cause resolution failure and dependency loading will be skipped.
-        Map<IModFile.Type, List<ModFile>> modFilesMap = Maps.newHashMap();
+        Map<IModFile.Type, List<ModFile>> modFilesMap = new EnumMap<>(IModFile.Type.class);
         try {
             final UniqueModListBuilder modsUniqueListBuilder = new UniqueModListBuilder(loadedFiles);
             final UniqueModListBuilder.UniqueModListData uniqueModsData = modsUniqueListBuilder.buildUniqueList();
@@ -134,7 +137,7 @@ public class ModDiscoverer {
             //Grab the temporary results.
             //This allows loading to continue to a base state, in case dependency loading fails.
             modFilesMap = uniqueModsData.modFiles().stream()
-                            .collect(Collectors.groupingBy(IModFile::getType));
+                            .collect(Collectors.groupingBy(IModFile::getType, () -> new EnumMap<>(IModFile.Type.class), Collectors.toList()));
             loadedFiles = uniqueModsData.modFiles();
         }
         catch (EarlyLoadingException exception) {
@@ -171,11 +174,11 @@ public class ModDiscoverer {
 
                 //We now only need the mod files map, not the list.
                 modFilesMap = uniqueModsAndDependenciesData.modFiles().stream()
-                                .collect(Collectors.groupingBy(IModFile::getType));
+                                .collect(Collectors.groupingBy(IModFile::getType, () -> new EnumMap<>(IModFile.Type.class), Collectors.toList()));
             } catch (EarlyLoadingException exception) {
                 LOGGER.error(LogMarkers.SCAN, "Failed to build unique mod list after dependency discovery.", exception);
                 discoveryErrorData.addAll(exception.getAllData());
-                modFilesMap = loadedFiles.stream().collect(Collectors.groupingBy(IModFile::getType));
+                modFilesMap = loadedFiles.stream().collect(Collectors.groupingBy(IModFile::getType, () -> new EnumMap<>(IModFile.Type.class), Collectors.toList()));
             }
         }
         else {
@@ -190,8 +193,7 @@ public class ModDiscoverer {
         return validator;
     }
 
-    private void handleLocatedFiles(final List<ModFile> loadedFiles, final List<IModFile> locatedFiles)
-    {
+    private static void handleLocatedFiles(final List<ModFile> loadedFiles, final List<IModFile> locatedFiles) {
         var locatedModFiles = locatedFiles.stream().filter(ModFile.class::isInstance).map(ModFile.class::cast).toList();
         for (IModFile mf : locatedModFiles) {
             LOGGER.info(LogMarkers.SCAN, "Found mod file {} of type {} with provider {}", mf.getFileName(), mf.getType(), mf.getProvider());

fmlloader/src/main/java/net/minecraftforge/fml/loading/moddiscovery/ModFile.java

@@ -45,13 +45,13 @@ public class ModFile implements IModFile {
     private Throwable scanError;
     private final SecureJar jar;
     private final Type modFileType;
-    private final Manifest     manifest;
     private final IModProvider provider;
     private       IModFileInfo modFileInfo;
     private ModFileScanData fileModFileScanData;
     private CompletableFuture<ModFileScanData> futureScanResult;
     private List<CoreModFile> coreMods;
     private Path accessTransformer;
+    private List<Path> accessTransformers = Collections.emptyList();
 
     static final Attributes.Name TYPE = new Attributes.Name("FMLModType");
     private SecureJar.Status securityStatus;
@@ -65,7 +65,7 @@ public class ModFile implements IModFile {
         this.jar = jar;
         this.parser = parser;
 
-        manifest = this.jar.moduleDataProvider().getManifest();
+        var manifest = this.jar.moduleDataProvider().getManifest();
         modFileType = Type.valueOf(type);
         jarVersion = Optional.ofNullable(manifest.getMainAttributes().getValue(Attributes.Name.IMPLEMENTATION_VERSION)).orElse("0.0NONE");
         this.modFileInfo = ModFileParser.readModList(this, this.parser);
@@ -95,8 +95,14 @@ public class ModFile implements IModFile {
         return modFileInfo.getMods();
     }
 
+    /** @deprecated Use {@link #getAccessTransformers()} instead*/
+    @Deprecated(forRemoval=true, since="1.21.11")
     public Optional<Path> getAccessTransformer() {
-        return Optional.ofNullable(Files.exists(accessTransformer) ? accessTransformer : null);
+        return Optional.ofNullable(accessTransformer);
+    }
+
+    public List<Path> getAccessTransformers() {
+        return accessTransformers;
     }
 
     public boolean identifyMods() {
@@ -105,7 +111,28 @@ public class ModFile implements IModFile {
         LOGGER.debug(LogMarkers.LOADING,"Loading mod file {} with languages {}", this.getFilePath(), this.modFileInfo.requiredLanguageLoaders());
         this.coreMods = ModFileParser.getCoreMods(this);
         this.coreMods.forEach(mi-> LOGGER.debug(LogMarkers.LOADING,"Found coremod {}", mi.getPath()));
-        this.accessTransformer = findResource("META-INF", "accesstransformer.cfg");
+        List<String> cfg;
+        // Note: Some mods may have invalid tomls copied from other projects.
+        // Unfortunately we must protect against those landmines.
+        try {
+            cfg = this.modFileInfo.getConfig().<List<String>>getConfigElement("accessTransformers").orElse(null);
+        } catch (Exception e) {
+            cfg = null;
+            LOGGER.warn("{} contains an invalid 'accessTransformers' TOML entry. Should be e.g. accessTransformers = [\"META-INF/accesstransformer.cfg\", \"META-INF/extra_at.cfg\"] or accessTransformers = [] for no ATs. Falling back to default.", this.getFileName());
+        }
+        if (cfg == null) {
+            var path = findResource("META-INF", "accesstransformer.cfg");
+            if (Files.exists(path)) {
+                this.accessTransformer = path;
+                this.accessTransformers = List.of(path);
+            }
+        } else if (!cfg.isEmpty()) {
+            var paths = new ArrayList<Path>(cfg.size());
+            for (var path : cfg) {
+                paths.add(getSecureJar().getPath(path.replace("\\","/")));
+            }
+            this.accessTransformers = List.copyOf(paths);
+        }
         return true;
     }
 

fmlloader/src/main/java/net/minecraftforge/fml/loading/moddiscovery/ModFileInfo.java

@@ -7,7 +7,6 @@ package net.minecraftforge.fml.loading.moddiscovery;
 
 import com.google.common.base.Strings;
 import com.mojang.logging.LogUtils;
-import cpw.mods.modlauncher.api.LamdbaExceptionUtils;
 import net.minecraftforge.fml.loading.LogMarkers;
 import net.minecraftforge.fml.loading.StringUtils;
 import net.minecraftforge.forgespi.language.IConfigurable;
@@ -18,17 +17,15 @@ import org.jetbrains.annotations.ApiStatus;
 import org.slf4j.Logger;
 import javax.security.auth.x500.X500Principal;
 import java.net.URL;
-import java.security.CodeSigner;
 import java.security.InvalidKeyException;
 import java.security.MessageDigest;
 import java.security.NoSuchAlgorithmException;
 import java.security.NoSuchProviderException;
 import java.security.SignatureException;
-import java.security.cert.Certificate;
+import java.security.cert.CertificateEncodingException;
 import java.security.cert.CertificateException;
 import java.security.cert.X509Certificate;
 import java.util.ArrayList;
-import java.util.Arrays;
 import java.util.Collections;
 import java.util.LinkedHashMap;
 import java.util.List;
@@ -37,10 +34,8 @@ import java.util.Objects;
 import java.util.Optional;
 import java.util.function.Consumer;
 import java.util.stream.Collectors;
-import java.util.stream.Stream;
 
-public class ModFileInfo implements IModFileInfo, IConfigurable
-{
+public class ModFileInfo implements IModFileInfo, IConfigurable {
     private static final Logger LOGGER = LogUtils.getLogger();
     private static final String MAYBE_NOT_JAVAFML_VER = "[2,)";
     private static final String JAVAFML = "javafml";
@@ -60,8 +55,7 @@ public class ModFileInfo implements IModFileInfo, IConfigurable
     private final String license;
     private final List<String> usesServices;
 
-    ModFileInfo(final ModFile modFile, final IConfigurable config, Consumer<IModFileInfo> configFileConsumer)
-    {
+    ModFileInfo(final ModFile modFile, final IConfigurable config, Consumer<IModFileInfo> configFileConsumer) {
         this.modFile = modFile;
         this.config = config;
         configFileConsumer.accept(this);
@@ -86,10 +80,6 @@ public class ModFileInfo implements IModFileInfo, IConfigurable
                 .orElse(false);
         this.clientSideOnly = config.<Boolean>getConfigElement("clientSideOnly")
                 .orElse(false);
-        if (this.clientSideOnly) {
-            // if clientSideOnly, then this is definitely a Forge mod
-            maybeNotAForgeMod = false;
-        }
         this.showAsDataPack = config.<Boolean>getConfigElement("showAsDataPack")
                 .orElse(false);
         this.usesServices = config.<List<String>>getConfigElement("services")
@@ -98,6 +88,10 @@ public class ModFileInfo implements IModFileInfo, IConfigurable
                 .map(StringUtils::toURL)
                 .orElse(null);
 
+        // if clientSideOnly, then this is definitely a Forge mod
+        if (this.clientSideOnly)
+            maybeNotAForgeMod = false;
+
         if (maybeNotAForgeMod) {
             // mark this file as not a Forge mod. Note: this marker may be removed later based on the mod dependencies
             this.properties = config.<Map<String, Object>>getConfigElement("properties")
@@ -110,15 +104,14 @@ public class ModFileInfo implements IModFileInfo, IConfigurable
         this.modFile.setFileProperties(this.properties);
 
         final List<? extends IConfigurable> modConfigs = config.getConfigList("mods");
-        if (modConfigs.isEmpty())
-        {
+        if (modConfigs == null || modConfigs.isEmpty())
             throw new InvalidModFileException("Missing mods list", this);
-        }
+
         this.mods = modConfigs.stream()
-                .map(mi-> (IModInfo)new ModInfo(this, mi))
+                .map(mi -> (IModInfo) ModInfo.of(this, mi))
                 .toList();
-        if (LOGGER.isDebugEnabled(LogMarkers.LOADING))
-        {
+
+        if (LOGGER.isDebugEnabled(LogMarkers.LOADING)) {
             LOGGER.debug(LogMarkers.LOADING, "Found valid mod file {} with {} mods - versions {}",
                     this.modFile.getFileName(),
                     this.mods.stream().map(IModInfo::getModId).collect(Collectors.joining(",", "{", "}")),
@@ -132,13 +125,11 @@ public class ModFileInfo implements IModFileInfo, IConfigurable
     }
 
     @Override
-    public List<IModInfo> getMods()
-    {
+    public List<IModInfo> getMods() {
         return mods;
     }
 
-    public ModFile getFile()
-    {
+    public ModFile getFile() {
         return this.modFile;
     }
 
@@ -148,44 +139,42 @@ public class ModFileInfo implements IModFileInfo, IConfigurable
     }
 
     @Override
-    public Map<String, Object> getFileProperties()
-    {
+    public Map<String, Object> getFileProperties() {
         return this.properties;
     }
 
     @Override
-    public boolean showAsResourcePack()
-    {
+    public boolean showAsResourcePack() {
         return this.showAsResourcePack;
     }
 
     @Override
-    public boolean isClientSideOnly()
-    {
+    public boolean isClientSideOnly() {
         return this.clientSideOnly;
     }
 
     @Override
-    public boolean showAsDataPack()
-    {
+    public boolean showAsDataPack() {
         return this.showAsDataPack;
     }
 
     @Override
-    public <T> Optional<T> getConfigElement(final String... key)
-    {
+    public <T> Optional<T> getConfigElement(final String key) {
         return this.config.getConfigElement(key);
     }
 
     @Override
-    public List<? extends IConfigurable> getConfigList(final String... key)
-    {
+    public <T> Optional<T> getConfigElement(final String... key) {
+        return this.config.getConfigElement(key);
+    }
+
+    @Override
+    public List<? extends IConfigurable> getConfigList(final String... key) {
         return this.config.getConfigList(key);
     }
 
     @Override
-    public String getLicense()
-    {
+    public String getLicense() {
         return license;
     }
 
@@ -194,54 +183,83 @@ public class ModFileInfo implements IModFileInfo, IConfigurable
         return this;
     }
 
-    public URL getIssueURL()
-    {
+    public URL getIssueURL() {
         return issueURL;
     }
 
-    public boolean missingLicense()
-    {
+    public boolean missingLicense() {
         return Strings.isNullOrEmpty(license);
     }
 
+    private static final char[] HEX = "0123456789ABCDEF".toCharArray();
     public Optional<String> getCodeSigningFingerprint() {
         var signers = this.modFile.getSecureJar().getManifestSigners();
-        return (signers == null ? Stream.<CodeSigner>of() : Arrays.stream(signers))
-                .flatMap(csa->csa.getSignerCertPath().getCertificates().stream())
-                .findFirst()
-                .map(LamdbaExceptionUtils.rethrowFunction(Certificate::getEncoded))
-                .map(bytes->LamdbaExceptionUtils.uncheck(()->MessageDigest.getInstance("SHA-256")).digest(bytes))
-                .map(StringUtils::binToHex)
-                .map(str-> String.join(":", str.split("(?<=\\G.{2})")));
+        if (signers == null)
+            return Optional.empty();
+
+        for (var signer : signers) {
+            for (var cert : signer.getSignerCertPath().getCertificates()) {
+                try {
+                    var encoded = cert.getEncoded();
+                    var sha256 = MessageDigest.getInstance("SHA-256");
+                    var digest = sha256.digest(encoded);
+                    var buf = new StringBuilder(digest.length * 3);
+                    for (int x = 0; x < digest.length - 1; x++) {
+                        buf.append(HEX[(digest[x] & 0xF0) >> 4]);
+                        buf.append(HEX[(digest[x] & 0x0F)     ]);
+                        buf.append(':');
+                    }
+                    buf.append(HEX[(digest[digest.length - 1] & 0xF0) >> 4]);
+                    buf.append(HEX[(digest[digest.length - 1] & 0x0F)     ]);
+
+                    // We only care about the first. Should we list them all?
+                    return Optional.of(buf.toString());
+                } catch (CertificateEncodingException | NoSuchAlgorithmException e) {
+                    sneak(e);
+                }
+            }
+        }
+
+        return Optional.empty();
+
     }
 
     public Optional<String> getTrustData() {
-        return Arrays.stream(this.modFile.getSecureJar().getManifestSigners())
-                .flatMap(csa->csa.getSignerCertPath().getCertificates().stream())
-                .findFirst()
-                .map(X509Certificate.class::cast)
-                .map(c->{
-                    StringBuffer sb = new StringBuffer();
-                    sb.append(c.getSubjectX500Principal().getName(X500Principal.RFC2253).split(",")[0]);
-                    boolean selfSigned = false;
-                   try {
-                       c.verify(c.getPublicKey());
-                       selfSigned = true;
-                   } catch (CertificateException | NoSuchAlgorithmException | InvalidKeyException | SignatureException | NoSuchProviderException e) {
-                       // not self signed
-                   }
-                   if (selfSigned) {
+        var signers = this.modFile.getSecureJar().getManifestSigners();
+        if (signers == null)
+            return Optional.empty();
+
+        for (var signer : signers) {
+            for (var cert : signer.getSignerCertPath().getCertificates()) {
+                if (!(cert instanceof X509Certificate x509))
+                    continue;
+
+                var sb = new StringBuilder();
+                sb.append(x509.getSubjectX500Principal().getName(X500Principal.RFC2253).split(",")[0]);
+
+                var selfSigned = false;
+                try {
+                    x509.verify(x509.getPublicKey());
+                    selfSigned = true;
+                } catch (CertificateException | NoSuchAlgorithmException | InvalidKeyException | SignatureException | NoSuchProviderException e) {
+                    // not self signed
+                }
+
+                if (selfSigned)
                     sb.append(" self-signed");
-                   } else {
-                       sb.append(" signed by ").append(c.getIssuerX500Principal().getName(X500Principal.RFC2253).split(",")[0]);
-                   };
-                   return sb.toString();
-                });
+                else
+                    sb.append(" signed by ").append(x509.getIssuerX500Principal().getName(X500Principal.RFC2253).split(",")[0]);
+
+               return Optional.of(sb.toString());
+            }
+        }
+
+        return Optional.empty();
     }
 
     @Override
     public String moduleName() {
-        return getMods().get(0).getModId();
+        return this.modFile.getSecureJar().name();
     }
 
     @Override
@@ -253,4 +271,9 @@ public class ModFileInfo implements IModFileInfo, IConfigurable
     public List<String> usesServices() {
         return usesServices;
     }
+
+    @SuppressWarnings("unchecked")
+    private static <E extends Throwable, R> R sneak(Throwable e) throws E {
+        throw (E)e;
+    }
 }

fmlloader/src/main/java/net/minecraftforge/fml/loading/moddiscovery/ModFileParser.java

@@ -6,6 +6,7 @@
 package net.minecraftforge.fml.loading.moddiscovery;
 
 import com.electronwill.nightconfig.core.file.FileConfig;
+import com.electronwill.nightconfig.core.io.ParsingException;
 import com.google.gson.Gson;
 import com.google.gson.reflect.TypeToken;
 import com.mojang.logging.LogUtils;
@@ -13,6 +14,7 @@ import net.minecraftforge.fml.loading.LogMarkers;
 import net.minecraftforge.forgespi.language.IModFileInfo;
 import net.minecraftforge.forgespi.locating.IModFile;
 import net.minecraftforge.forgespi.locating.ModFileFactory;
+import net.minecraftforge.forgespi.locating.ModFileLoadingException;
 import org.jetbrains.annotations.Nullable;
 import org.slf4j.Logger;
 
@@ -31,6 +33,7 @@ public class ModFileParser {
         return parser.build(modFile);
     }
 
+    // Note: Although @Nullable, several other places in FML assume ModFileInfo is not null. Keep this in mind
     public static @Nullable IModFileInfo modsTomlParser(final IModFile imodFile) {
         ModFile modFile = (ModFile) imodFile;
         LOGGER.debug(LogMarkers.LOADING,"Considering mod file candidate {}", modFile.getFilePath());
@@ -41,10 +44,15 @@ public class ModFileParser {
         }
 
         final FileConfig fileConfig = FileConfig.builder(modsjson).build();
-        fileConfig.load();
-        fileConfig.close();
-        final NightConfigWrapper configWrapper = new NightConfigWrapper(fileConfig);
-        return new ModFileInfo(modFile, configWrapper, configWrapper::setFile);
+        try {
+            fileConfig.load();
+            fileConfig.close();
+            final NightConfigWrapper configWrapper = new NightConfigWrapper(fileConfig);
+            return new ModFileInfo(modFile, configWrapper, configWrapper::setFile);
+        } catch (ParsingException e) {
+            LOGGER.error("Mod candidate {} contains a corrupt or misconfigured toml.", modFile.getFileName());
+            throw new ModFileLoadingException("Mod candidate " + modFile.getFileName() + " contains a corrupt or misconfigured toml.");
+        }
     }
 
     protected static List<CoreModFile> getCoreMods(final ModFile modFile) {

fmlloader/src/main/java/net/minecraftforge/fml/loading/moddiscovery/ModInfo.java

@@ -19,202 +19,189 @@ import org.jetbrains.annotations.ApiStatus;
 import org.slf4j.Logger;
 
 import java.net.URL;
+import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
-import java.util.function.Supplier;
 import java.util.regex.Pattern;
 
 @ApiStatus.Internal
-public class ModInfo implements IModInfo, IConfigurable {
+public record ModInfo(
+        ModFileInfo getOwningFile,
+        IConfigurable getConfig,
+
+        String getModId,
+        String getNamespace,
+        ArtifactVersion getVersion,
+
+        String getDisplayName,
+        String getDescription,
+        Optional<String> getLogoFile,
+        boolean getLogoBlur,
+        Optional<URL> getUpdateURL,
+        Optional<URL> getModURL,
+
+        Holder<List<? extends ModVersion>> dependencies,
+        Holder<List<ForgeFeature.Bound>> forgeFeatures,
+        Map<String, Object> getModProperties
+) implements IModInfo, IConfigurable {
     private static final Logger LOGGER = LogUtils.getLogger();
     private static final DefaultArtifactVersion DEFAULT_VERSION = new DefaultArtifactVersion("1");
     private static final Pattern VALID_MODID = Pattern.compile("^[a-z][a-z0-9_]{1,63}$");
     private static final Pattern VALID_NAMESPACE = Pattern.compile("^[a-z][a-z0-9_.-]{1,63}$");
     private static final Pattern VALID_VERSION = Pattern.compile("^\\d+.*");
 
-    private final ModFileInfo owningFile;
-    private final String modId;
-    private final String namespace;
-    private final ArtifactVersion version;
-    private final String displayName;
-    private final String description;
-    private final Optional<String> logoFile;
-    private final boolean logoBlur;
-    private final Optional<URL> updateJSONURL;
-    private final List<? extends IModInfo.ModVersion> dependencies;
-
-    private final List<ForgeFeature.Bound> features;
-    private final Map<String,Object> properties;
-    private final IConfigurable config;
-    private final Optional<URL> modUrl;
-
-    public ModInfo(final ModFileInfo owningFile, final IConfigurable config)
-    {
-        Optional<ModFileInfo> ownFile = Optional.ofNullable(owningFile);
-        this.owningFile = owningFile;
-        this.config = config;
+    public static ModInfo of(ModFileInfo owningFile, IConfigurable config) {
         // These are sourced from the mod specific [[mod]] entry
-        this.modId = config.<String>getConfigElement("modId")
-                .orElseThrow(() -> new InvalidModFileException("Missing modId", owningFile));
+        String modId = config.<String>getConfigElement("modId").orElse(null);
+        if (modId == null)
+            throw new InvalidModFileException("Missing modId", owningFile);
+
         // verify we have a valid modid
-        if (!VALID_MODID.matcher(this.modId).matches()) {
-            LOGGER.error(LogUtils.FATAL_MARKER, "Invalid modId found in file {} - {} does not match the standard: {}", this.owningFile.getFile().getFilePath(), this.modId, VALID_MODID.pattern());
-            throw new InvalidModFileException("Invalid modId found : " + this.modId, owningFile);
+        if (!VALID_MODID.matcher(modId).matches()) {
+            LOGGER.error(LogUtils.FATAL_MARKER, "Invalid modId found in file {} - {} does not match the standard: {}", owningFile.getFile().getFilePath(), modId, VALID_MODID.pattern());
+            throw new InvalidModFileException("Invalid modId found : " + modId, owningFile);
         }
-        this.namespace = config.<String>getConfigElement("namespace")
-                .orElse(this.modId);
+
+        String namespace = config.<String>getConfigElement("namespace")
+                .orElse(modId);
+
         // verify our namespace is valid
-        if (!VALID_NAMESPACE.matcher(this.namespace).matches()) {
-            LOGGER.error(LogUtils.FATAL_MARKER, "Invalid override namespace found in file {} - {} does not match the standard: {}", this.owningFile.getFile().getFilePath(), this.namespace, VALID_NAMESPACE.pattern());
-            throw new InvalidModFileException("Invalid override namespace found : " + this.namespace, owningFile);
+        if (!VALID_NAMESPACE.matcher(namespace).matches()) {
+            LOGGER.error(LogUtils.FATAL_MARKER, "Invalid override namespace found in file {} - {} does not match the standard: {}", owningFile.getFile().getFilePath(), namespace, VALID_NAMESPACE.pattern());
+            throw new InvalidModFileException("Invalid override namespace found : " + namespace, owningFile);
         }
-        this.version = config.<String>getConfigElement("version")
-                .map(s -> StringSubstitutor.replace(s, ownFile.map(ModFileInfo::getFile).orElse(null)))
+
+        ArtifactVersion version = config.<String>getConfigElement("version")
+                .map(s -> StringSubstitutor.replace(s, owningFile.getFile()))
                 .map(DefaultArtifactVersion::new)
                 .orElse(DEFAULT_VERSION);
+
         // verify we have a valid mod version
-        if (!VALID_VERSION.matcher(this.version.toString()).matches()) {
-            throw new InvalidModFileException("Illegal version number specified "+this.version, this.getOwningFile());
-        }
+        if (!VALID_VERSION.matcher(version.toString()).matches())
+            throw new InvalidModFileException("Illegal version number specified " + version, owningFile);
+
         // The remaining properties all default to sensible values and are not essential
-        this.displayName = config.<String>getConfigElement("displayName")
-                .orElse(this.modId);
-        this.description = config.<String>getConfigElement("description")
+        String displayName = config.<String>getConfigElement("displayName")
+                .orElse(modId);
+
+        String description = config.<String>getConfigElement("description")
                 .orElse("MISSING DESCRIPTION")
                 .replace("\r\n", "\n").stripIndent();
-        this.logoFile = Optional.ofNullable(config.<String>getConfigElement("logoFile")
-                .orElseGet(() -> ownFile.flatMap(mf -> mf.<String>getConfigElement("logoFile"))
-                        .orElse(null)));
-        this.logoBlur = config.<Boolean>getConfigElement("logoBlur")
-                .orElseGet(() -> ownFile.flatMap(f -> f.<Boolean>getConfigElement("logoBlur"))
-                        .orElse(true));
-        this.updateJSONURL = config.<String>getConfigElement("updateJSONURL")
+
+        Optional<String> logoFile = Optional.ofNullable(
+                config.<String>getConfigElement("logoFile")
+                        .orElseGet(() -> owningFile.<String>getConfigElement("logoFile").orElse(null))
+        );
+
+        Boolean logoBlur = config.<Boolean>getConfigElement("logoBlur").orElse(null);
+        if (logoBlur == null)
+            logoBlur = owningFile.<Boolean>getConfigElement("logoBlur").orElse(true);
+
+        Optional<URL> updateJSONURL = config.<String>getConfigElement("updateJSONURL")
                 .map(StringUtils::toURL);
-        this.modUrl = config.<String>getConfigElement("modUrl")
+
+        Optional<URL> modUrl = config.<String>getConfigElement("modUrl")
                 .map(StringUtils::toURL);
-        // These are sourced from the file rather than the mod-specific block, but with a modid tag
-        this.dependencies = ownFile.map(mfi -> mfi.getConfigList("dependencies", this.modId))
-                .orElse(Collections.emptyList())
-                .stream()
-                .map(dep -> new ModVersion(this, dep))
-                .toList();
-        this.features = ownFile.flatMap(mfi -> mfi.<Map<String, Object>>getConfigElement("features", this.modId))
-                .stream()
-                .flatMap(m->m.entrySet().stream())
-                .map(this::makeBound)
-                .toList();
-        this.properties = ownFile.flatMap(mfi -> mfi.<Map<String, Object>>getConfigElement("modproperties", this.modId))
+
+        // dependencies and features are done after the constructor as they need to reference the ModInfo we are creating
+        List<? extends ModVersion> dependencies = Collections.emptyList();
+        List<ForgeFeature.Bound> forgeFeatures = Collections.emptyList();
+
+        Map<String, Object> modProperties = owningFile.<Map<String, Object>>getConfigElement("modproperties", modId)
+                .map(Collections::unmodifiableMap)
                 .orElse(Collections.emptyMap());
+
+        return new ModInfo(
+                owningFile, config,
+                modId, namespace, version,
+                displayName, description, logoFile, logoBlur, updateJSONURL, modUrl,
+                new Holder<>(dependencies), new Holder<>(forgeFeatures), modProperties
+        ).setupDependencies().setupForgeFeatures();
     }
 
-    @Override
-    public ModFileInfo getOwningFile() {
-        return owningFile;
+    private ModInfo setupDependencies() {
+        var deps = getOwningFile.getConfigList("dependencies", getModId);
+        if (deps == null || deps.isEmpty()) {
+            dependencies.value = Collections.emptyList();
+            return this;
+        }
+
+        var tmp = new ModVersion[deps.size()];
+        for (int i = 0; i < deps.size(); i++) {
+            tmp[i] = ModVersion.of(this, deps.get(i));
+        }
+        dependencies.value = List.of(tmp);
+        return this;
     }
 
-    @Override
-    public String getModId() {
-        return modId;
-    }
+    private ModInfo setupForgeFeatures() {
+        var feats = getOwningFile.<Map<String, Object>>getConfigElement("features", getModId).orElse(null);
+        if (feats == null) {
+            forgeFeatures.value = Collections.emptyList();
+            return this;
+        }
 
-    @Override
-    public String getDisplayName()
-    {
-        return this.displayName;
-    }
-
-    @Override
-    public String getDescription()
-    {
-        return this.description;
-    }
-
-    @Override
-    public ArtifactVersion getVersion() {
-        return version;
-    }
-
-    @Override
-    public List<? extends IModInfo.ModVersion> getDependencies() {
-        return this.dependencies;
-    }
-
-    @Override
-    public String getNamespace() {
-        return this.namespace;
-    }
-
-    @Override
-    public Map<String, Object> getModProperties() {
-        return this.properties;
-    }
-
-    @Override
-    public Optional<URL> getUpdateURL() {
-        return this.updateJSONURL;
-    }
-
-    @Override
-    public Optional<String> getLogoFile()
-    {
-        return this.logoFile;
-    }
-
-    @Override
-    public boolean getLogoBlur()
-    {
-        return this.logoBlur;
-    }
-
-    @Override
-    public IConfigurable getConfig() {
+        var tmp = new ArrayList<ForgeFeature.Bound>();
+        for (var entry : feats.entrySet()) {
+            if (!(entry.getValue() instanceof String val))
+                throw new InvalidModFileException("Invalid feature bound {" + entry.getValue() + "} for key {" + entry.getKey() + "} only strings are accepted", getOwningFile);
+            tmp.add(new ForgeFeature.Bound(entry.getKey(), val, this));
+        }
+        forgeFeatures.value = List.copyOf(tmp);
         return this;
     }
 
     @Override
-    public List<? extends ForgeFeature.Bound> getForgeFeatures() {
-        return this.features;
+    public <T> Optional<T> getConfigElement(String key) {
+        return getConfig.getConfigElement(key);
     }
 
     @Override
-    public <T> Optional<T> getConfigElement(final String... key) {
-        return this.config.getConfigElement(key);
+    public <T> Optional<T> getConfigElement(String... key) {
+        return getConfig.getConfigElement(key);
     }
 
     @Override
-    public List<? extends IConfigurable> getConfigList(final String... key) {
+    public List<? extends IConfigurable> getConfigList(String... key) {
         return null;
     }
 
     @Override
-    public Optional<URL> getModURL() {
-        return modUrl;
+    public List<? extends IModInfo.ModVersion> getDependencies() {
+        return dependencies.value;
     }
 
-    private ForgeFeature.Bound makeBound(Map.Entry<String, Object> e) {
-        if (e.getValue() instanceof String val) {
-            return new ForgeFeature.Bound(e.getKey(), val, this);
-        } else {
-            throw new InvalidModFileException("Invalid feature bound {" + e.getValue() + "} for key {" + e.getKey() + "} only strings are accepted", this.owningFile);
+    @Override
+    public List<? extends ForgeFeature.Bound> getForgeFeatures() {
+        return forgeFeatures.value;
+    }
+
+    private static final class Holder<T> {
+        private T value;
+
+        public Holder(T value) {
+            this.value = value;
         }
     }
 
-    class ModVersion implements net.minecraftforge.forgespi.language.IModInfo.ModVersion {
-        private IModInfo owner;
-        private final String modId;
-        private final VersionRange versionRange;
-        private final boolean mandatory;
-        private final Ordering ordering;
-        private final DependencySide side;
-        private final Optional<URL> referralUrl;
+    private record ModVersion(
+            Holder<IModInfo> owner,
 
-        public ModVersion(final IModInfo owner, final IConfigurable config) {
-            this.owner = owner;
-            this.modId = config.<String>getConfigElement("modId")
-                    .orElseThrow(()->new InvalidModFileException("Missing required field modid in dependency", getOwningFile()));
-            if (this.modId.equals("forge")) {
+            String getModId,
+            VersionRange getVersionRange,
+            boolean isMandatory,
+            Ordering getOrdering,
+            DependencySide getSide,
+            Optional<URL> getReferralURL
+    ) implements IModInfo.ModVersion {
+        public static ModVersion of(IModInfo owner, IConfigurable config) {
+            var modId = config.<String>getConfigElement("modId").orElse(null);
+            if (modId == null)
+                throw new InvalidModFileException("Missing required field modid in dependency", owner.getOwningFile());
+
+            if (modId.equals("forge")) {
                 var fileProps = owner.getOwningFile().getFileProperties();
                 // Checking containsKey to avoid a possible exception if the property is not present (due to Collections.emptyMap())
                 if (!fileProps.isEmpty() && fileProps.containsKey(ModFileInfo.NOT_A_FORGE_MOD_PROP)) {
@@ -223,74 +210,42 @@ public class ModInfo implements IModInfo, IConfigurable {
                     fileProps.remove(ModFileInfo.NOT_A_FORGE_MOD_PROP);
                 }
             }
-            var mandatory = config.<Boolean>getConfigElement("mandatory");
-            if (mandatory.isPresent()) {
-                this.mandatory = mandatory.get();
-            } else if (owner.getOwningFile().getFileProperties().containsKey(ModFileInfo.NOT_A_FORGE_MOD_PROP)) {
-                this.mandatory = true;
-            } else {
-                throw new InvalidModFileException("Missing required field mandatory in dependency", getOwningFile());
-            }
-            this.versionRange = config.<String>getConfigElement("versionRange")
+
+            boolean mandatory;
+            var mandatoryValue = config.<Boolean>getConfigElement("mandatory");
+            if (mandatoryValue.isPresent())
+                mandatory = mandatoryValue.get();
+            else if (owner.getOwningFile().getFileProperties().containsKey(ModFileInfo.NOT_A_FORGE_MOD_PROP))
+                mandatory = true;
+            else
+                throw new InvalidModFileException("Missing required field mandatory in dependency", owner.getOwningFile());
+
+            var versionRange = config.<String>getConfigElement("versionRange")
                     .map(MavenVersionAdapter::createFromVersionSpec)
                     .orElse(UNBOUNDED);
-            this.ordering = config.<String>getConfigElement("ordering")
+            var ordering = config.<String>getConfigElement("ordering")
                     .map(Ordering::valueOf)
                     .orElse(Ordering.NONE);
-            this.side = config.<String>getConfigElement("side")
+            var side = config.<String>getConfigElement("side")
                     .map(DependencySide::valueOf)
                     .orElse(DependencySide.BOTH);
-            this.referralUrl = config.<String>getConfigElement("referralUrl")
+            var referralUrl = config.<String>getConfigElement("referralUrl")
                     .map(StringUtils::toURL);
-        }
 
-
-        @Override
-        public String getModId()
-        {
-            return modId;
+            return new ModVersion(
+                    new Holder<>(owner),
+                    modId, versionRange, mandatory, ordering, side, referralUrl
+            );
         }
 
         @Override
-        public VersionRange getVersionRange()
-        {
-            return versionRange;
+        public IModInfo getOwner() {
+            return owner.value;
         }
 
         @Override
-        public boolean isMandatory()
-        {
-            return mandatory;
-        }
-
-        @Override
-        public Ordering getOrdering()
-        {
-            return ordering;
-        }
-
-        @Override
-        public DependencySide getSide()
-        {
-            return side;
-        }
-
-        @Override
-        public void setOwner(final IModInfo owner)
-        {
-            this.owner = owner;
-        }
-
-        @Override
-        public IModInfo getOwner()
-        {
-            return owner;
-        }
-
-        @Override
-        public Optional<URL> getReferralURL() {
-            return referralUrl;
+        public void setOwner(IModInfo newOwner) {
+            owner.value = newOwner;
         }
     }
-
 }

fmlloader/src/main/java/net/minecraftforge/fml/loading/moddiscovery/ModJarMetadata.java

@@ -9,49 +9,64 @@ import cpw.mods.jarhandling.JarMetadata;
 import net.minecraftforge.forgespi.locating.IModFile;
 import java.lang.module.ModuleDescriptor;
 import java.util.Objects;
-
 import org.jetbrains.annotations.ApiStatus;
 
 @ApiStatus.Internal
 public final class ModJarMetadata implements JarMetadata {
+    private static final String AUTOMATIC_MODULE_NAME = "Automatic-Module-Name";
     private IModFile modFile;
+    private String name;
+    private String version;
     private ModuleDescriptor descriptor;
 
-    ModJarMetadata() {
-    }
+    ModJarMetadata() { }
 
     public void setModFile(IModFile file) {
         this.modFile = file;
+        var mods = this.modFile.getModFileInfo().getMods();
+
+        if (!mods.isEmpty()) {
+            var main = mods.get(0);
+            this.name = main.getModId();
+            this.version = main.getVersion().toString();
+        }
+
+        var jar = file.getSecureJar();
+        var aname = jar.moduleDataProvider().getManifest().getMainAttributes().getValue(AUTOMATIC_MODULE_NAME);
+        if (aname != null)
+            this.name = aname;
     }
 
     @Override
     public String name() {
-        return modFile.getModFileInfo().moduleName();
+        return this.name;
     }
 
     @Override
     public String version() {
-        return modFile.getModFileInfo().versionString();
+        return this.version;
     }
 
     @Override
     public ModuleDescriptor descriptor() {
-        if (descriptor != null) return descriptor;
+        if (descriptor != null)
+            return descriptor;
+
         var bld = ModuleDescriptor.newAutomaticModule(name())
-                .version(version())
-                .packages(modFile.getSecureJar().getPackages());
-        modFile.getSecureJar().getProviders().stream()
-                .filter(p -> !p.providers().isEmpty())
-                .forEach(p -> bld.provides(p.serviceName(), p.providers()));
-        modFile.getModFileInfo().usesServices().forEach(bld::uses);
+            .version(version())
+            .packages(modFile.getSecureJar().getPackages());
+
+        for (var provider : modFile.getSecureJar().getProviders()) {
+            if (provider.providers().isEmpty())
+                continue;
+
+            bld.provides(provider.serviceName(), provider.providers());
+        }
+
         descriptor = bld.build();
         return descriptor;
     }
 
-    public IModFile modFile() {
-        return modFile;
-    }
-
     @Override
     public boolean equals(Object obj) {
         if (obj == this) return true;

fmlloader/src/main/java/net/minecraftforge/fml/loading/moddiscovery/ModValidator.java

@@ -64,7 +64,7 @@ public class ModValidator {
     }
 
     @NotNull
-    private List<ModFile> validateFiles(final List<ModFile> mods) {
+    private static List<ModFile> validateFiles(final List<ModFile> mods) {
         final List<ModFile> brokenFiles = new ArrayList<>();
         for (Iterator<ModFile> iterator = mods.iterator(); iterator.hasNext();) {
             ModFile modFile = iterator.next();
@@ -106,8 +106,8 @@ public class ModValidator {
 
     private List<EarlyLoadingException.ExceptionData> validateLanguages() {
         List<EarlyLoadingException.ExceptionData> errorData = new ArrayList<>();
-        for (Iterator<ModFile> iterator = this.candidateMods.iterator(); iterator.hasNext(); ) {
-            final ModFile modFile = iterator.next();
+        for (Iterator<ModFile> iterator = this.candidateMods.iterator(); iterator.hasNext();) {
+            var modFile = iterator.next();
             try {
                 modFile.identifyLanguage();
             } catch (EarlyLoadingException e) {

fmlloader/src/main/java/net/minecraftforge/fml/loading/moddiscovery/ModsFolderLocator.java

@@ -16,7 +16,7 @@ import org.slf4j.Logger;
 import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Path;
-import java.util.Comparator;
+import java.util.ArrayList;
 import java.util.List;
 import java.util.Locale;
 
@@ -42,11 +42,21 @@ public class ModsFolderLocator extends AbstractModProvider implements IModLocato
     public List<IModLocator.ModFileOrException> scanMods() {
         LOGGER.debug(LogMarkers.SCAN, "Scanning mods dir {} for mods", this.modFolder);
         var excluded = ModDirTransformerDiscoverer.allExcluded();
-        try (var stream = Files.list(this.modFolder)) {
-            return stream.filter(path -> !excluded.contains(path) && path.getFileName().toString().toLowerCase(Locale.ROOT).endsWith(SUFFIX))
-                .sorted(Comparator.comparing(path -> path.getFileName().toString().toLowerCase(Locale.ROOT)))
-                .map(this::createMod)
-                .toList();
+        try {
+            var ret = new ArrayList<IModLocator.ModFileOrException>();
+            var files = Files.list(this.modFolder).toList();
+            for (var file : files) {
+                var name = file.getFileName().toString().toLowerCase(Locale.ROOT);
+                if (excluded.contains(file) || !name.endsWith(SUFFIX))
+                    continue;
+                var mod = this.createMod(file, true);
+                if (mod == null) {
+                    LOGGER.debug(LogMarkers.SCAN, "Found unknown jar file {} ignoring", file);
+                } else {
+                    ret.add(mod);
+                }
+            }
+            return ret;
         } catch (IOException e) {
             return sneak(e);
         }

fmlloader/src/main/java/net/minecraftforge/fml/loading/moddiscovery/NightConfigWrapper.java

@@ -6,6 +6,8 @@
 package net.minecraftforge.fml.loading.moddiscovery;
 
 import com.electronwill.nightconfig.core.UnmodifiableConfig;
+import com.google.common.collect.ImmutableMap;
+
 import net.minecraftforge.forgespi.language.IConfigurable;
 import net.minecraftforge.forgespi.language.IModFileInfo;
 
@@ -16,11 +18,12 @@ import java.util.Optional;
 import java.util.stream.Collectors;
 
 import org.jetbrains.annotations.ApiStatus;
+import org.jetbrains.annotations.Nullable;
 
 import static java.util.Arrays.asList;
 
 @ApiStatus.Internal
-class NightConfigWrapper implements IConfigurable {
+final class NightConfigWrapper implements IConfigurable {
     private final UnmodifiableConfig config;
     private IModFileInfo file;
 
@@ -28,35 +31,51 @@ class NightConfigWrapper implements IConfigurable {
         this.config = config;
     }
 
-    NightConfigWrapper setFile(IModFileInfo file) {
+    private NightConfigWrapper(UnmodifiableConfig config, IModFileInfo file) {
+        this.config = config;
+        this.file = file;
+    }
+
+    void setFile(IModFileInfo file) {
         this.file = file;
-        return this;
     }
 
     @Override
-    @SuppressWarnings("unchecked")
+    public <T> Optional<T> getConfigElement(String key) {
+        var path = List.of(key);
+        return Optional.ofNullable(validate(this.config.get(path), path));
+    }
+
+    @Override
     public <T> Optional<T> getConfigElement(final String... key) {
         var path = asList(key);
-        return this.config.getOptional(path).map(value -> {
-            if (value instanceof UnmodifiableConfig) {
-                return (T) ((UnmodifiableConfig) value).valueMap();
-            } else if (value instanceof ArrayList<?> al && al.size() > 0 && al.get(0) instanceof UnmodifiableConfig) {
-                throw new InvalidModFileException("The configuration path " + path + " is invalid. I wasn't expecting a multi-object list - remove one of the [[ ]]", file);
-            }
-            return (T) value;
-        });
+        return Optional.ofNullable(validate(this.config.get(path), path));
+    }
+
+    @SuppressWarnings("unchecked")
+    private <T> T validate(@Nullable T value, List<String> path) {
+        if (value instanceof UnmodifiableConfig cfg) {
+            // New Night config doesn't implement valueMap(), so do a copy.
+            var entries = cfg.entrySet();
+            var builder = ImmutableMap.builderWithExpectedSize(entries.size());
+            for (var e : entries)
+                builder.put(e.getKey(), e.getValue());
+            return (T) builder.build();
+        } else if (value instanceof ArrayList<?> al && !al.isEmpty() && al.getFirst() instanceof UnmodifiableConfig) {
+            throw new InvalidModFileException("The configuration path " + path + " is invalid. I wasn't expecting a multi-object list - remove one of the [[ ]]", file);
+        }
+        return value;
     }
 
     @Override
     public List<? extends IConfigurable> getConfigList(final String... key) {
         final List<String> path = asList(key);
         if (this.config.contains(path) && !(this.config.get(path) instanceof Collection)) {
-            throw new InvalidModFileException("The configuration path "+path+" is invalid. Expecting a collection!", file);
+            throw new InvalidModFileException("The configuration path " + path + " is invalid. Expecting a collection!", file);
         }
         final Collection<UnmodifiableConfig> nestedConfigs = this.config.getOrElse(path, ArrayList::new);
         return nestedConfigs.stream()
-                .map(NightConfigWrapper::new)
-                .map(cw->cw.setFile(file))
+                .map(conf -> new NightConfigWrapper(conf, file))
                 .collect(Collectors.toList());
     }
 }

fmlloader/src/main/java/net/minecraftforge/fml/loading/moddiscovery/Scanner.java

@@ -21,37 +21,36 @@ import java.nio.file.Path;
 import java.util.List;
 
 @ApiStatus.Internal
-class Scanner {
+record Scanner(ModFile fileToScan, ModFileScanData result) {
     private static final Logger LOGGER = LogUtils.getLogger();
-    private final ModFile fileToScan;
+    private static final boolean DEBUG = LOGGER.isDebugEnabled(LogMarkers.SCAN);
 
-    public Scanner(final ModFile fileToScan) {
-        this.fileToScan = fileToScan;
+    public Scanner(ModFile fileToScan) {
+        this(fileToScan, new ModFileScanData());
     }
 
     public ModFileScanData scan() {
-        ModFileScanData result = new ModFileScanData();
         result.addModFileInfo(fileToScan.getModFileInfo());
-        fileToScan.scanFile(p -> fileVisitor(p, result));
+        fileToScan.scanFile(this::fileVisitor);
         final List<IModLanguageProvider> loaders = fileToScan.getLoaders();
         if (loaders != null) {
-            loaders.forEach(loader -> {
-                LOGGER.debug(LogMarkers.SCAN, "Scanning {} with language loader {}", fileToScan.getFilePath(), loader.name());
+            for (IModLanguageProvider loader : loaders) {
+                if (DEBUG) LOGGER.debug("Scanning {} with language loader {}", fileToScan.getFilePath(), loader.name());
                 loader.getFileVisitor().accept(result);
-            });
+            }
         }
         return result;
     }
 
-    private void fileVisitor(final Path path, final ModFileScanData result) {
-        LOGGER.debug(LogMarkers.SCAN,"Scanning {} path {}", fileToScan, path);
-        try (InputStream in = Files.newInputStream(path)){
+    private void fileVisitor(final Path path) {
+        try (InputStream in = Files.newInputStream(path)) {
             ModClassVisitor mcv = new ModClassVisitor();
             ClassReader cr = new ClassReader(in);
-            cr.accept(mcv, 0);
+            cr.accept(mcv, ClassReader.SKIP_CODE | ClassReader.SKIP_DEBUG | ClassReader.SKIP_FRAMES);
             mcv.buildData(result.getClasses(), result.getAnnotations());
         } catch (IOException | IllegalArgumentException e) {
             // mark path bad
+            if (DEBUG) LOGGER.warn("Failed scanning {} path {}", fileToScan, path);
         }
     }
 }

fmlloader/src/main/java/net/minecraftforge/fml/loading/targets/ArgumentList.java

@@ -24,8 +24,8 @@ import java.util.function.Supplier;
 @ApiStatus.Internal
 class ArgumentList {
     private static final Logger LOGGER = LogUtils.getLogger();
-    private List<Supplier<String[]>> entries = new ArrayList<>();
-    private Map<String, EntryValue> values = new HashMap<>();
+    private final List<Supplier<String[]>> entries = new ArrayList<>();
+    private final Map<String, EntryValue> values = new HashMap<>();
 
     public static ArgumentList from(String... args) {
         ArgumentList ret = new ArgumentList();
@@ -77,8 +77,12 @@ class ArgumentList {
 
     public String[] getArguments() {
         return entries.stream()
-            .flatMap(e -> Arrays.asList(e.get()).stream())
-            .toArray(size -> new String[size]);
+            .flatMap(e -> Arrays.stream(e.get()))
+            .toArray(String[]::new);
+    }
+
+    public boolean has(String key) {
+        return this.values.containsKey(key);
     }
 
     public boolean hasValue(String key) {
@@ -122,7 +126,7 @@ class ArgumentList {
         return ent.getValue();
     }
 
-    private class EntryValue implements Supplier<String[]> {
+    private static final class EntryValue implements Supplier<String[]> {
         private final String prefix;
         private final String key;
         private final boolean split;

fmlloader/src/main/java/net/minecraftforge/fml/loading/targets/CommonDevLaunchHandler.java

@@ -22,6 +22,10 @@ abstract class CommonDevLaunchHandler extends CommonLaunchHandler {
         super(type, prefix);
     }
 
+    protected CommonDevLaunchHandler(String name) {
+        super(name);
+    }
+
     @Override public String getNaming() { return "mcp"; }
     @Override public boolean isProduction() { return false; }
 
@@ -29,18 +33,40 @@ abstract class CommonDevLaunchHandler extends CommonLaunchHandler {
     protected String[] preLaunch(String[] arguments, ModuleLayer layer) {
         super.preLaunch(arguments, layer);
 
+        var args = ArgumentList.from(arguments);
+
+        if (this.module == null) {
+            var entry = args.get("launchEntry");
+            if (entry == null)
+                throw new IllegalArgumentException("When using " + this.name() + " launch target you must specify a --launchEntry argument");
+
+            args.remove("launchEntry");
+
+            int idx = entry.indexOf('/');
+            if (idx == -1) {
+                this.module = "minecraft";
+                this.main = entry;
+            } else {
+                this.module = entry.substring(0, idx);
+                this.main = entry.substring(idx + 1);
+            }
+
+            if (args.has("launchData")) {
+                args.remove("launchData");
+                this.isData = true;
+            }
+        }
+
         if (getDist().isDedicatedServer())
-            return arguments;
+            return args.getArguments();
 
         if (isData())
-            return arguments;
-
-        var args = ArgumentList.from(arguments);
+            return args.getArguments();
 
         String username = args.get("username");
         if (username != null) { // Replace '#' placeholders with random numbers
             Matcher m = Pattern.compile("#+").matcher(username);
-            StringBuffer replaced = new StringBuffer();
+            StringBuilder replaced = new StringBuilder();
             while (m.find()) {
                 m.appendReplacement(replaced, getRandomNumbers(m.group().length()));
             }

fmlloader/src/main/java/net/minecraftforge/fml/loading/targets/CommonLaunchHandler.java

@@ -7,7 +7,6 @@ package net.minecraftforge.fml.loading.targets;
 
 import com.mojang.logging.LogUtils;
 import cpw.mods.modlauncher.api.ILaunchHandlerService;
-import cpw.mods.modlauncher.api.ITransformingClassLoaderBuilder;
 import cpw.mods.modlauncher.api.ServiceRunner;
 import net.minecraftforge.fml.loading.FMLLoader;
 import net.minecraftforge.api.distmarker.Dist;
@@ -19,7 +18,6 @@ import org.slf4j.Logger;
 import java.io.IOException;
 import java.net.URI;
 import java.nio.file.Path;
-import java.nio.file.Paths;
 import java.util.List;
 
 /**
@@ -31,26 +29,32 @@ import java.util.List;
 public abstract class CommonLaunchHandler implements ILaunchHandlerService {
     protected static final Logger LOGGER = LogUtils.getLogger();
 
-    protected final LaunchType type;
-    private final String prefix;
+    private final String name;
+    protected Dist dist = Dist.CLIENT;
+    protected boolean isData = false;
+    protected String module;
+    protected String main;
 
     protected CommonLaunchHandler(LaunchType type, String prefix) {
-        this.type = type;
-        this.prefix = prefix;
+        this(prefix + type.name());
+        this.dist = type.dist();
+        this.isData = type.data();
+        this.module = type.module();
+        this.main = type.main();
     }
 
-    @Override public String name() { return this.prefix + this.type.name(); }
-    public Dist getDist() { return this.type.dist(); }
-    public boolean isData() { return this.type.data(); }
+    protected CommonLaunchHandler(String name) {
+        this.name = name;
+    }
+
+    @Override public String name() { return this.name; }
+    public Dist getDist() { return this.dist; }
+    public boolean isData() { return this.isData; }
     public boolean isProduction() { return false; }
     public abstract String getNaming();
 
     public abstract List<Path> getMinecraftPaths();
 
-    @Override
-    public void configureTransformationClassLoader(final ITransformingClassLoaderBuilder builder) {
-    }
-
     protected String[] preLaunch(String[] arguments, ModuleLayer layer) {
         URI uri;
         try (var reader = layer.configuration().findModule("net.minecraftforge.fmlloader").orElseThrow().reference().open()) {
@@ -72,14 +76,15 @@ public abstract class CommonLaunchHandler implements ILaunchHandlerService {
     }
 
     protected ServiceRunner makeService(final String[] arguments, final ModuleLayer gameLayer) {
-        return () -> runTarget(this.type.module(), this.type.main(), arguments, gameLayer);
+        return () -> runTarget(this.module, this.main, arguments, gameLayer);
     }
 
     protected record LaunchType(String name, String module, String main, Dist dist, boolean data) {};
     protected static final LaunchType CLIENT          = new LaunchType("client", "minecraft", "net.minecraft.client.main.Main", Dist.CLIENT, false);
+    protected static final LaunchType CLIENT_DATA     = new LaunchType("client_data", "minecraft", "net.minecraft.client.data.Main", Dist.CLIENT, true);
     protected static final LaunchType DATA            = new LaunchType("data",   "minecraft", "net.minecraft.data.Main", Dist.CLIENT, true);
     protected static final LaunchType SERVER          = new LaunchType("server", "minecraft", "net.minecraft.server.Main", Dist.DEDICATED_SERVER, false);
-    protected static final LaunchType SERVER_GAMETEST = new LaunchType("server_gametest", "forge", "net.minecraftforge.gametest.GameTestMain", Dist.DEDICATED_SERVER, false);
+    protected static final LaunchType SERVER_GAMETEST = new LaunchType("server_gametest", "minecraft", "net.minecraft.gametest.Main", Dist.DEDICATED_SERVER, false);
 
     protected void runTarget(String module, String target, final String[] arguments, final ModuleLayer layer) throws Throwable {
         var mod = layer.findModule(module).orElse(null);
@@ -107,7 +112,7 @@ public abstract class CommonLaunchHandler implements ILaunchHandlerService {
             len += 2;
         }
         str = str.substring(0, str.length() - len);
-        var path = Paths.get(URI.create(str));
+        var path = Path.of(URI.create(str));
         return path;
     }
 }

fmlloader/src/main/java/net/minecraftforge/fml/loading/targets/ForgeDevLaunchHandler.java

@@ -9,17 +9,19 @@ import java.util.List;
 import org.jetbrains.annotations.ApiStatus;
 
 @ApiStatus.Internal
-abstract class ForgeDevLaunchHandler extends CommonDevLaunchHandler {
+sealed abstract class ForgeDevLaunchHandler extends CommonDevLaunchHandler {
     private ForgeDevLaunchHandler(LaunchType type) {
         super(type, "forge_dev_");
     }
 
+    private ForgeDevLaunchHandler(String name) {
+        super(name);
+    }
+
     @Override
     public List<Path> getMinecraftPaths() {
-
-        // The extra jar is on the classpath, so try and pull it out of the legacy classpath
-        var legacyCP = findClassPath();
-        var extra = findJarOnClasspath(legacyCP, "client-extra");
+        // The client extra jar is on the classpath we can try locating it using the .mcassetsroot which vanilla uses for loading data
+        var extra = getPathFromResource("assets/.mcassetsroot");
         // Minecraft is an exploded directory, so find it.
         var minecraft = getPathFromResource("net/minecraft/client/Minecraft.class");
         var forge = getPathFromResource("net/minecraftforge/common/MinecraftForge.class");
@@ -33,27 +35,39 @@ abstract class ForgeDevLaunchHandler extends CommonDevLaunchHandler {
         return List.of(filtered);
     }
 
-    public static class Client extends ForgeDevLaunchHandler {
+    public static final class Client extends ForgeDevLaunchHandler {
         public Client() {
             super(CLIENT);
         }
     }
 
-    public static class Data extends ForgeDevLaunchHandler {
+    public static final class ClientData extends ForgeDevLaunchHandler {
+        public ClientData() {
+            super(CLIENT_DATA);
+        }
+    }
+
+    public static final class Data extends ForgeDevLaunchHandler {
         public Data() {
             super(DATA);
         }
     }
 
-    public static class Server extends ForgeDevLaunchHandler {
+    public static final class Server extends ForgeDevLaunchHandler {
         public Server() {
             super(SERVER);
         }
     }
 
-    public static class ServerGameTest extends ForgeDevLaunchHandler {
+    public static final class ServerGameTest extends ForgeDevLaunchHandler {
         public ServerGameTest() {
             super(SERVER_GAMETEST);
         }
     }
+
+    public static final class Custom extends ForgeDevLaunchHandler {
+        public Custom() {
+            super("forge_dev");
+        }
+    }
 }

fmlloader/src/main/java/net/minecraftforge/fml/loading/targets/ForgeDevLocator.java

@@ -35,7 +35,7 @@ import net.minecraftforge.fml.loading.moddiscovery.AbstractModProvider;
 import net.minecraftforge.forgespi.locating.IModLocator;
 
 @ApiStatus.Internal
-public class ForgeDevLocator extends AbstractModProvider implements IModLocator {
+public final class ForgeDevLocator extends AbstractModProvider implements IModLocator {
     private static final String PACK_META = "pack.mcmeta";
 
     @Override
@@ -60,7 +60,7 @@ public class ForgeDevLocator extends AbstractModProvider implements IModLocator
         return ret;
     }
 
-    private List<Path> getMods() {
+    private static List<Path> getMods() {
         // Forge is an exploded directory as well
         var minecraft = ForgeDevLaunchHandler.getPathFromResource("net/minecraft/client/Minecraft.class");
         var forge = ForgeDevLaunchHandler.getPathFromResource("net/minecraftforge/common/MinecraftForge.class");
@@ -84,30 +84,31 @@ public class ForgeDevLocator extends AbstractModProvider implements IModLocator
         return ret;
     }
 
-    private List<Path> explodeTestMods(Path path) {
+    private static List<Path> explodeTestMods(Path path) {
         var mod = new ArrayList<Path>();
         var memory = Jimfs.newFileSystem();
 
         // First lets find all class files, that have the @Mod annotation and map packages to modids.
         var packages = findTestModPackages(path);
         for (var entry : packages.entrySet()) {
-            var pkg = entry.getKey();
+            var pkg = entry.getKey() + '/';
             var modids = entry.getValue();
 
             // Find resource directories for every mod in this group
-            var resourcePaths = new LinkedHashSet<Path>();
+            var paths = new LinkedHashSet<Path>();
             for (var modid : modids) {
                 var rsc = path.resolve(modid);
                 if (Files.exists(rsc))
-                    resourcePaths.add(rsc);
+                    paths.add(rsc);
             }
 
             var root = memory.getPath(modids.iterator().next()); // use the first modid as our root
-            buildModsToml(resourcePaths, modids, root);
-            buildPackMeta(resourcePaths, root);
+            buildModsToml(paths, modids, root);
+            buildPackMeta(paths, root);
+            moveModuleInfo(paths, root);
 
             if (Files.exists(root))
-                resourcePaths.add(root);
+                paths.add(root);
 
             // We want just the class files from the root of the input paths. So make a new union with a filter.
             var classes = UnionHelper.newFileSystem(
@@ -121,14 +122,10 @@ public class ForgeDevLocator extends AbstractModProvider implements IModLocator
                 }, new Path[] { path }
             );
 
-            // And we want the resources, and none of the classes, just in case things get kinda fucky and somehow a package overlaps a sub package {shading?}
-            var resources = UnionHelper.newFileSystem((name, base) -> !name.endsWith(".class"), resourcePaths.toArray(Path[]::new));
+            paths.addFirst(classes.getRootDirectories().iterator().next());
 
             // Union of unions, Yay!
-            var union = UnionHelper.newFileSystem(null, new Path[] {
-                classes.getRootDirectories().iterator().next(),
-                resources.getRootDirectories().iterator().next()
-            });
+            var union = UnionHelper.newFileSystem(null, paths.stream().toArray(Path[]::new));
             mod.add(union.getRootDirectories().iterator().next());
         }
 
@@ -137,7 +134,7 @@ public class ForgeDevLocator extends AbstractModProvider implements IModLocator
 
     // Find all the @Mods so we can generate tomls, and so we can pick packages. Right now it doesn't allow mods in parent directories,
     // I could make it merge all the way up, but I think this would be fine.
-    private Map<String, Set<String>> findTestModPackages(Path path) {
+    private static Map<String, Set<String>> findTestModPackages(Path path) {
         var mods = new HashMap<String, Set<String>>();
         try (var files = Files.walk(path)) {
             var classes = files
@@ -190,7 +187,7 @@ public class ForgeDevLocator extends AbstractModProvider implements IModLocator
     }
 
     // Builds or update the mods.toml file for all @Mods in this package
-    private void buildModsToml(Set<Path> resources, Set<String> modids, Path root) {
+    private static void buildModsToml(Set<Path> resources, Set<String> modids, Path root) {
         var toml = resources.stream()
             .map(p -> p.resolve(MODS_TOML))
             .filter(Files::exists)
@@ -226,7 +223,7 @@ public class ForgeDevLocator extends AbstractModProvider implements IModLocator
         }
 
         for (var modid : modids) {
-            if (!modlist.stream().anyMatch(c -> modid.equals(c.get("modId")))) {
+            if (modlist.stream().noneMatch(c -> modid.equals(c.get("modId")))) {
                 modified = true;
                 var tmp = Config.inMemory();
                 tmp.set("modId", modid);
@@ -248,7 +245,7 @@ public class ForgeDevLocator extends AbstractModProvider implements IModLocator
     }
 
     // This is optional, it just hides a warning screen when starting up. I should probably remove this once I restructure how data gen for test mods work and make it generate there.
-    private void buildPackMeta(Set<Path> paths, Path root) {
+    private static void buildPackMeta(Set<Path> paths, Path root) {
         var existing = paths.stream()
                 .map(p -> p.resolve(PACK_META))
                 .filter(Files::exists)
@@ -274,6 +271,25 @@ public class ForgeDevLocator extends AbstractModProvider implements IModLocator
         }
     }
 
+    private static void moveModuleInfo(Set<Path> paths, Path root) {
+        var existing = paths.stream()
+            .map(p -> p.resolve("module-info.dat"))
+            .filter(Files::exists)
+            .findFirst()
+            .orElse(null);
+
+        if (existing == null)
+            return;
+
+        var target = root.resolve("module-info.class");
+        try {
+            Files.createDirectories(target.getParent());
+            Files.copy(existing, target);
+        } catch (IOException e) {
+            throw new IllegalStateException("Failed to copy module-info.dat to memory: " + target, e);
+        }
+    }
+
     @SuppressWarnings("unchecked")
     private static <E extends Throwable, R> R sneak(Throwable e) throws E {
         throw (E)e;

fmlloader/src/main/java/net/minecraftforge/fml/loading/targets/ForgeProdLaunchHandler.java

@@ -10,15 +10,15 @@ import java.util.List;
 import org.jetbrains.annotations.ApiStatus;
 
 @ApiStatus.Internal
-abstract class ForgeProdLaunchHandler extends CommonLaunchHandler {
+sealed abstract class ForgeProdLaunchHandler extends CommonLaunchHandler {
     protected ForgeProdLaunchHandler(LaunchType type) {
         super(type, "forge_");
     }
 
-    @Override public String getNaming() { return "srg"; }
+    @Override public String getNaming() { return "mcp"; }
     @Override public boolean isProduction() { return true; }
 
-    public static class Client extends ForgeProdLaunchHandler {
+    public static final class Client extends ForgeProdLaunchHandler {
         public Client() {
             super(CLIENT);
         }
@@ -29,7 +29,7 @@ abstract class ForgeProdLaunchHandler extends CommonLaunchHandler {
         }
     }
 
-    public static class Server extends ForgeProdLaunchHandler {
+    public static final class Server extends ForgeProdLaunchHandler {
         public Server() {
             super(SERVER);
         }

fmlloader/src/main/java/net/minecraftforge/fml/loading/targets/ForgeUserdevLaunchHandler.java

@@ -8,17 +8,18 @@ package net.minecraftforge.fml.loading.targets;
 import net.minecraftforge.fml.loading.FMLLoader;
 import java.nio.file.Path;
 import java.util.List;
-import java.util.function.BiPredicate;
 import org.jetbrains.annotations.ApiStatus;
 
-import cpw.mods.jarhandling.SecureJar;
-
 @ApiStatus.Internal
-abstract class ForgeUserdevLaunchHandler extends CommonDevLaunchHandler {
+sealed abstract class ForgeUserdevLaunchHandler extends CommonDevLaunchHandler {
     private ForgeUserdevLaunchHandler(LaunchType type) {
         super(type, "forge_userdev_");
     }
 
+    private ForgeUserdevLaunchHandler(String name) {
+        super(name);
+    }
+
     @Override
     public List<Path> getMinecraftPaths() {
         var legacyCP = findClassPath();
@@ -26,34 +27,46 @@ abstract class ForgeUserdevLaunchHandler extends CommonDevLaunchHandler {
 
         // Minecraft is extra jar {resources} + forge jar {patches}
         // The MC extra and forge jars are on the classpath, so try and pull them out
-        var extra = findJarOnClasspath(legacyCP, "client-extra");
+        var extra = findJarOnClasspath(legacyCP, "client-extra"); // This should be "client-" + vers.mcAndMCPVersion() + "-extra" but FG6 qwerks
         var forge = findJarOnClasspath(legacyCP, "forge-" + vers.mcAndForgeVersion());
         // We need to filter the forge jar to just MC code
         var minecraft = CommonDevLaunchHandler.getMinecraftOnly(extra, forge);
         return List.of(minecraft);
     }
 
-    public static class Client extends ForgeUserdevLaunchHandler {
+    public static final class Client extends ForgeUserdevLaunchHandler {
         public Client() {
             super(CLIENT);
         }
     }
 
-    public static class Data extends ForgeUserdevLaunchHandler {
+    public static final class ClientData extends ForgeUserdevLaunchHandler {
+        public ClientData() {
+            super(CLIENT_DATA);
+        }
+    }
+
+    public static final class Data extends ForgeUserdevLaunchHandler {
         public Data() {
             super(DATA);
         }
     }
 
-    public static class Server extends ForgeUserdevLaunchHandler {
+    public static final class Server extends ForgeUserdevLaunchHandler {
         public Server() {
             super(SERVER);
         }
     }
 
-    public static class ServerGameTest extends ForgeUserdevLaunchHandler {
+    public static final class ServerGameTest extends ForgeUserdevLaunchHandler {
         public ServerGameTest() {
             super(SERVER_GAMETEST);
         }
     }
+
+    public static final class Custom extends ForgeUserdevLaunchHandler {
+        public Custom() {
+            super("forge_userdev");
+        }
+    }
 }

fmlloader/src/main/java/net/minecraftforge/fml/loading/targets/ForgeUserdevLocator.java

@@ -12,7 +12,7 @@ import net.minecraftforge.fml.loading.moddiscovery.AbstractModProvider;
 import net.minecraftforge.forgespi.locating.IModLocator;
 
 @ApiStatus.Internal
-public class ForgeUserdevLocator extends AbstractModProvider implements IModLocator {
+public final class ForgeUserdevLocator extends AbstractModProvider implements IModLocator {
     @Override
     public String name() {
         return "forge_userdev_locator";

fmlloader/src/main/java/net/minecraftforge/fml/loading/toposort/StronglyConnectedComponentDetector.java

@@ -25,7 +25,7 @@ import java.util.Set;
  */
 public class StronglyConnectedComponentDetector<T> {
     private final Graph<T> graph;
-    private Map<T, Integer> ids;
+    private final Map<T, Integer> ids = new HashMap<>();
     private T[] elements;
     private int[] dfn;
     private int[] low;
@@ -49,7 +49,6 @@ public class StronglyConnectedComponentDetector<T> {
     private void calculate() {
         components = new HashSet<>();
         int t = 0;
-        ids = new HashMap<>();
         Set<T> nodes = graph.nodes();
         elements = (T[]) new Object[nodes.size()];
         for (T node : nodes) {

fmlloader/src/main/resources/META-INF/services/cpw.mods.modlauncher.api.ILaunchHandlerService

@@ -4,12 +4,16 @@ net.minecraftforge.fml.loading.targets.ForgeProdLaunchHandler$Server
 
 # Mod Developers
 net.minecraftforge.fml.loading.targets.ForgeUserdevLaunchHandler$Client
+net.minecraftforge.fml.loading.targets.ForgeUserdevLaunchHandler$ClientData
+net.minecraftforge.fml.loading.targets.ForgeUserdevLaunchHandler$Custom
 net.minecraftforge.fml.loading.targets.ForgeUserdevLaunchHandler$Data
 net.minecraftforge.fml.loading.targets.ForgeUserdevLaunchHandler$Server
 net.minecraftforge.fml.loading.targets.ForgeUserdevLaunchHandler$ServerGameTest
 
 #Working on Forge itself
 net.minecraftforge.fml.loading.targets.ForgeDevLaunchHandler$Client
+net.minecraftforge.fml.loading.targets.ForgeDevLaunchHandler$ClientData
+net.minecraftforge.fml.loading.targets.ForgeDevLaunchHandler$Custom
 net.minecraftforge.fml.loading.targets.ForgeDevLaunchHandler$Data
 net.minecraftforge.fml.loading.targets.ForgeDevLaunchHandler$Server
 net.minecraftforge.fml.loading.targets.ForgeDevLaunchHandler$ServerGameTest

fmlloader/src/main/resources/log4j2.xml

@@ -4,7 +4,7 @@
     SPDX-License-Identifier: LGPL-2.1-only
 -->
 
-<Configuration status="warn" packages="net.minecrell.terminalconsole,net.minecrell.terminalconsole.util,com.mojang.util,cpw.mods.modlauncher.log,net.minecraftforge.fml.loading.log4j" shutdownHook="disable">
+<Configuration status="warn" shutdownHook="disable">
     <filters>
         <ThresholdFilter level="WARN" onMatch="ACCEPT" onMismatch="NEUTRAL"/>
         <MarkerFilter marker="NETWORK_PACKETS" onMatch="${sys:forge.logging.marker.networking:-DENY}" onMismatch="NEUTRAL"/>

gradle.properties

@@ -1,12 +1,17 @@
 # Sets default memory used for gradle commands. Can be overridden by user or command line properties.
 # This is required to provide enough memory for the Minecraft decompilation process.
-org.gradle.jvmargs=-Xmx3G
+org.gradle.jvmargs=-Xmx6G
 org.gradle.daemon=false
 org.gradle.parallel=true
 
-JAVA_VERSION=17
-MC_VERSION=1.20.4
-MC_NEXT_VERSION=1.21
-MCP_VERSION=20231207.112700
+JAVA_VERSION=21
+MC_VERSION=1.21.5
+MC_NEXT_VERSION=1.22
+MCP_VERSION=20250325.155543
 MAPPING_CHANNEL=official
-MAPPING_VERSION=1.20.4
+MAPPING_VERSION=1.21.5
+
+# Set to true before the first build of a new MC version, so we don't do compatibility checks
+CHECK_COMPATIBILITY=false
+# Set to true to allow for fuzzy patching. Useful during updateing
+UPDATING=false

gradle/wrapper/gradle-wrapper.properties

@@ -1,6 +1,7 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-8.4-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.12.1-bin.zip
 networkTimeout=10000
+validateDistributionUrl=true
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists

gradlew

@@ -83,7 +83,8 @@ done
 # This is normally unused
 # shellcheck disable=SC2034
 APP_BASE_NAME=${0##*/}
-APP_HOME=$( cd "${APP_HOME:-./}" && pwd -P ) || exit
+# Discard cd standard output in case $CDPATH is set (https://github.com/gradle/gradle/issues/25036)
+APP_HOME=$( cd "${APP_HOME:-./}" > /dev/null && pwd -P ) || exit
 
 # Use the maximum available, or set MAX_FD != -1 to use that value.
 MAX_FD=maximum
@@ -130,10 +131,13 @@ location of your Java installation."
     fi
 else
     JAVACMD=java
-    which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+    if ! command -v java >/dev/null 2>&1
+    then
+        die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
 
 Please set the JAVA_HOME variable in your environment to match the
 location of your Java installation."
+    fi
 fi
 
 # Increase the maximum file descriptors if we can.
@@ -141,7 +145,7 @@ if ! "$cygwin" && ! "$darwin" && ! "$nonstop" ; then
     case $MAX_FD in #(
       max*)
         # In POSIX sh, ulimit -H is undefined. That's why the result is checked to see if it worked.
-        # shellcheck disable=SC3045
+        # shellcheck disable=SC2039,SC3045
         MAX_FD=$( ulimit -H -n ) ||
             warn "Could not query maximum file descriptor limit"
     esac
@@ -149,7 +153,7 @@ if ! "$cygwin" && ! "$darwin" && ! "$nonstop" ; then
       '' | soft) :;; #(
       *)
         # In POSIX sh, ulimit -n is undefined. That's why the result is checked to see if it worked.
-        # shellcheck disable=SC3045
+        # shellcheck disable=SC2039,SC3045
         ulimit -n "$MAX_FD" ||
             warn "Could not set maximum file descriptor limit to $MAX_FD"
     esac
@@ -198,11 +202,11 @@ fi
 # Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
 DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
 
-# Collect all arguments for the java command;
-#   * $DEFAULT_JVM_OPTS, $JAVA_OPTS, and $GRADLE_OPTS can contain fragments of
-#     shell script including quotes and variable substitutions, so put them in
-#     double quotes to make sure that they get re-expanded; and
-#   * put everything else in single quotes, so that it's not re-expanded.
+# Collect all arguments for the java command:
+#   * DEFAULT_JVM_OPTS, JAVA_OPTS, JAVA_OPTS, and optsEnvironmentVar are not allowed to contain shell fragments,
+#     and any embedded shellness will be escaped.
+#   * For example: A user cannot expect ${Hostname} to be expanded, as it is an environment variable and will be
+#     treated as '${Hostname}' itself on the command line.
 
 set -- \
         "-Dorg.gradle.appname=$APP_BASE_NAME" \

gradlew.bat

@@ -43,11 +43,11 @@ set JAVA_EXE=java.exe
 %JAVA_EXE% -version >NUL 2>&1
 if %ERRORLEVEL% equ 0 goto execute
 
-echo.
-echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
-echo.
-echo Please set the JAVA_HOME variable in your environment to match the
-echo location of your Java installation.
+echo. 1>&2
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH. 1>&2
+echo. 1>&2
+echo Please set the JAVA_HOME variable in your environment to match the 1>&2
+echo location of your Java installation. 1>&2
 
 goto fail
 
@@ -57,11 +57,11 @@ set JAVA_EXE=%JAVA_HOME%/bin/java.exe
 
 if exist "%JAVA_EXE%" goto execute
 
-echo.
-echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
-echo.
-echo Please set the JAVA_HOME variable in your environment to match the
-echo location of your Java installation.
+echo. 1>&2
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME% 1>&2
+echo. 1>&2
+echo Please set the JAVA_HOME variable in your environment to match the 1>&2
+echo location of your Java installation. 1>&2
 
 goto fail
 

javafmllanguage/build.gradle

@@ -13,6 +13,8 @@ dependencies {
     compileOnly(libs.nulls)
     implementation(project(':fmlloader'))
     implementation(project(':fmlcore'))
+    implementation(libs.unsafe)
+    implementation(libs.securemodules)
 }
 
 java {
@@ -57,7 +59,7 @@ publishing {
             license PomUtils.Licenses.LGPLv2_1
         }
     }
-    
+
     repositories {
         maven gradleutils.publishingForgeMaven
     }

javafmllanguage/src/main/java/net/minecraftforge/fml/javafmlmod/AutomaticEventSubscriber.java

@@ -6,6 +6,7 @@
 package net.minecraftforge.fml.javafmlmod;
 
 import net.minecraftforge.api.distmarker.Dist;
+import net.minecraftforge.api.distmarker.OnlyIn;
 import net.minecraftforge.fml.Logging;
 import net.minecraftforge.fml.ModContainer;
 import net.minecraftforge.fml.common.Mod;
@@ -19,19 +20,21 @@ import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import org.objectweb.asm.Type;
 
+import java.util.Collections;
 import java.util.List;
 import java.util.Objects;
 import java.util.stream.Collectors;
 
 /**
  * Automatic eventbus subscriber - reads {@link EventBusSubscriber}
- * annotations and passes the class instances to the {@link nBus}
+ * annotations and passes the class instances to the {@link Bus}
  * defined by the annotation. Defaults to {@code MinecraftForge#EVENT_BUS}
  */
 public class AutomaticEventSubscriber {
     private static final Logger LOGGER = LogManager.getLogger();
     private static final Type AUTO_SUBSCRIBER = Type.getType(EventBusSubscriber.class);
     private static final Type MOD_TYPE = Type.getType(Mod.class);
+    private static final Type ONLY_IN_TYPE = Type.getType(OnlyIn.class);
 
     public static void inject(ModContainer mod, ModFileScanData scanData, ClassLoader loader) {
         if (scanData == null) return;
@@ -41,6 +44,11 @@ public class AutomaticEventSubscriber {
             .filter(data -> AUTO_SUBSCRIBER.equals(data.annotationType()))
             .toList();
 
+        var onlyIns = FMLEnvironment.production ? Collections.emptySet() : scanData.getAnnotations().stream()
+                .filter(data -> ONLY_IN_TYPE.equals(data.annotationType()))
+                .map(data -> data.clazz().getClassName())
+                .collect(Collectors.toSet());
+
         var modids = scanData.getAnnotations().stream()
             .filter(data -> MOD_TYPE.equals(data.annotationType()))
             .collect(Collectors.toMap(a -> a.clazz().getClassName(), a -> (String)a.annotationData().get("value")));
@@ -49,6 +57,10 @@ public class AutomaticEventSubscriber {
         var defaultBus = new EnumData(null, "FORGE");
 
         for (var data : targets) {
+            if (!FMLEnvironment.production && onlyIns.contains(data.clazz().getClassName())) {
+                throw new RuntimeException("Found @OnlyIn on @EventBusSubscriber class " + data.clazz().getClassName() + " - this is not allowed as it causes crashes. Remove the OnlyIn and set value=Dist.CLIENT in the EventBusSubscriber annotation instead");
+            }
+
             var modId = modids.getOrDefault(data.clazz().getClassName(), mod.getModId());
             modId = value(data, "modid", modId);
 

javafmllanguage/src/main/java/net/minecraftforge/fml/javafmlmod/FMLJavaModLanguageProvider.java

@@ -31,21 +31,8 @@ public class FMLJavaModLanguageProvider implements IModLanguageProvider
 {
     private static final Logger LOGGER = LogManager.getLogger();
 
-    private static class FMLModTarget implements IModLanguageProvider.IModLanguageLoader {
+    private record FMLModTarget(String className, String modId) implements IModLanguageProvider.IModLanguageLoader {
         private static final Logger LOGGER = FMLJavaModLanguageProvider.LOGGER;
-        private final String className;
-        private final String modId;
-
-        private FMLModTarget(String className, String modId)
-        {
-            this.className = className;
-            this.modId = modId;
-        }
-
-        public String getModId()
-        {
-            return modId;
-        }
 
         @SuppressWarnings("unchecked")
         @Override
@@ -94,7 +81,7 @@ public class FMLJavaModLanguageProvider implements IModLanguageProvider
                     .filter(ad -> ad.annotationType().equals(MODANNOTATION))
                     .peek(ad -> LOGGER.debug(SCAN, "Found @Mod class {} with id {}", ad.clazz().getClassName(), ad.annotationData().get("value")))
                     .map(ad -> new FMLModTarget(ad.clazz().getClassName(), (String)ad.annotationData().get("value")))
-                    .collect(Collectors.toMap(FMLModTarget::getModId, Function.identity(), (a,b)->a));
+                    .collect(Collectors.toMap(FMLModTarget::modId, Function.identity(), (a,b)->a));
             scanResult.addLanguageLoader(modTargetMap);
         };
     }

javafmllanguage/src/main/java/net/minecraftforge/fml/javafmlmod/FMLJavaModLoadingContext.java

@@ -8,7 +8,10 @@ package net.minecraftforge.fml.javafmlmod;
 import net.minecraftforge.eventbus.api.IEventBus;
 import net.minecraftforge.fml.ModLoadingContext;
 
-public class FMLJavaModLoadingContext
+/**
+ * Use the context provided by your language loader in your mod's constructor
+ */
+public class FMLJavaModLoadingContext extends ModLoadingContext
 {
     private final FMLModContainer container;
 
@@ -24,11 +27,21 @@ public class FMLJavaModLoadingContext
         return container.getEventBus();
     }
 
+    /**
+     * @return {@link FMLModContainer} by default.
+     */
+    @Override
+    public FMLModContainer getContainer() {
+        return container;
+    }
 
     /**
      * Helper to get the right instance from the {@link ModLoadingContext} correctly.
      * @return The FMLJavaMod language specific extension from the ModLoadingContext
+     *
+     * @deprecated use {@link FMLJavaModLoadingContext} in your mod constructor
      */
+    @Deprecated(forRemoval = true, since="1.21.1")
     public static FMLJavaModLoadingContext get() {
         return ModLoadingContext.get().extension();
     }

javafmllanguage/src/main/java/net/minecraftforge/fml/javafmlmod/FMLModContainer.java

@@ -13,17 +13,24 @@ import net.minecraftforge.eventbus.api.IEventListener;
 import net.minecraftforge.fml.ModContainer;
 import net.minecraftforge.fml.ModLoadingException;
 import net.minecraftforge.fml.ModLoadingStage;
+import net.minecraftforge.fml.config.IConfigEvent;
 import net.minecraftforge.fml.event.IModBusEvent;
 import net.minecraftforge.forgespi.language.IModInfo;
 import net.minecraftforge.forgespi.language.ModFileScanData;
+import net.minecraftforge.unsafe.UnsafeHacks;
+
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import org.apache.logging.log4j.Marker;
 import org.apache.logging.log4j.MarkerManager;
 
+import cpw.mods.jarhandling.SecureJar;
+
+import java.lang.reflect.Constructor;
 import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
 import java.util.Objects;
-import java.util.Optional;
+import java.util.jar.Attributes;
 
 public class FMLModContainer extends ModContainer {
     private static final Logger LOGGER = LogManager.getLogger();
@@ -32,38 +39,109 @@ public class FMLModContainer extends ModContainer {
     private final IEventBus eventBus;
     private Object modInstance;
     private final Class<?> modClass;
+    private final FMLJavaModLoadingContext context = new FMLJavaModLoadingContext(this);
 
     public FMLModContainer(IModInfo info, String className, ModFileScanData modFileScanResults, ModuleLayer gameLayer) {
         super(info);
         LOGGER.debug(LOADING,"Creating FMLModContainer instance for {}", className);
         this.scanResults = modFileScanResults;
         activityMap.put(ModLoadingStage.CONSTRUCT, this::constructMod);
-        this.eventBus = BusBuilder.builder().setExceptionHandler(this::onEventFailed).setTrackPhases(false).markerType(IModBusEvent.class).useModLauncher().build();
-        this.configHandler = Optional.of(ce->this.eventBus.post(ce.self()));
-        final FMLJavaModLoadingContext contextExtension = new FMLJavaModLoadingContext(this);
-        this.contextExtension = () -> contextExtension;
-
-
+        this.eventBus = BusBuilder.builder().setExceptionHandler(FMLModContainer::onEventFailed).setTrackPhases(false).markerType(IModBusEvent.class).useModLauncher().build();
+        this.contextExtension = () -> context;
         try {
             var moduleName = info.getOwningFile().moduleName();
             var module = gameLayer.findModule(moduleName)
                 .orElseThrow(() -> new IllegalStateException("Failed to find " + moduleName + " in " + gameLayer));
+
+            openModules(gameLayer, module, info.getOwningFile().getFile().getSecureJar());
+
             modClass = Class.forName(module, className);
-            LOGGER.trace(LOADING,"Loaded modclass {} with {}", modClass.getName(), modClass.getClassLoader());
+            LOGGER.debug(LOADING,"Loaded modclass {}/{} with {}", modClass.getModule().getName(), modClass.getName(), modClass.getClassLoader());
         } catch (Throwable e) {
             LOGGER.error(LOADING, "Failed to load class {}", className, e);
             throw new ModLoadingException(info, ModLoadingStage.CONSTRUCT, "fml.modloading.failedtoloadmodclass", e);
         }
     }
 
-    private void onEventFailed(IEventBus iEventBus, Event event, IEventListener[] iEventListeners, int i, Throwable throwable) {
+    /**
+     * <pre>
+     * Reads the Add-Exports and Add-Opens attributes (see note) from a mod file and
+     * attempts to apply them. This differers from the JEP in two significant ways:
+     *   1) Instead of opening things to ALL-UNNAMED it instead only opens to the
+     *      mod's module itself. Because I don't want other mods accidently relying
+     *      on transitive behavior
+     *   2) It is read from all mods not just the executable jars.
+     *
+     * From <a href = "https://openjdk.org/jeps/261">JEP 261: Module System</a>
+     *
+     * Two new JDK-specific JAR-file manifest attributes are defined to correspond
+     * to the --add-exports and --add-opens command-line options:
+     *     Add-Exports: &lt;module&gt;/&lt;package&gt;( &lt;module&gt;/&lt;package&gt;)*
+     *     Add-Opens: &lt;module&gt;/&lt;package&gt;( &lt;module&gt;/&lt;package&gt;)*
+     *
+     * The value of each attribute is a space-separated list of slash-separated
+     * module-name/package-name pairs. A &gt;module&lt;/&gt;package&lt; pair in
+     * the value of an Add-Exports attribute has the same meaning as the
+     * command-line option --add-exports &gt;module&lt;/&gt;package&lt;=ALL-UNNAMED.
+     *
+     * A &gt;module&lt;/&gt;package&lt; pair in the value of an Add-Opens attribute has the
+     * same meaning as the command-line option --add-opens &gt;module&lt;/&gt;package&lt;=ALL-UNNAMED.
+     *
+     * Each attribute can occur at most once, in the main section of a MANIFEST.MF file.
+     * A particular pair can be listed more than once. If a specified module was not
+     * resolved, or if a specified package does not exist, then the corresponding pair
+     * is ignored.
+     */
+    private static void openModules(ModuleLayer layer, Module self, SecureJar jar) throws NoSuchMethodException, SecurityException, IllegalAccessException, InvocationTargetException {
+        var manifest = jar.moduleDataProvider().getManifest().getMainAttributes();
+        addOpenOrExports(layer, self, true, manifest);
+        addOpenOrExports(layer, self, false, manifest);
+    }
+
+    private static void addOpenOrExports(ModuleLayer layer, Module self, boolean open, Attributes attrs) throws NoSuchMethodException, SecurityException, IllegalAccessException, InvocationTargetException {
+        var key = open ? "Add-Opens" : "Add-Exports";
+        var entry = attrs.getValue(key);
+        if (entry == null)
+            return;
+
+        for (var pair : entry.split(" ")) {
+            var pts = pair.trim().split("/");
+            if (pts.length == 2) {
+                var target = layer.findModule(pts[0]).orElse(null);
+                if (target == null || !target.getDescriptor().packages().contains(pts[1]))
+                    continue;
+                addOpenOrExport(target, pts[1], self, open);
+            } else {
+                LOGGER.warn(LOADING, "Invalid {} entry in {}: {}", key, self.getName(), pair);
+            }
+        }
+    }
+
+    private static Method implAddExportsOrOpens;
+    private static void addOpenOrExport(Module target, String pkg, Module reader, boolean open) throws NoSuchMethodException, SecurityException, IllegalAccessException, InvocationTargetException {
+        if (implAddExportsOrOpens == null) {
+            implAddExportsOrOpens = Module.class.getDeclaredMethod("implAddExportsOrOpens", String.class, Module.class, boolean.class, boolean.class);
+            UnsafeHacks.setAccessible(implAddExportsOrOpens);
+        }
+
+        LOGGER.info(LOADING, "{} {}/{} to {}", open ? "Opening" : "Exporting", target.getName(), pkg, reader.getName());
+        implAddExportsOrOpens.invoke(target, pkg, reader, open, /*syncVM*/true);
+    }
+
+    private static void onEventFailed(IEventBus iEventBus, Event event, IEventListener[] iEventListeners, int i, Throwable throwable) {
         LOGGER.error(new EventBusErrorMessage(event, i, iEventListeners, throwable));
     }
 
     private void constructMod() {
         try {
             LOGGER.trace(LOADING, "Loading mod instance {} of type {}", getModId(), modClass.getName());
-            this.modInstance = modClass.getDeclaredConstructor().newInstance();
+            Constructor<?> constructor;
+            try {
+                constructor = modClass.getDeclaredConstructor(context.getClass());
+            } catch (NoSuchMethodException | SecurityException exception) {
+                constructor = modClass.getDeclaredConstructor();
+            }
+            this.modInstance = constructor.getParameterCount() == 0 ? constructor.newInstance() : constructor.newInstance(context);
             LOGGER.trace(LOADING, "Loaded mod instance {} of type {}", getModId(), modClass.getName());
         } catch (Throwable e) {
             // When a mod constructor throws an exception, it's wrapped in an InvocationTargetException which hides the
@@ -110,4 +188,14 @@ public class FMLModContainer extends ModContainer {
             throw new ModLoadingException(modInfo, modLoadingStage, "fml.modloading.errorduringevent", t);
         }
     }
+
+    @Override
+    public void dispatchConfigEvent(IConfigEvent event) {
+        this.eventBus.post(event.self());
+    }
+
+    @Override
+    public String toString() {
+        return "FMLModContainer[" + this.getModInfo().getModId() + ", " + this.getClass().getName() + "]";
+    }
 }

lowcodelanguage/src/main/java/net/minecraftforge/fml/lowcodemod/LowCodeModContainer.java

@@ -21,14 +21,12 @@ import static net.minecraftforge.fml.loading.LogMarkers.LOADING;
 public class LowCodeModContainer extends ModContainer
 {
     private static final Logger LOGGER = LogUtils.getLogger();
-    private final ModFileScanData scanResults;
-    private Object modInstance;
+    private final Object modInstance;
 
     public LowCodeModContainer(IModInfo info, ModFileScanData modFileScanResults, ModuleLayer gameLayer)
     {
         super(info);
         LOGGER.debug(LOADING, "Creating LowCodeModContainer for {}", info.getModId());
-        this.scanResults = modFileScanResults;
         this.modInstance = new Object();
         this.contextExtension = () -> null;
         this.extensionPoints.remove(IExtensionPoint.DisplayTest.class);
@@ -45,9 +43,4 @@ public class LowCodeModContainer extends ModContainer
     {
         return modInstance;
     }
-
-    @Override
-    protected <T extends Event & IModBusEvent> void acceptEvent(final T e)
-    {
-    }
 }