Merge the Forge manifest with the Minecraft manifest, ignoring any class sections

2 files changed, 43 insertions, 11 deletions

diff --git a/src/main/java/net/fabricmc/loom/providers/ForgeUniversalProvider.java b/src/main/java/net/fabricmc/loom/providers/ForgeUniversalProvider.java
index 93e54050..e46bd520 100644
--- a/src/main/java/net/fabricmc/loom/providers/ForgeUniversalProvider.java
+++ b/src/main/java/net/fabricmc/loom/providers/ForgeUniversalProvider.java
@@ -32,9 +32,11 @@ import org.gradle.api.Project;
 
 import net.fabricmc.loom.util.Constants;
 import net.fabricmc.loom.util.DependencyProvider;
+import net.fabricmc.loom.util.JarUtil;
 
 public class ForgeUniversalProvider extends DependencyProvider {
 	private File forge;
+	private File forgeManifest;
 
 	public ForgeUniversalProvider(Project project) {
 		super(project);
@@ -43,17 +45,26 @@ public class ForgeUniversalProvider extends DependencyProvider {
 	@Override
 	public void provide(DependencyInfo dependency, Consumer<Runnable> postPopulationScheduler) throws Exception {
 		forge = new File(getExtension().getProjectPersistentCache(), "forge-" + dependency.getDependency().getVersion() + "-universal.jar");
+		forgeManifest = new File(getExtension().getProjectPersistentCache(), "forge-" + dependency.getDependency().getVersion() + "-manifest.mf");
 
 		if (!forge.exists() || isRefreshDeps()) {
 			File dep = dependency.resolveFile().orElseThrow(() -> new RuntimeException("Could not resolve Forge"));
 			Files.copy(dep, forge);
 		}
+
+		if (!forgeManifest.exists() || isRefreshDeps()) {
+			JarUtil.extractFile(forge, "META-INF/MANIFEST.MF", forgeManifest);
+		}
 	}
 
 	public File getForge() {
 		return forge;
 	}
 
+	public File getForgeManifest() {
+		return forgeManifest;
+	}
+
 	@Override
 	public String getTargetConfig() {
 		return Constants.Configurations.FORGE_UNIVERSAL;
diff --git a/src/main/java/net/fabricmc/loom/providers/MinecraftMappedProvider.java b/src/main/java/net/fabricmc/loom/providers/MinecraftMappedProvider.java
index f328cce3..ddbddc72 100644
--- a/src/main/java/net/fabricmc/loom/providers/MinecraftMappedProvider.java
+++ b/src/main/java/net/fabricmc/loom/providers/MinecraftMappedProvider.java
@@ -25,18 +25,21 @@
 package net.fabricmc.loom.providers;
 
 import java.io.File;
+import java.io.FileInputStream;
 import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
 import java.net.URI;
 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.Arrays;
 import java.util.Collection;
-import java.util.List;
 import java.util.Map;
 import java.util.function.Consumer;
+import java.util.jar.Attributes;
+import java.util.jar.Manifest;
 
 import com.google.common.collect.ImmutableMap;
 import org.gradle.api.Project;
@@ -145,17 +148,35 @@ public class MinecraftMappedProvider extends DependencyProvider {
 				try (FileSystem fs = FileSystems.newFileSystem(URI.create("jar:" + output.toUri()), ImmutableMap.of("create", false))) {
 					Path manifestPath = fs.getPath("META-INF", "MANIFEST.MF");
 					ForgeProvider.ForgeVersion version = getExtension().getForgeProvider().getVersion();
-					List<String> lines = new ArrayList<>(Files.readAllLines(manifestPath));
-
-					lines.add("");
-					lines.add("Name: net/minecraftforge/fml/javafmlmod/");
-					lines.add("Implementation-Version: " + version.getForgeVersion());
-					lines.add("");
-					lines.add("Name: net/minecraftforge/fml/mclanguageprovider/");
-					lines.add("Implementation-Version: " + version.getMinecraftVersion());
+					Manifest minecraftManifest;
+					Manifest forgeManifest;
+
+					try (InputStream in = Files.newInputStream(manifestPath)) {
+						minecraftManifest = new Manifest(in);
+					}
+
+					try (InputStream in = new FileInputStream(getExtension().getForgeUniversalProvider().getForgeManifest())) {
+						forgeManifest = new Manifest(in);
+					}
+
+					for (Map.Entry<String, Attributes> forgeEntry : forgeManifest.getEntries().entrySet()) {
+						if (!forgeEntry.getKey().endsWith(".class")) {
+							minecraftManifest.getEntries().put(forgeEntry.getKey(), forgeEntry.getValue());
+						}
+					}
+
+					Attributes javafmlmod = new Attributes();
+					javafmlmod.put("Implementation-Version", version.getForgeVersion());
+					Attributes mclanguageprovider = new Attributes();
+					mclanguageprovider.put("Implementation-Version", version.getMinecraftVersion());
+					minecraftManifest.getEntries().putIfAbsent("net/minecraftforge/fml/javafmlmod/", javafmlmod);
+					minecraftManifest.getEntries().putIfAbsent("net/minecraftforge/fml/mclanguageprovider/", mclanguageprovider);
 
 					Files.delete(manifestPath);
-					Files.write(manifestPath, lines);
+
+					try (OutputStream out = Files.newOutputStream(manifestPath)) {
+						minecraftManifest.write(out);
+					}
 				}
 
 				TinyTree yarnWithSrg = getExtension().getMappingsProvider().getMappingsWithSrg();