Support split client/server intermediary for old Minecraft versions

build.gradle

@@ -111,7 +111,7 @@ dependencies {
 	// impl dependencies
 	include 'org.ow2.sat4j:org.ow2.sat4j.core:2.3.6'
 	include 'org.ow2.sat4j:org.ow2.sat4j.pb:2.3.6'
-	include "net.fabricmc:tiny-remapper:0.10.1"
+	include "net.fabricmc:tiny-remapper:0.10.2"
 	include "net.fabricmc:access-widener:2.1.0"
 	include ('net.fabricmc:mapping-io:0.5.0') {
 		// Mapping-io depends on ASM, dont bundle

minecraft/src/main/java/net/fabricmc/loader/impl/game/minecraft/MinecraftGameProvider.java

@@ -35,8 +35,10 @@
 
 import net.fabricmc.api.EnvType;
 import net.fabricmc.loader.api.ObjectShare;
+import net.fabricmc.loader.api.Version;
 import net.fabricmc.loader.api.VersionParsingException;
 import net.fabricmc.loader.api.metadata.ModDependency;
+import net.fabricmc.loader.api.metadata.version.VersionPredicate;
 import net.fabricmc.loader.impl.FabricLoaderImpl;
 import net.fabricmc.loader.impl.FormattedException;
 import net.fabricmc.loader.impl.game.GameProvider;
@@ -318,10 +320,22 @@ public void initialize(FabricLauncher launcher) {
 				obfJars.put("realms", realmsJar);
 			}
 
+			String sourceNamespace = "official";
+
+			try {
+				VersionPredicate mergedVersionPredicate = VersionPredicate.parse(">=1.3");
+
+				if (!mergedVersionPredicate.test(Version.parse(getNormalizedGameVersion()))) {
+					sourceNamespace = envType == EnvType.CLIENT ? "clientOfficial" : "serverOfficial";
+				}
+			} catch (VersionParsingException ignored) {
+				Log.warn(LogCategory.GAME_PROVIDER, "Failed to determine source namespace for remapping, defaulting to 'official'...");
+			}
+
 			obfJars = GameProviderHelper.deobfuscate(obfJars,
 					getGameId(), getNormalizedGameVersion(),
 					getLaunchDirectory(),
-					launcher);
+					launcher, sourceNamespace);
 
 			for (int i = 0; i < gameJars.size(); i++) {
 				Path newJar = obfJars.get(names[i]);

src/main/java/net/fabricmc/loader/impl/game/GameProviderHelper.java

@@ -156,6 +156,10 @@ public static final class FindResult {
 	private static boolean emittedInfo = false;
 
 	public static Map<String, Path> deobfuscate(Map<String, Path> inputFileMap, String gameId, String gameVersion, Path gameDir, FabricLauncher launcher) {
+		return deobfuscate(inputFileMap, gameId, gameVersion, gameDir, launcher, "official");
+	}
+
+	public static Map<String, Path> deobfuscate(Map<String, Path> inputFileMap, String gameId, String gameVersion, Path gameDir, FabricLauncher launcher, String sourceNamespace) {
 		Log.debug(LogCategory.GAME_REMAP, "Requesting deobfuscation of %s", inputFileMap);
 
 		if (launcher.isDevelopment()) { // in-dev is already deobfuscated
@@ -184,7 +188,7 @@ public static Map<String, Path> deobfuscate(Map<String, Path> inputFileMap, Stri
 			return inputFileMap;
 		}
 
-		if (!namespaces.contains(targetNamespace)) {
+		if (!namespaces.contains(targetNamespace) || !namespaces.contains(sourceNamespace)) {
 			Log.debug(LogCategory.GAME_REMAP, "Missing namespace in mappings, using input files");
 			return inputFileMap;
 		}
@@ -239,7 +243,7 @@ public static Map<String, Path> deobfuscate(Map<String, Path> inputFileMap, Stri
 
 		try {
 			Files.createDirectories(deobfJarDir);
-			deobfuscate0(inputFiles, outputFiles, tmpFiles, mappingConfig.getMappings(), targetNamespace, launcher);
+			deobfuscate0(inputFiles, outputFiles, tmpFiles, mappingConfig.getMappings(), sourceNamespace, targetNamespace, launcher);
 		} catch (IOException e) {
 			throw new RuntimeException("error remapping game jars "+inputFiles, e);
 		}
@@ -266,9 +270,9 @@ private static Path getDeobfJarDir(Path gameDir, String gameId, String gameVersi
 		return ret.resolve(versionDirName.toString().replaceAll("[^\\w\\-\\. ]+", "_"));
 	}
 
-	private static void deobfuscate0(List<Path> inputFiles, List<Path> outputFiles, List<Path> tmpFiles, MappingTree mappings, String targetNamespace, FabricLauncher launcher) throws IOException {
+	private static void deobfuscate0(List<Path> inputFiles, List<Path> outputFiles, List<Path> tmpFiles, MappingTree mappings, String sourceNamespace, String targetNamespace, FabricLauncher launcher) throws IOException {
 		TinyRemapper remapper = TinyRemapper.newRemapper()
-				.withMappings(TinyRemapperMappingsHelper.create(mappings, "official", targetNamespace))
+				.withMappings(TinyRemapperMappingsHelper.create(mappings, sourceNamespace, targetNamespace))
 				.rebuildSourceFilenames(true)
 				.build();
 

src/main/java/net/fabricmc/loader/impl/util/mappings/TinyRemapperMappingsHelper.java

@@ -18,38 +18,12 @@
 
 import net.fabricmc.mappingio.tree.MappingTree;
 import net.fabricmc.tinyremapper.IMappingProvider;
+import net.fabricmc.tinyremapper.TinyUtils;
 
 public class TinyRemapperMappingsHelper {
 	private TinyRemapperMappingsHelper() { }
 
-	private static IMappingProvider.Member memberOf(String className, String memberName, String descriptor) {
-		return new IMappingProvider.Member(className, memberName, descriptor);
-	}
-
 	public static IMappingProvider create(MappingTree mappings, String from, String to) {
-		return (acceptor) -> {
-			final int fromId = mappings.getNamespaceId(from);
-			final int toId = mappings.getNamespaceId(to);
-
-			for (MappingTree.ClassMapping classDef : mappings.getClasses()) {
-				final String className = classDef.getName(fromId);
-				String dstName = classDef.getName(toId);
-
-				if (dstName == null) {
-					dstName = className;
-				}
-
-				acceptor.acceptClass(className, dstName);
-
-				for (MappingTree.FieldMapping field : classDef.getFields()) {
-					acceptor.acceptField(memberOf(className, field.getName(fromId), field.getDesc(fromId)), field.getName(toId));
-				}
-
-				for (MappingTree.MethodMapping method : classDef.getMethods()) {
-					IMappingProvider.Member methodIdentifier = memberOf(className, method.getName(fromId), method.getDesc(fromId));
-					acceptor.acceptMethod(methodIdentifier, method.getName(toId));
-				}
-			}
-		};
+		return TinyUtils.createMappingProvider(mappings, from, to);
 	}
 }