From 2a47b28fde45db3d43dc12aa69f5d606912bff00 Mon Sep 17 00:00:00 2001
From: Juuxel <6596629+Juuxel@users.noreply.github.com>
Date: Tue, 29 Jun 2021 00:15:16 +0300
Subject: [PATCH] Ignore Forge name mapping service provider

---
 .../providers/forge/MinecraftPatchedProvider.java    | 12 +++++++++---
 .../providers/mappings/MappingsProviderImpl.java     |  1 -
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/src/main/java/net/fabricmc/loom/configuration/providers/forge/MinecraftPatchedProvider.java b/src/main/java/net/fabricmc/loom/configuration/providers/forge/MinecraftPatchedProvider.java
index 995cb208..786d5509 100644
--- a/src/main/java/net/fabricmc/loom/configuration/providers/forge/MinecraftPatchedProvider.java
+++ b/src/main/java/net/fabricmc/loom/configuration/providers/forge/MinecraftPatchedProvider.java
@@ -28,7 +28,6 @@ import java.io.BufferedWriter;
 import java.io.File;
 import java.io.FileOutputStream;
 import java.io.IOException;
-import java.io.InputStream;
 import java.io.InputStreamReader;
 import java.io.PrintStream;
 import java.io.UncheckedIOException;
@@ -76,7 +75,6 @@ import org.objectweb.asm.tree.ClassNode;
 import org.zeroturnaround.zip.ZipUtil;
 
 import net.fabricmc.loom.configuration.DependencyProvider;
-import net.fabricmc.loom.configuration.providers.MinecraftProvider;
 import net.fabricmc.loom.configuration.providers.MinecraftProviderImpl;
 import net.fabricmc.loom.configuration.providers.minecraft.MinecraftMappedProvider;
 import net.fabricmc.loom.util.Checksum;
@@ -92,6 +90,8 @@ import net.fabricmc.loom.util.srg.SpecialSourceExecutor;
 import net.fabricmc.mapping.tree.TinyTree;
 
 public class MinecraftPatchedProvider extends DependencyProvider {
+	private static final String NAME_MAPPING_SERVICE_PATH = "/META-INF/services/cpw.mods.modlauncher.api.INameMappingService";
+
 	// Step 1: Remap Minecraft to SRG
 	private File minecraftClientSrgJar;
 	private File minecraftServerSrgJar;
@@ -557,7 +557,13 @@ public class MinecraftPatchedProvider extends DependencyProvider {
 	}
 
 	private void copyUserdevFiles(File source, File target) throws IOException {
-		walkFileSystems(source, target, file -> true, fs -> Collections.singleton(fs.getPath("inject")), (sourceFs, targetFs, sourcePath, targetPath) -> {
+		// Removes the Forge name mapping service definition so that our own is used.
+		// If there are multiple name mapping services with the same "understanding" pair
+		// (source -> target namespace pair), modlauncher throws a fit and will crash.
+		// To use our YarnNamingService instead of MCPNamingService, we have to remove this file.
+		Predicate<Path> filter = file -> !file.toString().equals(NAME_MAPPING_SERVICE_PATH);
+
+		walkFileSystems(source, target, filter, fs -> Collections.singleton(fs.getPath("inject")), (sourceFs, targetFs, sourcePath, targetPath) -> {
 			Path parent = targetPath.getParent();
 
 			if (parent != null) {
diff --git a/src/main/java/net/fabricmc/loom/configuration/providers/mappings/MappingsProviderImpl.java b/src/main/java/net/fabricmc/loom/configuration/providers/mappings/MappingsProviderImpl.java
index 8f319f61..373f6ab5 100644
--- a/src/main/java/net/fabricmc/loom/configuration/providers/mappings/MappingsProviderImpl.java
+++ b/src/main/java/net/fabricmc/loom/configuration/providers/mappings/MappingsProviderImpl.java
@@ -46,7 +46,6 @@ import com.google.common.base.Preconditions;
 import com.google.common.base.Stopwatch;
 import com.google.common.net.UrlEscapers;
 import com.google.gson.JsonObject;
-import dev.architectury.mappingslayers.api.utils.MappingsUtils;
 import org.apache.commons.io.FileUtils;
 import org.apache.tools.ant.util.StringUtils;
 import org.gradle.api.Project;