From 1fae124089bf5067a2386c7f275e226814195a25 Mon Sep 17 00:00:00 2001
From: Space Walker <spacedoesrs@gmail.com>
Date: Fri, 13 Dec 2024 12:23:51 +0100
Subject: [PATCH] only merge jars if remapping occurred

---
 .../AbstractMappedMinecraftProvider.java      | 19 +++++++++++++++++-
 .../mapped/IntermediaryMinecraftProvider.java | 20 ++++++++++++-------
 .../mapped/NamedMinecraftProvider.java        | 20 ++++++++++++-------
 3 files changed, 44 insertions(+), 15 deletions(-)

diff --git a/src/main/java/net/fabricmc/loom/configuration/providers/minecraft/mapped/AbstractMappedMinecraftProvider.java b/src/main/java/net/fabricmc/loom/configuration/providers/minecraft/mapped/AbstractMappedMinecraftProvider.java
index e55c9928d..49b85b63d 100644
--- a/src/main/java/net/fabricmc/loom/configuration/providers/minecraft/mapped/AbstractMappedMinecraftProvider.java
+++ b/src/main/java/net/fabricmc/loom/configuration/providers/minecraft/mapped/AbstractMappedMinecraftProvider.java
@@ -85,7 +85,7 @@ public List<MinecraftJar> provide(ProvideContext context) throws Exception {
 			throw new IllegalStateException("No remapped jars provided");
 		}
 
-		if (!areOutputsValid(remappedJars) || context.refreshOutputs() || !hasBackupJars(minecraftJars)) {
+		if (shouldRemapInputs(context, remappedJars, minecraftJars)) {
 			try {
 				remapInputs(remappedJars, context.configContext());
 				createBackupJars(minecraftJars);
@@ -193,6 +193,23 @@ protected String getDependencyNotation(MinecraftJar.Type type) {
 		return "net.minecraft:%s:%s".formatted(getName(type), getVersion());
 	}
 
+	protected boolean shouldRemapInputs(ProvideContext context) {
+		final List<RemappedJars> remappedJars = getRemappedJars();
+		final List<MinecraftJar> minecraftJars = remappedJars.stream()
+				.map(RemappedJars::outputJar)
+				.toList();
+
+		if (remappedJars.isEmpty()) {
+			throw new IllegalStateException("No remapped jars provided");
+		}
+
+		return shouldRemapInputs(context, remappedJars, minecraftJars);
+	}
+
+	private boolean shouldRemapInputs(ProvideContext context, List<RemappedJars> remappedJars, List<MinecraftJar> minecraftJars) {
+		return !areOutputsValid(remappedJars) || context.refreshOutputs() || !hasBackupJars(minecraftJars);
+	}
+
 	private boolean areOutputsValid(List<RemappedJars> remappedJars) {
 		for (RemappedJars remappedJar : remappedJars) {
 			if (!getMavenHelper(remappedJar.type()).exists(null)) {
diff --git a/src/main/java/net/fabricmc/loom/configuration/providers/minecraft/mapped/IntermediaryMinecraftProvider.java b/src/main/java/net/fabricmc/loom/configuration/providers/minecraft/mapped/IntermediaryMinecraftProvider.java
index 74c70c2e9..f1fe3f6b9 100644
--- a/src/main/java/net/fabricmc/loom/configuration/providers/minecraft/mapped/IntermediaryMinecraftProvider.java
+++ b/src/main/java/net/fabricmc/loom/configuration/providers/minecraft/mapped/IntermediaryMinecraftProvider.java
@@ -80,18 +80,24 @@ public LegacyMergedImpl(Project project, LegacyMergedMinecraftProvider minecraft
 		public List<MinecraftJar> provide(ProvideContext context) throws Exception {
 			final List<MinecraftJar> minecraftJars = List.of(getMergedJar());
 
+			// this check must be done before the client and server impls are provided
+			// because the merging only needs to happen if the remapping step is run
+			final boolean mergeJars = client.shouldRemapInputs(context) || server.shouldRemapInputs(context);
+
 			// Map the client and server jars separately
 			server.provide(context);
 			client.provide(context);
 
-			// then merge them
-			MergedMinecraftProvider.mergeJars(
-						client.getEnvOnlyJar().toFile(),
-						server.getEnvOnlyJar().toFile(),
-						getMergedJar().toFile()
-			);
+			if (mergeJars) {
+				// then merge them
+				MergedMinecraftProvider.mergeJars(
+							client.getEnvOnlyJar().toFile(),
+							server.getEnvOnlyJar().toFile(),
+							getMergedJar().toFile()
+				);
+			}
 
-			if (!hasBackupJars(minecraftJars)) {
+			if (mergeJars || !hasBackupJars(minecraftJars)) {
 				createBackupJars(minecraftJars);
 			}
 
diff --git a/src/main/java/net/fabricmc/loom/configuration/providers/minecraft/mapped/NamedMinecraftProvider.java b/src/main/java/net/fabricmc/loom/configuration/providers/minecraft/mapped/NamedMinecraftProvider.java
index 4cb1b9db4..39e589377 100644
--- a/src/main/java/net/fabricmc/loom/configuration/providers/minecraft/mapped/NamedMinecraftProvider.java
+++ b/src/main/java/net/fabricmc/loom/configuration/providers/minecraft/mapped/NamedMinecraftProvider.java
@@ -87,18 +87,24 @@ public List<MinecraftJar> provide(ProvideContext context) throws Exception {
 			final ProvideContext childContext = context.withApplyDependencies(false);
 			final List<MinecraftJar> minecraftJars = List.of(getMergedJar());
 
+			// this check must be done before the client and server impls are provided
+			// because the merging only needs to happen if the remapping step is run
+			final boolean mergeJars = client.shouldRemapInputs(childContext) || server.shouldRemapInputs(childContext);
+
 			// Map the client and server jars separately
 			server.provide(childContext);
 			client.provide(childContext);
 
-			// then merge them
-			MergedMinecraftProvider.mergeJars(
-						client.getEnvOnlyJar().toFile(),
-						server.getEnvOnlyJar().toFile(),
-						getMergedJar().toFile()
-			);
+			if (mergeJars) {
+				// then merge them
+				MergedMinecraftProvider.mergeJars(
+							client.getEnvOnlyJar().toFile(),
+							server.getEnvOnlyJar().toFile(),
+							getMergedJar().toFile()
+				);
+			}
 
-			if (!hasBackupJars(minecraftJars)) {
+			if (mergeJars || !hasBackupJars(minecraftJars)) {
 				createBackupJars(minecraftJars);
 			}