Prevent depending on jars built with newer loom versions.

src/main/java/net/fabricmc/loom/configuration/mods/ArtifactMetadata.java

@@ -46,7 +46,7 @@
 public record ArtifactMetadata(boolean isFabricMod, RemapRequirements remapRequirements, @Nullable InstallerData installerData, MixinRemapType mixinRemapType) {
 	private static final String INSTALLER_PATH = "fabric-installer.json";
 
-	public static ArtifactMetadata create(ArtifactRef artifact) throws IOException {
+	public static ArtifactMetadata create(ArtifactRef artifact, String currentLoomVersion) throws IOException {
 		boolean isFabricMod;
 		RemapRequirements remapRequirements = RemapRequirements.DEFAULT;
 		InstallerData installerData = null;
@@ -60,13 +60,18 @@ public static ArtifactMetadata create(ArtifactRef artifact) throws IOException {
 				final var manifest = new Manifest(new ByteArrayInputStream(Files.readAllBytes(manifestPath)));
 				final Attributes mainAttributes = manifest.getMainAttributes();
 				final String remapValue = mainAttributes.getValue(Constants.Manifest.REMAP_KEY);
+				final String loomVersion = mainAttributes.getValue(Constants.Manifest.LOOM_VERSION);
 				final String mixinRemapType = mainAttributes.getValue(Constants.Manifest.MIXIN_REMAP_TYPE);
 
 				if (remapValue != null) {
 					// Support opting into and out of remapping with "Fabric-Loom-Remap" manifest entry
 					remapRequirements = Boolean.parseBoolean(remapValue) ? RemapRequirements.OPT_IN : RemapRequirements.OPT_OUT;
 				}
 
+				if (loomVersion != null) {
+					validateLoomVersion(loomVersion, currentLoomVersion);
+				}
+
 				if (mixinRemapType != null) {
 					try {
 						refmapRemapType = MixinRemapType.valueOf(mixinRemapType.toUpperCase(Locale.ROOT));
@@ -87,6 +92,25 @@ public static ArtifactMetadata create(ArtifactRef artifact) throws IOException {
 		return new ArtifactMetadata(isFabricMod, remapRequirements, installerData, refmapRemapType);
 	}
 
+	// Validates that the version matches or is less than the current loom version
+	private static void validateLoomVersion(String version, String currentLoomVersion) {
+		final String[] versionParts = version.split("\\.");
+		final String[] currentVersionParts = currentLoomVersion.split("\\.");
+
+		// Check major and minor version
+		for (int i = 0; i < 2; i++) {
+			final int versionPart = Integer.parseInt(versionParts[i]);
+			final int currentVersionPart = Integer.parseInt(currentVersionParts[i]);
+
+			if (versionPart > currentVersionPart) {
+				throw new IllegalStateException("Mod was built with a newer version of Loom (%s), you are using Loom (%s)".formatted(version, currentLoomVersion));
+			} else if (versionPart < currentVersionPart) {
+				// Older version, no need to check further
+				break;
+			}
+		}
+	}
+
 	public boolean shouldRemap() {
 		return remapRequirements().getShouldRemap().test(this);
 	}

src/main/java/net/fabricmc/loom/configuration/mods/ModConfigurationRemapper.java

@@ -56,13 +56,15 @@
 import org.jetbrains.annotations.Nullable;
 
 import net.fabricmc.loom.LoomGradleExtension;
+import net.fabricmc.loom.LoomGradlePlugin;
 import net.fabricmc.loom.api.RemapConfigurationSettings;
 import net.fabricmc.loom.configuration.RemapConfigurations;
 import net.fabricmc.loom.configuration.mods.dependency.ModDependency;
 import net.fabricmc.loom.configuration.mods.dependency.ModDependencyFactory;
 import net.fabricmc.loom.configuration.providers.minecraft.MinecraftSourceSets;
 import net.fabricmc.loom.util.Checksum;
 import net.fabricmc.loom.util.Constants;
+import net.fabricmc.loom.util.ExceptionUtil;
 import net.fabricmc.loom.util.SourceRemapper;
 import net.fabricmc.loom.util.gradle.SourceSetHelper;
 import net.fabricmc.loom.util.service.SharedServiceManager;
@@ -137,9 +139,9 @@ public static void supplyModConfigurations(Project project, SharedServiceManager
 				final ArtifactMetadata artifactMetadata;
 
 				try {
-					artifactMetadata = ArtifactMetadata.create(artifact);
+					artifactMetadata = ArtifactMetadata.create(artifact, LoomGradlePlugin.LOOM_VERSION);
 				} catch (IOException e) {
-					throw new UncheckedIOException("Failed to read metadata from" + artifact.path(), e);
+					throw ExceptionUtil.createDescriptiveWrapper(UncheckedIOException::new, "Failed to read metadata from " + artifact.path(), e);
 				}
 
 				if (artifactMetadata.installerData() != null) {

src/test/groovy/net/fabricmc/loom/test/unit/ArtifactMetadataTest.groovy

@@ -34,7 +34,8 @@ import net.fabricmc.loom.configuration.mods.ArtifactRef
 import static net.fabricmc.loom.configuration.mods.ArtifactMetadata.MixinRemapType.MIXIN
 import static net.fabricmc.loom.configuration.mods.ArtifactMetadata.MixinRemapType.STATIC
 import static net.fabricmc.loom.configuration.mods.ArtifactMetadata.RemapRequirements.*
-import static net.fabricmc.loom.test.util.ZipTestUtils.*
+import static net.fabricmc.loom.test.util.ZipTestUtils.createZip
+import static net.fabricmc.loom.test.util.ZipTestUtils.manifest
 
 class ArtifactMetadataTest extends Specification {
 	def "is fabric mod"() {
@@ -119,8 +120,50 @@ class ArtifactMetadataTest extends Specification {
 		STATIC  	| ["fabric.mod.json": "{}", "META-INF/MANIFEST.MF": manifest("Fabric-Loom-Mixin-Remap-Type", "static")]	// Fabric mod opt-in
 	}
 
-	private static ArtifactMetadata createMetadata(Path zip) {
-		return ArtifactMetadata.create(createArtifact(zip))
+	// Test that a mod with the same or older version of loom can be read
+	def "Valid loom version"() {
+		given:
+		def zip = createMod(modLoomVersion)
+		when:
+		def metadata = createMetadata(zip, loomVersion)
+		then:
+		metadata != null
+		where:
+		loomVersion | modLoomVersion
+		"1.4"       | "1.0.1"
+		"1.4"       | "1.0.99"
+		"1.4"       | "1.4"
+		"1.4"       | "1.4.0"
+		"1.4"       | "1.4.1"
+		"1.4"       | "1.4.99"
+		"1.4"       | "1.4.local"
+		"1.5"		| "1.4.99"
+		"2.0"		| "1.4.99"
+	}
+
+	// Test that a mod with the same or older version of loom can be read
+	def "Invalid loom version"() {
+		given:
+		def zip = createMod(modLoomVersion)
+		when:
+		def metadata = createMetadata(zip, loomVersion)
+		then:
+		def e = thrown(IllegalStateException)
+		e.message == "Mod was built with a newer version of Loom ($modLoomVersion), you are using Loom ($loomVersion)"
+		where:
+		loomVersion | modLoomVersion
+		"1.4"       | "1.5"
+		"1.4"       | "1.5.00"
+		"1.4"       | "2.0"
+		"1.4"       | "2.4"
+	}
+
+	private static Path createMod(String loomVersion) {
+		return createZip(["fabric.mod.json": "{}", "META-INF/MANIFEST.MF": manifest("Fabric-Loom-Version", loomVersion)])
+	}
+
+	private static ArtifactMetadata createMetadata(Path zip, String loomVersion = "1.4") {
+		return ArtifactMetadata.create(createArtifact(zip), loomVersion)
 	}
 
 	private static ArtifactRef createArtifact(Path zip) {