feat(ios): support Swift package macros (#6059)

Author: NathanWalker

lib/services/ios/xcodebuild-args-service.ts

@@ -167,11 +167,17 @@ export class XcodebuildArgsService implements IXcodebuildArgsService {
 		// Introduced in Xcode 14+
 		// ref: https://forums.swift.org/t/telling-xcode-14-beta-4-to-trust-build-tool-plugins-programatically/59305/5
 		const skipPackageValidation = "-skipPackagePluginValidation";
-
+		// Introduced in Xcode 15+ to trust Swift macros (compiler plugins)
+		// non-interactively. Required for SPM packages that ship macros
+		// (e.g. apple/RealityKitScripting), otherwise the build fails with:
+		// "Macro '...' from package '...' must be enabled before it can be used"
+		// ref: https://developer.apple.com/documentation/xcode/writing-swift-macros
+		const skipMacroValidation = "-skipMacroValidation";
 		const extraArgs: string[] = [
 			"-scheme",
 			projectData.projectName,
 			skipPackageValidation,
+			skipMacroValidation,
 		];
 
 		const BUILD_SETTINGS_FILE_PATH = path.join(
@@ -187,6 +193,22 @@ export class XcodebuildArgsService implements IXcodebuildArgsService {
 		// references: https://medium.com/@iostechset/why-cocoapods-eats-app-icons-79fe729808d4
 		// https://github.com/CocoaPods/CocoaPods/issues/7003
 
+		// Xcode 26 makes Swift "explicitly built modules" the default. A
+		// regression there prevents macro/compiler-plugin SPM targets from
+		// resolving their swift-syntax module dependencies, failing with:
+		// "Unable to resolve module dependency: 'SwiftSyntax'" (and SwiftParser,
+		// SwiftSyntaxMacros, SwiftCompilerPlugin, SwiftDiagnostics).
+		// Passed as a command-line build setting so it overrides ALL targets,
+		// including the package targets we don't control.
+		// ref: https://forums.swift.org/t/xcode-26-unable-to-find-module-dependency/80516
+		const explicitModulesProperty = "SWIFT_ENABLE_EXPLICIT_MODULES";
+		const explicitModulesValue =
+			this.$xcconfigService.readPropertyValue(
+				BUILD_SETTINGS_FILE_PATH,
+				explicitModulesProperty,
+			) || "NO";
+		extraArgs.push(`${explicitModulesProperty}=${explicitModulesValue}`);
+
 		const deployTargetProperty = "IPHONEOS_DEPLOYMENT_TARGET";
 		const deployTargetVersion = this.$xcconfigService.readPropertyValue(
 			BUILD_SETTINGS_FILE_PATH,

test/services/ios/xcodebuild-args-service.ts

@@ -11,6 +11,7 @@ function createTestInjector(data: {
 	logLevel: string;
 	hasProjectWorkspace: boolean;
 	connectedDevices?: any[];
+	buildXcconfigContent?: string;
 }): IInjector {
 	const injector = new Yok();
 	injector.register("devicePlatformsConstants", DevicePlatformsConstants);
@@ -19,8 +20,11 @@ function createTestInjector(data: {
 		getDevicesForPlatform: () => data.connectedDevices || [],
 	});
 	injector.register("fs", {
-		exists: () => data.hasProjectWorkspace,
-		readText: () => "",
+		exists: (filePath: string) =>
+			filePath.endsWith("build.xcconfig")
+				? data.buildXcconfigContent !== undefined
+				: data.hasProjectWorkspace,
+		readText: () => data.buildXcconfigContent || "",
 	});
 	injector.register("logger", {
 		getLevel: () => data.logLevel,
@@ -49,7 +53,13 @@ function getCommonArgs() {
 }
 
 function getXcodeProjectArgs(data?: { hasProjectWorkspace: boolean }) {
-	const extraArgs = ["-scheme", projectName, "-skipPackagePluginValidation"];
+	const extraArgs = [
+		"-scheme",
+		projectName,
+		"-skipPackagePluginValidation",
+		"-skipMacroValidation",
+		"SWIFT_ENABLE_EXPLICIT_MODULES=NO",
+	];
 	return data && data.hasProjectWorkspace
 		? [
 				"-workspace",
@@ -72,6 +82,27 @@ function getBuildLoggingArgs(logLevel: string): string[] {
 }
 
 describe("xcodebuildArgsService", () => {
+	describe("getXcodeProjectArgs", () => {
+		it("should allow SWIFT_ENABLE_EXPLICIT_MODULES to be overridden from build.xcconfig", () => {
+			const injector = createTestInjector({
+				logLevel: "INFO",
+				hasProjectWorkspace: false,
+				buildXcconfigContent: "SWIFT_ENABLE_EXPLICIT_MODULES = YES",
+			});
+			const xcodebuildArgsService: IXcodebuildArgsService = injector.resolve(
+				"xcodebuildArgsService",
+			);
+
+			const actualArgs = xcodebuildArgsService.getXcodeProjectArgs(
+				<any>{ projectRoot, normalizedPlatformName },
+				<any>{ projectName, appResourcesDirectoryPath },
+			);
+
+			assert.include(actualArgs, "SWIFT_ENABLE_EXPLICIT_MODULES=YES");
+			assert.notInclude(actualArgs, "SWIFT_ENABLE_EXPLICIT_MODULES=NO");
+		});
+	});
+
 	describe("getBuildForSimulatorArgs", () => {
 		_.each([true, false], (hasProjectWorkspace) => {
 			_.each(["INFO", "TRACE"], (logLevel) => {