Disallow the "watchOS" supported destination for multiplatform apps

CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## Next Version
 
+### Fixed
+
+- Fixed `supportedDestinations` validation when it contains watchOS for multiplatform apps. #1470 @tatsuky
+
 ## 2.40.1
 
 ### Fixed

Docs/ProjectSpec.md

@@ -500,7 +500,7 @@ targets:
         destinationFilters: [iOS]
 ```
 
-Note that the definition of supported destinations can be applied to every type of bundle making everything more easy to manage (app targets, unit tests, UI tests etc).
+Note that the definition of supported destinations can be applied to almost every type of bundle making everything more easy to manage (app targets, unit tests, UI tests etc). App targets currently do not support the watchOS destination. Create a separate target using `platform` for watchOS apps. See Apple's [Configuring a multiplatform app](https://developer.apple.com/documentation/xcode/configuring-a-multiplatform-app-target) for details.
 
 ### Sources
 

Sources/ProjectSpec/SpecValidation.swift

@@ -185,6 +185,12 @@ extension Project {
                 errors.append(.unexpectedTargetPlatformForSupportedDestinations(target: target.name, platform: target.platform))
             }
 
+            if let supportedDestinations = target.supportedDestinations,
+               target.type.isApp,
+               supportedDestinations.contains(.watchOS) {
+                errors.append(.containsWatchOSDestinationForMultiplatformApp(target: target.name))
+            }
+
             if target.supportedDestinations?.contains(.macOS) == true,
                target.supportedDestinations?.contains(.macCatalyst) == true {
 

Sources/ProjectSpec/SpecValidationError.swift

@@ -19,6 +19,7 @@ public struct SpecValidationError: Error, CustomStringConvertible {
         case invalidTargetSchemeTest(target: String, testTarget: String)
         case invalidTargetPlatformForSupportedDestinations(target: String)
         case unexpectedTargetPlatformForSupportedDestinations(target: String, platform: Platform)
+        case containsWatchOSDestinationForMultiplatformApp(target: String)
         case multipleMacPlatformsInSupportedDestinations(target: String)
         case missingTargetPlatformInSupportedDestinations(target: String, platform: Platform)
         case invalidSchemeTarget(scheme: String, target: String, action: String)
@@ -66,6 +67,8 @@ public struct SpecValidationError: Error, CustomStringConvertible {
                 return "Target \(target.quoted) has multiple definitions of mac platforms in supported destinations"
             case let .missingTargetPlatformInSupportedDestinations(target, platform):
                 return "Target \(target.quoted) has platform \(platform.rawValue.quoted) that is missing in supported destinations"
+            case let .containsWatchOSDestinationForMultiplatformApp(target):
+                return "Multiplatform app \(target.quoted) cannot contain watchOS in \"supportedDestinations\". Create a separate target using \"platform\" for watchOS apps"
             case let .invalidConfigFile(configFile, config):
                 return "Invalid config file \(configFile.quoted) for config \(config.quoted)"
             case let .invalidSchemeTarget(scheme, target, action):

Tests/ProjectSpecTests/ProjectSpecTests.swift

@@ -203,6 +203,32 @@ class ProjectSpecTests: XCTestCase {
                 try expectValidationError(project, .unexpectedTargetPlatformForSupportedDestinations(target: "target1", platform: .watchOS))
             }
 
+            $0.it("watchOS in multiplatform app's supported destinations") {
+                var project = baseProject
+                project.targets = [
+                    Target(
+                        name: "target1",
+                        type: .application,
+                        platform: .auto,
+                        supportedDestinations: [.watchOS]
+                    )
+                ]
+                try expectValidationError(project, .containsWatchOSDestinationForMultiplatformApp(target: "target1"))
+            }
+
+            $0.it("watchOS in non-app's supported destinations") {
+                var project = baseProject
+                project.targets = [
+                    Target(
+                        name: "target1",
+                        type: .framework,
+                        platform: .auto,
+                        supportedDestinations: [.watchOS]
+                    )
+                ]
+                try expectNoValidationError(project, .containsWatchOSDestinationForMultiplatformApp(target: "target1"))
+            }
+
             $0.it("multiple definitions of mac platform in supported destinations") {
                 var project = baseProject
                 project.targets = [

Tests/XcodeGenKitTests/ProjectGeneratorTests.swift

@@ -485,8 +485,8 @@ class ProjectGeneratorTests: XCTestCase {
                 try expect(targetConfig1.buildSettings["CODE_SIGN_IDENTITY"] as? String) == "iPhone Developer"
             }
 
-            $0.it("supportedDestinations merges settings - iOS, watchOS") {
-                let target = Target(name: "Target", type: .application, platform: .auto, supportedDestinations: [.iOS, .watchOS])
+            $0.it("supportedDestinations merges settings - iOS, watchOS (framework)") {
+                let target = Target(name: "Target", type: .framework, platform: .auto, supportedDestinations: [.iOS, .watchOS])
                 let project = Project(name: "", targets: [target])
 
                 let pbxProject = try project.generatePbxProj()
@@ -499,8 +499,8 @@ class ProjectGeneratorTests: XCTestCase {
                 try expect(targetConfig1.buildSettings["SUPPORTS_XR_DESIGNED_FOR_IPHONE_IPAD"] as? Bool) == true
             }
 
-            $0.it("supportedDestinations merges settings - visionOS, watchOS") {
-                let target = Target(name: "Target", type: .application, platform: .auto, supportedDestinations: [.visionOS, .watchOS])
+            $0.it("supportedDestinations merges settings - visionOS, watchOS (framework)") {
+                let target = Target(name: "Target", type: .framework, platform: .auto, supportedDestinations: [.visionOS, .watchOS])
                 let project = Project(name: "", targets: [target])
 
                 let pbxProject = try project.generatePbxProj()