Propagate '-application-extension' to module interface loader sub-invocations.

This flag restricts availability of certain symbols to ensure the code cannot use declarations that are explicitly unavalable to extensions. This restriction should be passed down to dependency modules also.

Author: artemcm

lib/Frontend/ModuleInterfaceLoader.cpp

@@ -1559,6 +1559,11 @@ InterfaceSubContextDelegateImpl::InterfaceSubContextDelegateImpl(
     genericSubInvocation.getFrontendOptions().DisableImplicitModules = true;
     GenericArgs.push_back("-disable-implicit-swift-modules");
   }
+  // If building an application extension, make sure API use
+  // is restricted accordingly in downstream dependnecies.
+  if (langOpts.EnableAppExtensionRestrictions) {
+    GenericArgs.push_back("-application-extension");
+  }
   // Save the parent invocation's Target Triple
   ParentInvocationTarget = langOpts.Target;
 

test/ModuleInterface/Inputs/extension-available.swift

@@ -0,0 +1,3 @@
+@available(macOS 10.0, *)
+public func extensionAvailable() {
+}

test/ModuleInterface/extension-transitive-availability.swift

@@ -0,0 +1,48 @@
+// REQUIRES: OS=macosx
+// RUN: %empty-directory(%t)
+
+// RUN: %target-swift-emit-module-interface(%t/ExtensionAvailable.swiftinterface) %S/Inputs/extension-available.swift -module-name ExtensionAvailable -I%t -disable-implicit-concurrency-module-import -disable-implicit-string-processing-module-import
+
+// RUN: %target-swift-frontend -scan-dependencies %s -o %t/deps.json -I%t -application-extension -disable-implicit-concurrency-module-import -disable-implicit-string-processing-module-import
+// RUN: %FileCheck %s < %t/deps.json
+
+import ExtensionAvailable
+func foo() {
+    extensionAvailable()
+}
+
+// CHECK:      "directDependencies": [
+// CHECK-NEXT:        {
+// CHECK-NEXT:          "swift": "ExtensionAvailable"
+// CHECK-NEXT:        },
+// CHECK-NEXT:        {
+// CHECK-NEXT:          "swift": "Swift"
+// CHECK-NEXT:        },
+// CHECK-NEXT:        {
+// CHECK-NEXT:          "swift": "SwiftOnoneSupport"
+// CHECK-NEXT:        }
+// CHECK-NEXT:      ],
+
+
+// CHECK:      "swift": "ExtensionAvailable"
+// CHECK-NEXT:    },
+// CHECK-NEXT:    {
+// CHECK-NEXT:      "modulePath": "ExtensionAvailable.swiftmodule",
+// CHECK-NEXT:      "sourceFiles": [
+// CHECK-NEXT:      ],
+// CHECK-NEXT:      "directDependencies": [
+// CHECK-NEXT:        {
+// CHECK-NEXT:          "swift": "Swift"
+// CHECK-NEXT:        },
+// CHECK-NEXT:        {
+// CHECK-NEXT:          "swift": "SwiftOnoneSupport"
+// CHECK-NEXT:        }
+// CHECK-NEXT:      ],
+// CHECK-NEXT:      "details": {
+// CHECK-NEXT:        "swift": {
+// CHECK-NEXT:          "moduleInterfacePath": 
+// CHECK-NEXT:          "contextHash":
+// CHECK-NEXT:          "commandLine": [
+// CHECK-NEXT:            "-frontend",
+// CHECK-NEXT:            "-compile-module-from-interface",
+// CHECK:            "-application-extension",