[interop][SwiftToCxx] do not error out on -Wnon-modular-include-in-framework-module clang diagnostic when importing the generated header as part of a framework back into C++ via a Clang module

test/Interop/SwiftToCxx/stdlib/swift-stdlib-imported-into-framework-module.swift

@@ -0,0 +1,83 @@
+// RUN: %empty-directory(%t)
+// RUN: split-file %s %t
+
+// RUN: %target-swift-frontend -typecheck %t/TestFmSwift.swift -typecheck -module-name TestFm -enable-experimental-cxx-interop -emit-clang-header-path %t/TestFm.framework/Headers/TestFm-Swift.h
+
+// RUN: %target-swift-frontend -typecheck %t/SecondSwift.swift -typecheck -module-name Second -enable-experimental-cxx-interop -emit-clang-header-path %t/Second.framework/Headers/Second-Swift.h
+
+// RUN: %target-interop-build-clangxx -std=gnu++17 -fmodules -fcxx-modules -c %t/consumer.cpp -F %t -fsyntax-only -Werror=non-modular-include-in-framework-module
+
+// Check that a client C++ file can use Swift stdlib APIs from two
+// mixed-language C++ and Swift frameworks.
+
+// This will only pass on Darwin with -Werror=non-modular-include-in-framework-module,
+// as the SDK is not modularized on other platforms.
+// REQUIRES: OS=macosx
+
+//--- TestFm.framework/Headers/TestFm.h
+#pragma once
+
+class CxxClass {
+public:
+    int testMethod() const {
+        return 42;
+    }
+};
+
+//--- TestFm.framework/Modules/module.modulemap
+framework module TestFm {
+    umbrella header "TestFm.h"
+
+    export *
+    module * { export * }
+}
+
+module TestFm.Swift {
+    header "TestFm-Swift.h"
+}
+
+//--- TestFmSwift.swift
+
+public func testSwiftFunc() -> String {
+    return ""
+}
+
+//--- Second.framework/Headers/Second.h
+#pragma once
+
+class CxxSecondClass {
+public:
+    int testMethodTwo() const {
+        return 42;
+    }
+};
+
+//--- Second.framework/Modules/module.modulemap
+framework module Second {
+    umbrella header "Second.h"
+
+    export *
+    module * { export * }
+}
+
+module Second.Swift {
+    header "Second-Swift.h"
+}
+
+//--- SecondSwift.swift
+
+public func testSwiftFuncTwo() -> String {
+    return ""
+}
+
+//--- consumer.cpp
+
+#pragma clang module import TestFm
+#pragma clang module import Second
+
+void testUseSwiftStdlibAPIsFromTwoFrameworksImportedViaModules() {
+    auto swiftString = TestFm::testSwiftFunc();
+    auto c1 = swiftString.getCount();
+    auto swiftString2 = Second::testSwiftFuncTwo();
+    auto c2 = swiftString.getCount();
+}