[cxx-interop] Add test to re-exposing C++ enum through Swift to C++

rdar://132065665

Author: Gabor Horvath

test/Interop/CxxToSwiftToCxx/bridge-cxx-enum-back-to-cxx-execution.cpp

@@ -0,0 +1,58 @@
+// RUN: %empty-directory(%t)
+// RUN: split-file %s %t
+
+// RUN: %target-swift-frontend -parse-as-library %platform-module-dir/Swift.swiftmodule/%module-target-triple.swiftinterface -enable-library-evolution -disable-objc-attr-requires-foundation-module -typecheck -module-name Swift -parse-stdlib -enable-experimental-cxx-interop -clang-header-expose-decls=has-expose-attr -emit-clang-header-path %t/Swift.h  -experimental-skip-all-function-bodies
+// RUN: %target-swift-frontend -typecheck %t/use-cxx-types.swift -typecheck -module-name UseCxx -emit-clang-header-path %t/UseCxx.h -I %t -enable-experimental-cxx-interop -clang-header-expose-decls=all-public
+
+// RUN: %target-interop-build-clangxx -std=c++20 -c %t/use-swift-cxx-types.cpp -I %t -o %t/swift-cxx-execution.o -g
+// RUN: %target-interop-build-swift %t/use-cxx-types.swift -o %t/swift-cxx-execution -Xlinker %t/swift-cxx-execution.o -module-name UseCxx -Xfrontend -entry-point-function-name -Xfrontend swiftMain -I %t -g
+
+// RUN: %target-codesign %t/swift-cxx-execution
+// RUN: %target-run %t/swift-cxx-execution
+
+// REQUIRES: executable_test
+
+//--- header.h
+enum class SomeEnum {
+  first,
+  second
+};
+
+//--- module.modulemap
+module CxxTest {
+    header "header.h"
+    requires cplusplus
+}
+
+//--- use-cxx-types.swift
+import CxxTest
+
+public class SomethingSwift {
+  public var someEnum: SomeEnum { get { return .first } }
+  public init() {}
+}
+
+//--- use-swift-cxx-types.cpp
+
+#include "header.h"
+#include "Swift.h"
+#include "UseCxx.h"
+#include <assert.h>
+
+class SomethingCxx {
+public:
+  SomethingCxx(UseCxx::SomethingSwift swiftPart): _swiftPart(swiftPart) { }
+
+  SomeEnum getSomeEnum() { return _swiftPart.getSomeEnum(); }
+
+private:
+  UseCxx::SomethingSwift _swiftPart;
+};
+
+int main() {
+  auto sp = UseCxx::SomethingSwift::init();
+  auto sc = SomethingCxx(sp);
+  auto e = sc.getSomeEnum();
+  assert(e == SomeEnum::first);
+  return 0;
+}