Add cxx interop support to symbol graph extract

Author: rauhul

include/swift/Option/Options.td

@@ -758,7 +758,7 @@ def enable_experimental_cxx_interop :
 
 def cxx_interoperability_mode :
   Joined<["-"], "cxx-interoperability-mode=">,
-  Flags<[FrontendOption, ModuleInterfaceOption]>,
+  Flags<[FrontendOption, ModuleInterfaceOption, SwiftSymbolGraphExtractOption]>,
   HelpText<"Enables C++ interoperability; pass 'default' to enable or 'off' to disable">;
 
 def experimental_c_foreign_reference_types :

lib/DriverTool/swift_symbolgraph_extract_main.cpp

@@ -30,8 +30,50 @@
 using namespace swift;
 using namespace options;
 
+enum class CxxCompatMode {
+  invalid,
+  enabled,
+  off
+};
+
+static std::pair<CxxCompatMode, version::Version>
+validateCxxInteropCompatibilityMode(StringRef mode) {
+  if (mode == "off")
+    return {CxxCompatMode::off, {}};
+  if (mode == "default")
+    return {CxxCompatMode::enabled, {}};
+  if (mode == "upcoming-swift")
+    return {CxxCompatMode::enabled,
+            version::Version({version::getUpcomingCxxInteropCompatVersion()})};
+  if (mode == "swift-6")
+    return {CxxCompatMode::enabled, version::Version({6})};
+  // Swift-5.9 corresponds to the Swift 5 language mode when
+  // Swift 5 is the default language version.
+  if (mode == "swift-5.9")
+    return {CxxCompatMode::enabled, version::Version({5})};
+  // Note: If this is updated, corresponding code in
+  // InterfaceSubContextDelegateImpl::InterfaceSubContextDelegateImpl needs
+  // to be updated also.
+  return {CxxCompatMode::invalid, {}};
+}
+
+static void diagnoseCxxInteropCompatMode(llvm::opt::Arg *verArg,
+                                         llvm::opt::InputArgList &Args,
+                                         DiagnosticEngine &diags) {
+  // General invalid argument error
+  diags.diagnose(SourceLoc(), diag::error_invalid_arg_value,
+                 verArg->getAsString(Args), verArg->getValue());
+
+  // Note valid C++ interoperability modes.
+  auto validVers = {llvm::StringRef("off"), llvm::StringRef("default"),
+                    llvm::StringRef("swift-6"), llvm::StringRef("swift-5.9")};
+  auto versStr = "'" + llvm::join(validVers, "', '") + "'";
+  diags.diagnose(SourceLoc(), diag::valid_cxx_interop_modes, versStr);
+}
+
 int swift_symbolgraph_extract_main(ArrayRef<const char *> Args,
                                    const char *Argv0, void *MainAddr) {
+  printf("hello rauhul\n");
   INITIALIZE_LLVM();
 
   CompilerInvocation Invocation;
@@ -196,6 +238,23 @@ int swift_symbolgraph_extract_main(ArrayRef<const char *> Args,
             .Default(AccessLevel::Public);
   }
 
+  LangOptions& LangOpts = Invocation.getLangOptions();
+  if (auto *A = ParsedArgs.getLastArg(OPT_cxx_interoperability_mode)) {
+    auto interopCompatMode = validateCxxInteropCompatibilityMode(A->getValue());
+    LangOpts.EnableCXXInterop |=
+        (interopCompatMode.first == CxxCompatMode::enabled);
+    if (LangOpts.EnableCXXInterop) {
+      LangOpts.cxxInteropCompatVersion = interopCompatMode.second;
+      // The default is tied to the current language version.
+      if (LangOpts.cxxInteropCompatVersion.empty())
+        LangOpts.cxxInteropCompatVersion =
+            LangOpts.EffectiveLanguageVersion.asMajorVersion();
+    }
+
+    if (interopCompatMode.first == CxxCompatMode::invalid)
+      diagnoseCxxInteropCompatMode(A, ParsedArgs, Diags);
+  }
+
   std::string InstanceSetupError;
   if (CI.setup(Invocation, InstanceSetupError)) {
     llvm::outs() << InstanceSetupError << '\n';