1 files changed, 10 insertions, 0 deletions
diff --git a/lib/Frontend/FrontendActions.cpp b/lib/Frontend/FrontendActions.cpp
index 0fbcc1c7399e..d42400183a43 100644
--- a/lib/Frontend/FrontendActions.cpp
+++ b/lib/Frontend/FrontendActions.cpp
@@ -163,6 +163,16 @@ GenerateModuleAction::CreateASTConsumer(CompilerInstance &CI,
   return llvm::make_unique<MultiplexConsumer>(std::move(Consumers));
 }
 
+bool GenerateModuleFromModuleMapAction::BeginSourceFileAction(
+    CompilerInstance &CI) {
+  if (!CI.getLangOpts().Modules) {
+    CI.getDiagnostics().Report(diag::err_module_build_requires_fmodules);
+    return false;
+  }
+
+  return GenerateModuleAction::BeginSourceFileAction(CI);
+}
+
 std::unique_ptr<raw_pwrite_stream>
 GenerateModuleFromModuleMapAction::CreateOutputFile(CompilerInstance &CI,
                                                     StringRef InFile) {