1 files changed, 14 insertions, 0 deletions
diff --git a/test/Modules/diagnostics.modulemap b/test/Modules/diagnostics.modulemap
new file mode 100644
index 0000000..aef094d
--- /dev/null
+++ b/test/Modules/diagnostics.modulemap
@@ -0,0 +1,14 @@
+// RUN: not %clang_cc1 -fmodules -fmodules-cache-path=%t -fmodule-map-file=%S/Inputs/diagnostics-aux.modulemap -fmodule-map-file=%s -fsyntax-only -x c++ /dev/null 2>&1 | FileCheck %s
+
+// PR22299: Ensure we can produce diagnostics for duplicate modules from -fmodule-map-file=.
+//
+// CHECK: diagnostics.modulemap:[[@LINE+2]]:8: error: redefinition of module 'foo'
+// CHECK: diagnostics-aux.modulemap:1:8: note: previously defined here
+module foo {}
+
+//* Check that we accept BCPL comments properly, not just as an extension. */
+
+module bad_use {
+  // CHECK: diagnostics.modulemap:[[@LINE+1]]:22: error: use declarations are only allowed in top-level modules
+  module submodule { use foo }
+}