Improve -Wheader-hygiene to warn about using directives inside linkage

specifications within the global scope, from Elliot Glaysher.

llvm-svn: 128352

1 files changed, 27 insertions, 0 deletions

diff --git a/clang/test/SemaCXX/warn-using-namespace-in-header.h b/clang/test/SemaCXX/warn-using-namespace-in-header.h
index 677c4ac51ae..57bb5d91be4 100644
--- a/clang/test/SemaCXX/warn-using-namespace-in-header.h
+++ b/clang/test/SemaCXX/warn-using-namespace-in-header.h
@@ -13,3 +13,30 @@ using namespace warn_in_header_in_global_context;
 namespace dont_warn_here {
 using namespace warn_in_header_in_global_context;
 }
+
+// We should warn in toplevel extern contexts.
+namespace warn_inside_linkage {}
+extern "C++" {
+using namespace warn_inside_linkage;
+}
+
+// This is really silly, but we should warn on it:
+extern "C++" {
+extern "C" {
+extern "C++" {
+using namespace warn_inside_linkage;
+}
+}
+}
+
+// But we shouldn't warn in extern contexts inside namespaces.
+namespace dont_warn_here {
+extern "C++" {
+using namespace warn_in_header_in_global_context;
+}
+}
+
+// We also shouldn't warn in case of functions.
+inline void foo() {
+  using namespace warn_in_header_in_global_context;
+}