1 files changed, 17 insertions, 0 deletions
diff --git a/test/Sema/ms-keyword-system-header.c b/test/Sema/ms-keyword-system-header.c
new file mode 100644
index 0000000..b4ff568
--- /dev/null
+++ b/test/Sema/ms-keyword-system-header.c
@@ -0,0 +1,17 @@
+// RUN: %clang_cc1 -fms-extensions -D MS -isystem %S/Inputs %s -fsyntax-only -verify
+// RUN: %clang_cc1 -fms-extensions -D MS -Wno-keyword-compat -I %S/Inputs %s -fsyntax-only -verify
+// RUN: %clang_cc1 -fms-extensions -D MS -D NOT_SYSTEM -I %S/Inputs %s -fsyntax-only -verify
+// RUN: %clang_cc1 -isystem %S/Inputs %s -fsyntax-only -verify
+
+// PR17824: GNU libc uses MS keyword __uptr as an identifier in C mode
+#include <ms-keyword-system-header.h>
+
+void fn() {
+  WS ws;
+  ws.__uptr = 0;
+#ifdef MS
+  // expected-error@-2 {{expected identifier}}
+#else
+  // expected-no-diagnostics
+#endif
+}