--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/clang/test/PCH/chain-late-anonymous-namespace.cpp	Thu Feb 13 15:10:13 2020 +0900
@@ -0,0 +1,63 @@
+// no PCH
+// RUN: %clang_cc1 -include %s -include %s -fsyntax-only %s
+// with PCH
+// RUN: %clang_cc1 -chain-include %s -chain-include %s -fsyntax-only %s
+// with PCH, with modules enabled
+// RUN: %clang_cc1 -chain-include %s -chain-include %s -fsyntax-only -fmodules %s
+#if !defined(PASS1)
+#define PASS1
+
+namespace ns {}
+namespace os {}
+
+#elif !defined(PASS2)
+#define PASS2
+
+namespace ns {
+  namespace {
+    extern int x;
+  }
+}
+
+namespace {
+  extern int y;
+}
+namespace {
+}
+
+namespace os {
+  extern "C" {
+    namespace {
+      extern int z;
+    }
+  }
+}
+
+#else
+
+namespace ns {
+  namespace {
+    int x;
+  }
+  void test() {
+    (void)x;
+  }
+}
+
+namespace {
+  int y;
+}
+void test() {
+  (void)y;
+}
+
+namespace os {
+  namespace {
+    int z;
+  }
+  void test() {
+    (void)z;
+  }
+}
+
+#endif