[modules] If we re-enter a submodule from within itself (when submodule

visibility is enabled) or leave and re-enter it, restore the macro and module
visibility state from last time we were in that submodule.

This allows mutually-#including header files to stand a chance at being
modularized with local visibility enabled.

llvm-svn: 237871

3 files changed, 21 insertions, 0 deletions

diff --git a/clang/test/Modules/Inputs/submodule-visibility/cycle1.h b/clang/test/Modules/Inputs/submodule-visibility/cycle1.h
new file mode 100644
index 00000000000..05e85aef10d
--- /dev/null
+++ b/clang/test/Modules/Inputs/submodule-visibility/cycle1.h
@@ -0,0 +1,8 @@
+#ifndef CYCLE1
+#define CYCLE1
+
+#include "cycle2.h"
+
+struct C1 {};
+
+#endif
diff --git a/clang/test/Modules/Inputs/submodule-visibility/cycle2.h b/clang/test/Modules/Inputs/submodule-visibility/cycle2.h
new file mode 100644
index 00000000000..de9fd8e01aa
--- /dev/null
+++ b/clang/test/Modules/Inputs/submodule-visibility/cycle2.h
@@ -0,0 +1,8 @@
+#ifndef CYCLE2
+#define CYCLE2
+
+#include "cycle1.h"
+
+struct C2 {};
+
+#endif
diff --git a/clang/test/Modules/Inputs/submodule-visibility/module.modulemap b/clang/test/Modules/Inputs/submodule-visibility/module.modulemap
index 447a1f42d45..2e13344dc63 100644
--- a/clang/test/Modules/Inputs/submodule-visibility/module.modulemap
+++ b/clang/test/Modules/Inputs/submodule-visibility/module.modulemap
@@ -1 +1,6 @@
 module x { module a { header "a.h" } module b { header "b.h" } }
+
+module cycles {
+  module cycle1 { header "cycle1.h" }
+  module cycle2 { header "cycle2.h" }
+}