[modules] Fix macro hiding bug exposed if:

 * A submodule of module A is imported into module B
 * Another submodule of module A that is not imported into B exports a macro
 * Some submodule of module B also exports a definition of the macro, and
   happens to be the first submodule of B that imports module A.

In this case, we would incorrectly determine that A's macro redefines B's
macro, and so we don't need to re-export B's macro at all.

This happens with the 'assert' macro in an LLVM self-host. =(

llvm-svn: 213348

6 files changed, 16 insertions, 0 deletions

diff --git a/clang/test/Modules/Inputs/macro-hiding/a1.h b/clang/test/Modules/Inputs/macro-hiding/a1.h
new file mode 100644
index 00000000000..b17c8eeb69a
--- /dev/null
+++ b/clang/test/Modules/Inputs/macro-hiding/a1.h
@@ -0,0 +1 @@
+#define assert(x)
diff --git a/clang/test/Modules/Inputs/macro-hiding/a2.h b/clang/test/Modules/Inputs/macro-hiding/a2.h
new file mode 100644
index 00000000000..e69de29bb2d
--- /dev/null
+++ b/clang/test/Modules/Inputs/macro-hiding/a2.h
diff --git a/clang/test/Modules/Inputs/macro-hiding/b1.h b/clang/test/Modules/Inputs/macro-hiding/b1.h
new file mode 100644
index 00000000000..e69de29bb2d
--- /dev/null
+++ b/clang/test/Modules/Inputs/macro-hiding/b1.h
diff --git a/clang/test/Modules/Inputs/macro-hiding/b2.h b/clang/test/Modules/Inputs/macro-hiding/b2.h
new file mode 100644
index 00000000000..83918489e92
--- /dev/null
+++ b/clang/test/Modules/Inputs/macro-hiding/b2.h
@@ -0,0 +1,2 @@
+#include "a2.h"
+#define assert(x)
diff --git a/clang/test/Modules/Inputs/macro-hiding/c1.h b/clang/test/Modules/Inputs/macro-hiding/c1.h
new file mode 100644
index 00000000000..4b78b3c2734
--- /dev/null
+++ b/clang/test/Modules/Inputs/macro-hiding/c1.h
@@ -0,0 +1,2 @@
+#include "b1.h"
+#define assert(x)
diff --git a/clang/test/Modules/Inputs/macro-hiding/module.modulemap b/clang/test/Modules/Inputs/macro-hiding/module.modulemap
new file mode 100644
index 00000000000..2657ab1692a
--- /dev/null
+++ b/clang/test/Modules/Inputs/macro-hiding/module.modulemap
@@ -0,0 +1,11 @@
+module a {
+  module a1 { header "a1.h" export * }
+  module a2 { header "a2.h" export * }
+}
+module b {
+  module b1 { header "b1.h" export * }
+  module b2 { header "b2.h" export * }
+}
+module c {
+  module c1 { header "c1.h" export * }
+}