[modules] If we reach a definition of a class for which we already have a

non-visible definition, skip the new definition and make the old one visible
instead of trying to parse it again and failing horribly. C++'s ODR allows
us to assume that the two definitions are identical.

llvm-svn: 233250

1 files changed, 13 insertions, 0 deletions

diff --git a/clang/test/Modules/submodules-merge-defs.cpp b/clang/test/Modules/submodules-merge-defs.cpp
new file mode 100644
index 00000000000..48d4feb7cfe
--- /dev/null
+++ b/clang/test/Modules/submodules-merge-defs.cpp
@@ -0,0 +1,13 @@
+// RUN: rm -rf %t
+// RUN: %clang_cc1 -x c++ -fmodules-cache-path=%t -fmodules -I %S/Inputs/submodules-merge-defs %s -verify -fno-modules-error-recovery
+
+// Trigger import of definitions, but don't make them visible.
+#include "empty.h"
+
+A pre_a; // expected-error {{must be imported}} expected-error {{must use 'struct'}}
+// expected-note@defs.h:1 {{here}}
+
+// Make definitions from second module visible.
+#include "import-and-redefine.h"
+
+A post_a;