Fix interaction of max_align_t and modules.

When building with modules enabled, we were defining max_align_t as a typedef
for a different anonymous struct type each time it was included, resulting in
an error if <stddef.h> is not covered by a module map and is included more than
once in the same modules-enabled compilation of C11 or C++11 code.

llvm-svn: 218931

1 files changed, 13 insertions, 0 deletions

diff --git a/clang/test/Modules/stddef.c b/clang/test/Modules/stddef.c
new file mode 100644
index 00000000000..aefc90f9a11
--- /dev/null
+++ b/clang/test/Modules/stddef.c
@@ -0,0 +1,13 @@
+// RUN: rm -rf %t
+// RUN: %clang_cc1 -fmodules -fmodules-cache-path=%t -I%S/Inputs/StdDef %s -verify -fno-modules-error-recovery
+
+#include "ptrdiff_t.h"
+
+ptrdiff_t pdt;
+
+size_t st; // expected-error {{must be imported}}
+// expected-note@stddef.h:* {{previous}}
+
+#include "include_again.h"
+
+size_t st2;