1 files changed, 6 insertions, 0 deletions

diff --git a/test/SemaCXX/libstdcxx_is_pod_hack.cpp b/test/SemaCXX/libstdcxx_is_pod_hack.cpp
index 7a4bebca864e..2e9203219536 100644
--- a/test/SemaCXX/libstdcxx_is_pod_hack.cpp
+++ b/test/SemaCXX/libstdcxx_is_pod_hack.cpp
@@ -1,5 +1,11 @@
 // RUN: %clang_cc1 -fsyntax-only %s
 
+// This is a test for an egregious hack in Clang that works around
+// issues with GCC's evolution. libstdc++ 4.2.x uses __is_pod as an
+// identifier (to declare a struct template like the one below), while
+// GCC 4.3 and newer make __is_pod a keyword. Clang treats __is_pod as
+// a keyword *unless* it is introduced following the struct keyword.
+
 template<typename T>
 struct __is_pod {
 };