Introduce an egregious hack to work around a bug in libstdc++ 4.2.x's

<tr1/hashtable> header, where a friend class template
std::tr1::__detail::_Map_base is declared with the wrong template
parameters. GCC doesn't catch the problem, so Clang does a little
back-flip to avoid diagnosing just this one instance of the problem.

llvm-svn: 100790

1 files changed, 6 insertions, 0 deletions

diff --git a/clang/test/SemaCXX/libstdcxx_is_pod_hack.cpp b/clang/test/SemaCXX/libstdcxx_is_pod_hack.cpp
index 7a4bebca864..2e920321953 100644
--- a/clang/test/SemaCXX/libstdcxx_is_pod_hack.cpp
+++ b/clang/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 {
 };