http://llvm.org/bugs/show_bug.cgi?id=10248

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@134327 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/bitset b/include/bitset
index de0a201..f0e8027 100644
--- a/include/bitset
+++ b/include/bitset
@@ -130,6 +130,15 @@
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 template <size_t _N_words, size_t _Size>
+class __bitset;
+
+template <size_t _N_words, size_t _Size>
+struct __has_storage_type<__bitset<_N_words, _Size> >
+{
+    static const bool value = true;
+};
+
+template <size_t _N_words, size_t _Size>
 class __bitset
 {
 public: