Fixed possible UB

include/boost/type_index/ctti_type_index.hpp

@@ -42,17 +42,27 @@ namespace detail {
 //      4) we need a compile-time control to make shure that user does not copy or 
 // default construct `struct-that-represents-type`
 //
-// Solution would be a forward declared structure.
-struct ctti_data;
+// Solution would be a standard-layout class with private constructors and assignment operators.
+class ctti_data {
+private:
+    ctti_data();
+    ctti_data(const ctti_data&);
+    ctti_data& operator=(const ctti_data&);
+};
 
 } // namespace detail
 
 /// Helper method for getting detail::ctti_data of a tempalte patameter T.
 template <class T>
 inline const detail::ctti_data& ctti_construct() BOOST_NOEXCEPT {
-    // Standard C++11, 5.2.10 Reinterpret cast: Converting a prvalue of type “pointer to T1” to the
-    // type “pointer to T2” (where T1 and T2 are object types and where the alignment requirements of T2 are no
-    // stricter than those of T1) and back to its original type yields the original pointer value.
+    // Standard C++11, 5.2.10 Reinterpret cast:
+    // An object pointer can be explicitly converted to an object pointer of a different type. When a prvalue
+    // v of type “pointer to T1” is converted to the type “pointer to cv T2”, the result is static_cast<cv
+    // T2*>(static_cast<cv void*>(v)) if both T1 and T2 are standard-layout types (3.9) and the alignment
+    // requirements of T2 are no stricter than those of T1, or if either type is void. Converting a prvalue of type
+    // “pointer to T1” to the type “pointer to T2” (where T1 and T2 are object types and where the alignment
+    // requirements of T2 are no stricter than those of T1) and back to its original type yields the original pointer
+    // value.
     return *reinterpret_cast<const detail::ctti_data*>(boost::detail::ctti<T>::n());
 }