Fix Traits::IsSpecializationOf for references

This check is also supposed to work for references so use the same approach
as for ignoring cv qualifiers.

misc/traits.h

@@ -65,9 +65,10 @@ template <template <typename...> class Template, typename... Args> struct IsSpec
 };
 } // namespace Detail
 /// \endcond
-/// \brief Evaluates to Bool<true> if the specified type is based on the specified \tparam Template; otherwise evaluates to Bool<false>.
+/// \brief Evaluates to Bool<true> if the specified type is based on the specified template; otherwise evaluates to Bool<false>.
 template <typename Type, template <typename...> class... TemplateTypes>
-struct IsSpecializationOf : Detail::IsSpecializationOfHelper<typename std::remove_cv<Type>::type, TemplateTypes...> {
+struct IsSpecializationOf
+    : Detail::IsSpecializationOfHelper<typename std::remove_cv<typename std::remove_reference<Type>::type>::type, TemplateTypes...> {
 };
 /// \brief Evaluates to Bool<true> if the specified type is based on one of the specified templates; otherwise evaluates to Bool<false>.
 template <typename Type, template <typename...> class... TemplateTypes> struct IsSpecializingAnyOf : Bool<false> {

tests/traitstests.cpp

@@ -43,6 +43,9 @@ static_assert(None<Bool<false>, Bool<false>>::value, "None: positive case");
 
 static_assert(!IsSpecializationOf<string, basic_stringbuf>::value, "IsSpecializationOf: negative case");
 static_assert(IsSpecializationOf<string, basic_string>::value, "IsSpecializationOf: positive case");
+static_assert(IsSpecializationOf<string &, basic_string>::value, "IsSpecializationOf: positive case");
+static_assert(IsSpecializationOf<const string &, basic_string>::value, "IsSpecializationOf: positive case");
+static_assert(IsSpecializationOf<volatile string, basic_string>::value, "IsSpecializationOf: positive case");
 static_assert(!IsSpecializingAnyOf<string, basic_stringbuf, vector>::value, "IsSpecializingAnyOf: negative case");
 static_assert(!IsSpecializingAnyOf<string, basic_stringbuf, list, vector>::value, "IsSpecializingAnyOf: negative case");
 static_assert(IsSpecializingAnyOf<string, basic_stringbuf, basic_string, vector>::value, "IsSpecializingAnyOf: positive case");