Function isReservedTag

lib/catch2/catch.hpp:14041–14043

                return TestCaseInfo::None;
        }
        bool isReservedTag( std::string const& tag ) {
            return parseSpecialTag( tag ) == TestCaseInfo::None && tag.size() > 0 && !std::isalnum( static_cast<unsigned char>(tag[0]) );
        }
        void enforceNotReservedTag( std::string const& tag, SourceLineInfo const& _lineInfo ) {
            CATCH_ENFORCE( !isReservedTag(tag),
                          "Tag name: [" << tag << "] is not allowed.\n"