Rule M9-6-4 (required, implementation, automated)
Named bit-fields with signed integer type shall have a length of more than one bit. See MISRA C++ 2008 [7] Note: The signed exact-width integer types like std::int16_t are guaranteed to have a two’s complement representation (see also A9-6-1). In this case, a single bit signed bit-field contains only a sign bit, thus it can represent values either (-1) or (0). Therefore, to avoid developers’ confusion, it is recommended to use unsigned types for single bit bit-fields.