[adrian_b]

A 1-bit integer can be interpreted as either a signed integer or as an unsigned integer, exactly like an integer number of any other size.

Converting a 1-bit integer to a byte-sized or word-sized integer, by using the same extension rules as for any other size (i.e. by using either sign extension or zero extension), yields as the converted value for "true" either "1" for the unsigned integer interpretation or the value with all ones (i.e. "-1") for the signed integer interpretation.

So you could have "unsigned bool" and "signed bool", exactly like you have "unsigned char" and "signed char", to choose between the 2 possible representations.