Rule 6.5 and unnamed 0-length bit field

[pkruk]

What about following case:

Code:

struct s {
    signed int : 0;        /* Is Rule 6.5 violated? */
  };

Rule 6.5 explicitly says that \"Bit fields of type signed int shall be at least 2 bits long.\" (or \"Bit fields of signed type shall be at least 2 bits long.\" in TC1).

This bit field is clearly smaller than 2 bits, but it serves other purpose than \"normal\" positive-size bit fields.

Should the code be changed to use \"unsigned int\" type (the rule would not apply), or is the 0-size bit field an exception to this rule?