See the WG14 reflector thread starting with <http://www.open-std.org/jtc1/sc22/wg14/13560>, and the reference back to the analysis of the textual history in <http://www.open-std.org/jtc1/sc22/wg14/11100>. Effectively, you can treat choices in this area as being implementation-defined or unspecified (they can only arise when an implementation defines that types other than "a qualified or unqualified version of _Bool, signed int, unsigned int" can be used to declare bit-fields).
Nothing has ever defined how conversions to store out-of-range values in bit-fields (other than _Bool bit-fields) would work for C if an implementation defines such a bit-field not to have its own type (whereas as noted in DR#120, this all falls out naturally if you treat the type as including the width). -- Joseph S. Myers jos...@codesourcery.com
