On Sun, 9 Nov 2014, Sandra Loosemore wrote: > Hrmmm. In C, sp->a has type "3-bit unsigned integer" which is promoted to int > by the integral promotions since all values are representable as int. sp->c > has type "5-bit unsigned integer" which is likewise promoted to int. In C++, > sp->a has type "unsigned char" and sp->c has type "unsigned long long". By > the C++ conversion rules, "unsigned char" is promoted to int (again since all > values are representable), and "unsigned long long" is not promoted to > anything else.
But C++ does still promote the unsigned long long:5 bit-field to int (4.5 [conv.prom]#5, in C++11: "A prvalue for an integral bit-field (9.6) can be converted to a prvalue of type int if int can represent all the values of the bit-field; otherwise, it can be converted to unsigned int if unsigned int can represent all the values of the bit-field. If the bit-field is larger yet, no integral promotion applies to it. If the bit-field has an enumerated type, it is treated as any other value of that type for promotion purposes."). -- Joseph S. Myers jos...@codesourcery.com
