------- Comment #2 from rguenth at gcc dot gnu dot org 2010-03-17 10:47 ------- From
[3] ISO/IEC 14882-1998 [conv.prom] An rvalue for an integral bit-field can be converted to an rvalue 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. I read that t.f promotes to int. And that is exactly what the C++ frontend does: (void) printf ((const char *) "%lx %lx %lx\n", (long unsigned int) t.f, (long unsigned int) ((int) t.f << 17), (long unsigned int) (((int) t.f << 17) >> 17)) -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43393
