Question

Possible Duplicate:
C++ bitfield packing with bools

Is it guaranteed to be safe to use C++’s bool keyword inside a bitfield definition?

Something like:

struct flags {
    bool a : 1;
    bool b : 1;
}

Answer 1

Yes. In practice, you can use sizeof(bool) * CHAR_BIT as your guide to knowing how many bits are available.

From C++98, § 9.6.3

A bit-field shall have integral or enumeration type (3.9.1).

From C++98, § 3.9.1.7

Types bool, char, wchar_t, and the signed and unsigned integer types are collectively called integral
types