Thread: Semantics of bit inversion operator

Hi,

what is the return type of the operator~ for integral types? I thought no promotion needs to be done here, but from a question to the gcc-help mailing list I got the following explanations:

The problem is that the operator "~" when applied upon the unsigned
char returns always a signed char.

and

Integral promotions are performed for operator ~ and int can represent
all the values of unsigned char, so the operand is promoted to int.

So my questions are

1. what are the promotion rules for bit inversion regarding integral types?
2. is this behaviour implementation defined?

bye,
deVas