What are the semantics of a const member function?

Question

I understand that the function is not allowed to change the state of the object, but I thought I read somewhere that the compiler was allowed to assume that if the function

Answer 1

const methods are also allowed to modify static locals. For example, the following is perfectly legal (and repeated calls to bar() will return increasing values - not a cached 0):

class Foo
{
public:
    int bar() const
    {
        static int x = 0;
        return x++;
    }
};