typeof() macro

[yumamur]

I assume this definition violates some rules

void    func(int x)
{
    typeof(x) k = x;
    if (k)
        ++k;
    else
        --k;
}

and also this

void    func(int x)
{
    int a;

    typeof(a) k = x;
    if (k)
    {
        typeof(x) b = 10;
        --b;
        ++k;
    }
    else
        --k;
}