Fix S4070: False positive with combined values

[Chelaris182]

The current implementation of the rule raises violation of S4070 for the following code:

    [Flags]
    public enum Foo
    {
        N1 = 1,
        N2 = 2,
        N3 = N1 | N2,
        N4 = 4,
        N5 = N4 | N1
    }

If you remove N5, the violation goes away.

[michalb-sonar]

Thanks for report and sample code @Chelaris182. I was able to reproduce the problem, we'll fix that.

[Chelaris182]

Looking at the rule code I also came up with a false negative case:

    [Flags]
    public enum Options
    {
        N1 = 1,
        N2 = 2,
        N3 = N1 | N2,
        N5 = 5
    }

[michalb-sonar]

Good catch @Chelaris182!