Not inferring nullability of non-nullable value compared to null

[cston]

Should report warnings for s.Length and c.F.ToString():

#pragma warning disable 0649
#pragma warning disable 8618

class C
{
    internal object F;
}

class Program
{
    static void F(string s, C c)
    {
        if (s == null)
            _ = s.Length;

        if (c.F != null) return;
        c.F.ToString();
    }
}

[gafter]

I'm not sure I agree. These are the moral equivalent of dead code.

[jcouv]

Subsumed by #33526 (Pure null tests should affect both branches)

[jcouv]

Re-opening issue as it is referenced in code (those references need to be removed first).
Sorry about that.