Null dereference warning within local function

[cston]

The compiler generates a warning for y.ToString() in 16.4 but no warning in 16.3.

class Program
{
    static void F(System.Action a) { }

    static void M(string? x)
    {
        string? y = x;
        if (y == null) return;

        F(Local);
        return;

        void Local()
        {
            y.ToString();
        }
    }
}

[jnm2]

Updating to 16.4 caused a new incorrect warning to break a build. The repro is the same as this issue.

[andrewsav-bt]

Another repo:

#nullable enable
class Program
{
    static void Main()
    {
        var s = "";
        var b = s == null;
        var i = s.Length;
    }
}

[jnm2]

@andrewsav-datacom I think that one is by design. In any case, it doesn't involve local functions.