Incorrect nullability warning in local function

[JohanLarsson]

void M()
{
    if (Try(out var s))
    {
        int Local()
        {
            //     ↓ CS8602 here with 16.4
            return s.Length;
        }
    }
}

bool Try([NotNullWhen(true)] out string? text)
{
    text = string.Empty;
    return true;
}

[jnm2]

I think this is #38548?

[JohanLarsson]

Looks similar, I would add tests for both.

[jcouv]

This is a problem with analysis of local functions, which doesn't seem particularly related to the attribute.
Here's a repro without attribute:

using System.Diagnostics.CodeAnalysis;

#nullable enable
class C
{
void M(string? s)
{
    
    if (s is null)
    {
    }
    else
    {
        int Local()
        {
            //     ↓ CS8602 here with 16.4
            return s.Length;
        }
    }
}

bool Try([NotNullWhen(true)] out string? text)
{
    text = string.Empty;
    return true;
}
}