MemberNotNull not works for local functions

[GF-Huang]

Version Used:

Microsoft Visual Studio Community 2022
版本 17.8.2
VisualStudio.17.Release/17.8.2+34322.80
Microsoft .NET Framework
版本 4.8.09032

已安装的版本: Community

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Steps to Reproduce:

class MyClass {
    private object? _obj;

    public void Method() {
        LocalFunction();

        Console.WriteLine(_obj.ToString()); // CS8602 _obj may be null here!!!!!!!!

        [MemberNotNull(nameof(_obj))]
        void LocalFunction() {
            _obj = new object();
        }
    }
}

Diagnostic Id:

If this is a report about a bug in an analyzer, please include the diagnostic if possible (e.g. "IDE0030").

Expected Behavior:
No CS8602.

Actual Behavior:
There is CS8602.

[dotnet-issue-labeler]

I couldn't figure out the best area label to add to this issue. If you have write-permissions please help me learn by adding exactly one area label.

[huoyaoyuan]

I believe MemberNotNull is only expected to work on member functions/properties instead of local functions, but there's no documentation says that, nor analyzer indicates that.

[GF-Huang]

I believe MemberNotNull is only expected to work on member functions/properties instead of local functions, but there's no documentation says that, nor analyzer indicates that.

https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/proposals/csharp-9.0/local-function-attributes

[huoyaoyuan]

That's unrelated. Attributes can be applied onto local functions doesn't mean NRT analysis will follow it.

[jcouv]

Closing as duplicate of #56256 (which states that LDM agreed this should work).