[MemberNotNull] isn't respected on local functions

[stephentoub]

Version Used:
9525fa5

Steps to Reproduce:
https://sharplab.io/#v2:EYLgtghglgdgPgYhgVwDaosVBTABNmTHAWACgABABl3IEYA6AESggHMYB7AZwBcoBjLvQDCHACbYAgoVQBPLlC4BuMmXIBmGgCZcwsgG8yuY7gAOAJygA3CDzwdgAK2z8eAflwB9B45WkTuEYmGriwPLgAsgAUAJRBxob+ASYAkjBQPLF+ycEA7F4+9ADi2DwAEhBcABaiElnxyQ0BANoR2GDA2OYAchw83WioUYRg2BwAZlHeTjExALpNwQAsuGkZsbgAvAB8BU5buDDYAO64Pi6ZMdkmAL5kN0A===

#nullable enable
using System.Diagnostics.CodeAnalysis;

public class C
{
    private object? _obj;
    
    public int M()
    {
        Init();
        return _obj.GetHashCode();
        
        [MemberNotNull(nameof(_obj))]
        void Init() => _obj = new object();
    }
}

Expected Behavior:
No warning.

Actual Behavior:
warning CS8602: Dereference of a possibly null reference.

[stephentoub]

Ah, dup of #47896

[stephentoub]

Apparently I opened the same issue last year ;-)
#49234

[Youssef1313]

@stephentoub #47896 was closed as fixed, but this issue still repros. This issue wasn't probably an exact dupe of #47896 and should be reopened. Can you reopen? Thanks!

[RikkiGibson]

LDM did decide on an internal thread that we should do this and that MemberNotNull applied to the function modifies the state of members of the captured this.

[jcouv]

Implemented in 17.13 :-)