Self-assignment instead of delegate creation

[PetSerAl]

runtime/src/libraries/System.Security.Claims/src/System/Security/Claims/ClaimsPrincipal.cs

Line 31 in 1303e42

private static Func<ClaimsPrincipal> s_principalSelector = ClaimsPrincipalSelector;

Here it is basically self-assignment: ClaimsPrincipalSelector property read the same field it is assigned to. As result ClaimsPrincipalSelector property ends up being null: https://sharplab.io/#v2:C4LgTgrgdgNAJiA1AHwAIEYB0GCcAKDTAZQFMBjCMAS2AE9MBhAGwEMqBbAZ0dY84AVqUMlQAOLJjzZdBVYWImkm5YAHswAAiqcNUCEyYBKANxA=
Looks like it should be SelectClaimsPrincipal (to create delegate from method) instead of ClaimsPrincipalSelector.

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[KalleOlaviNiemitalo]

It looks like a bug indeed. But .NET Framework behaves the same, and ClaimsPrincipal.Current tolerates s_principalSelector being null, so I don't think it's causing any actual problem. https://learn.microsoft.com/dotnet/api/system.security.claims.claimsprincipal.claimsprincipalselector?view=net-9.0 even documents that the default value is null.

I think the initialisation of ClaimsPrincipal.s_principalSelector should be just removed, and the type of ClaimsPrincipal.s_principalSelector and ClaimsPrincipal.ClaimsPrincipalSelector should be changed to nullable Func<ClaimsPrincipal>?.

[jeffhandley]

Assigned to @bartonjs for triage

[bartonjs]

Given that everything is working (and matches .NET Framework), this isn't really important.

But, if someone wants to go clean it up, correcting the nullability annotations on the field and the property may help someone in the future.

While changing the nullability annotations will edit the .ref.cs file, no API Review is required for adding a ? where null is already being returned.

If there isn't already a test that shows it's null by default (which will probably require using RemoteExecutor), one should probably be added with the change.