Rule C#:S3655 false positive for pattern

Language: C# 8 on .NET Framework 4.8

Rule: S3655 (reference is null on at least one execution path)


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This code gives warning:

MyObject? myObject = GetObjectOrNull();
if (myObject is { SomeProperty: true })

This results in the following message on myObject.Value (line 4):

S3655: ‘myObject’ is null on at least one execution path.

The given if-statement is equal to if (myObject != null && myobject.Value.SomeProperty), and the warning should not show.

Matching with pattern was introduced in C# 8, and using is { } checks if the variable contains reference to an object (not null).

Hi @Gakk,

Thank you for reporting this, I can confirm it’s a False Positive and created an issue for it here that you can track:

We plan to rework this rule in Q1 and that should also fix this issue.

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