CA1508 is raised incorrectly after a switch expression

[rampaa]

Version Used:
Visual Studio 2026 v18.4.1
.NET 9

Steps to Reproduce:

1. Use the following minimal code sample:

    public static void Test(string? text)
    {
        text = text switch
        {
            "test" => "tesuto",
            _ => text
        };

        if (text?.Length > 2) // CA1508
        {
            Console.WriteLine("Yay!");
        }
    }

Diagnostic Id:

CA1508: Avoid dead conditional code

Expected Behavior:

CA1508 should not get raised incorrectly

Actual Behavior:

CA1508 is being raised incorrectly