IDE0072: False positive in switch statement with tuples

[BieleckiLtd]

Analyzer

Diagnostic ID: IDE0072: Add missing cases to switch expression

Analyzer source

SDK: Built-in CA analyzers in .NET 5 SDK or later

Version: SDK 8.0.303

Describe the bug

The switch expression covers all possible cases, yet the analyzer requests a default case, which would be unreachable.

Steps To Reproduce

private bool isRed = true;
private bool isRound = false;
private string result => (isRed, isRound) switch
{
    (true, true) => "Red and round",
    (true, false) => "Red but not round",
    (false, true) => "Not red but round",
    (false, false) => "Not red and not round",
};

[Thomas-Shephard]

I believe this is issue should be under the Roslyn repository as the area that causes this diagnostic is PopulateSwitch.

Although from a cursory look, I don't think this is particularly trivial issue to fix as the issue is because switches are currently only analyzed in a more detailed manner for Booleans and Enums. Tuples can contain other tuples and each tuple may contain up to 8 types.

See the AnalyzeSwitch method

[BieleckiLtd]

If I add default case, analyser detects unreachable code and raises CS0162 so it is somehow breaking down this tuple.