Roslyn: IDE0066 (switch pattern) code fix is incorrect

[Evangelink]

Version Used: 16.8.0 Preview 3.0

Steps to Reproduce:

The following snippet

switch (invocation.TargetMethod.Name)
{
    case "Last":
    case "First":
    case "Count":
        return true;
    default:
        return false;
}

gets refactored into the following form:

return invocation.TargetMethod.Name switch
{
    "Last" => true,
    _ => false,
};

which is incorrect.

Expected Behavior:

All cases are correctly converted.

Actual Behavior:

The code fix only take the first case declared.

[CyrusNajmabadi]

@alrz ?

[alrz]

Couldn't repro on master. With 8.0 it's missing and with 9.0 we correctly rewrite to or patterns.

        public async Task TestOnMultiCaseSection_String_CSharp9()
        {
            var testCode = @"
class Program
{
    bool M(string s)
    {
        [|switch|] (s)
        {
            case ""Last"":
            case ""First"":
            case ""Count"":
                return true;
            default:
                return false;
        }
    }
}";
            var fixedCode = @"
class Program
{
    bool M(string s)
    {
        return s switch
        {
            ""Last"" or ""First"" or ""Count"" => true,
            _ => false,
        };
    }
}";

            await new VerifyCS.Test
            {
                TestCode = testCode,
                FixedCode = fixedCode,
                LanguageVersion = CSharp9,
            }.RunAsync();
        }

[alrz]

Is it possible that the code is in error state? @Evangelink

[Evangelink]

I have reproduced the error multiple time when working on roslyn analyzers. I have just tried now and the code is compiling but still giving me the invalid code:

Maybe this is something that is fixed on current master of roslyn but not on the version used by the analyzer. As far as I can see we use v3.3.1 in https://github.com/dotnet/roslyn-analyzers/blob/master/eng/Versions.props#L25

And I am using VS Version 16.8.0 Preview 3.1

[CyrusNajmabadi]

Doesn't repro for me either. Likely fixed at some point. Have created test to validate this is workign and will not regress.

[Evangelink]

Just for my curiosity, if you create the following snippet somewhere in the code of your preview of VS do you have the right behavior?

[sharwell]

It was originally excluded rather than use lightup:

https://github.com/dotnet/roslyn/blob/85601f9301e2790ed23ec189412e28b60b48d838/src/Analyzers/CSharp/CodeFixes/ConvertSwitchStatementToExpression/ConvertSwitchStatementToExpressionCodeFixProvider.Rewriter.cs#L132-L142

Fixed by #46873