Sonar-dotnet: Fix S1172 FP: Tuple as private method argument is marked as unused

Created on 18 Feb 2020 · 5Comments · Source: SonarSource/sonar-dotnet

Description

When using a tuple as a parameter in a method, S1172 pops even if the tuple is used in the method.

Repro steps

Code example:

        void UpdateControlsOnSignalChanged((InputsOutputs adress, bool state)? e) // <= False positive here
        {
            var call = new IPCQuery(nameof(DiagnosticsAPI.SignalChanged))
            { Data = (e?.adress, e?.state) };
            _pollingPublisher.Send(call);
        }

Expected behavior

if the tuple passed as a parameter is used in the method, S1172 shouldn't pop.

Actual behavior

S1172 pops no matter what is the usage of the tuple passed as a parameter.

Known workarounds

Suppress the warning locally.

Related information

SonarLint 4.17.0.14702
Visual Studio 2019 v 16.4.5
.Net Core 3.1 - LangVersion 8 - Nullable activated
Windows 10 Pro 1909

C# CFG False Positive

Source

Thieum

All 5 comments

Hi @Thieum ,

thank you for reporting this. We're able to reproduce the issue. Minimum reproducible scenario looks like this:

object TupleArgument((string adress, bool state)? e) // Noncompliant FP
{
    return new { Data = (e?.adress, e?.state) };
}

Interesting thing is that FP is not raised with public method.

public object PublicTupleArgument((string adress, bool state)? e) // Compliant for public method
{
    return new { Data = (e?.adress, e?.state) };
}

pavel-mikula-sonarsource on 19 Feb 2020

👍1

Hey,

I see this is marked as merged, but I still see the issue?

// a & b are marked with S1172           
            public void Test(string a, string b)
            {
                Test2((a, b));
            }

            public void Test2((string, string) a)
            {
                Test(a.Item1, a.Item2);
            }