Fix S1104 FP: Should be ignored on classes and structs marked as [Serializable]

[dukobpa3]

Description

S1104 FP: Should be ignored on classes and structs marked as [Serializable]

Repro steps

This kind of classes/structs always have an issue on each field.

        [Serializable]
        public class ConfigOptionDto
        {
            public string type;

            public string key;

            public string value;
        }

Expected behavior

If object have [Serializable] attribute then 99.9% it will have a lot of public fields, so this rule is not relevant in this case

Actual behavior

This kind of classes/structs always have an issue on each field.

Known workarounds

Something like this. But in this case we really don't need it since all compilers already understand [Serializable] objects and will not strip it, an even Rider/Resharper will not highlite this issue etc...

            [UsedImplicitly]
            public string type;

            [UsedImplicitly]
            public string key;

            [UsedImplicitly]
            public string value;

Related information

• Visual Studio version – 2022
• MSBuild / dotnet version – latest from VS 2022
• SonarScanner for .NET version (if used) – 6.xx
• Operating System – Windows 10

[Tim-Pohlmann]

Hello @dukobpa3, thanks for the report.
For clarification: Using properties instead of fields would be another workaround, correct? Is there a particular reason why you prefer fields over properties for serializable classes?

[dukobpa3]

Using properties instead of fields would be another workaround, correct?

Actually not because many serializers can't work with properties.

[Tim-Pohlmann]

Good point. Then, this must be frustrating to deal with; I apologize. We will fix it in a future hardening sprint.

[Tim-Pohlmann]

I don't think making the fields private is a solution in most cases, so I clarified this to be an FP for S1104 but not S1144.

[Tim-Pohlmann]

For transparency: I updated the code sample to use a public class, since the rule doesn't raise for private ones.

[dukobpa3]

S1144 I think relevant also

Sometimes I should add the fields just to copy serializing source structure, but not all of them will be used after that

Especially when working with some 3-d parties.
Or in case implementing network protocols with sending serialized data
I should implement some protocol DTO but not each field will be used after that

[Tim-Pohlmann]

@dukobpa3 You are making some great points. I have created another issue. Thanks!