Messagepack-csharp: MessagePackAnalyzer does not consider types marked by [DataContract] as valid

[JiriZidek]

Bug description

The documentaion states:
_You can use [DataContract] instead of [MessagePackObject]. If type is marked DataContract, you can use [DataMember] instead of [Key] and [IgnoreDataMember] instead of [IgnoreMember]._

But the analyzer considers types with [DataContract] not compliant. In fact they work well with MessagePack (1.9 and 2.1 as well).

Repro steps

    [DataContract]
    public struct Party {

        [DataMember(Order = 0)]
        public int Type;
        [DataMember(Order = 1)]
        public string Number;
    }

    [MessagePackObject]
    public class CallItemPoco
    {
        [Key(0)]
        public string Id { get; set; }
        [Key(1)]
        public Party Remote { get; set; }  // THIS IS MARKED WITH ERROR
   }

Expected behavior

No error should be generated.

Actual behavior

MsgPack003 Use MessagePackObjectAttribute

• Version used: 2.1.90
• Runtime: VS2019 16.4.5

Additional context

An exception was caught by VS, difficult to say, whether it is related to this bug:

System.ArgumentNullException : Value cannot be null.
Parameter name: document
at async Microsoft.CodeAnalysis.Editing.DocumentEditor.CreateAsync()
at async MessagePackAnalyzer.MessagePackCodeFixProvider.AddKeyAttributeAsync()
at async Microsoft.CodeAnalysis.CodeActions.CodeAction.GetChangedSolutionAsync()
at async Microsoft.CodeAnalysis.CodeActions.CodeAction.ComputeOperationsAsync()
at async Microsoft.CodeAnalysis.CodeActions.CodeAction.GetPreviewOperationsAsync()
at async Microsoft.CodeAnalysis.Editor.Implementation.Suggestions.SuggestedAction.GetPreviewResultAsync()
at async Microsoft.CodeAnalysis.Editor.Implementation.Suggestions.SuggestedActionWithNestedFlavors.<>c__DisplayClass11_0.b__0()
at async Microsoft.CodeAnalysis.Extensions.IExtensionManagerExtensions.PerformFunctionAsyncT

[neuecc]

DataContract is used in various way.
Considering that it is not used only for MessagePack, it is excluded from detection.

[AArnott]

Are you saying this is by design, @neuecc? I'm hoping you won't object to (my) fixing this.

I don't see why we would want to produce an error in this case since we do in fact support DataContract attributes. And the analyzer is clearly throwing an exception, making a nasty looking infobar in VS. So we clearly have something to fix here.

[neuecc]

error is bug, should fix.
What I'm saying is whether to target DataContract to the Analyzer.
Current design is only work for MessagePackObjectAttribute.
https://github.com/neuecc/MessagePack-CSharp/blob/master/src/MessagePackAnalyzer/MessagePackAnalyzer.cs#L89-L91

[JiriZidek]

Since you have this (very needed feature!) of respecting DataContract attribute, the analyzer should tolerate it as well. For me this means that I:

• want to check my POCO objects - so I install analyzer
• do the build, check result, mentally filter-out false positives
• uninstall analyzer, since it would bother me during days when we do not touch pocos with errors and break possible builds
• I guess that this is not solvable by some #pragma declarations, sine afaik work for warnings only ?

[github-actions[bot]]

This issue is stale because it has been open 90 days with no activity. Remove stale label or comment or this will be closed in 5 days.

[JiriZidek]

This is probably low-priority issue... no idea how much work it requires.

[github-actions[bot]]

This issue is stale because it has been open 90 days with no activity. Remove stale label or comment or this will be closed in 5 days.