CA1801 false positive on record parameter if any parameter has a default value

[thomaslevesque]

Analyzer

Diagnostic ID: CA1801: Review unused parameters

Analyzer source

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

Version: SDK 5.0.100-rc.2

Describe the bug

If any parameter of a positional record has a default value, CA1801 is reported on all parameters.

Steps To Reproduce

Write this code:

public record Foo(string Name, int Age = 0);

Expected behavior

No warning

Actual behavior

CA1801 is reported on all parameters:

Parameter Name of method .ctor is never used. Remove the parameter or use it in the method body.
Parameter Age of method .ctor is never used. Remove the parameter or use it in the method body.

Additional context

Looks very similar to #4397

[Evangelink]

I confirm that I can reproduce the issue.

Regarding how to fix the issue, I am not sure what to do. I think there is a bug (or at least something missing) on roslyn because the property IsImplicitlyDeclared returns false while IMO it should return true.

@mavasani let me know if I am missing something.

[Youssef1313]

@Evangelink See similar discussion in dotnet/roslyn#48193 and also in dotnet/roslyn#48176

[fjallemark]

Is this same issue? I get CA1801 on parameter AssignedRoute i.e. when "subclassing" record and add properties on the sub-record.

public abstract record MovableEvent(long Id, DateTimeOffset Timestamp);
public abstract record InputEvent(long Id, DateTimeOffset Timestamp) : MovableEvent(Id, Timestamp);
public sealed record AssignRouteEvent(long Id, DateTimeOffset Timestamp, Route AssignedRoute) : InputEvent(Id, Timestamp);

[Evangelink]

@fjallemark For me the issues look the same.