Code inspection: Type member is never accessed via base type (non-private accessibility)

This inspection reports interface members that have no direct usages in the solution, where only their implementations from derived classes are used. It suggests that such a member may not necessarily need to be a part of the interface, in which case it can be safely removed to simplify your code.

Although this might be an issue in the current state of your codebase, the inspection cannot account for planned future usages of the interface. So if you plan to use the reported member through the interface, you may ignore this suggestion.

In the example below, the Name property is never used through the IPage interface; only its implementation in the Post class is used. Removing Name from IPage would make your code more straightforward, indicating that Name is a part of the Post class.

        
public interface IPage
{
    public string Name { get; set; }
}

public class Post : IPage
{
    public string Name { get; set; }

    public Post(string name) => Name = name;

    public void PrintName() => Console.WriteLine(Name);
}

public class Test
{
    public Test()
    {
        var post = new Post("New post");
        post.PrintName();
    }
}

    

For the solution-wide inspection to work, you need to enable at least one of the following:

Simplified global usage checking: select Show unused non-private type members when solution-wide analysis is off on the Editor | Inspection Settings page of JetBrains Rider settings Ctrl+Alt+S.
Solution-wide analysis: select Enable solution-wide analysis on the Editor | Inspection Settings page of JetBrains Rider settings Ctrl+Alt+S.

Note that even if the reported member has no direct usages in your solution, there could be cases where it is used indirectly — for example, via reflection — or it could just be designed as public API. In all those cases, you would want to suppress the usage-checking inspection for the member in one of the following ways:

The recommended way is to decorate the implicitly used member with a code annotation attribute. There are two attributes for this purpose: [UsedImplicitly] and [PublicAPI], which are functionally similar, but let you and your teammates understand how the member is actually used.
You can also suppress usage-checking inspections with any custom attribute. To do so, mark the definition of that attribute with the [MeansImplicitUse] attribute.
And finally, you can suppress a specific usage-checking inspection as any other code inspection with a suppression comment or a suppression attribute.

Last modified: 29 May 2024