Code Inspection: Class is never instantiated (non-private accessibility)
JetBrains Rider determines if no objects of a class were created in a project — in fact, if no direct instances or usages of the class were found. If the class only contains static members (and/or constant fields), JetBrains Rider suggests making the class static. In other cases JetBrains Rider suggests making the class abstract, if possible.
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 page of JetBrains Rider settings Ctrl+Alt+S.
Solution-wide analysis: select Enable solution-wide analysis on the page of JetBrains Rider settings Ctrl+Alt+S.
Note that even if the reported symbol 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 symbol in one of the following ways:
The recommended way is to decorate the implicitly used symbol 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 symbol 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.