Addressing 'This async method lacks 'await' operators' warning in overriding method

I have a method in my base class with the following signature.

public virtual async Task<TagBuilder> RenderAsync(int columnWidth)
{
    // ...
}

This works fine, but I have a lot of derived classes that override this method. And some of those overrides do not use await.

This gives me a warning.

Warning CS1998 This async method lacks ‘await’ operators and will run synchronously. Consider using the ‘await’ operator to await non-blocking API calls, or ‘await Task.Run(…)’ to do CPU-bound work on a background thread.

What is the best way to address this warning? First off, I don’t want warnings all over my code. But I need async in the base class. And I want to address this in a sanctioned way that doesn’t introduce any unnecessary overhead.

>Solution :

You can remove async from your derived classes and return a value using Task.FromResult()

Base:

public virtual async Task<TagBuilder> RenderAsync(int columnWidth)
{
    // ...
}

Derived:

public override Task<TagBuilder> RenderAsync(int columnWidth)
{
    TagBuilder tag = GetTag();
    return Task.FromResult(tag);
}