JetBrains Rider 2026.1 Help

Code inspection: Replace with OfType<T>().First()

This inspection reports a LINQ query that casts elements with as and then uses First(...) to find the first non-null cast result. The same intent is clearer with OfType<T>().First().

Example

var first = items.Select(x => x as string).First(y => y != null);
var first = items.OfType<string>().First();

Quick-fix

Replace the Select(... as T).First(y => y != null) pattern with OfType<T>().First().

29 March 2026
Code inspection: Replace with OfType<T>().Count() (replace with OfType<T>().Count(..))Code inspection: Replace with OfType<T>().First() (replace with OfType<T>().First(..))