JetBrains Rider 2026.1 Help

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

This inspection reports a LINQ query that casts elements with as and then counts non-null results with LongCount(...). The same count is more direct with OfType<T>().LongCount().

Example

long count = items.Select(x => x as string).LongCount(y => y != null);
long count = items.OfType<string>().LongCount();

Quick-fix

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

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