Quick fix 'Cast to...' is incorrectly suggested when there is no suitable type to cast to (and the quick fix inserts a cast to a generic paremeter, not argument)
List<IDeclaredElement> elements = new List<IDeclaredElement> ();
CollectionUtil.ConvertLazy(elements, ); // quick fix inserts cast to IEnumerable<TInput>
Description
Try typing :
List<IDeclaredElement> elements = new List<IDeclaredElement> ();
CollectionUtil.ConvertLazy(elements, ); // quick fix inserts cast to IEnumerable<TInput>