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Code Analyzer for C#

There is a newer version: 10.2.0.105762

Why is this an issue?
In C#, the is
type testing operator can be used to check if the run-time type of an object is compatible with a given type. If the object is not null, then the
is operator performs a cast, and so performing another cast following the check result is redundant.
This can impact:

   Performance: Performing the type check and cast separately can lead to minor performance issues. While this might not be noticeable in small
  applications, it can add up in larger, more complex systems. 
   Readability: The code is less readable and less clean because it requires two lines (and two operations) to achieve something that could be
  done in one. 

How to fix it
Use pattern macthing to perform the check
and retrieve the cast result.
Code examples
Noncompliant code example
if (x is Fruit)  // Noncompliant
{
  var f = (Fruit)x; // or x as Fruit
  // ...
}

Compliant solution
if (x is Fruit fruit)
{
  // ...
}

Resources
Documentation

   Microsoft Learn - Type-testing
  operators and cast expressions - is, as, typeof and casts 
   Microsoft Learn - is operator (C# reference)
  
   Microsoft Learn - Pattern matching
  overview