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Code Analyzer for C#

There is a newer version: 10.2.0.105762

Why is this an issue?
A cast is an explicit
conversion, which is a way to tell the compiler the intent to convert from one type to another.
void Method(object value)
{
    int i;
    i = (int)value;   // Casting (explicit conversion) from float to int
}

In most cases, the compiler will be able to catch invalid casts between incompatible value types or reference types.
However, the compiler will not be able to detect invalid casts to interfaces.
What is the potential impact?
Invalid casts will lead to unexpected behaviors or runtime errors such as InvalidCastException.
Exceptions
No issue is reported if the interface has no implementing class in the assembly.
How to fix it
To prevent an InvalidCastException from raising during an explicit conversion, it is recommended to use the as operator.
When the conversion is not possible, the as operator returns null and will never raise an exception.
Code examples
Noncompliant code example
public interface IMyInterface
{ /* ... */ }

public class Implementer : IMyInterface
{ /* ... */ }

public class AnotherClass
{ /* ... */ }

public static class Program
{
  public static void Main()
  {
    var another = new AnotherClass();
    var x = (IMyInterface)another;     // Noncompliant: InvalidCastException is being thrown
  }
}

Compliant solution
public interface IMyInterface
{ /* ... */ }

public class Implementer : IMyInterface
{ /* ... */ }

public class AnotherClass
{ /* ... */ }

public static class Program
{
  public static void Main()
  {
    var another = new AnotherClass();
    var x = another as IMyInterface;    // Compliant: but will always be null
  }
}

Resources
Documentation

   Casting and
  type conversions - Explicit conversion 
   Type-testing operators and cast
  expressions
    
       is
      operator 
       as
      operator 
    
  
   Conversions -
  Explicit conversions in C#
    
       Conversions - Explicit reference conversions in C# 
    
  
   CWE - CWE-588 - Attempt to Access Child of a Non-structure Pointer 
   CWE - CWE-704 - Incorrect Type Conversion or Cast