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Code Analyzer for C#

There is a newer version: 10.2.0.105762

Why is this an issue?
In C#, without constraints on a generic type parameter, both reference and value types can be passed. However, comparing
this type parameter to null can be misleading as value types, like struct, can never be null.
How to fix it
To avoid unexpected comparisons:

   if you expect a value type, use default() for comparison 
   if you expect a reference type, add a constraint to prevent value
  types from being passed 

Code examples
Noncompliant code example
bool IsDefault<T>(T value)
{
  if (value == null) // Noncompliant
  {
    // ...
  }
}

Compliant solution
bool IsDefault<T>(T value)
{
  if (EqualityComparer<T>.Default.Equals(value, default(T)))
  {
    // ...
  }
}

or
bool IsDefault<T>(T value) where T : class
{
  if (value == null)
  {
    // ...
  }
}

Resources
Documentation

   Microsoft Learn - Constraints on type parameters
  
   Microsoft Learn - Reference types
  
   Microsoft Learn - Value types 
   Microsoft Learn - default operator