V3212. Unity Engine. Pattern matching does not correctly handle destroyed objects derived from 'UnityEngine.Object'.

The analyzer has detected a potential error related to the object derived from UnityEngine.Object. The object was used with pattern matching to check for null.

According to the Unity documentation, it is not recommended to use pattern matching with objects derived from UnityEngine.Object.

The check for null using pattern matching does not consider that objects derived from UnityEngine.Object may be destroyed. Therefore, the check may have an incorrect result.

Look at the example:

class CustomComponent: MonoBehaviour
{
  public bool HitConfirm(....)
  {  
    Projectile bullet;
    ....
    if(....)
      Destroy(bullet);

    if (bullet is not null) 
    {....}
  }
}

In this case, the check of bullet using pattern matching will not consider that the object may be destroyed.

To fix this, use a check with the == or != operator.

The fixed code:

class CustomComponent: MonoBehaviour
{
  public bool HitConfirm(....)
  {  
    Projectile bullet;
    ....
    if(....)
      Destroy(bullet);

    if (bullet != null) 
    {....}
  }
}