== Why is this an issue?

Making a `base` call when overriding a method is generally a good idea, but not in the case of https://learn.microsoft.com/en-us/dotnet/api/system.object.gethashcode[`GetHashCode`] and https://learn.microsoft.com/en-us/dotnet/api/system.object.equals[`Equals`] for classes that directly extend `Object`. These methods are based on the object's reference, meaning that no two objects that use those `base` methods can be equal or have the same hash.

=== Exceptions

This rule doesn't report on guard conditions checking for reference equality.
For example:

[source,csharp]
----

public override bool Equals(object obj)
{
  if (base.Equals(obj)) // Compliant, it's a guard condition.
  {
    return true;
  }
  ...
}

----

== How to fix it

=== Code examples

==== Noncompliant code example

[source,csharp,diff-id=1,diff-type=noncompliant]
----
var m1 = new MyClass(2);
var m2 = new MyClass(2);

m1.Equals(m2) // False
m1.GetHashCode(); // 43942919
m2.GetHashCode(); // 59941935

class MyClass
{
    private readonly int x;
    public MyClass(int x) =>
        this.x = x;

    public override bool Equals(Object obj) =>
        base.Equals();

    public override int GetHashCode() =>
        x.GetHashCode() ^ base.GetHashCode(); // Noncompliant, base.GetHashCode returns a code based on the objects reference
}
----

==== Compliant solution

[source,csharp,diff-id=1,diff-type=compliant]
----
var m1 = new MyClass(2);
var m2 = new MyClass(2);

m1.Equals(m2) // True
m1.GetHashCode(); // 2
m2.GetHashCode(); // 2

class MyClass
{
    private readonly int x;
    public MyClass(int x) =>
        this.x = x;

    public override bool Equals(Object obj) =>
        this.x == ((MyClass)obj).x;

    public override int GetHashCode() =>
        x.GetHashCode()
}
----


== Resources


=== Documentation

* Microsoft Learn - https://learn.microsoft.com/en-us/dotnet/api/system.object.gethashcode?view=net-7.0[Object.GetHashCode Method]
* Microsoft Learn - https://learn.microsoft.com/en-us/dotnet/api/system.object.equals[Object.Equals Method]