rspec/rules/S3875/csharp/rule.adoc

== Why is this an issue?

The use of `==` to compare two objects is expected to do a reference comparison. That is, it is expected to return `true` if and only if they are the same object instance. Overloading the operator to do anything else will inevitably lead to the introduction of bugs by callers. 

[source,csharp]
----
public static bool operator ==(MyType x, MyType y) // Noncompliant: confusing for the caller
{
    // custom implementation
}
----

On the other hand, overloading it to do exactly that is pointless; that's what `==` does by default.

[source,csharp]
----
public static bool operator ==(MyType x, MyType y) // Noncompliant: redundant 
{
    if (x == null)
    {
        return y == null;
    }
    
    return object.ReferenceEquals(x,y);
}
----

=== Exceptions

* Classes with overloaded `operator +` or `operator -` are ignored.
* Classes that implement `IComparable<T>` or `IEquatable<T>` most probably behave as value-type objects and are ignored.

== Resources

=== Documentation

* https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/keywords/reference-types[Reference types]
* https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/operators/equality-operators[Equality operators]

ifdef::env-github,rspecator-view[]

== Implementation Specification
(visible only on this page)

=== Message

Remove this overload of "==".

=== Highlighting

`==`

== Comments And Links
(visible only on this page)

include::../comments-and-links.adoc[]

endif::env-github,rspecator-view[]