What is the default equality comparer for a set type?

Question

In the MSDN API for the HashSet constructor with no arguments it states

Initializes a new instance of the HashSet class that is empty and uses the d

Answer 1

By default, it will delegate to EqualityComparer.Default. This returns a comparer that can compare two objects of type T.

For a custom class, this does a few things in this order:

• if the class implements IEquatable, it will delegate to the class's implementation of this interface
• if the class has an Equals method defined, it will use that
• as a last resort, it will use reference equality