At least one parameter type of this binary operator must be the containing type '<typename>'
A definition of a binary operator specifies both parameters with types other than that of the class or structure in which the operator is defined.
When you define an operator in a class or structure, at least one of the parameters must be of the type of that class or structure.
Error ID: BC33021
To correct this error
Change the type of one or both of the parameters to the type of the class or structure in which the operator is defined.