Millised piirangud on Go keeles, et liidest ei saaks olla tühi?

In the Go language, an interface can be declared as empty — this is a special case of an interface that contains no methods and is denoted as interface{}.

An empty interface can hold values of any type, as all types automatically implement it.

Therefore, there are no restrictions on declaring an empty interface in Go — it is a valid and commonly used technique.

If the question is how to make an interface not empty, it is enough to declare at least one method within it:

// Empty interface
var i interface{}

// Interface with a method
type Reader interface {
    Read(p []byte) (n int, err error)
}

Thus, an empty interface is a fundamental building block in Go, and there are no restrictions on its declaration.