Does the equals method have access to fields declared inside a data class?

Yes, the equals method in a Kotlin data class has access to all fields declared within that class, including private ones. When compiling, Kotlin automatically generates an equals implementation that compares all properties declared in the primary constructor of the data class.

For example:

data class User(val id: Int, val name: String)

The generated equals method compares the id and name of two User objects.

Thus, equals considers all properties declared in the data class, regardless of their access modifiers.