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kotlinlang

Examples in the ticket show a class not a data object?  

when you create a data class, the compiler generates `copy` methods with default arguments. If you then define your own copy method, it won't compile because the method is already defined. It's not reserved, it's just that the method is automatically generated and your own one clashes with it

the ticket refers to the new `data object` construct that doesn’t support `copy` as objects are singletons.

yes, a `data object` is just a singleton so a copy does't make sense.

correct.  so if there is no copy method generated, why does Kotlin prevent providing one named that? (regardless of what that method does or whether its appropriate)

it's interesting that the error is the same as for data classes, but the decompiled bytecode does not have a `copy` method

likely somewhere in the compiler theres something shared between data objects and data classes that gets this wrong.

yea, it shouldn’t be possible for syntactically valid Kotlin to crash the compiler.  bug somewhere.