Scala 3: incosistent behavior of Decoder for sealed traits in presence of additional fields. #2368
Description
import io.circe.literal.*
import io.circe.generic.semiauto.deriveDecoder
object TestCirceScala3 extends App {
sealed trait Case
object Case {
case class C1(b: Int) extends Case
case class C2(a: String) extends Case
implicit val decoder: io.circe.Decoder[Case] = deriveDecoder
}
println(json"""{"C2" : {"a" : "", "extraFieldC2": true}}""".as[Case]) // (1)
println(json"""{"C2" : {"a" : "", "extraFieldC2": true}, "extraField" : ""}""".as[Case]) // (2)
println(json"""{"extraField" : "", "C2" : {"a" : "", "extraFieldC2": true}}""".as[Case]) // (3)
}prints
Right(C2())
Right(C2())
Left(DecodingFailure at .extraField: type Case has no class/object/case named 'extraField'.)
In (1) C2 is correctly decoded (extraFieldC2 is ignored).
Same for (2), where the decoding stops before reaching extraField.
In (3) decoding fails.
The only difference between the inputs of (2) and (3) is the ordering of the fields in the Json object.
Expected behavior: (3) should decode as Right(C2()). This is what happens in Scala 2.