Codec.from changes decoder behaviour

[jakubdaniel]

Assuming

val e = io.circe.Encoder.instance[Option[Int]] { _ => ??? } // fake, not used in this example
val d = io.circe.Decoder.decodeOption[Int]
val c = io.circe.Codec.from(d, e)
val h = io.circe.Json.obj().hcursor

is

scala> d.at("x").tryDecode(h)
val res0: io.circe.Decoder.Result[Option[Int]] = Right(None)

scala> c.at("x").tryDecode(h)
val res1: io.circe.Decoder.Result[Option[Int]] = Left(DecodingFailure at .x: Missing required field)

expected?

I'd expect c to behave exactly as d on all inputs to any of the Decoder methods. But it obviously doesn't. This is because it falls back to the default implementations of tryDecode etc instead of properly delegating all the methods to any potential overrides already baked into d.

[zarthross]

Looks to me like the Codec.from method only overrides the 2 abstract methods from Encoder and Decoder, but in reality, we override various other methods from Encoder/Decoder all the time... we need to update that Codec.from implementation (and any other implementations of Codec for that matter) so that it correctly proxies ALL methods to the correct underlying Encoder/Decoder

[satorg]

It seems, this one was resolved via #2131 , wasn't it?