[Bug] Recursive ADTs fail to Derive

[zarthross]

This simple recursive data structure fails to derive an Encoder:

sealed trait Tree; 
case class Branch(l: Tree, r: Tree) extends Tree; 
case object Leaf extends Tree;

With this error:

Welcome to Scala 3.2.2 (17.0.6, Java OpenJDK 64-Bit Server VM).
Type in expressions for evaluation. Or try :help.
                                                                                
scala> import _root_.io.circe._
                                                                                
scala> sealed trait Tree; case class Branch(l: Tree, r: Tree) extends Tree; case object Leaf extends Tree;;Encoder.AsObject.derived[Tree]
-- Error: ----------------------------------------------------------------------
  1 |sealed trait Tree; case class Branch(l: Tree, r: Tree) extends Tree; case object Leaf extends Tree;;Encoder.AsObject.derived[Tree]
    |                                                                                                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |                   Maximal number of successive inlines (32) exceeded,
    |                   Maybe this is caused by a recursive inline method?
    |                   You can use -Xmax-inlines to change the limit.
    |---------------------------------------------------------------------------
    |Inline stack trace
    |- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    |This location contains code that was inlined from rs$line$2:1
 20 |    case _: Mirror.Of[A]     => ConfiguredEncoder.derived[A]
    |                                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    |This location contains code that was inlined from rs$line$2:1
 15 |    case _: (t *: ts)  => summonEncoder[t] :: summonEncoders[ts]
    |                          ^^^^^^^^^^^^^^^^
    |- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    |This location contains code that was inlined from rs$line$2:1
 32 |      lazy val elemEncoders: List[Encoder[?]] = summonEncoders[mirror.MirroredElemTypes]
    |                                                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    |This location contains code that was inlined from rs$line$2:1
 20 |    case _: Mirror.Of[A]     => ConfiguredEncoder.derived[A]
    |                                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    |This location contains code that was inlined from rs$line$2:1
 15 |    case _: (t *: ts)  => summonEncoder[t] :: summonEncoders[ts]
    |                          ^^^^^^^^^^^^^^^^
    |- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    |This location contains code that was inlined from rs$line$2:1
 32 |      lazy val elemEncoders: List[Encoder[?]] = summonEncoders[mirror.MirroredElemTypes]
    |                                                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    |This location contains code that was inlined from rs$line$2:1
 20 |    case _: Mirror.Of[A]     => ConfiguredEncoder.derived[A]
    |                                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    |This location contains code that was inlined from rs$line$2:1
 15 |    case _: (t *: ts)  => summonEncoder[t] :: summonEncoders[ts]
    |                          ^^^^^^^^^^^^^^^^
    |- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    |This location contains code that was inlined from rs$line$2:1
 32 |      lazy val elemEncoders: List[Encoder[?]] = summonEncoders[mirror.MirroredElemTypes]
    |                                                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
.........

[plokhotnyuk]

A better option would be enabling derivation of codecs for recursive ADTs by configuration, and have it turned off by default for the security reason.

Malicious counterparts can submit too deeply nested JSON that will DoS systems opened to untrusted input by stack overflows.

[Lasering]

If the implementation does not cause stack overflow there is no need to have a configuration for it.