json4s & Jackson StackOverflow error when serializing case class with Char field

README.md

Using the model.scala and build.sbt files defined in this gist, perform the following to reproduce a StackOverflowError when serializing a case class instance that has a Char field.

Now start sbt console:

sbt console

and paste the following:

import org.json4s._
import org.json4s.jackson.JsonMethods._
import org.json4s.jackson.Serialization
import org.json4s.{DefaultFormats, Formats}
import org.json4s.jackson.Json
import model.SomeType

val json = Json(DefaultFormats)
json.write(SomeType('a'))

You should now see a stacktrace along the lines of:

java.lang.StackOverflowError
  at scala.reflect.Manifest$class.canEqual(Manifest.scala:52)
  at scala.reflect.ManifestFactory$ClassTypeManifest.canEqual(Manifest.scala:239)
  at scala.reflect.Manifest$class.equals(Manifest.scala:58)
  at scala.reflect.ManifestFactory$ClassTypeManifest.equals(Manifest.scala:239)
  at java.util.concurrent.ConcurrentHashMap.containsKey(ConcurrentHashMap.java:1024)
  at org.json4s.reflect.package$Memo.apply(package.scala:36)
  at org.json4s.reflect.ScalaType$.apply(descriptors.scala:33)
  at org.json4s.reflect.Reflector$.scalaTypeOf(Reflector.scala:33)
  at org.json4s.Extraction$.decomposeObject$1(Extraction.scala:89)
  at org.json4s.Extraction$.internalDecomposeWithBuilder(Extraction.scala:196)
  at org.json4s.Extraction$.addField$1(Extraction.scala:82)
  at org.json4s.Extraction$.decomposeObject$1(Extraction.scala:110)
  at org.json4s.Extraction$.internalDecomposeWithBuilder(Extraction.scala:196)
  at org.json4s.Extraction$.addField$1(Extraction.scala:82)
  at org.json4s.Extraction$.decomposeObject$1(Extraction.scala:110)
  at org.json4s.Extraction$.internalDecomposeWithBuilder(Extraction.scala:196)
  at org.json4s.Extraction$.addField$1(Extraction.scala:82)
  at org.json4s.Extraction$.decomposeObject$1(Extraction.scala:110)

etc

build.sbt

name := """json4s_test"""

version := "1.0"

scalaVersion := "2.11.6"

libraryDependencies ++= Seq(
  "org.json4s" %% "json4s-jackson" % "3.2.11"
)

javacOptions ++= Seq("-source", "1.6", "-target", "1.6")

model.scala

package model

case class SomeType(charField: Char) {}