fix AbstractMethodError

fix json4s#550 scala/bug#9948
xuwei-k · Jun 26, 2019 · 864d22b · 864d22b
1 parent 97548b7
commit 864d22b
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Showing 2 changed files with 20 additions and 6 deletions.
diff --git a/core/src/main/scala/org/json4s/Formats.scala b/core/src/main/scala/org/json4s/Formats.scala
@@ -271,7 +271,6 @@ trait KeySerializer[A] {
  * </pre>
  */
 trait TypeHints {
-  import ClassDelta._
 
   val hints: List[Class[_]]
 
@@ -295,9 +294,13 @@ trait TypeHints {
   /**
    * Adds the specified type hints to this type hints.
    */
-  def + (hints: TypeHints): TypeHints = CompositeTypeHints(hints.components ::: components)
+  def + (hints: TypeHints): TypeHints = TypeHints.CompositeTypeHints(hints.components ::: components)
 
-  private[TypeHints] case class CompositeTypeHints(override val components: List[TypeHints]) extends TypeHints {
+}
+
+private[json4s] object TypeHints {
+
+  private case class CompositeTypeHints(override val components: List[TypeHints]) extends TypeHints {
     val hints: List[Class[_]] = components.flatMap(_.hints)
 
     /**
@@ -307,15 +310,15 @@ trait TypeHints {
       (components.reverse
         filter (_.containsHint(clazz))
         map (th => (th.hintFor(clazz), th.classFor(th.hintFor(clazz)).getOrElse(sys.error("hintFor/classFor not invertible for " + th))))
-        sortWith ((x, y) => (delta(x._2, clazz) - delta(y._2, clazz)) <= 0)).head._1
+        sortWith((x, y) => (ClassDelta.delta(x._2, clazz) - ClassDelta.delta(y._2, clazz)) <= 0)).head._1
     }
 
     def classFor(hint: String): Option[Class[_]] = {
       def hasClass(h: TypeHints) =
         scala.util.control.Exception.allCatch opt (h.classFor(hint)) map (_.isDefined) getOrElse(false)
 
       components find (hasClass) flatMap (_.classFor(hint))
-  }
+    }
 
     override def deserialize: PartialFunction[(String, JObject), Any] = components.foldLeft[PartialFunction[(String, JObject),Any]](Map()) {
       (result, cur) => result.orElse(cur.deserialize)
@@ -325,6 +328,7 @@ trait TypeHints {
       (result, cur) => result.orElse(cur.serialize)
     }
   }
+
 }
 
 private[json4s] object ClassDelta {

diff --git a/tests/src/test/scala/org/json4s/FormatsSpec.scala b/tests/src/test/scala/org/json4s/FormatsSpec.scala
@@ -28,5 +28,15 @@ class FormatsSpec extends Specification {
     }
   }
 
-
+  // https://github.com/json4s/json4s/issues/550
+  // https://github.com/scala/bug/issues/9948
+  "issue#550 avoid scalac bug" in {
+    val a = new TypeHints {
+      override val hints: List[Class[_]] = List.empty
+      override def hintFor(clazz: Class[_]): String = ""
+      override def classFor(hint: String): Option[Class[_]] = None
+    }
+    a + a
+    success
+  }
 }