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2.13.0: mutable.HashSet.addAll processes parameter twice #11601

miteshaghera opened this issue Jul 2, 2019 · 1 comment


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commented Jul 2, 2019

addAll method of mutable.HashSet will process parameter twice if it's not a mutable.HashSet or immutable.HashSet. It potentially can cause duplicate elements in collection.

Please refer following testing code.

import java.util
import scala.jdk.CollectionConverters._

object HashSet {
  def main(args: Array[String]): Unit = {
    val jhs = new util.HashSet[Obj]()
    jhs.add(new Obj("A"))
    jhs.add(new Obj("B"))
    val shs = => new Obj2(x.f))
    println("java set: " + jhs.size)
    println("scala set: " + shs.size)

class Obj(val f:String) {

class Obj2(val f:String) {

It will not cause a problem if proper hashCode and equals are present in Obj2.


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commented Jul 2, 2019

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