Gatling compatibility issue with Scala 2.13.0 in IntelliJ

Question

Problem

I'm extending an existing performance test project, which is a Scala project that uses Gatling for simulations and Maven as a build tool. I need Scalaj as a new depenency. I changed Scala version from 2.12.8 to 2.13.0 so that I could use the most recent version of Scalaj (2.4.2) and this resulted in a compile error from a class that uses the / operator from io.gatling.commons.util.PathHelper.

Some things I tried

I only get this error if I run the project using IntelliJ config but not if I run mvn package and mvn gatling:test. I also don't get the error if I go with the IntelliJ config and Scala 2.12.8.

I thought this could be a compatibility issue and checked the Gatling documentation & release notes but the last thing they mentioned concerning Scala compatibility was that from 2.3 on Gatling requires Scala 2.12. I suppose it means 2.12 or higher. Am I wrong at this point?

I also checked if there's an update to the IntelliJ Scala plugin but found nothing.

Code for reproducing the problem

Here's the relevant part of my pom.xml file:

    <dependencies>
        <dependency>
            <groupId>io.gatling.highcharts</groupId>
            <artifactId>gatling-charts-highcharts</artifactId>
            <version>3.0.2</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.scala-lang</groupId>
            <artifactId>scala-library</artifactId>
            <version>2.13.0</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.scalaj/scalaj-http -->
        <dependency>
            <groupId>org.scalaj</groupId>
            <artifactId>scalaj-http_2.13</artifactId>
            <version>2.4.2</version>
        </dependency>
    </dependencies>

The class that doesn't compile (where / is a function from the imported class):

package com.example.mypackage
import io.gatling.commons.util.PathHelper._


object PathHelper {
  val projectRootDir: Path = "root_directory"
  val mavenSourcesDirectory: Path = projectRootDir / "src"
}

An example entry point:

package com.example.mypackage

object ApplicationRunner {

  def main(args: Array[String]): Unit = {
    println(mavenSourcesDirectory.toString)
  }

}

My result

The error message I get after I hit IntelliJ's Run button (I changed some irrelevant project-specific info to comments between <>'s):

Error:scalac: Error: assertion failed: 
  no extension method found for:
  method /:(pathString: String)java.nio.file.Path
 Candidates:

 Candidates (signatures normalized):
 " 
     while compiling: /home/me/example-repo/src/test/scala/com/example/mypackage/PathHelper.scala
        during phase: globalPhase=erasure, enteringPhase=refchecks
     library version: version 2.13.0
    compiler version: version 2.13.0
  reconstructed args: -classpath <.jar path for every dependency I use>
  last tree to typer: Select(Apply(method to), foreach$mVc$sp)
       tree position: <some line in an entirely different class where I don't use PathHelper>
            tree tpe: (f: Int => Unit)Unit
              symbol: (final override) method foreach$mVc$sp in class Range
   symbol definition: final override def foreach$mVc$sp(f: Int => Unit): Unit (a MethodSymbol)
      symbol package: scala.collection.immutable
       symbol owners: method foreach$mVc$sp -> class Range
           call site: object PathHelper in package mypackage in package mypackage
== Source file context for tree position ==
  12    <line from file>
  13    <line from file>
  14    <tree position>
  15    <line from file>
    at scala.reflect.internal.SymbolTable.throwAssertionError(SymbolTable.scala:170)
    at scala.tools.nsc.transform.ExtensionMethods.$anonfun$extensionMethod$1(ExtensionMethods.scala:54)
    at scala.tools.nsc.transform.ExtensionMethods.extensionMethod(ExtensionMethods.scala:49)
    at scala.tools.nsc.transform.Erasure$ErasureTransformer$$anon$4.preEraseNormalApply(Erasure.scala:1102)
    at scala.tools.nsc.transform.Erasure$ErasureTransformer$$anon$4.preEraseApply(Erasure.scala:1204)
    at scala.tools.nsc.transform.Erasure$ErasureTransformer$$anon$4.preErase(Erasure.scala:1214)
    at scala.tools.nsc.transform.Erasure$ErasureTransformer$$anon$4.transform(Erasure.scala:1333)
    at scala.tools.nsc.transform.Erasure$ErasureTransformer$$anon$4.transform(Erasure.scala:993)
    at scala.reflect.internal.Trees$ValDef.$anonfun$transform$4(Trees.scala:405)
    at scala.reflect.api.Trees$Transformer.atOwner(Trees.scala:2625)
    <and so on for 78 more lines of stack trace>

Notes

After all, it looks like an IntelliJ dependency handling issue to me. I already found two workarounds so this problem isn't killing me but it's inconvenient and I'm interested in learning about fixing it. Also, I'm fairly new to Scala so there's a good chance I'm missing something.

Any insight would be appreciated.

Answer 1

Haven't tried it myself but it seems Gatling is not yet compatible with Scala 2.13:

https://github.com/gatling/gatling/issues/3566

It might be easiest to go back to 2.12.