Scala 3 REPL does not appear to be loading resources properly

[kapunga]

I'm unable to properly load resources from the Scala 3 REPL. Reference project/code is here:
https://github.com/kapunga/whats-up-resources/branches

core/src/main/scala/wur/Main.scala

package wur

object Hello:
  def world: String = io.Source.fromResource("hello.txt").getLines.mkString("\n")

@main def run = println(Hello.world)

core/src/main/resources/hello.txt

Hello,
World!

For this project, I can read them just fine when running the project:

kapunga ~/whats-up-resources (master)$ sbt core/run
[info] welcome to sbt 1.6.1 (AdoptOpenJDK Java 1.8.0_282)
 ...
[info] running wur.run
Hello,
World!
[success] Total time: 4 s, completed Jan 17, 2022 12:12:32 AM

However, when I try and load the resources from the repl, they are not found:

kapunga ~/whats-up-resources (master)$ scala3-repl -classpath core/target/scala-3.1.0/core_3-0.1.0-SNAPSHOT.jar
Welcome to Scala 3.1.0 (11.0.10, Java OpenJDK 64-Bit Server VM).
Type in expressions for evaluation. Or try :help.

scala> import wur._

scala> Hello.world
java.io.FileNotFoundException: resource 'hello.txt' was not found in the classpath from the given classloader.
  at scala.io.Source$.fromResource(Source.scala:183)
  at wur.Hello$.world(Main.scala:5)
  ... 34 elided

scala>

The resource file is definitely there:

kapunga ~/whats-up-resources (master)$ jar tf core/target/scala-3.1.0/core_3-0.1.0-SNAPSHOT.jar
META-INF/MANIFEST.MF
wur/
hello.txt
wur/Hello$.class
wur/Hello.class
wur/Hello.tasty
wur/Main$package$.class
wur/Main$package.class
wur/Main$package.tasty
wur/run.class
wur/run.tasty

I've confirmed that this is not an issue with SBT or in Scala 2.13.8, where the resource loads just fine.

[som-snytt]

It works using

io.Source.fromResource("hello.txt", getClass.getClassLoader)

as the default arg is Thread.currentThread().getContextClassLoader()

➜  whats-up-resources git:(master) scala -classpath core/target/scala-3.1.0/core_3-0.1.0-SNAPSHOT.jar
Welcome to Scala 3.1.0 (17.0.1, Java OpenJDK 64-Bit Server VM).
Type in expressions for evaluation. Or try :help.

scala> wur.run
java.io.FileNotFoundException: resource 'hello.txt' was not found in the classpath from the given classloader.
  at scala.io.Source$.fromResource(Source.scala:183)
  at wur.Hello$.world(Main.scala:5)
  at wur.Main$package$.run(Main.scala:7)
  ... 30 elided

scala> Thread.currentThread.getContextClassLoader
val res0: ClassLoader = jdk.internal.loader.ClassLoaders$AppClassLoader@30946e09

scala> getClass.getClassLoader
val res1: ClassLoader = dotty.tools.repl.AbstractFileClassLoader@40bf0e15

scala>

Note that the ScalaClassLoader is on a reducing diet at #14261, where one of the conveniences in Scala 2 was to set and restore the context class loader when running script code.

[kapunga]

Is this something I can set myself as a default? I've trimmed this problem here to the source, but the actual practical repercussions of this problem for me are that I am unable to read configuration files from the SBT console with Typesafe config (and in turn with pure-config).

Edit: Looks like I may be able to work around this in typesafe config.

[som-snytt]

I'm glad there is a workaround for your use case. I don't see a way to automate in Scala 3.

I think it's reasonable for REPL to set context class loader for REPL environment, and I will PR that fix.