Fix sbt/sbt#3736. Recurse into classloader of the class not the root

[ravwojdyla]

sbt/sbt#3736

[lightbend-cla-validator]

Hi @ravwojdyla,

Thank you for your contribution! We really value the time you've taken to put this together.

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[jvican]

Thanks for the contribution @ravwojdyla ❤️. Could you check if this fixes sbt/sbt#3736? I would like to see some tests here to be 100% sure that this does the right thing.

[jvican]

I’ve gone into the details of this patch and the fix looks good to me, by the way. I’m surprised it hasn’t been caught before.

[dwijnand]

Given ClasspathFilter's purpose is to verify "that all classes loaded through parent either come from root or classpath" (from its scaladoc) I agree changing from traversing the root classloader's parents to the class's classloader's parents looks right.

And I'm equally surprised this wasn't caught before.

Ideally we'd have a test that accurately reproduces the downstream issue, but I'm happy to merge this without.

[ravwojdyla]

Thanks for reviews @dwijnand, @jvican. Sorry, I have made a mistake by referencing wrong sbt issue, this solves only sbt/sbt#3736. I updated the commit message and title of this PR. Regarding sbt/sbt#3515, this change does not solve it.

[jvican]

To me, this is good to go IMO. Further investigation can take care of sbt/sbt#3736 😄.

[ravwojdyla]

@jvican thanks. This patch also fixes sbt/sbt/issues/3647, sbt/sbt/issues/3608 and sbt/sbt/issues/3733

[ravwojdyla]

FYI I have signed the CLA.

[eed3si9n]

@ravwojdyla Hi, thanks for your contribution.

I'm trying to verify this by adding a scripted test locally, and I am unable to confirm using https://github.com/raboof/sbt-run-classloading/blob/master/src/main/scala/Main.scala. Does it run for you?

I am still getting

[error] Caused by: java.lang.ClassNotFoundException: scala.Int
[error] 	at sbt.internal.inc.classpath.ClasspathFilter.loadClass(ClassLoaders.scala:74)
[error] 	at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
[error] 	at java.lang.Class.forName0(Native Method)
[error] 	at java.lang.Class.forName(Class.java:348)
[error] 	at Main$.delayedEndpoint$Main$1(A.scala:7)

[eed3si9n]

Never mind. I think there was some internal discrepancy in scripted due to relative path vs absolute path. Let me send a PR on top of your PR.

[eed3si9n]

ravwojdyla#1

[ravwojdyla]

Thanks @eed3si9n . Merged.

[raboof]

Thanks @ravwojdyla! 🎉

[elliotvilhelm]

Having this issue on sbt: stable 1.2.8 running quickstart https://developer.lightbend.com/guides/akka-quickstart-scala/

System: Mac OSX Mojave 10.14.3 (18D109)

[raboof]

@elliotvilhelm hmm, I can't reproduce that (though I'm running Linux, so that might be a difference)

How exactly did you test this? Did you use the 'Create a project for me' button and then run 'sbt run'? What does the error look like, exactly, for you?