Scala plugin's scaladoc task broken with Scala 2.13.0

[dubinsky]

Expected Behavior

When gradle scaladoc is run, Scaladoc should be generated.

Current Behavior

When using Scala 2.13.0:

  Execution failed for task ':scaladoc'.
  java.net.MalformedURLException

Context

When publishing to JCenter, I include Scaladoc jar - which is impossible to generate with Scala 2.13.

Steps to Reproduce

In the attached project gradle-scaladoc-bug.zip

  $ gradle scaladoc -PscalaVersion=2.13.0

Reason:
https://github.com/gradle/gradle/blob/master/subprojects/scala/src/main/java/org/gradle/api/internal/tasks/scala/AntScalaDoc.java#L53 assumes presence of scala/tools/ant/antlib.xml, which was removed: scala/scala#6255; see also https://users.scala-lang.org/t/scala-2-13-0-ant-support/4694/11

Your Environment

Build scan URL: https://scans.gradle.com/s/7wmsskmoua3uu

[barrybecker4]

I have encountered the same problem using Scale 13.1 and using either gradle 4.10.2 or 5.6.2.

[ljacomet]

Gradle 6.0 will have improvements, including better support of Scala 2.13.

When 6.0 RC1 is out, could you test again?

[dubinsky]

@ljacomet :

Gradle 6.0 will have improvements, including better support of Scala 2.13.
When 6.0 RC1 is out, could you test again?

I did; it breaks the same way. "Better support for Scala 2.13" is not going to fix this issue; Gradle Scala plugin needs to be reworked to NOT use scala/tools/ant/antlib.xml (removed in Scala 2.13.0) to generate Scaladoc.

[lacasseio]

Scala 2.13 indeed broke everyone by removing the Ant support. We looked into fixing the issue by executing the work directly inside a worker action (https://github.com/gradle/gradle/tree/lacasseio/scala-doc-fix-for-2.13) however we hit an issue with the classloader which makes it impossible to run the action hence doesn't fix the issue.

At the moment, it would be recommended to build https://github.com/cigaly/scala-ant and adding that JAR to the ScalaDoc task's scalaClasspath property. We didn't confirm nor wrote a sample for this workaround, however, it should be the path forward to unblock users immediately.

We will look into the classloader issue with the worker API to see what needs to be fixed so we can move forward with a proper fix to handle 2.13 breakage.

[dubinsky]

We will look into the classloader issue with the worker API to see what needs to be fixed so we can move forward with a proper fix to handle 2.13 breakage.

Thank you!!!

[SimY4]

Just if anyone is interested. Minimal gradle build configuration that worked for me:

configurations {
    scaladocExtras
}

dependencies {
    scaladocExtras 'org.scala-lang:scala-library:2.13.1'
    scaladocExtras 'org.scala-lang:scala-compiler:2.13.1'
    scaladocExtras 'org.scala-lang:scala-reflect:2.13.1'
    scaladocExtras 'org.apache.ant:ant:1.9.14'
}

scaladoc {
    scalaClasspath = configurations.scaladocExtras + files("lib/scala-ant-2.13.1.jar")
}

[barrybecker4]

Just to be clear, it looks like this should be fixed in release 6.2 of Gradle. Please correct me if that is not correct.

[big-guy]

Yep, this is fixed in release and will be in 6.2