methodCodeHashSignatures throw a os.ResourceNotFoundException

[lefou]

Just before the build failure, I deleted the tests object from a Scala source file under mill-build/src (see below). I did not change the Mill version.

> mill --version
Mill Build Tool version 0.12.1-7-d8bbe5
Java version: 21.0.4, vendor: Eclipse Adoptium, runtime: /opt/openjdk-bin-21.0.4_p7
Default locale: de_DE, platform encoding: UTF-8
OS name: "Linux", version: 6.1.90-gentoo-x86_64, arch: amd64

This is probably related to

• Be more resilient when reading previous code hash signatures #3849

Here's the stack trace:

1 tasks failed
methodCodeHashSignatures os.ResourceNotFoundException: java.net.URLClassLoader@1450ee23/comfisbuild/BuildTemplate$tests$.class
    os.ResourcePath.getInputStream(ResourcePath.scala:21)
    os.read$inputStream$.apply(ReadWriteOps.scala:245)
    mill.codesig.ExternalSummary$.load0$1(ExternalSummary.scala:55)
    mill.codesig.ExternalSummary$.$anonfun$apply$6(ExternalSummary.scala:48)
    scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.scala:18)
    scala.collection.mutable.HashMap.getOrElse(HashMap.scala:451)
    mill.codesig.ExternalSummary$.load$1(ExternalSummary.scala:48)
    mill.codesig.ExternalSummary$.$anonfun$apply$9(ExternalSummary.scala:69)
    mill.codesig.ExternalSummary$.$anonfun$apply$9$adapted(ExternalSummary.scala:69)
    scala.collection.immutable.BitmapIndexedSetNode.foreach(HashSet.scala:951)
    scala.collection.immutable.HashSet.foreach(HashSet.scala:958)
    mill.codesig.ExternalSummary$.apply(ExternalSummary.scala:69)
    mill.codesig.CodeSig$.compute(CodeSig.scala:17)
    mill.runner.MillBuildRootModule.$anonfun$methodCodeHashSignatures$2(MillBuildRootModule.scala:173)
    mill.define.Task$TraverseCtx.evaluate(Task.scala:215)

This project has a meta-build which defines some traits to be used in the build.sc.

Here is a sketch of the relevant parts of the project:

// file: build.sc
package build

object `package` extends RootModule with comfisbuild.BuildTemplate 

// file: mill-build/src/BuildTemplate.scala
package comfisbuild

trait BuildTemplate extends Module {

  // this one I deleted just before the os.ResourcesNotFoundException
  object tests extends TaskModule {
    override def defaultCommandName(): String = "tests"
    /** Prints a test summary for each passed test task. */
    def tests(@mainargs.arg(positional = true) testTasks: mill.main.Tasks[(String, Seq[TestResult])]): Command[Unit] = T.command {
      val res = T.sequence(testTasks.value)()
      T.log.outputStream.println(ComfisUtil.formatTestSummary(res))
    }
  }
}

[lihaoyi]

@lefou did you manage to zip up the classfiles in out/mill-build/compile.dest/ to look at? So we can see which class is still referencing BuildTemplate$tests$.class and causing Mill to try and load it