Compiles Error: ClassBType.info not yet assigned

[He-Pin]

When run mill __.compile with Java 21 gets:

java 21.0.5 2024-10-15 LTS
Java(TM) SE Runtime Environment (build 21.0.5+9-LTS-239)
Java HotSpot(TM) 64-Bit Server VM (build 21.0.5+9-LTS-239, mixed mode, sharing)

2 tasks failed
sjsonnet.jvm[2.12.18].compile Compilation failed
sjsonnet.jvm[2.13.12].compile java.lang.AssertionError: assertion failed: ClassBType.info not yet assigned: Ljava/lang/Object;
    scala.tools.nsc.backend.jvm.BTypes$ClassBType.info(BTypes.scala:608)
    scala.tools.nsc.backend.jvm.opt.CallGraph.samTypes(CallGraph.scala:274)
    scala.tools.nsc.backend.jvm.opt.CallGraph.samParamTypes(CallGraph.scala:266)
    scala.tools.nsc.backend.jvm.opt.CallGraph.analyzeCallsite(CallGraph.scala:355)
    scala.tools.nsc.backend.jvm.opt.CallGraph.$anonfun$addMethod$6(CallGraph.scala:176)
    scala.tools.nsc.backend.jvm.opt.CallGraph.$anonfun$addMethod$4(CallGraph.scala:173)
    scala.tools.nsc.backend.jvm.opt.CallGraph.$anonfun$addMethod$1(CallGraph.scala:172)
    scala.tools.nsc.backend.jvm.opt.CallGraph.$anonfun$addMethod$1$adapted(CallGraph.scala:140)
    scala.collection.IterableOnceOps.foreach(IterableOnce.scala:576)
    scala.collection.IterableOnceOps.foreach$(IterableOnce.scala:574)
    scala.collection.AbstractIterator.foreach(Iterator.scala:1300)
    scala.tools.nsc.backend.jvm.opt.CallGraph.addMethod(CallGraph.scala:140)
    scala.tools.nsc.backend.jvm.opt.CallGraph.$anonfun$addClass$1(CallGraph.scala:121)
    scala.tools.nsc.backend.jvm.opt.CallGraph.$anonfun$addClass$1$adapted(CallGraph.scala:121)
    scala.collection.IterableOnceOps.foreach(IterableOnce.scala:576)
    scala.collection.IterableOnceOps.foreach$(IterableOnce.scala:574)
    scala.collection.AbstractIterable.foreach(Iterable.scala:933)
    scala.tools.nsc.backend.jvm.opt.CallGraph.addClass(CallGraph.scala:121)
    scala.tools.nsc.backend.jvm.PostProcessor.$anonfun$runGlobalOptimizations$5(PostProcessor.scala:120)
    scala.tools.nsc.backend.jvm.PostProcessor.$anonfun$runGlobalOptimizations$5$adapted(PostProcessor.scala:118)
    scala.collection.IterableOnceOps.foreach(IterableOnce.scala:576)
    scala.collection.IterableOnceOps.foreach$(IterableOnce.scala:574)
    scala.collection.AbstractIterable.foreach(Iterable.scala:933)
    scala.collection.IterableOps$WithFilter.foreach(Iterable.scala:903)
    scala.tools.nsc.backend.jvm.PostProcessor.$anonfun$runGlobalOptimizations$3(PostProcessor.scala:118)
    scala.tools.nsc.backend.jvm.PostProcessor.$anonfun$runGlobalOptimizations$3$adapted(PostProcessor.scala:118)
    scala.collection.immutable.List.foreach(List.scala:333)
    scala.tools.nsc.backend.jvm.PostProcessor.runGlobalOptimizations(PostProcessor.scala:118)
    scala.tools.nsc.backend.jvm.GeneratedClassHandler$GlobalOptimisingGeneratedClassHandler.complete(GeneratedClassHandler.scala:98)
    scala.tools.nsc.backend.jvm.GenBCode$BCodePhase.$anonfun$run$1(GenBCode.scala:81)
    scala.tools.nsc.backend.jvm.GenBCode$BCodePhase.run(GenBCode.scala:78)
    scala.tools.nsc.Global$Run.compileUnitsInternal(Global.scala:1546)
    scala.tools.nsc.Global$Run.compileUnits(Global.scala:1530)
    scala.tools.nsc.Global$Run.compileSources(Global.scala:1522)
    scala.tools.nsc.Global$Run.compileFiles(Global.scala:1635)
    xsbt.CachedCompiler0.run(CompilerBridge.scala:165)
    xsbt.CachedCompiler0.run(CompilerBridge.scala:134)
    xsbt.CompilerBridge.run(CompilerBridge.scala:39)
    sbt.internal.inc.AnalyzingCompiler.compile(AnalyzingCompiler.scala:91)
    sbt.internal.inc.MixedAnalyzingCompiler.$anonfun$compile$7(MixedAnalyzingCompiler.scala:196)
    scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.scala:18)
    sbt.internal.inc.MixedAnalyzingCompiler.timed(MixedAnalyzingCompiler.scala:252)
    sbt.internal.inc.MixedAnalyzingCompiler.$anonfun$compile$4(MixedAnalyzingCompiler.scala:186)
    sbt.internal.inc.MixedAnalyzingCompiler.$anonfun$compile$4$adapted(MixedAnalyzingCompiler.scala:166)
    sbt.internal.inc.JarUtils$.withPreviousJar(JarUtils.scala:241)
    sbt.internal.inc.MixedAnalyzingCompiler.compileScala$1(MixedAnalyzingCompiler.scala:166)
    sbt.internal.inc.MixedAnalyzingCompiler.compile(MixedAnalyzingCompiler.scala:214)
    sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileInternal$1(IncrementalCompilerImpl.scala:542)
    sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileInternal$1$adapted(IncrementalCompilerImpl.scala:542)
    sbt.internal.inc.Incremental$.$anonfun$apply$3(Incremental.scala:178)
    sbt.internal.inc.Incremental$.$anonfun$apply$3$adapted(Incremental.scala:176)
    sbt.internal.inc.Incremental$$anon$2.run(Incremental.scala:454)
    sbt.internal.inc.IncrementalCommon$CycleState.next(IncrementalCommon.scala:117)
    sbt.internal.inc.IncrementalCommon$$anon$1.next(IncrementalCommon.scala:56)
    sbt.internal.inc.IncrementalCommon$$anon$1.next(IncrementalCommon.scala:52)
    sbt.internal.inc.IncrementalCommon.cycle(IncrementalCommon.scala:265)
    sbt.internal.inc.Incremental$.$anonfun$incrementalCompile$8(Incremental.scala:409)
    sbt.internal.inc.Incremental$.withClassfileManager(Incremental.scala:496)
    sbt.internal.inc.Incremental$.incrementalCompile(Incremental.scala:396)
    sbt.internal.inc.Incremental$.apply(Incremental.scala:204)
    sbt.internal.inc.IncrementalCompilerImpl.compileInternal(IncrementalCompilerImpl.scala:542)
    sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileIncrementally$1(IncrementalCompilerImpl.scala:496)
    sbt.internal.inc.IncrementalCompilerImpl.handleCompilationError(IncrementalCompilerImpl.scala:332)
    sbt.internal.inc.IncrementalCompilerImpl.compileIncrementally(IncrementalCompilerImpl.scala:433)
    sbt.internal.inc.IncrementalCompilerImpl.compile(IncrementalCompilerImpl.scala:137)
    mill.scalalib.worker.ZincWorkerImpl.compileInternal(ZincWorkerImpl.scala:638)
    mill.scalalib.worker.ZincWorkerImpl.$anonfun$compileMixed$1(ZincWorkerImpl.scala:447)
    mill.scalalib.worker.ZincWorkerImpl.$anonfun$withCompilers$2(ZincWorkerImpl.scala:481)
    mill.api.CachedFactory.withValue(CachedFactory.scala:39)
    mill.scalalib.worker.ZincWorkerImpl.withCompilers(ZincWorkerImpl.scala:480)
    mill.scalalib.worker.ZincWorkerImpl.compileMixed(ZincWorkerImpl.scala:446)
    mill.scalalib.ScalaModule.$anonfun$compile$2(ScalaModule.scala:266)
    mill.define.Task$TraverseCtx.evaluate(Task.scala:215)

[JoshRosen]

Based on some searches on scala/bug and scala/scala, I'm guessing that we might need to bump the Scala maintenance release version in order to support compilation on newer JDKs.

[He-Pin]

that's true.

[stephenamar-db]

I do believe we are running the appropriate versions here per https://docs.scala-lang.org/overviews/jdk-compatibility/overview.html

Right now, I think the reasonable objective is to move to JDK17