Java method with varargs fails with NoType

[DieBauer]

Minimized code

The Java class with two methods (the Java logger class is an excerpt from Slf4j)

public class JavaLogger {
    public void info(String format, Object arg) {}

    public void info(String in, Object... args){}
}

class LogNoType {
  val logger = new JavaLogger
  def log(): Unit = {
      logger.info(
        "My {} String {} with multiple args {}",
        Array("a", "b", "c"): _*
      )
  }
}

Output (click arrow to expand)

This works in scala 2.13, and dotty 0.26.0, in Dotty 0.27.0-RC1 it fails compilation, latest snapshots it crashes.

In dotty 0.27.0-RC1 it fails with

[error] -- [E051] Reference Error: /Users/Jens/Developer/chapter/dotty/chapter/src/main/scala/NoType.scala:9:13 
[error] 9 |      logger.info(
[error]   |      ^^^^^^^^^^^
[error]   |Ambiguous overload. The overloaded alternatives of method info in class JavaLogger with types
[error]   | (in: String, args: Object*): Unit
[error]   | (format: String, arg: Object): Unit
[error]   |both match arguments (("My {} String {} with multiple args {}" : String), String*)
[error] one error found
[error] (Compile / compileIncremental) Compilation failed

in latest snapshots (0.28.0-bin-20200928-09eaed7-NIGHTLY) it crashes the compiler.

[error] ## Exception when compiling 6 sources to /Users/Jens/Developer/chapter/dotty/chapter/target/scala-0.28/classes
[error] java.lang.AssertionError: assertion failed: NoType
[error] dotty.DottyPredef$.assertFail(DottyPredef.scala:17)
[error] dotty.tools.dotc.core.Types$TypeBounds.<init>(Types.scala:4560)
[error] dotty.tools.dotc.core.Types$AliasingBounds.<init>(Types.scala:4624)
[error] dotty.tools.dotc.core.Types$TypeAlias.<init>(Types.scala:4646)
[error] dotty.tools.dotc.core.Types$TypeAlias$.apply(Types.scala:4679)
[error] dotty.tools.dotc.core.Types$Type.bounds(Types.scala:1538)
[error] dotty.tools.dotc.transform.ElimRepeated.$anonfun$1(ElimRepeated.scala:142)
[error] scala.collection.immutable.List.mapConserve(List.scala:472)
[error] dotty.tools.dotc.transform.ElimRepeated.transformApply(ElimRepeated.scala:147)
[error] dotty.tools.dotc.transform.MegaPhase.goApply(MegaPhase.scala:644)
[error] dotty.tools.dotc.transform.MegaPhase.transformUnnamed$1(MegaPhase.scala:281)
[error] dotty.tools.dotc.transform.MegaPhase.transformTree(MegaPhase.scala:429)
[error] dotty.tools.dotc.transform.MegaPhase.transformUnnamed$1(MegaPhase.scala:300)
[error] dotty.tools.dotc.transform.MegaPhase.transformTree(MegaPhase.scala:429)
[error] dotty.tools.dotc.transform.MegaPhase.mapDefDef$1(MegaPhase.scala:249)
[error] dotty.tools.dotc.transform.MegaPhase.transformNamed$1(MegaPhase.scala:252)
[error] dotty.tools.dotc.transform.MegaPhase.transformTree(MegaPhase.scala:427)
[error] dotty.tools.dotc.transform.MegaPhase.transformStat$2(MegaPhase.scala:437)
[error] dotty.tools.dotc.transform.MegaPhase.recur$1(MegaPhase.scala:442)
[error] dotty.tools.dotc.transform.MegaPhase.recur$1(MegaPhase.scala:1061)
[error] dotty.tools.dotc.transform.MegaPhase.transformStats(MegaPhase.scala:442)
[error] dotty.tools.dotc.transform.MegaPhase.transformUnnamed$1(MegaPhase.scala:362)
[error] dotty.tools.dotc.transform.MegaPhase.transformTree(MegaPhase.scala:429)
[error] dotty.tools.dotc.transform.MegaPhase.transformNamed$1(MegaPhase.scala:256)
[error] dotty.tools.dotc.transform.MegaPhase.transformTree(MegaPhase.scala:427)
[error] dotty.tools.dotc.transform.MegaPhase.transformStat$2(MegaPhase.scala:437)
[error] dotty.tools.dotc.transform.MegaPhase.recur$1(MegaPhase.scala:442)
[error] dotty.tools.dotc.transform.MegaPhase.transformStats(MegaPhase.scala:442)
[error] dotty.tools.dotc.transform.MegaPhase.mapPackage$1(MegaPhase.scala:382)
[error] dotty.tools.dotc.transform.MegaPhase.transformUnnamed$1(MegaPhase.scala:385)
[error] dotty.tools.dotc.transform.MegaPhase.transformTree(MegaPhase.scala:429)
[error] dotty.tools.dotc.transform.MegaPhase.transformUnit(MegaPhase.scala:448)
[error] dotty.tools.dotc.transform.MegaPhase.run(MegaPhase.scala:460)
[error] dotty.tools.dotc.core.Phases$Phase.runOn$$anonfun$1(Phases.scala:296)
[error] scala.collection.immutable.List.map(List.scala:250)
[error] dotty.tools.dotc.core.Phases$Phase.runOn(Phases.scala:297)
[error] dotty.tools.dotc.Run.runPhases$4$$anonfun$4(Run.scala:185)
[error] dotty.runtime.function.JProcedure1.apply(JProcedure1.java:15)
[error] dotty.runtime.function.JProcedure1.apply(JProcedure1.java:10)
[error] scala.collection.ArrayOps$.foreach$extension(ArrayOps.scala:1323)
[error] dotty.tools.dotc.Run.runPhases$5(Run.scala:195)
[error] dotty.tools.dotc.Run.compileUnits$$anonfun$1(Run.scala:203)
[error] dotty.runtime.function.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:12)
[error] dotty.tools.dotc.util.Stats$.maybeMonitored(Stats.scala:63)
[error] dotty.tools.dotc.Run.compileUnits(Run.scala:210)
[error] dotty.tools.dotc.Run.compileSources(Run.scala:147)
[error] dotty.tools.dotc.Run.compile(Run.scala:129)
[error] dotty.tools.dotc.Driver.doCompile(Driver.scala:38)
[error] dotty.tools.dotc.Driver.process(Driver.scala:195)
[error] dotty.tools.dotc.Main.process(Main.scala)
[error] xsbt.CachedCompilerImpl.run(CachedCompilerImpl.java:69)
[error] xsbt.CompilerInterface.run(CompilerInterface.java:41)
[error] java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
[error] java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:64)
[error] java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
[error] java.base/java.lang.reflect.Method.invoke(Method.java:564)
[error] sbt.internal.inc.AnalyzingCompiler.call(AnalyzingCompiler.scala:248)
[error] sbt.internal.inc.AnalyzingCompiler.compile(AnalyzingCompiler.scala:122)
[error] sbt.internal.inc.AnalyzingCompiler.compile(AnalyzingCompiler.scala:95)
[error] sbt.internal.inc.MixedAnalyzingCompiler.$anonfun$compile$4(MixedAnalyzingCompiler.scala:91)
[error] scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:23)
[error] sbt.internal.inc.MixedAnalyzingCompiler.timed(MixedAnalyzingCompiler.scala:186)
[error] sbt.internal.inc.MixedAnalyzingCompiler.$anonfun$compile$3(MixedAnalyzingCompiler.scala:82)
[error] sbt.internal.inc.MixedAnalyzingCompiler.$anonfun$compile$3$adapted(MixedAnalyzingCompiler.scala:77)
[error] sbt.internal.inc.JarUtils$.withPreviousJar(JarUtils.scala:215)
[error] sbt.internal.inc.MixedAnalyzingCompiler.compileScala$1(MixedAnalyzingCompiler.scala:77)
[error] sbt.internal.inc.MixedAnalyzingCompiler.compile(MixedAnalyzingCompiler.scala:146)
[error] sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileInternal$1(IncrementalCompilerImpl.scala:343)
[error] sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileInternal$1$adapted(IncrementalCompilerImpl.scala:343)
[error] sbt.internal.inc.Incremental$.doCompile(Incremental.scala:120)
[error] sbt.internal.inc.Incremental$.$anonfun$compile$4(Incremental.scala:100)
[error] sbt.internal.inc.IncrementalCommon.recompileClasses(IncrementalCommon.scala:180)
[error] sbt.internal.inc.IncrementalCommon.cycle(IncrementalCommon.scala:98)
[error] sbt.internal.inc.Incremental$.$anonfun$compile$3(Incremental.scala:102)
[error] sbt.internal.inc.Incremental$.manageClassfiles(Incremental.scala:155)
[error] sbt.internal.inc.Incremental$.compile(Incremental.scala:92)
[error] sbt.internal.inc.IncrementalCompile$.apply(Compile.scala:75)
[error] sbt.internal.inc.IncrementalCompilerImpl.compileInternal(IncrementalCompilerImpl.scala:348)
[error] sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileIncrementally$1(IncrementalCompilerImpl.scala:301)
[error] sbt.internal.inc.IncrementalCompilerImpl.handleCompilationError(IncrementalCompilerImpl.scala:168)
[error] sbt.internal.inc.IncrementalCompilerImpl.compileIncrementally(IncrementalCompilerImpl.scala:248)
[error] sbt.internal.inc.IncrementalCompilerImpl.compile(IncrementalCompilerImpl.scala:74)
[error] sbt.Defaults$.compileIncrementalTaskImpl(Defaults.scala:1765)
[error] sbt.Defaults$.$anonfun$compileIncrementalTask$1(Defaults.scala:1738)
[error] scala.Function1.$anonfun$compose$1(Function1.scala:49)
[error] sbt.internal.util.$tilde$greater.$anonfun$$u2219$1(TypeFunctions.scala:62)
[error] sbt.std.Transform$$anon$4.work(Transform.scala:67)
[error] sbt.Execute.$anonfun$submit$2(Execute.scala:281)
[error] sbt.internal.util.ErrorHandling$.wideConvert(ErrorHandling.scala:19)
[error] sbt.Execute.work(Execute.scala:290)
[error] sbt.Execute.$anonfun$submit$1(Execute.scala:281)
[error] sbt.ConcurrentRestrictions$$anon$4.$anonfun$submitValid$1(ConcurrentRestrictions.scala:178)
[error] sbt.CompletionService$$anon$2.call(CompletionService.scala:37)
[error] java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
[error] java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515)
[error] java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
[error] java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1130)
[error] java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:630)
[error] java.base/java.lang.Thread.run(Thread.java:832)
[error]            
[error] stack trace is suppressed; run last Compile / compileIncremental for the full output
[error] (Compile / compileIncremental) java.lang.AssertionError: assertion failed: NoType
[error] Total time: 0 s, completed 29 Sep 2020, 13:31:30

[TheElectronWill]

May be the same root cause as #9749.