internal error: type of ClassTag argument T is not fully defined, pos = <550..550>

[scf37]

Compiler version

3.1.2

Minimized code

import scala.reflect.ClassTag

class Test {
  private def test[A](result: A)(implicit ct: ClassTag[A]): Unit = {
  }

  test(1, 2) -> Array(),
}

Output (click arrow to expand)

java.lang.Error: internal error: type of ClassTag argument T is not fully defined, pos = <516..516>
	at dotty.tools.dotc.typer.Inferencing$.fullyDefinedType(Inferencing.scala:57)
	at dotty.tools.dotc.typer.Synthesizer.$init$$$anonfun$1$$anonfun$1(Synthesizer.scala:31)
	at dotty.tools.dotc.typer.Synthesizer.recur$1(Synthesizer.scala:505)
	at dotty.tools.dotc.typer.Synthesizer.tryAll(Synthesizer.scala:510)
	at dotty.tools.dotc.typer.Implicits.inferImplicitArg(Implicits.scala:863)
	at dotty.tools.dotc.typer.Implicits.inferImplicitArg$(Implicits.scala:791)
	at dotty.tools.dotc.typer.Typer.inferImplicitArg(Typer.scala:119)
	at dotty.tools.dotc.typer.Typer.implicitArgs$1(Typer.scala:3428)
	at dotty.tools.dotc.typer.Typer.addImplicitArgs$1(Typer.scala:3464)
	at dotty.tools.dotc.typer.Typer.adaptNoArgsImplicitMethod$1(Typer.scala:3544)
	at dotty.tools.dotc.typer.Typer.adaptNoArgs$1(Typer.scala:3742)
	at dotty.tools.dotc.typer.Typer.adapt1(Typer.scala:3976)
	at dotty.tools.dotc.typer.Typer.adapt(Typer.scala:3306)
	at dotty.tools.dotc.typer.Typer.adapt(Typer.scala:3311)
	at dotty.tools.dotc.typer.Applications$TypedApply.addArg(Applications.scala:738)
	at dotty.tools.dotc.typer.Applications$TypedApply.addArg(Applications.scala:737)
	at dotty.tools.dotc.typer.Applications$Application.addTyped$1(Applications.scala:544)
	at dotty.tools.dotc.typer.Applications$Application.matchArgs(Applications.scala:609)
	at dotty.tools.dotc.typer.Applications$Application.init(Applications.scala:447)
	at dotty.tools.dotc.typer.Applications$TypedApply.<init>(Applications.scala:735)
	at dotty.tools.dotc.typer.Applications$ApplyToTyped.<init>(Applications.scala:862)
	at dotty.tools.dotc.typer.Applications.ApplyTo(Applications.scala:1049)
	at dotty.tools.dotc.typer.Applications.ApplyTo$(Applications.scala:317)
	at dotty.tools.dotc.typer.Typer.ApplyTo(Typer.scala:119)
	at dotty.tools.dotc.typer.Applications.simpleApply$1(Applications.scala:898)
	at dotty.tools.dotc.typer.Applications.tryWithImplicitOnQualifier$1$$anonfun$1$$anonfun$1(Applications.scala:918)
	at dotty.tools.dotc.typer.Typer.tryEither(Typer.scala:3081)
	at dotty.tools.dotc.typer.Applications.tryWithImplicitOnQualifier$1$$anonfun$1(Applications.scala:921)
	at scala.Option.flatMap(Option.scala:283)
	at dotty.tools.dotc.typer.Applications.tryWithImplicitOnQualifier$1(Applications.scala:921)
	at dotty.tools.dotc.typer.Applications.realApply$1$$anonfun$4(Applications.scala:986)
	at dotty.tools.dotc.typer.Typer.tryEither(Typer.scala:3084)
	at dotty.tools.dotc.typer.Applications.realApply$1(Applications.scala:989)
	at dotty.tools.dotc.typer.Applications.typedApply(Applications.scala:1027)
	at dotty.tools.dotc.typer.Applications.typedApply$(Applications.scala:317)
	at dotty.tools.dotc.typer.Typer.typedApply(Typer.scala:119)
	at dotty.tools.dotc.typer.Typer.typedInfixOp(Typer.scala:2695)
	at dotty.tools.dotc.typer.Typer.typedUnnamed$1(Typer.scala:2848)
	at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2872)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2937)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2941)
	at dotty.tools.dotc.typer.Typer.traverse$1(Typer.scala:2990)
	at dotty.tools.dotc.typer.Typer.typedStats(Typer.scala:3013)
	at dotty.tools.dotc.typer.Typer.typedClassDef(Typer.scala:2454)
	at dotty.tools.dotc.typer.Typer.typedTypeOrClassDef$1(Typer.scala:2797)
	at dotty.tools.dotc.typer.Typer.typedNamed$1(Typer.scala:2801)
	at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2871)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2937)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2941)
	at dotty.tools.dotc.typer.Typer.traverse$1(Typer.scala:2963)
	at dotty.tools.dotc.typer.Typer.typedStats(Typer.scala:3013)
	at dotty.tools.dotc.typer.Typer.typedClassDef(Typer.scala:2454)
	at dotty.tools.dotc.typer.Typer.typedTypeOrClassDef$1(Typer.scala:2797)
	at dotty.tools.dotc.typer.Typer.typedNamed$1(Typer.scala:2801)
	at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2871)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2937)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2941)
	at dotty.tools.dotc.typer.Typer.traverse$1(Typer.scala:2963)
	at dotty.tools.dotc.typer.Typer.typedStats(Typer.scala:3013)
	at dotty.tools.dotc.typer.Typer.typedPackageDef(Typer.scala:2581)
	at dotty.tools.dotc.typer.Typer.typedUnnamed$1(Typer.scala:2842)
	at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2872)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2937)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2941)
	at dotty.tools.dotc.typer.Typer.typedExpr(Typer.scala:3057)
	at dotty.tools.dotc.typer.TyperPhase.typeCheck$$anonfun$1(TyperPhase.scala:47)
	at dotty.tools.dotc.core.Phases$Phase.monitor(Phases.scala:411)
	at dotty.tools.dotc.typer.TyperPhase.typeCheck(TyperPhase.scala:54)
	at dotty.tools.dotc.typer.TyperPhase.runOn$$anonfun$3(TyperPhase.scala:88)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
	at scala.collection.immutable.List.foreach(List.scala:333)
	at dotty.tools.dotc.typer.TyperPhase.runOn(TyperPhase.scala:88)
	at dotty.tools.dotc.Run.runPhases$1$$anonfun$1(Run.scala:259)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
	at scala.collection.ArrayOps$.foreach$extension(ArrayOps.scala:1328)
	at dotty.tools.dotc.Run.runPhases$1(Run.scala:270)
	at dotty.tools.dotc.Run.compileUnits$$anonfun$1(Run.scala:278)
	at scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.scala:18)
	at dotty.tools.dotc.util.Stats$.maybeMonitored(Stats.scala:68)
	at dotty.tools.dotc.Run.compileUnits(Run.scala:287)
	at dotty.tools.dotc.Run.compileSources(Run.scala:220)
	at dotty.tools.dotc.Run.compile(Run.scala:204)
	at dotty.tools.dotc.Driver.doCompile(Driver.scala:39)
	at dotty.tools.xsbt.CompilerBridgeDriver.run(CompilerBridgeDriver.java:88)
	at dotty.tools.xsbt.CompilerBridge.run(CompilerBridge.java:22)
	at sbt.internal.inc.AnalyzingCompiler.compile(AnalyzingCompiler.scala:91)
	at sbt.internal.inc.MixedAnalyzingCompiler.$anonfun$compile$7(MixedAnalyzingCompiler.scala:192)
	at scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:23)
	at sbt.internal.inc.MixedAnalyzingCompiler.timed(MixedAnalyzingCompiler.scala:247)
	at sbt.internal.inc.MixedAnalyzingCompiler.$anonfun$compile$4(MixedAnalyzingCompiler.scala:182)
	at sbt.internal.inc.MixedAnalyzingCompiler.$anonfun$compile$4$adapted(MixedAnalyzingCompiler.scala:163)
	at sbt.internal.inc.JarUtils$.withPreviousJar(JarUtils.scala:239)
	at sbt.internal.inc.MixedAnalyzingCompiler.compileScala$1(MixedAnalyzingCompiler.scala:163)
	at sbt.internal.inc.MixedAnalyzingCompiler.compile(MixedAnalyzingCompiler.scala:210)
	at sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileInternal$1(IncrementalCompilerImpl.scala:528)
	at sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileInternal$1$adapted(IncrementalCompilerImpl.scala:528)
	at sbt.internal.inc.Incremental$.$anonfun$apply$5(Incremental.scala:177)
	at sbt.internal.inc.Incremental$.$anonfun$apply$5$adapted(Incremental.scala:175)
	at sbt.internal.inc.Incremental$$anon$2.run(Incremental.scala:461)
	at sbt.internal.inc.IncrementalCommon$CycleState.next(IncrementalCommon.scala:116)
	at sbt.internal.inc.IncrementalCommon$$anon$1.next(IncrementalCommon.scala:56)
	at sbt.internal.inc.IncrementalCommon$$anon$1.next(IncrementalCommon.scala:52)
	at sbt.internal.inc.IncrementalCommon.cycle(IncrementalCommon.scala:263)
	at sbt.internal.inc.Incremental$.$anonfun$incrementalCompile$8(Incremental.scala:416)
	at sbt.internal.inc.Incremental$.withClassfileManager(Incremental.scala:503)
	at sbt.internal.inc.Incremental$.incrementalCompile(Incremental.scala:403)
	at sbt.internal.inc.Incremental$.apply(Incremental.scala:169)
	at sbt.internal.inc.IncrementalCompilerImpl.compileInternal(IncrementalCompilerImpl.scala:528)
	at sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileIncrementally$1(IncrementalCompilerImpl.scala:482)
	at sbt.internal.inc.IncrementalCompilerImpl.handleCompilationError(IncrementalCompilerImpl.scala:332)
	at sbt.internal.inc.IncrementalCompilerImpl.compileIncrementally(IncrementalCompilerImpl.scala:420)
	at sbt.internal.inc.IncrementalCompilerImpl.compile(IncrementalCompilerImpl.scala:137)
	at sbt.Defaults$.compileIncrementalTaskImpl(Defaults.scala:2366)
	at sbt.Defaults$.$anonfun$compileIncrementalTask$2(Defaults.scala:2316)
	at sbt.internal.server.BspCompileTask$.$anonfun$compute$1(BspCompileTask.scala:30)
	at sbt.internal.io.Retry$.apply(Retry.scala:46)
	at sbt.internal.io.Retry$.apply(Retry.scala:28)
	at sbt.internal.io.Retry$.apply(Retry.scala:23)
	at sbt.internal.server.BspCompileTask$.compute(BspCompileTask.scala:30)
	at sbt.Defaults$.$anonfun$compileIncrementalTask$1(Defaults.scala:2314)
	at scala.Function1.$anonfun$compose$1(Function1.scala:49)
	at sbt.internal.util.$tilde$greater.$anonfun$$u2219$1(TypeFunctions.scala:62)
	at sbt.std.Transform$$anon$4.work(Transform.scala:68)
	at sbt.Execute.$anonfun$submit$2(Execute.scala:282)
	at sbt.internal.util.ErrorHandling$.wideConvert(ErrorHandling.scala:23)
	at sbt.Execute.work(Execute.scala:291)
	at sbt.Execute.$anonfun$submit$1(Execute.scala:282)
	at sbt.ConcurrentRestrictions$$anon$4.$anonfun$submitValid$1(ConcurrentRestrictions.scala:265)
	at sbt.CompletionService$$anon$2.call(CompletionService.scala:64)
	at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
	at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515)
	at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1135)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
	at java.base/java.lang.Thread.run(Thread.java:831)

[som-snytt]

Same exception without trailing comma.

➜ ~/projects/dotty/bin/scalac -d /tmp i15372.scala
-- Error: i15372.scala:7:23 --------------------------------------------------------------------------------------------
7 |  test(1, 2) -> Array(),
  |                       ^
  |                       end of statement expected but ',' found
exception occurred while typechecking i15372.scala
exception occurred while compiling i15372.scala
java.lang.Error: internal error: type of ClassTag argument T is not fully defined, pos = <139..139> while compiling i15372.scala
Exception in thread "main" java.lang.Error: internal error: type of ClassTag argument T is not fully defined, pos = <139..139>
        at dotty.tools.dotc.typer.Inferencing$.fullyDefinedType(Inferencing.scala:54)