dotty-cps-async icon indicating copy to clipboard operation
dotty-cps-async copied to clipboard

Published 20 hours ago • verified publisher icon rssh

Macro throws java.lang.AssertionError: assertion failed: unresolved symbols on Scala 3.1.3-RC5

Open andrzejressel opened this issue 2 years ago • 2 comments

Hi,

I've found bug in Scala compiler and/or this macro. I'd love to post it to dotty repo, but unfortunately I cannot minimize it.

Github repo: https://github.com/andrzejressel/scala-3-unresolved-symbols

Example code:

Main.scala

import scala.concurrent.{Future}
import cps.monads.FutureAsyncMonad
import cps.monads.FutureAsyncMonadAPI
import cps.async
import scala.concurrent.ExecutionContext

def hello: Future[?] = {

  given ExecutionContext = ExecutionContext.global

  async {
    val a: Seq[Generic[?]] = null
    a
      .foreach { to =>
        to.mthd()
      }
  }
}

trait Generic[+T] {
  def mthd(): Generic[T] = this
}

Error

[error] ## Exception when compiling 1 sources to XXXXXX\target\scala-3.1.3-RC5\classes
[error] java.lang.AssertionError: assertion failed: unresolved symbols: parameter to (line 13) #16695 when pickling XXXXXX\src\main\scala\Main.scala
[error] scala.runtime.Scala3RunTime$.assertFailed(Scala3RunTime.scala:8)
[error] dotty.tools.dotc.core.tasty.TreePickler.pickle(TreePickler.scala:776)
[error] dotty.tools.dotc.transform.Pickler.run$$anonfun$1$$anonfun$1(Pickler.scala:72)
[error] scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
[error] scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
[error] scala.collection.immutable.List.foreach(List.scala:333)
[error] dotty.tools.dotc.transform.Pickler.run$$anonfun$1(Pickler.scala:109)
[error] scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
[error] scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
[error] scala.collection.immutable.List.foreach(List.scala:333)
[error] dotty.tools.dotc.transform.Pickler.run(Pickler.scala:109)
[error] dotty.tools.dotc.core.Phases$Phase.runOn$$anonfun$1(Phases.scala:311)
[error] scala.collection.immutable.List.map(List.scala:246)
[error] dotty.tools.dotc.core.Phases$Phase.runOn(Phases.scala:312)
[error] dotty.tools.dotc.transform.Pickler.runOn(Pickler.scala:114)
[error] dotty.tools.dotc.Run.runPhases$1$$anonfun$1(Run.scala:225)
[error] scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
[error] scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
[error] scala.collection.ArrayOps$.foreach$extension(ArrayOps.scala:1328)
[error] dotty.tools.dotc.Run.runPhases$1(Run.scala:236)
[error] dotty.tools.dotc.Run.compileUnits$$anonfun$1(Run.scala:244)
[error] dotty.tools.dotc.Run.compileUnits$$anonfun$adapted$1(Run.scala:253)
[error] dotty.tools.dotc.util.Stats$.maybeMonitored(Stats.scala:68)
[error] dotty.tools.dotc.Run.compileUnits(Run.scala:253)
[error] dotty.tools.dotc.Run.compileSources(Run.scala:186)
[error] dotty.tools.dotc.Run.compile(Run.scala:170)
[error] dotty.tools.dotc.Driver.doCompile(Driver.scala:35)
[error] dotty.tools.xsbt.CompilerBridgeDriver.run(CompilerBridgeDriver.java:88)
[error] dotty.tools.xsbt.CompilerBridge.run(CompilerBridge.java:22)
[error] sbt.internal.inc.AnalyzingCompiler.compile(AnalyzingCompiler.scala:91)
[error] sbt.internal.inc.MixedAnalyzingCompiler.$anonfun$compile$7(MixedAnalyzingCompiler.scala:192)
[error] scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:23)
[error] sbt.internal.inc.MixedAnalyzingCompiler.timed(MixedAnalyzingCompiler.scala:247)
[error] sbt.internal.inc.MixedAnalyzingCompiler.$anonfun$compile$4(MixedAnalyzingCompiler.scala:182)
[error] sbt.internal.inc.MixedAnalyzingCompiler.$anonfun$compile$4$adapted(MixedAnalyzingCompiler.scala:163)
[error] sbt.internal.inc.JarUtils$.withPreviousJar(JarUtils.scala:239)
[error] sbt.internal.inc.MixedAnalyzingCompiler.compileScala$1(MixedAnalyzingCompiler.scala:163)
[error] sbt.internal.inc.MixedAnalyzingCompiler.compile(MixedAnalyzingCompiler.scala:210)
[error] sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileInternal$1(IncrementalCompilerImpl.scala:528)
[error] sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileInternal$1$adapted(IncrementalCompilerImpl.scala:528)
[error] sbt.internal.inc.Incremental$.$anonfun$apply$5(Incremental.scala:177)
[error] sbt.internal.inc.Incremental$.$anonfun$apply$5$adapted(Incremental.scala:175)
[error] sbt.internal.inc.Incremental$$anon$2.run(Incremental.scala:461)
[error] sbt.internal.inc.IncrementalCommon$CycleState.next(IncrementalCommon.scala:116)
[error] sbt.internal.inc.IncrementalCommon$$anon$1.next(IncrementalCommon.scala:56)
[error] sbt.internal.inc.IncrementalCommon$$anon$1.next(IncrementalCommon.scala:52)
[error] sbt.internal.inc.IncrementalCommon.cycle(IncrementalCommon.scala:263)
[error] sbt.internal.inc.Incremental$.$anonfun$incrementalCompile$8(Incremental.scala:416)
[error] sbt.internal.inc.Incremental$.withClassfileManager(Incremental.scala:503)
[error] sbt.internal.inc.Incremental$.incrementalCompile(Incremental.scala:403)
[error] sbt.internal.inc.Incremental$.apply(Incremental.scala:169)
[error] sbt.internal.inc.IncrementalCompilerImpl.compileInternal(IncrementalCompilerImpl.scala:528)
[error] sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileIncrementally$1(IncrementalCompilerImpl.scala:482)
[error] sbt.internal.inc.IncrementalCompilerImpl.handleCompilationError(IncrementalCompilerImpl.scala:332)
[error] sbt.internal.inc.IncrementalCompilerImpl.compileIncrementally(IncrementalCompilerImpl.scala:420)
[error] sbt.internal.inc.IncrementalCompilerImpl.compile(IncrementalCompilerImpl.scala:137)
[error] sbt.Defaults$.compileIncrementalTaskImpl(Defaults.scala:2366)
[error] sbt.Defaults$.$anonfun$compileIncrementalTask$2(Defaults.scala:2316)
[error] sbt.internal.server.BspCompileTask$.$anonfun$compute$1(BspCompileTask.scala:30)
[error] sbt.internal.io.Retry$.apply(Retry.scala:46)
[error] sbt.internal.io.Retry$.apply(Retry.scala:28)
[error] sbt.internal.io.Retry$.apply(Retry.scala:23)
[error] sbt.internal.server.BspCompileTask$.compute(BspCompileTask.scala:30)
[error] sbt.Defaults$.$anonfun$compileIncrementalTask$1(Defaults.scala:2314)
[error] scala.Function1.$anonfun$compose$1(Function1.scala:49)
[error] sbt.internal.util.$tilde$greater.$anonfun$$u2219$1(TypeFunctions.scala:62)
[error] sbt.std.Transform$$anon$4.work(Transform.scala:68)
[error] sbt.Execute.$anonfun$submit$2(Execute.scala:282)
[error] sbt.internal.util.ErrorHandling$.wideConvert(ErrorHandling.scala:23)
[error] sbt.Execute.work(Execute.scala:291)
[error] sbt.Execute.$anonfun$submit$1(Execute.scala:282)
[error] sbt.ConcurrentRestrictions$$anon$4.$anonfun$submitValid$1(ConcurrentRestrictions.scala:265)
[error] sbt.CompletionService$$anon$2.call(CompletionService.scala:64)
[error] java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
[error] java.base/java.util.concurrent.Executors$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:1128)
[error] java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
[error] java.base/java.lang.Thread.run(Thread.java:829)
[error]

andrzejressel avatar Jun 13 '22 21:06 andrzejressel

Reproduction without cps:

Two files:

package x

import scala.quoted.*


transparent inline def xtransform[T](inline expr:T) = ${
   X.transform('expr)
}

object X {

   def transform[T:Type](x: Expr[T])(using Quotes):Expr[T] = {
      import quotes.reflect.*
      x
   }

}

and Main.scala:

package x

def hello = {
  //async1[Future] {
  xtransform {
    val a: Seq[Generic[?]] = null
    a
      .foreach { to =>
        to.mthd()
      }
  }
}

trait Generic[+T] {
  def mthd(): Generic[T] = this
}

rssh avatar Jun 19 '22 07:06 rssh

Let's think why -- if we add to the original file

given printCode: cps.macros.flags.PrintCode.type = cps.macros.flags.PrintCode;

we will see:

before transformed: {
  val a: scala.Seq[Generic[_ >: scala.Nothing <: scala.Any]] = null
  a.foreach[Generic[to.T]](((to: Generic[_ >: scala.Nothing <: scala.Any]) => to.mthd()))
}
transformed value: {
  val cpsMonad: cps.monads.FutureAsyncMonadAPI = cps.monads.FutureAsyncMonad(given_ExecutionContext)
  cpsMonad.spawn[scala.Unit](cpsMonad.pure[scala.Unit](({
    val a: scala.Seq[Generic[_ >: scala.Nothing <: scala.Any]] = null
    a.foreach[Generic[to.T]](((to: Generic[_ >: scala.Nothing <: scala.Any]) => to.mthd()))
  }: scala.Unit)))
}

I.e. inferred type parameter for foreach is dependent on the parameter of foreach. And any pickling/unpickling of the code (i.e., any macros) will trigger this bug.

So, this bug is in dotty, and the source is inferring parameter-depended return values. Fill free to submit ;)

Regards!

rssh avatar Jun 19 '22 07:06 rssh