Compiler crash when using macro annotation with local class: "asTerm called on not-a-Term val <none>"

[tschuchortdev]

Compiler crashes when running a macro annotation on a local class. The same macro annotation works correctly with top-level classes.

Compiler version

3.6.2

Minimized code

import scala.annotation.{MacroAnnotation, experimental}
import scala.quoted.{Expr, Quotes, Type}

@experimental
class backedByLazyVal extends MacroAnnotation {

  override def transform(using q: Quotes)(definition: q.reflect.Definition,
                                          companion: Option[q.reflect.Definition]): List[q.reflect.Definition] = {
    import q.reflect.{*, given}

    val defdef: DefDef = definition.asInstanceOf[DefDef]
     
    val lazyValSym =
      Symbol.newVal(parent = Symbol.spliceOwner,
                    Symbol.freshName(defdef.name + "_lazyval"),
                    defdef.returnTpt.tpe,
                    Flags.Lazy | Flags.Private,
                    privateWithin = Symbol.noSymbol)

    val lazyValDef = ValDef(lazyValSym, rhs = defdef.rhs.map(_.changeOwner(lazyValSym)))

    val redirectedDefDef =
      DefDef.copy(defdef)(
        name = defdef.name,
        paramss = defdef.paramss,
        tpt = defdef.tpt,
        rhs = Some(
          // This seems to be the problem
          Ref(lazyValSym).changeOwner(defdef.symbol))
      )

    List(lazyValDef, redirectedDefDef)
  }
}

This test works:

import org.scalatest.flatspec.AnyFlatSpec
import org.scalatest.matchers.should.Matchers

var executedCount = 0

class MacroTestClass {
  @backedByLazyVal
  def foo: Int = {
    println("executed")
    executedCount += 1
    1234
  }
}

class LazyValMacroTest extends AnyFlatSpec with Matchers {
  "LazyValMacro" should "run body only once" in {
    val c = new MacroTestClass

    assert(c.foo == 1234)
    assert(executedCount == 1)
    assert(c.foo == 1234)
    assert(executedCount == 1)
  }
}

This test crashes the compiler:

import org.scalatest.flatspec.AnyFlatSpec
import org.scalatest.matchers.should.Matchers

class LazyValMacroTest extends AnyFlatSpec with Matchers {
  "LazyValMacro" should "run body only once" in {
    var executedCount = 0
    class MacroTestClass {
      @backedByLazyVal
      def foo: Int = {
        println("executed")
        executedCount += 1
        1234
      }
    }

    val c = new MacroTestClass

    assert(c.foo == 1234)
    assert(executedCount == 1)
    assert(c.foo == 1234)
    assert(executedCount == 1)
  }
}

Output

[error] java.lang.AssertionError: assertion failed: asTerm called on not-a-Term val <none>
[error] scala.runtime.Scala3RunTime$.assertFailed(Scala3RunTime.scala:8)
[error] dotty.tools.dotc.core.Symbols$Symbol.asTerm(Symbols.scala:186)
[error] dotty.tools.dotc.transform.ParamForwarding.transformIfParamAlias(ParamForwarding.scala:43)
[error] dotty.tools.dotc.transform.ParamForwarding.transformValDef(ParamForwarding.scala:66)
[error] dotty.tools.dotc.transform.MegaPhase.goValDef(MegaPhase.scala:1026)
[error] dotty.tools.dotc.transform.MegaPhase.goValDef(MegaPhase.scala:1027)
[error] dotty.tools.dotc.transform.MegaPhase.goValDef(MegaPhase.scala:1027)
[error] dotty.tools.dotc.transform.MegaPhase.goValDef(MegaPhase.scala:1027)
[error] dotty.tools.dotc.transform.MegaPhase.transformNamed$1(MegaPhase.scala:257)
[error] dotty.tools.dotc.transform.MegaPhase.transformTree(MegaPhase.scala:452)
[error] dotty.tools.dotc.transform.MegaPhase.loop$1(MegaPhase.scala:465)
[error] dotty.tools.dotc.transform.MegaPhase.transformStats(MegaPhase.scala:465)
[error] dotty.tools.dotc.transform.MegaPhase.transformUnnamed$1(MegaPhase.scala:376)
[error] dotty.tools.dotc.transform.MegaPhase.transformTree(MegaPhase.scala:454)
[error] dotty.tools.dotc.transform.MegaPhase.transformNamed$1(MegaPhase.scala:272)
[error] dotty.tools.dotc.transform.MegaPhase.transformTree(MegaPhase.scala:452)
[error] dotty.tools.dotc.transform.MegaPhase.loop$2(MegaPhase.scala:471)
[error] dotty.tools.dotc.transform.MegaPhase.transformBlock(MegaPhase.scala:476)
[error] dotty.tools.dotc.transform.MegaPhase.transformUnnamed$1(MegaPhase.scala:315)
[error] dotty.tools.dotc.transform.MegaPhase.transformTree(MegaPhase.scala:454)
[error] dotty.tools.dotc.transform.MegaPhase.mapDefDef$1(MegaPhase.scala:265)
[error] dotty.tools.dotc.transform.MegaPhase.transformNamed$1(MegaPhase.scala:268)
[error] dotty.tools.dotc.transform.MegaPhase.transformTree(MegaPhase.scala:452)
[error] dotty.tools.dotc.transform.MegaPhase.loop$3(MegaPhase.scala:486)
[error] dotty.tools.dotc.transform.MegaPhase.transformTrees(MegaPhase.scala:486)
[error] dotty.tools.dotc.transform.MegaPhase.transformSpecificTrees(MegaPhase.scala:489)
[error] dotty.tools.dotc.transform.MegaPhase.transformUnnamed$1(MegaPhase.scala:410)
[error] dotty.tools.dotc.transform.MegaPhase.transformTree(MegaPhase.scala:454)
[error] dotty.tools.dotc.transform.MegaPhase.loop$1(MegaPhase.scala:465)
[error] dotty.tools.dotc.transform.MegaPhase.transformStats(MegaPhase.scala:465)
[error] dotty.tools.dotc.transform.MegaPhase.transformUnnamed$1(MegaPhase.scala:376)
[error] dotty.tools.dotc.transform.MegaPhase.transformTree(MegaPhase.scala:454)
[error] dotty.tools.dotc.transform.MegaPhase.transformNamed$1(MegaPhase.scala:272)
[error] dotty.tools.dotc.transform.MegaPhase.transformTree(MegaPhase.scala:452)
[error] dotty.tools.dotc.transform.MegaPhase.loop$1(MegaPhase.scala:465)
[error] dotty.tools.dotc.transform.MegaPhase.transformStats(MegaPhase.scala:465)
[error] dotty.tools.dotc.transform.MegaPhase.mapPackage$1(MegaPhase.scala:396)
[error] dotty.tools.dotc.transform.MegaPhase.transformUnnamed$1(MegaPhase.scala:399)
[error] dotty.tools.dotc.transform.MegaPhase.transformTree(MegaPhase.scala:454)
[error] dotty.tools.dotc.transform.MegaPhase.transformUnit(MegaPhase.scala:481)
[error] dotty.tools.dotc.transform.MegaPhase.run(MegaPhase.scala:493)
[error] dotty.tools.dotc.core.Phases$Phase.runOn$$anonfun$1(Phases.scala:380)
[error] scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
[error] scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
[error] scala.collection.immutable.List.foreach(List.scala:334)
[error] dotty.tools.dotc.core.Phases$Phase.runOn(Phases.scala:373)
[error] dotty.tools.dotc.Run.runPhases$1$$anonfun$1(Run.scala:343)
[error] scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
[error] scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
[error] scala.collection.ArrayOps$.foreach$extension(ArrayOps.scala:1323)
[error] dotty.tools.dotc.Run.runPhases$1(Run.scala:336)
[error] dotty.tools.dotc.Run.compileUnits$$anonfun$1(Run.scala:384)
[error] dotty.tools.dotc.Run.compileUnits$$anonfun$adapted$1(Run.scala:396)
[error] dotty.tools.dotc.util.Stats$.maybeMonitored(Stats.scala:69)
[error] dotty.tools.dotc.Run.compileUnits(Run.scala:396)
[error] dotty.tools.dotc.Run.compileSources(Run.scala:282)
[error] dotty.tools.dotc.Run.compile(Run.scala:267)
[error] dotty.tools.dotc.Driver.doCompile(Driver.scala:37)
[error] dotty.tools.xsbt.CompilerBridgeDriver.run(CompilerBridgeDriver.java:141)
[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$7(MixedAnalyzingCompiler.scala:196)
[error] scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:23)
[error] sbt.internal.inc.MixedAnalyzingCompiler.timed(MixedAnalyzingCompiler.scala:252)
[error] sbt.internal.inc.MixedAnalyzingCompiler.$anonfun$compile$4(MixedAnalyzingCompiler.scala:186)
[error] sbt.internal.inc.MixedAnalyzingCompiler.$anonfun$compile$4$adapted(MixedAnalyzingCompiler.scala:166)
[error] sbt.internal.inc.JarUtils$.withPreviousJar(JarUtils.scala:241)
[error] sbt.internal.inc.MixedAnalyzingCompiler.compileScala$1(MixedAnalyzingCompiler.scala:166)
[error] sbt.internal.inc.MixedAnalyzingCompiler.compile(MixedAnalyzingCompiler.scala:204)
[error] sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileInternal$1(IncrementalCompilerImpl.scala:542)
[error] sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileInternal$1$adapted(IncrementalCompilerImpl.scala:542)
[error] sbt.internal.inc.Incremental$.$anonfun$apply$3(Incremental.scala:178)
[error] sbt.internal.inc.Incremental$.$anonfun$apply$3$adapted(Incremental.scala:176)
[error] sbt.internal.inc.Incremental$$anon$2.run(Incremental.scala:454)
[error] sbt.internal.inc.IncrementalCommon$CycleState.next(IncrementalCommon.scala:117)
[error] sbt.internal.inc.IncrementalCommon$$anon$1.next(IncrementalCommon.scala:56)
[error] sbt.internal.inc.IncrementalCommon$$anon$1.next(IncrementalCommon.scala:52)
[error] sbt.internal.inc.IncrementalCommon.cycle(IncrementalCommon.scala:265)
[error] sbt.internal.inc.Incremental$.$anonfun$incrementalCompile$8(Incremental.scala:409)
[error] sbt.internal.inc.Incremental$.withClassfileManager(Incremental.scala:496)
[error] sbt.internal.inc.Incremental$.incrementalCompile(Incremental.scala:396)
[error] sbt.internal.inc.Incremental$.apply(Incremental.scala:204)
[error] sbt.internal.inc.IncrementalCompilerImpl.compileInternal(IncrementalCompilerImpl.scala:542)
[error] sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileIncrementally$1(IncrementalCompilerImpl.scala:496)
[error] sbt.internal.inc.IncrementalCompilerImpl.handleCompilationError(IncrementalCompilerImpl.scala:332)
[error] sbt.internal.inc.IncrementalCompilerImpl.compileIncrementally(IncrementalCompilerImpl.scala:433)
[error] sbt.internal.inc.IncrementalCompilerImpl.compile(IncrementalCompilerImpl.scala:137)
[error] sbt.Defaults$.compileIncrementalTaskImpl(Defaults.scala:2419)
[error] sbt.Defaults$.$anonfun$compileIncrementalTask$2(Defaults.scala:2369)
[error] sbt.internal.server.BspCompileTask$.$anonfun$compute$1(BspCompileTask.scala:41)
[error] sbt.internal.io.Retry$.apply(Retry.scala:47)
[error] sbt.internal.io.Retry$.apply(Retry.scala:29)
[error] sbt.internal.io.Retry$.apply(Retry.scala:24)
[error] sbt.internal.server.BspCompileTask$.compute(BspCompileTask.scala:41)
[error] sbt.Defaults$.$anonfun$compileIncrementalTask$1(Defaults.scala:2367)
[error] scala.Function1.$anonfun$compose$1(Function1.scala:49)
[error] sbt.internal.util.$tilde$greater.$anonfun$$u2219$1(TypeFunctions.scala:63)
[error] sbt.std.Transform$$anon$4.work(Transform.scala:69)
[error] sbt.Execute.$anonfun$submit$2(Execute.scala:283)
[error] sbt.internal.util.ErrorHandling$.wideConvert(ErrorHandling.scala:24)
[error] sbt.Execute.work(Execute.scala:292)
[error] sbt.Execute.$anonfun$submit$1(Execute.scala:283)
[error] sbt.ConcurrentRestrictions$$anon$4.$anonfun$submitValid$1(ConcurrentRestrictions.scala:265)
[error] sbt.CompletionService$$anon$2.call(CompletionService.scala:65)
[error] java.base/java.util.concurrent.FutureTask.run(FutureTask.java:317)
[error] java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:572)
[error] java.base/java.util.concurrent.FutureTask.run(FutureTask.java:317)
[error] java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1144)
[error] java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:642)

Expectation

Macro annotation should work correctly even for local classes.

[Gedochao]

[error] ./Macro.scala:13:38
[error] Not found: defdef - did you mean DefDef?
[error]                     Symbol.freshName(defdef.name + "_lazyval"),
[error]                                      ^^^^^^
[error] ./Macro.scala:14:21
[error] Not found: defdef - did you mean DefDef?
[error]                     defdef.returnTpt.tpe,
[error]                     ^^^^^^
[error] ./Macro.scala:18:47
[error] Not found: defdef - did you mean DefDef?
[error]     val lazyValDef = ValDef(lazyValSym, rhs = defdef.rhs.map(_.changeOwner(lazyValSym)))
[error]                                               ^^^^^^
[error] ./Macro.scala:21:19
[error] Not found: defdef - did you mean DefDef?
[error]       DefDef.copy(defdef)(
[error]                   ^^^^^^
[error] ./Macro.scala:22:16
[error] Not found: defdef - did you mean DefDef?
[error]         name = defdef.name,
[error]                ^^^^^^
[error] ./Macro.scala:23:19
[error] Not found: defdef - did you mean DefDef?
[error]         paramss = defdef.paramss,
[error]                   ^^^^^^
[error] ./Macro.scala:24:15
[error] Not found: defdef - did you mean DefDef?
[error]         tpt = defdef.tpt,
[error]               ^^^^^^
[error] ./Macro.scala:27:39
[error] Not found: defdef - did you mean DefDef?
[error]           Ref(lazyValSym).changeOwner(defdef.symbol))
[error]                                       ^^^^^^

@tschuchortdev are we missing a piece of the code? I think defdef hasn't been defined anywhere.

[tschuchortdev]

Oops, you are right. I removed some error handling code which also assigned this variable. I have updated the code sample.

[Gedochao]

Ah ok.
I managed to reproduce it now. 👍

Scala CLI directives necessary to reproduce:

//> using test.dep org.scalatest::scalatest:3.2.19
//> using options -experimental

no need to run the tests, just compile them with --test:

scala-cli compile --test .