`Symbol.asQuotes` not working for quote that creates a context function

[pweisenburger]

Compiler version

3.3.1-RC1-bin-20230216-2507577-NIGHTLY

Minimized code

Consider the following macro definition, which replaces the context function body of a def with another context function:

import scala.quoted.*

inline def test(inline v: Unit) = ${ testImpl('v) }

def testImpl(using Quotes)(v: Expr[Unit]) =
  import quotes.reflect.*

  val block @ Block(List(defdef @ DefDef(name, paramss, tpt, Some(Lambda(_, body)))), expr) = v.asTerm.underlyingArgument: @unchecked

  val rhs =
    given Quotes = defdef.symbol.asQuotes
    '{ (_: String) ?=> ??? }.asTerm

  Block.copy(block)(List(DefDef.copy(defdef)(name, paramss, tpt, Some(rhs))), expr).asExprOf[Unit]

Macro call site:

def method: Unit = test {
  def innerMethod = { (_: String) ?=> ??? }
}

Output

The compiler crashes.

Compiler Error and Stack Trace

[info] compiling 4 Scala sources
exception while typing @ContextResultCount(1) def innerMethod: (String) ?=> Nothing =
  {
    def $anonfun(using _$1: String): Nothing = ???
    closure($anonfun)
  } of class class dotty.tools.dotc.ast.Trees$DefDef # -1
exception while typing {
  @ContextResultCount(1) def innerMethod: (String) ?=> Nothing =
    {
      def $anonfun(using _$1: String): Nothing = ???
      closure($anonfun)
    }
  ()
} of class class dotty.tools.dotc.ast.Trees$Block # -1
exception while typing {
  @ContextResultCount(1) def innerMethod: ((String) ?=> Nothing) =
    {
      def $anonfun(using _$1: String): Nothing = ???
      closure($anonfun)
    }
  ()
}:Unit of class class dotty.tools.dotc.ast.Trees$Typed # -1
exception while typing {
  @ContextResultCount(1) def innerMethod: ((String) ?=> Nothing) =
    {
      def $anonfun(using _$1: String): Nothing = ???
      closure($anonfun)
    }
  ()
}:Unit of class class dotty.tools.dotc.ast.Trees$Inlined # -1
exception while typing def method: Unit =
  {
    @ContextResultCount(1) def innerMethod: ((String) ?=> Nothing) =
      {
        def $anonfun(using _$1: String): Nothing = ???
        closure($anonfun)
      }
    ()
  }:Unit of class class dotty.tools.dotc.ast.Trees$DefDef # -1
exception while typing @SourceFile("src/main/scala/Test.scala") final module class Test$package()
   extends Object() {
  private def writeReplace(): AnyRef =
    new scala.runtime.ModuleSerializationProxy(classOf[Test$package.type])
  def method: Unit =
    {
      @ContextResultCount(1) def innerMethod: ((String) ?=> Nothing) =
        {
          def $anonfun(using _$1: String): Nothing = ???
          closure($anonfun)
        }
      ()
    }:Unit
} of class class dotty.tools.dotc.ast.Trees$TypeDef # -1
exception while typing [cannot display due to ImportType(Select(Ident(scala),quoted)) (of class dotty.tools.dotc.core.Types$ImportType), raw string = PackageDef(Ident(<empty>),List(Import(Select(Ident(scala),quoted),List(ImportSelector(Ident(_),EmptyTree,EmptyTree))), ValDef(Test$package,TypeTree[TypeRef(ThisType(TypeRef(NoPrefix,module class <empty>)),module class Test$package$)],Apply(Select(New(TypeTree[TypeRef(ThisType(TypeRef(NoPrefix,module class <empty>)),module class Test$package$)]),<init>),List())), TypeDef(Test$package$,Template(DefDef(<init>,List(List()),TypeTree[TypeRef(ThisType(TypeRef(NoPrefix,module class scala)),class Unit)],EmptyTree),List(Apply(Select(New(TypeTree[TypeRef(ThisType(TypeRef(NoPrefix,module class lang)),class Object)]),<init>),List())),ValDef(_,EmptyTree,EmptyTree),List(DefDef(writeReplace,List(List()),TypeTree[TypeRef(ThisType(TypeRef(NoPrefix,module class scala)),type AnyRef)],Apply(Select(New(TypeTree[TypeRef(ThisType(TypeRef(NoPrefix,module class runtime)),class ModuleSerializationProxy)]),<init>),List(Literal(Constant(TermRef(ThisType(TypeRef(NoPrefix,module class <empty>)),object Test$package)))))), DefDef(method,List(),TypeTree[TypeRef(TermRef(ThisType(TypeRef(NoPrefix,module class <root>)),object scala),class Unit)],Inlined(Apply(Ident(test),List(Block(List(DefDef(innerMethod,List(),TypeTree[AppliedType(TypeRef(ThisType(TypeRef(NoPrefix,module class scala)),trait ContextFunction1),List(TypeRef(TermRef(ThisType(TypeRef(NoPrefix,module class scala)),object Predef),type String), TypeRef(ThisType(TypeRef(NoPrefix,module class scala)),class Nothing)))],Block(List(),Block(List(DefDef($anonfun,List(List(ValDef(_$2,Ident(String),EmptyTree))),TypeTree[TypeRef(ThisType(TypeRef(NoPrefix,module class scala)),class Nothing)],Block(List(),Ident(???)))),Closure(List(),Ident($anonfun),EmptyTree))))),Literal(Constant(()))))),List(),Typed(Block(List(DefDef(innerMethod,List(),TypeTree[AppliedType(TypeRef(ThisType(TypeRef(NoPrefix,module class scala)),trait ContextFunction1),List(TypeRef(TermRef(ThisType(TypeRef(NoPrefix,module class scala)),object Predef),type String), TypeRef(ThisType(TypeRef(NoPrefix,module class scala)),class Nothing)))],Inlined(Ident(TestMacro$package$),List(),Block(List(DefDef($anonfun,List(List(ValDef(_$1,TypeTree[TypeRef(TermRef(TermRef(ThisType(TypeRef(NoPrefix,module class <root>)),object scala),Predef),String)],EmptyTree))),TypeTree[TypeRef(TermRef(ThisType(TypeRef(NoPrefix,module class <root>)),object scala),Nothing)],Ident(???))),Closure(List(),Ident($anonfun),EmptyTree))))),Literal(Constant(()))),TypeTree[TypeRef(ThisType(TypeRef(NoPrefix,module class scala)),class Unit)]))))))))] of class class dotty.tools.dotc.ast.Trees$PackageDef # -1
scala.MatchError: Inlined(Ident(TestMacro$package$),List(),Block(List(DefDef($anonfun,List(List(ValDef(_$1,TypeTree[TypeRef(TermRef(TermRef(ThisType(TypeRef(NoPrefix,module class <root>)),object scala),Predef),String)],EmptyTree))),TypeTree[TypeRef(TermRef(ThisType(TypeRef(NoPrefix,module class <root>)),object scala),Nothing)],Ident(???))),Closure(List(),Ident($anonfun),EmptyTree))) (of class dotty.tools.dotc.ast.Trees$Inlined) while running erasure
scala.MatchError: Inlined(Ident(TestMacro$package$),List(),Block(List(DefDef($anonfun,List(List(ValDef(_$1,TypeTree[TypeRef(TermRef(TermRef(ThisType(TypeRef(NoPrefix,module class <root>)),object scala),Predef),String)],EmptyTree))),TypeTree[TypeRef(TermRef(ThisType(TypeRef(NoPrefix,module class <root>)),object scala),Nothing)],Ident(???))),Closure(List(),Ident($anonfun),EmptyTree))) (of class dotty.tools.dotc.ast.Trees$Inlined)
[error] ## Exception when compiling 4 sources
[error] scala.MatchError: Inlined(Ident(TestMacro$package$),List(),Block(List(DefDef($anonfun,List(List(ValDef(_$1,TypeTree[TypeRef(TermRef(TermRef(ThisType(TypeRef(NoPrefix,module class <root>)),object scala),Predef),String)],EmptyTree))),TypeTree[TypeRef(TermRef(ThisType(TypeRef(NoPrefix,module class <root>)),object scala),Nothing)],Ident(???))),Closure(List(),Ident($anonfun),EmptyTree))) (of class dotty.tools.dotc.ast.Trees$Inlined)
[error] dotty.tools.dotc.transform.Erasure$Typer.skipContextClosures$1(Erasure.scala:928)
[error] dotty.tools.dotc.transform.Erasure$Typer.typedDefDef(Erasure.scala:930)
[error] dotty.tools.dotc.typer.Typer.typedNamed$1(Typer.scala:2923)
[error] dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:3009)
[error] dotty.tools.dotc.typer.ReTyper.typedUnadapted(ReTyper.scala:126)
[error] dotty.tools.dotc.typer.Typer.typed(Typer.scala:3077)
[error] dotty.tools.dotc.typer.Typer.typed(Typer.scala:3081)
[error] dotty.tools.dotc.typer.Typer.traverse$1(Typer.scala:3103)
[error] dotty.tools.dotc.typer.Typer.typedStats(Typer.scala:3149)
[error] dotty.tools.dotc.transform.Erasure$Typer.typedStats(Erasure.scala:1047)
[error] dotty.tools.dotc.typer.Typer.typedBlockStats(Typer.scala:1099)
[error] dotty.tools.dotc.typer.Typer.typedBlock(Typer.scala:1103)
[error] dotty.tools.dotc.typer.Typer.typedUnnamed$1(Typer.scala:2955)
[error] dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:3010)
[error] dotty.tools.dotc.typer.ReTyper.typedUnadapted(ReTyper.scala:126)
[error] dotty.tools.dotc.typer.Typer.typed(Typer.scala:3077)
[error] dotty.tools.dotc.typer.Typer.typed(Typer.scala:3074)
[error] dotty.tools.dotc.typer.Typer.typed(Typer.scala:3081)
[error] dotty.tools.dotc.transform.Erasure$Typer.typedTyped(Erasure.scala:625)
[error] dotty.tools.dotc.typer.Typer.typedUnnamed$1(Typer.scala:2952)
[error] dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:3010)
[error] dotty.tools.dotc.typer.ReTyper.typedUnadapted(ReTyper.scala:126)
[error] dotty.tools.dotc.typer.Typer.typed(Typer.scala:3077)
[error] dotty.tools.dotc.typer.Typer.typed(Typer.scala:3074)
[error] dotty.tools.dotc.typer.Typer.typed(Typer.scala:3081)
[error] dotty.tools.dotc.typer.Typer.typedInlined(Typer.scala:1974)
[error] dotty.tools.dotc.transform.Erasure$Typer.typedInlined(Erasure.scala:892)
[error] dotty.tools.dotc.typer.Typer.typedUnnamed$1(Typer.scala:2969)
[error] dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:3010)
[error] dotty.tools.dotc.typer.ReTyper.typedUnadapted(ReTyper.scala:126)
[error] dotty.tools.dotc.typer.Typer.typed(Typer.scala:3077)
[error] dotty.tools.dotc.typer.Typer.typed(Typer.scala:3081)
[error] dotty.tools.dotc.typer.Typer.typedExpr(Typer.scala:3193)
[error] dotty.tools.dotc.typer.Typer.$anonfun$50(Typer.scala:2401)
[error] dotty.tools.dotc.inlines.PrepareInlineable$.dropInlineIfError(PrepareInlineable.scala:249)
[error] dotty.tools.dotc.typer.Typer.typedDefDef(Typer.scala:2401)
[error] dotty.tools.dotc.transform.Erasure$Typer.typedDefDef(Erasure.scala:948)
[error] dotty.tools.dotc.typer.Typer.typedNamed$1(Typer.scala:2923)
[error] dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:3009)
[error] dotty.tools.dotc.typer.ReTyper.typedUnadapted(ReTyper.scala:126)
[error] dotty.tools.dotc.typer.Typer.typed(Typer.scala:3077)
[error] dotty.tools.dotc.typer.Typer.typed(Typer.scala:3081)
[error] dotty.tools.dotc.typer.Typer.traverse$1(Typer.scala:3103)
[error] dotty.tools.dotc.typer.Typer.typedStats(Typer.scala:3149)
[error] dotty.tools.dotc.transform.Erasure$Typer.typedStats(Erasure.scala:1047)
[error] dotty.tools.dotc.typer.Typer.typedClassDef(Typer.scala:2581)
[error] dotty.tools.dotc.transform.Erasure$Typer.typedClassDef(Erasure.scala:1036)
[error] dotty.tools.dotc.typer.Typer.typedTypeOrClassDef$1(Typer.scala:2935)
[error] dotty.tools.dotc.typer.Typer.typedNamed$1(Typer.scala:2939)
[error] dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:3009)
[error] dotty.tools.dotc.typer.ReTyper.typedUnadapted(ReTyper.scala:126)
[error] dotty.tools.dotc.typer.Typer.typed(Typer.scala:3077)
[error] dotty.tools.dotc.typer.Typer.typed(Typer.scala:3081)
[error] dotty.tools.dotc.typer.Typer.traverse$1(Typer.scala:3103)
[error] dotty.tools.dotc.typer.Typer.typedStats(Typer.scala:3149)
[error] dotty.tools.dotc.transform.Erasure$Typer.typedStats(Erasure.scala:1047)
[error] dotty.tools.dotc.typer.Typer.typedPackageDef(Typer.scala:2711)
[error] dotty.tools.dotc.typer.Typer.typedUnnamed$1(Typer.scala:2980)
[error] dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:3010)
[error] dotty.tools.dotc.typer.ReTyper.typedUnadapted(ReTyper.scala:126)
[error] dotty.tools.dotc.typer.Typer.typed(Typer.scala:3077)
[error] dotty.tools.dotc.typer.Typer.typed(Typer.scala:3081)
[error] dotty.tools.dotc.typer.Typer.typedExpr(Typer.scala:3193)
[error] dotty.tools.dotc.transform.Erasure.run(Erasure.scala:144)
[error] dotty.tools.dotc.core.Phases$Phase.runOn$$anonfun$1(Phases.scala:324)
[error] scala.collection.immutable.List.map(List.scala:246)
[error] dotty.tools.dotc.core.Phases$Phase.runOn(Phases.scala:328)
[error] dotty.tools.dotc.Run.runPhases$1$$anonfun$1(Run.scala:247)
[error] scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
[error] scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
[error] scala.collection.ArrayOps$.foreach$extension(ArrayOps.scala:1321)
[error] dotty.tools.dotc.Run.runPhases$1(Run.scala:263)
[error] dotty.tools.dotc.Run.compileUnits$$anonfun$1(Run.scala:271)
[error] dotty.tools.dotc.Run.compileUnits$$anonfun$adapted$1(Run.scala:280)
[error] dotty.tools.dotc.util.Stats$.maybeMonitored(Stats.scala:67)
[error] dotty.tools.dotc.Run.compileUnits(Run.scala:280)
[error] dotty.tools.dotc.Run.compileUnits(Run.scala:201)
[error] dotty.tools.dotc.Driver.finish(Driver.scala:56)
[error] dotty.tools.dotc.Driver.doCompile(Driver.scala:36)
[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$7(MixedAnalyzingCompiler.scala:193)
[error] scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:23)
[error] sbt.internal.inc.MixedAnalyzingCompiler.timed(MixedAnalyzingCompiler.scala:248)
[error] sbt.internal.inc.MixedAnalyzingCompiler.$anonfun$compile$4(MixedAnalyzingCompiler.scala:183)
[error] sbt.internal.inc.MixedAnalyzingCompiler.$anonfun$compile$4$adapted(MixedAnalyzingCompiler.scala:163)
[error] sbt.internal.inc.JarUtils$.withPreviousJar(JarUtils.scala:239)
[error] sbt.internal.inc.MixedAnalyzingCompiler.compileScala$1(MixedAnalyzingCompiler.scala:163)
[error] sbt.internal.inc.MixedAnalyzingCompiler.compile(MixedAnalyzingCompiler.scala:211)
[error] sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileInternal$1(IncrementalCompilerImpl.scala:534)
[error] sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileInternal$1$adapted(IncrementalCompilerImpl.scala:534)
[error] sbt.internal.inc.Incremental$.$anonfun$apply$5(Incremental.scala:179)
[error] sbt.internal.inc.Incremental$.$anonfun$apply$5$adapted(Incremental.scala:177)
[error] sbt.internal.inc.Incremental$$anon$2.run(Incremental.scala:463)
[error] sbt.internal.inc.IncrementalCommon$CycleState.next(IncrementalCommon.scala:116)
[error] sbt.internal.inc.IncrementalCommon$$anon$1.next(IncrementalCommon.scala:56)
[error] sbt.internal.inc.IncrementalCommon$$anon$1.next(IncrementalCommon.scala:52)
[error] sbt.internal.inc.IncrementalCommon.cycle(IncrementalCommon.scala:263)
[error] sbt.internal.inc.Incremental$.$anonfun$incrementalCompile$8(Incremental.scala:418)
[error] sbt.internal.inc.Incremental$.withClassfileManager(Incremental.scala:506)
[error] sbt.internal.inc.Incremental$.incrementalCompile(Incremental.scala:405)
[error] sbt.internal.inc.Incremental$.apply(Incremental.scala:171)
[error] sbt.internal.inc.IncrementalCompilerImpl.compileInternal(IncrementalCompilerImpl.scala:534)
[error] sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileIncrementally$1(IncrementalCompilerImpl.scala:488)
[error] sbt.internal.inc.IncrementalCompilerImpl.handleCompilationError(IncrementalCompilerImpl.scala:332)
[error] sbt.internal.inc.IncrementalCompilerImpl.compileIncrementally(IncrementalCompilerImpl.scala:425)
[error] sbt.internal.inc.IncrementalCompilerImpl.compile(IncrementalCompilerImpl.scala:137)
[error] sbt.Defaults$.compileIncrementalTaskImpl(Defaults.scala:2363)
[error] sbt.Defaults$.$anonfun$compileIncrementalTask$2(Defaults.scala:2313)
[error] sbt.internal.server.BspCompileTask$.$anonfun$compute$1(BspCompileTask.scala:30)
[error] sbt.internal.io.Retry$.apply(Retry.scala:46)
[error] sbt.internal.io.Retry$.apply(Retry.scala:28)
[error] sbt.internal.io.Retry$.apply(Retry.scala:23)
[error] sbt.internal.server.BspCompileTask$.compute(BspCompileTask.scala:30)
[error] sbt.Defaults$.$anonfun$compileIncrementalTask$1(Defaults.scala:2311)
[error] scala.Function1.$anonfun$compose$1(Function1.scala:49)
[error] sbt.internal.util.$tilde$greater.$anonfun$$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:539)
[error] java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
[error] java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
[error] java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
[error] java.base/java.lang.Thread.run(Thread.java:833)
[error]            
[error] stack trace is suppressed; run last Compile / compileIncremental for the full output
[error] (Compile / compileIncremental) scala.MatchError: Inlined(Ident(TestMacro$package$),List(),Block(List(DefDef($anonfun,List(List(ValDef(_$1,TypeTree[TypeRef(TermRef(TermRef(ThisType(TypeRef(NoPrefix,module class <root>)),object scala),Predef),String)],EmptyTree))),TypeTree[TypeRef(TermRef(ThisType(TypeRef(NoPrefix,module class <root>)),object scala),Nothing)],Ident(???))),Closure(List(),Ident($anonfun),EmptyTree))) (of class dotty.tools.dotc.ast.Trees$Inlined)

[nicolasstucki]

Not that the code used underlyingArgument to get a tree that was not in scope. This tree should not be used in the generated code. This might be the cause of the crash.

[pweisenburger]

You are right, in general you should not rely on underlyingArgument working in such situations. But I do not think this is an issue in this specific example as v has the form Inlined(EmptyTree, List(), ``block``), i.e., the bindings part is empty. So the code is not cutting out definitions that may be referenced in the body and the code should be safe; is that correct?

Further observation: Adding yet another underlyingArgument to '{ (_: String) ?=> ??? }.asTerm.underlyingArgument makes the code compile, which does not make much sense to me.

Side note: The code compiles in Scala 3.2.2.

[nicolasstucki]

Minimized

import scala.quoted.*

inline def myMacro = ${ myMacroExpr }

def myMacroExpr(using Quotes) =
  import quotes.reflect.*

  '{ def innerMethod = (_: String) ?=> ???; () }.asTerm match
    case block @ Inlined(_, _, Block(List(defdef: DefDef), _)) =>
      val rhs =
        given Quotes = defdef.symbol.asQuotes
        '{ (x: String) ?=> ??? }.asTerm

      Block(List(DefDef(defdef.symbol, _ => Some(rhs))), '{}.asTerm).asExprOf[Unit]

def method: Unit = myMacro

[Kordyjan]

According to bisect, it was broken by #16377 (in 229fdaa)