Stale symbol crash

[soronpo]

Could be related somehow to #17152, but this also occurs for older compiler versions and this minimization is far simpler.
It may be that this should just yield a cyclic dependency error instead of a crash. I'm not sure what the cross-file macro dependency limitations are.

Compiler version

v3.2.2
Also tested on the latest nightly: scala-3.3.1-RC1-bin-20230416-2f4cc4c-NIGHTLY

Minimized code

DFVal.scala

package crash

def bits[T](t: T)(using w: Width[T]): w.Out = ???

Width.scala

package crash

import scala.quoted.*

trait Width[T]:
  type Out
object Width:
  transparent inline given [T]: Width[T] = ${ getWidthMacro[T] }
  def getWidthMacro[T](using Quotes, Type[T]): Expr[Width[T]] =
    '{ new Width[T] {} }
end Width

val x = bits(1)

Output (click arrow to expand)

[error] dotty.tools.dotc.core.Denotations$StaleSymbol: stale symbol; type Out#4554 in trait Width, defined in Period(1..63, run = 2), is referred to in run Period(2..2, run = 3)
[error] dotty.tools.dotc.core.Denotations$SingleDenotation.staleSymbolError(Denotations.scala:948)
[error] dotty.tools.dotc.core.Denotations$SingleDenotation.bringForward(Denotations.scala:752)
[error] dotty.tools.dotc.core.Denotations$SingleDenotation.toNewRun$1(Denotations.scala:799)
[error] dotty.tools.dotc.core.Denotations$SingleDenotation.current(Denotations.scala:870)
[error] dotty.tools.dotc.core.Symbols$Symbol.recomputeDenot(Symbols.scala:120)
[error] dotty.tools.dotc.core.Symbols$Symbol.computeDenot(Symbols.scala:114)
[error] dotty.tools.dotc.core.Symbols$Symbol.denot(Symbols.scala:107)
[error] dotty.tools.dotc.core.Symbols$.toDenot(Symbols.scala:494)
[error] dotty.tools.dotc.core.Types$NamedType.derivedSelect(Types.scala:2657)
[error] dotty.tools.dotc.core.Substituters$.subst(Substituters.scala:18)
[error] dotty.tools.dotc.core.Types$Type.subst(Types.scala:1798)
[error] dotty.tools.dotc.core.Types$LambdaType.newLikeThis$$anonfun$2(Types.scala:3679)
[error] dotty.tools.dotc.core.Types$MethodType.<init>(Types.scala:3934)
[error] dotty.tools.dotc.core.Types$CachedMethodType.<init>(Types.scala:3953)
[error] dotty.tools.dotc.core.Types$MethodTypeCompanion.apply(Types.scala:4045)
[error] dotty.tools.dotc.core.Types$MethodTypeCompanion.apply(Types.scala:4044)
[error] dotty.tools.dotc.core.Types$LambdaType.newLikeThis(Types.scala:3679)
[error] dotty.tools.dotc.core.Types$LambdaType.newLikeThis$(Types.scala:3606)
[error] dotty.tools.dotc.core.Types$MethodOrPoly.newLikeThis(Types.scala:3692)
[error] dotty.tools.dotc.core.Types$LambdaType.derivedLambdaType(Types.scala:3669)
[error] dotty.tools.dotc.core.Types$LambdaType.derivedLambdaType$(Types.scala:3606)
[error] dotty.tools.dotc.core.Types$MethodOrPoly.derivedLambdaType(Types.scala:3692)
[error] dotty.tools.dotc.core.Types$TypeMap.derivedLambdaType(Types.scala:5655)
[error] dotty.tools.dotc.core.Types$TypeMap.mapOverLambda(Types.scala:5674)
[error] dotty.tools.dotc.core.Types$TypeMap.mapOver(Types.scala:5701)
[error] dotty.tools.dotc.core.Substituters$.substParams(Substituters.scala:163)
[error] dotty.tools.dotc.core.Substituters$SubstParamsMap.apply(Substituters.scala:201)
[error] dotty.tools.dotc.core.Types$TypeMap.mapOverLambda(Types.scala:5674)
[error] dotty.tools.dotc.core.Types$TypeMap.mapOver(Types.scala:5701)
[error] dotty.tools.dotc.core.Substituters$.substParams(Substituters.scala:163)
[error] dotty.tools.dotc.core.Types$Type.substParams(Types.scala:1818)
[error] dotty.tools.dotc.core.Types$LambdaType.instantiate(Types.scala:3645)
[error] dotty.tools.dotc.core.Types$LambdaType.instantiate$(Types.scala:3606)
[error] dotty.tools.dotc.core.Types$MethodOrPoly.instantiate(Types.scala:3692)
[error] dotty.tools.dotc.typer.TypeAssigner.assignType(TypeAssigner.scala:360)
[error] dotty.tools.dotc.typer.TypeAssigner.assignType$(TypeAssigner.scala:16)
[error] dotty.tools.dotc.typer.Typer.assignType(Typer.scala:116)
[error] dotty.tools.dotc.ast.tpd$.TypeApply(tpd.scala:58)
[error] dotty.tools.dotc.ast.tpd$TreeOps$.appliedToTypeTrees$extension(tpd.scala:979)
[error] dotty.tools.dotc.typer.Typer.adapt1(Typer.scala:4171)
[error] dotty.tools.dotc.typer.Typer.adapt(Typer.scala:3503)
[error] dotty.tools.dotc.typer.Typer.typed(Typer.scala:3126)
[error] dotty.tools.dotc.typer.Typer.typed(Typer.scala:3130)
[error] dotty.tools.dotc.typer.Typer.typedExpr(Typer.scala:3242)
[error] dotty.tools.dotc.typer.Applications.realApply$1(Applications.scala:941)
[error] dotty.tools.dotc.typer.Applications.typedApply(Applications.scala:1101)
[error] dotty.tools.dotc.typer.Applications.typedApply$(Applications.scala:352)
[error] dotty.tools.dotc.typer.Typer.typedApply(Typer.scala:116)
[error] dotty.tools.dotc.typer.Typer.typedUnnamed$1(Typer.scala:2991)
[error] dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:3054)
[error] dotty.tools.dotc.typer.Typer.typed(Typer.scala:3126)
[error] dotty.tools.dotc.typer.Typer.typed(Typer.scala:3130)
[error] dotty.tools.dotc.typer.Typer.typedExpr(Typer.scala:3242)
[error] dotty.tools.dotc.typer.Namer.typedAheadExpr$$anonfun$1(Namer.scala:1645)
[error] dotty.tools.dotc.typer.Namer.typedAhead(Namer.scala:1635)
[error] dotty.tools.dotc.typer.Namer.typedAheadExpr(Namer.scala:1645)
[error] dotty.tools.dotc.typer.Namer.typedAheadRhs$1$$anonfun$1(Namer.scala:1898)
[error] dotty.tools.dotc.inlines.PrepareInlineable$.dropInlineIfError(PrepareInlineable.scala:250)
[error] dotty.tools.dotc.typer.Namer.typedAheadRhs$1(Namer.scala:1898)
[error] dotty.tools.dotc.typer.Namer.rhsType$1(Namer.scala:1906)
[error] dotty.tools.dotc.typer.Namer.cookedRhsType$1(Namer.scala:1924)
[error] dotty.tools.dotc.typer.Namer.lhsType$1(Namer.scala:1925)
[error] dotty.tools.dotc.typer.Namer.inferredResultType(Namer.scala:1936)
[error] dotty.tools.dotc.typer.Namer.inferredType$1(Namer.scala:1683)
[error] dotty.tools.dotc.typer.Namer.valOrDefDefSig(Namer.scala:1690)
[error] dotty.tools.dotc.typer.Namer$Completer.typeSig(Namer.scala:787)
[error] dotty.tools.dotc.typer.Namer$Completer.completeInCreationContext(Namer.scala:926)
[error] dotty.tools.dotc.typer.Namer$Completer.complete(Namer.scala:814)
[error] dotty.tools.dotc.core.SymDenotations$SymDenotation.completeFrom(SymDenotations.scala:174)
[error] dotty.tools.dotc.core.Denotations$Denotation.completeInfo$1(Denotations.scala:187)
[error] dotty.tools.dotc.core.Denotations$Denotation.info(Denotations.scala:189)
[error] dotty.tools.dotc.core.SymDenotations$SymDenotation.ensureCompleted(SymDenotations.scala:393)
[error] dotty.tools.dotc.typer.Typer.retrieveSym(Typer.scala:2932)
[error] dotty.tools.dotc.typer.Typer.typedNamed$1(Typer.scala:2957)
[error] dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:3053)
[error] dotty.tools.dotc.typer.Typer.typed(Typer.scala:3126)
[error] dotty.tools.dotc.typer.Typer.typed(Typer.scala:3130)
[error] dotty.tools.dotc.typer.Typer.traverse$1(Typer.scala:3152)
[error] dotty.tools.dotc.typer.Typer.typedStats(Typer.scala:3198)
[error] dotty.tools.dotc.typer.Typer.typedClassDef(Typer.scala:2612)
[error] dotty.tools.dotc.typer.Typer.typedTypeOrClassDef$1(Typer.scala:2979)
[error] dotty.tools.dotc.typer.Typer.typedNamed$1(Typer.scala:2983)
[error] dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:3053)
[error] dotty.tools.dotc.typer.Typer.typed(Typer.scala:3126)
[error] dotty.tools.dotc.typer.Typer.typed(Typer.scala:3130)
[error] dotty.tools.dotc.typer.Typer.traverse$1(Typer.scala:3152)
[error] dotty.tools.dotc.typer.Typer.typedStats(Typer.scala:3198)
[error] dotty.tools.dotc.typer.Typer.typedPackageDef(Typer.scala:2755)
[error] dotty.tools.dotc.typer.Typer.typedUnnamed$1(Typer.scala:3024)
[error] dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:3054)
[error] dotty.tools.dotc.typer.Typer.typed(Typer.scala:3126)
[error] dotty.tools.dotc.typer.Typer.typed(Typer.scala:3130)
[error] dotty.tools.dotc.typer.Typer.typedExpr(Typer.scala:3242)
[error] dotty.tools.dotc.typer.TyperPhase.typeCheck$$anonfun$1(TyperPhase.scala:44)
[error] dotty.tools.dotc.typer.TyperPhase.typeCheck$$anonfun$adapted$1(TyperPhase.scala:54)
[error] scala.Function0.apply$mcV$sp(Function0.scala:42)
[error] dotty.tools.dotc.core.Phases$Phase.monitor(Phases.scala:437)
[error] dotty.tools.dotc.typer.TyperPhase.typeCheck(TyperPhase.scala:54)
[error] dotty.tools.dotc.typer.TyperPhase.runOn$$anonfun$3(TyperPhase.scala:88)
[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.typer.TyperPhase.runOn(TyperPhase.scala:88)
[error] dotty.tools.dotc.Run.runPhases$1$$anonfun$1(Run.scala:246)
[error] scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
[error] scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
[error] scala.collection.ArrayOps$.foreach$extension(ArrayOps.scala:1321)
[error] dotty.tools.dotc.Run.runPhases$1(Run.scala:262)
[error] dotty.tools.dotc.Run.compileUnits$$anonfun$1(Run.scala:270)
[error] dotty.tools.dotc.Run.compileUnits$$anonfun$adapted$1(Run.scala:279)
[error] dotty.tools.dotc.util.Stats$.maybeMonitored(Stats.scala:67)
[error] dotty.tools.dotc.Run.compileUnits(Run.scala:279)
[error] dotty.tools.dotc.Run.compileUnits(Run.scala:200)
[error] dotty.tools.dotc.Driver.finish(Driver.scala:58)
[error] dotty.tools.dotc.Driver.doCompile(Driver.scala:38)
[error] dotty.tools.xsbt.CompilerBridgeDriver.run(CompilerBridgeDriver.java:88)
[error] dotty.tools.xsbt.CompilerBridge.run(CompilerBridge.java:22)
[error] sbt.internal.inc.AnalyzingCompiler.compile(AnalyzingCompiler.scala:91)
[error] sbt.internal.inc.MixedAnalyzingCompiler.$anonfun$compile$7(MixedAnalyzingCompiler.scala:193)
[error] scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:23)
[error] sbt.internal.inc.MixedAnalyzingCompiler.timed(MixedAnalyzingCompiler.scala:248)
[error] sbt.internal.inc.MixedAnalyzingCompiler.$anonfun$compile$4(MixedAnalyzingCompiler.scala:183)
[error] sbt.internal.inc.MixedAnalyzingCompiler.$anonfun$compile$4$adapted(MixedAnalyzingCompiler.scala:163)
[error] sbt.internal.inc.JarUtils$.withPreviousJar(JarUtils.scala:239)
[error] sbt.internal.inc.MixedAnalyzingCompiler.compileScala$1(MixedAnalyzingCompiler.scala:163)
[error] sbt.internal.inc.MixedAnalyzingCompiler.compile(MixedAnalyzingCompiler.scala:211)
[error] sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileInternal$1(IncrementalCompilerImpl.scala:534)
[error] sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileInternal$1$adapted(IncrementalCompilerImpl.scala:534)
[error] sbt.internal.inc.Incremental$.$anonfun$apply$5(Incremental.scala:179)
[error] sbt.internal.inc.Incremental$.$anonfun$apply$5$adapted(Incremental.scala:177)
[error] sbt.internal.inc.Incremental$$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: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$Worker.run(ThreadPoolExecutor.java:628)
[error] java.base/java.lang.Thread.run(Thread.java:829)
[error]
[error] stack trace is suppressed; run last core / Compile / compileIncremental for the full output
[error] (core / Compile / compileIncremental) dotty.tools.dotc.core.Denotations$StaleSymbol: stale symbol; type Out#4554 in trait Width, defined in Period(1..63, run = 2), is referred to in run Period(2..2, run = 3)

[ftucky]

Hello,
I encounter the same symptom:
dotty.tools.dotc.core.Denotations$StaleSymbol: stale symbol; method definition$lzyINIT2#52624 in class Generator, defined in Period(76..93, run = 2), is referred to in run Period(92..92, run = 3)

dotty.tools.dotc.core.Denotations$StaleSymbol: stale symbol; method definition$lzyINIT2#52624 in class Generator, defined in Period(76..93, run = 2), is referred to in run Period(92..92, run = 3) | => root / Compile / compileIncremental 1s at dotty.tools.dotc.core.Denotations$SingleDenotation.staleSymbolError(Denotations.scala:948) at dotty.tools.dotc.core.Denotations$SingleDenotation.bringForward(Denotations.scala:752) at dotty.tools.dotc.core.Denotations$SingleDenotation.toNewRun$1(Denotations.scala:799) at dotty.tools.dotc.core.Denotations$SingleDenotation.current(Denotations.scala:870) at dotty.tools.dotc.core.Symbols$Symbol.recomputeDenot(Symbols.scala:120) at dotty.tools.dotc.core.Symbols$Symbol.computeDenot(Symbols.scala:114) at dotty.tools.dotc.core.Symbols$Symbol.denot(Symbols.scala:107) at dotty.tools.dotc.core.Symbols$Symbol.name(Symbols.scala:260) at dotty.tools.dotc.core.SymDenotations$ClassDenotation.computeMemberNames$$anonfun$2(SymDenotations.scala:2328)

Observations

No metaprogramming

Code is difficult to minimize, however metaprogramming or quotes do not seem to be involved.

Apparent workaround

The faulty symbol definition$lzyINIT2#52624 is associated to a declaration

object definition extends Definition: 
  ...

Changing the line for the declaration below acts as a work-around.

val definition = new Definition:
  ...

Caching Issue

Running the sbt build a second time succeeds after the crash.

sbt:> clean 
sbt:> compile /// Crashes
sbt:> compile /// with no source change. NO CRASH. (and correct behavior!)

Hope this helps.

[Pyromuffin]

Still seeing this on 3.4.2

My repro is very complicated involving macros unfortunately, but I am seeing the same symptoms as #17294 (comment): it happens with a top level object and goes away when either making it a top level val or on the second compile.

[joan38]

Hey,
I'm having the same issue on 3.5.2.

Here is the code of the macro:

import scala.quoted.*

/**
 * Scala 3 macro which finds all objects that inherit from a given type T as a compile-time / static metaprogramming operation.
 *
 * Example usage:
 *   import com.netflix.measures.library.macros.ObjectInheritanceFinder.findAllInheritingObjects
 *   val measureParsers: Set[MeasureParser] = findAllInheritingObjects[MeasureParser]
 */
object ObjectInheritanceFinder {
  inline def findAllInheritingObjects[T]: Set[T] = ${ findAllInheritingObjectsImpl[T] }

  private def findAllInheritingObjectsImpl[T: Type](using Quotes): Expr[Set[T]] = {
    // Context-sensitive reflection import is tied to specific instance of Quotes that's created for each specific macro invocation
    import quotes.reflect._

    // Get the TypeRepr of the type parameter T to be used for inheritance checks
    val baseType = TypeRepr.of[T]

    /**
     * Check if the symbol is an object and a subtype of baseType.
     *
     * @param sym The symbol to check.
     * @return True if the symbol is an object and a subtype of baseType, otherwise false.
     */
    def isObjectInheritingFromBaseType(sym: Symbol): Boolean =
      // All symbols are terms or types, and some types throw when checking sym.flags.is, so this check is necessary before it is called
      sym.isTerm &&
        // flags.is(Flags.Module) is equivalent to checking if the symbol is an object
        sym.flags.is(Flags.Module) &&
        // termRef <:< baseType is equivalent to checking if the symbol is a subtype of baseType
        sym.termRef <:< baseType

    /**
     * Recursively traverse a package and its subpackages to find objects that are subtypes of baseType.
     *
     * We convert to a Set because there are no guarantees that the same object won't be referenced in multiple packages.
     *
     * @param pkg The package symbol to start the search from.
     * @return A sequence of fully qualified names representing the inheriting objects.
     */
    def findAllInheritingObjectsInPackage(pkg: Symbol): Set[String] =
      pkg.declarations.flatMap {
        case sym if sym.isPackageDef                    => findAllInheritingObjectsInPackage(sym) // Recurse
        case sym if isObjectInheritingFromBaseType(sym) => Some(sym.fullName)                     // Include
        case _                                          => None                                   // Skip
      }.toSet

    // Root package symbol
    val packageSymbol: Symbol = Symbol.requiredPackage("com.netflix.measures.library")

    // Find all objects that inherit from T starting from the root package
    val inheritingObjects: Set[Expr[T]] = findAllInheritingObjectsInPackage(packageSymbol)
      // Map fully qualified names to Expr[T]
      .map(x => Ref(Symbol.requiredModule(x)).asExprOf[T])

    // Convert Set[Expr[T]] to Expr[Set[T]]
    '{ Set(${ Expr.ofSeq(inheritingObjects.toSeq) }*) }
  }
}

Anything wrong with it?