Scala reflection: scala.reflect.internal.Symbols$CyclicReference: illegal cyclic reference involving class X

[wajda]

reproduction steps

Tested in Scala 2.11.12, 2.12.12, 2.13.3

having a Java annotation defined as:

@A.B
public class A {
    @Retention(RUNTIME)
    public @interface B {}
}

an attempt to get a class symbol using Scala reflection fails:

@A.B()
class Foo

rootMirror.classSymbol(classOf[Foo]) // throws scala.reflect.internal.Symbols$CyclicReference

problem

scala.reflect.api.RuntimeMirror.classSymbol() method fails when reflecting a class annotated with a "cyclic" Java annotation.

scala.reflect.internal.Symbols$CyclicReference: illegal cyclic reference involving class A
Exception in thread "main" java.lang.RuntimeException: error reading Scala signature of org.example.ScalaBugTest: illegal cyclic reference involving class A
	at scala.reflect.internal.pickling.UnPickler.unpickle(UnPickler.scala:51)
	at scala.reflect.runtime.JavaMirrors$JavaMirror.unpickleClass(JavaMirrors.scala:653)
	at scala.reflect.runtime.SymbolLoaders$TopClassCompleter.$anonfun$complete$2(SymbolLoaders.scala:37)
	at scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:23)
	at scala.reflect.internal.SymbolTable.slowButSafeEnteringPhaseNotLaterThan(SymbolTable.scala:332)
	at scala.reflect.runtime.SymbolLoaders$TopClassCompleter.complete(SymbolLoaders.scala:34)
	at scala.reflect.internal.Symbols$Symbol.info(Symbols.scala:1542)
	at scala.reflect.runtime.SynchronizedSymbols$SynchronizedSymbol$$anon$8.scala$reflect$runtime$SynchronizedSymbols$SynchronizedSymbol$$super$info(SynchronizedSymbols.scala:206)
	at scala.reflect.runtime.SynchronizedSymbols$SynchronizedSymbol.$anonfun$info$1(SynchronizedSymbols.scala:158)
	at scala.reflect.runtime.SynchronizedSymbols$SynchronizedSymbol.info(SynchronizedSymbols.scala:149)
	at scala.reflect.runtime.SynchronizedSymbols$SynchronizedSymbol.info$(SynchronizedSymbols.scala:158)
	at scala.reflect.runtime.SynchronizedSymbols$SynchronizedSymbol$$anon$8.info(SynchronizedSymbols.scala:206)
	at scala.reflect.runtime.JavaMirrors$JavaMirror.coreLookup$1(JavaMirrors.scala:1031)
	at scala.reflect.runtime.JavaMirrors$JavaMirror.lookupClass$1(JavaMirrors.scala:1037)
	at scala.reflect.runtime.JavaMirrors$JavaMirror.classToScala1(JavaMirrors.scala:1042)
	at scala.reflect.runtime.JavaMirrors$JavaMirror.$anonfun$classToScala$1(JavaMirrors.scala:1019)
	at scala.reflect.runtime.JavaMirrors$JavaMirror.$anonfun$toScala$1(JavaMirrors.scala:130)
	at scala.reflect.runtime.TwoWayCaches$TwoWayCache.$anonfun$toScala$1(TwoWayCaches.scala:50)
	at scala.reflect.runtime.TwoWayCaches$TwoWayCache.toScala(TwoWayCaches.scala:46)
	at scala.reflect.runtime.JavaMirrors$JavaMirror.toScala(JavaMirrors.scala:128)
	at scala.reflect.runtime.JavaMirrors$JavaMirror.classToScala(JavaMirrors.scala:1019)
	at scala.reflect.runtime.JavaMirrors$JavaMirror.classSymbol(JavaMirrors.scala:231)
	at scala.reflect.runtime.JavaMirrors$JavaMirror.classSymbol(JavaMirrors.scala:68)
	at org.example.ScalaBugTest$.delayedEndpoint$org$example$ScalaBugTest$1(ScalaBugTest.scala:26)
	at org.example.ScalaBugTest$delayedInit$body.apply(ScalaBugTest.scala:21)
	at scala.Function0.apply$mcV$sp(Function0.scala:39)
	at scala.Function0.apply$mcV$sp$(Function0.scala:39)
	at scala.runtime.AbstractFunction0.apply$mcV$sp(AbstractFunction0.scala:17)
	at scala.App.$anonfun$main$1$adapted(App.scala:80)
	at scala.collection.immutable.List.foreach(List.scala:392)
	at scala.App.main(App.scala:80)
	at scala.App.main$(App.scala:78)
	at org.example.ScalaBugTest$.main(ScalaBugTest.scala:21)
	at org.example.ScalaBugTest.main(ScalaBugTest.scala)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:566)
	at com.intellij.rt.execution.application.AppMainV2.main(AppMainV2.java:128)

[SethTisue]

is the problem reproducible on 2.13.3?

[wajda]

Yes, the same issue on 2.13.3

[som-snytt]

There ought to be an umbrella ticket for "static inner classes (interfaces) in Java."

I think I just saw such a ticket, I'll link it if I find it again.

[wajda]

2.13.3 stack trace:

scala.reflect.internal.Symbols$CyclicReference: illegal cyclic reference involving class A
Exception in thread "main" java.lang.RuntimeException: error reading Scala signature of example.TestApp: illegal cyclic reference involving class A
	at scala.reflect.internal.pickling.UnPickler.unpickle(UnPickler.scala:48)
	at scala.reflect.runtime.JavaMirrors$JavaMirror.unpickleClass(JavaMirrors.scala:661)
	at scala.reflect.runtime.SymbolLoaders$TopClassCompleter.$anonfun$complete$3(SymbolLoaders.scala:37)
	at scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.scala:18)
	at scala.reflect.internal.SymbolTable.slowButSafeEnteringPhaseNotLaterThan(SymbolTable.scala:318)
	at scala.reflect.runtime.SymbolLoaders$TopClassCompleter.complete(SymbolLoaders.scala:34)
	at scala.reflect.internal.Symbols$Symbol.completeInfo(Symbols.scala:1555)
	at scala.reflect.internal.Symbols$Symbol.info(Symbols.scala:1518)
	at scala.reflect.runtime.SynchronizedSymbols$SynchronizedSymbol$$anon$8.scala$reflect$runtime$SynchronizedSymbols$SynchronizedSymbol$$super$info(SynchronizedSymbols.scala:206)
	at scala.reflect.runtime.SynchronizedSymbols$SynchronizedSymbol.info(SynchronizedSymbols.scala:158)
	at scala.reflect.runtime.SynchronizedSymbols$SynchronizedSymbol.info$(SynchronizedSymbols.scala:158)
	at scala.reflect.runtime.SynchronizedSymbols$SynchronizedSymbol$$anon$8.info(SynchronizedSymbols.scala:206)
	at scala.reflect.runtime.JavaMirrors$JavaMirror.coreLookup$1(JavaMirrors.scala:1038)
	at scala.reflect.runtime.JavaMirrors$JavaMirror.lookupClass$1(JavaMirrors.scala:1044)
	at scala.reflect.runtime.JavaMirrors$JavaMirror.classToScala1(JavaMirrors.scala:1049)
	at scala.reflect.runtime.JavaMirrors$JavaMirror.$anonfun$classToScala$1(JavaMirrors.scala:1026)
	at scala.reflect.runtime.JavaMirrors$JavaMirror.$anonfun$toScala$1(JavaMirrors.scala:138)
	at scala.reflect.runtime.TwoWayCaches$TwoWayCache.toScala(TwoWayCaches.scala:50)
	at scala.reflect.runtime.JavaMirrors$JavaMirror.toScala(JavaMirrors.scala:136)
	at scala.reflect.runtime.JavaMirrors$JavaMirror.classToScala(JavaMirrors.scala:1026)
	at scala.reflect.runtime.JavaMirrors$JavaMirror.classSymbol(JavaMirrors.scala:239)
	at scala.reflect.runtime.JavaMirrors$JavaMirror.classSymbol(JavaMirrors.scala:70)
	at example.TestApp$.delayedEndpoint$example$TestApp$1(TestApp.scala:10)
	at example.TestApp$delayedInit$body.apply(TestApp.scala:5)
	at scala.Function0.apply$mcV$sp(Function0.scala:39)
	at scala.Function0.apply$mcV$sp$(Function0.scala:39)
	at scala.runtime.AbstractFunction0.apply$mcV$sp(AbstractFunction0.scala:17)
	at scala.App.$anonfun$main$1(App.scala:73)
	at scala.App.$anonfun$main$1$adapted(App.scala:73)
	at scala.collection.IterableOnceOps.foreach(IterableOnce.scala:553)
	at scala.collection.IterableOnceOps.foreach$(IterableOnce.scala:551)
	at scala.collection.AbstractIterable.foreach(Iterable.scala:920)
	at scala.App.main(App.scala:73)
	at scala.App.main$(App.scala:71)
	at example.TestApp$.main(TestApp.scala:5)
	at example.TestApp.main(TestApp.scala)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at com.intellij.rt.execution.application.AppMainV2.main(AppMainV2.java:128)

[som-snytt]

Another ticket just asked whether reflect error manifest differently under intellij.

[wajda]

@som-snytt
Thanks for the hint. When run from a shell the error is indeed different (see below).
About the other ticker, please link it if you can. I couldn't find one, the search returned a few similar ones but related to the compiler, not reflection.

[wajda@alex-xps Shadow]$ java -classpath /home/wajda/Projects/Shadow/target/classes:/home/wajda/.m2/repository/org/scala-lang/scala-library/2.13.3/scala-library-2.13.3.jar:/home/wajda/.m2/repository/org/scala-lang/scala-reflect/2.13.3/scala-reflect-2.13.3.jar example.TestApp
java.lang.AssertionError: unsafe symbol B (child of package A) in runtime reflection universe
        at scala.reflect.internal.Symbols$Symbol.<init>(Symbols.scala:232)
        at scala.reflect.internal.Symbols$TypeSymbol.<init>(Symbols.scala:3139)
        at scala.reflect.internal.Symbols$ClassSymbol.<init>(Symbols.scala:3325)
        at scala.reflect.internal.Symbols$StubClassSymbol.<init>(Symbols.scala:3604)
        at scala.reflect.internal.Symbols.newStubSymbol(Symbols.scala:215)
        at scala.reflect.internal.Symbols.newStubSymbol$(Symbols.scala:211)
        at scala.reflect.internal.SymbolTable.newStubSymbol(SymbolTable.scala:28)
        at scala.reflect.internal.Symbols$Symbol.newStubSymbol(Symbols.scala:536)
        at scala.reflect.internal.pickling.UnPickler$Scan.$anonfun$readSymbol$6(UnPickler.scala:268)
        at scala.reflect.internal.pickling.UnPickler$Scan.$anonfun$readSymbol$5(UnPickler.scala:255)
        at scala.reflect.internal.pickling.UnPickler$Scan.$anonfun$readSymbol$4(UnPickler.scala:255)
        at scala.reflect.internal.pickling.UnPickler$Scan.readExtSymbol$1(UnPickler.scala:253)
        at scala.reflect.internal.pickling.UnPickler$Scan.readSymbol(UnPickler.scala:276)
        at scala.reflect.internal.pickling.UnPickler$Scan.readSymbolRef(UnPickler.scala:647)
        at scala.reflect.internal.pickling.UnPickler$Scan.readType(UnPickler.scala:414)
        at scala.reflect.internal.pickling.UnPickler$Scan.$anonfun$readTypeRef$1(UnPickler.scala:656)
        at scala.reflect.internal.pickling.UnPickler$Scan.at(UnPickler.scala:182)
        at scala.reflect.internal.pickling.UnPickler$Scan.readTypeRef(UnPickler.scala:656)
        at scala.reflect.internal.pickling.UnPickler$Scan.readAnnotationInfo(UnPickler.scala:490)
        at scala.reflect.internal.pickling.UnPickler$Scan.readSymbolAnnotation(UnPickler.scala:513)
        at scala.reflect.internal.pickling.UnPickler$Scan.run(UnPickler.scala:105)
        at scala.reflect.internal.pickling.UnPickler.unpickle(UnPickler.scala:44)
        at scala.reflect.runtime.JavaMirrors$JavaMirror.unpickleClass(JavaMirrors.scala:661)
        at scala.reflect.runtime.SymbolLoaders$TopClassCompleter.$anonfun$complete$3(SymbolLoaders.scala:37)
        at scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.scala:18)
        at scala.reflect.internal.SymbolTable.slowButSafeEnteringPhaseNotLaterThan(SymbolTable.scala:318)
        at scala.reflect.runtime.SymbolLoaders$TopClassCompleter.complete(SymbolLoaders.scala:34)
        at scala.reflect.internal.Symbols$Symbol.completeInfo(Symbols.scala:1555)
        at scala.reflect.internal.Symbols$Symbol.info(Symbols.scala:1518)
        at scala.reflect.runtime.SynchronizedSymbols$SynchronizedSymbol$$anon$8.scala$reflect$runtime$SynchronizedSymbols$SynchronizedSymbol$$super$info(SynchronizedSymbols.scala:206)
        at scala.reflect.runtime.SynchronizedSymbols$SynchronizedSymbol.info(SynchronizedSymbols.scala:158)
        at scala.reflect.runtime.SynchronizedSymbols$SynchronizedSymbol.info$(SynchronizedSymbols.scala:158)
        at scala.reflect.runtime.SynchronizedSymbols$SynchronizedSymbol$$anon$8.info(SynchronizedSymbols.scala:206)
        at scala.reflect.runtime.JavaMirrors$JavaMirror.coreLookup$1(JavaMirrors.scala:1038)
        at scala.reflect.runtime.JavaMirrors$JavaMirror.lookupClass$1(JavaMirrors.scala:1044)
        at scala.reflect.runtime.JavaMirrors$JavaMirror.classToScala1(JavaMirrors.scala:1049)
        at scala.reflect.runtime.JavaMirrors$JavaMirror.$anonfun$classToScala$1(JavaMirrors.scala:1026)
        at scala.reflect.runtime.JavaMirrors$JavaMirror.$anonfun$toScala$1(JavaMirrors.scala:138)
        at scala.reflect.runtime.TwoWayCaches$TwoWayCache.toScala(TwoWayCaches.scala:50)
        at scala.reflect.runtime.JavaMirrors$JavaMirror.toScala(JavaMirrors.scala:136)
        at scala.reflect.runtime.JavaMirrors$JavaMirror.classToScala(JavaMirrors.scala:1026)
        at scala.reflect.runtime.JavaMirrors$JavaMirror.classSymbol(JavaMirrors.scala:239)
        at scala.reflect.runtime.JavaMirrors$JavaMirror.classSymbol(JavaMirrors.scala:70)
        at example.TestApp$.delayedEndpoint$example$TestApp$1(TestApp.scala:10)
        at example.TestApp$delayedInit$body.apply(TestApp.scala:5)
        at scala.Function0.apply$mcV$sp(Function0.scala:39)
        at scala.Function0.apply$mcV$sp$(Function0.scala:39)
        at scala.runtime.AbstractFunction0.apply$mcV$sp(AbstractFunction0.scala:17)
        at scala.App.$anonfun$main$1(App.scala:73)
        at scala.App.$anonfun$main$1$adapted(App.scala:73)
        at scala.collection.IterableOnceOps.foreach(IterableOnce.scala:553)
        at scala.collection.IterableOnceOps.foreach$(IterableOnce.scala:551)
        at scala.collection.AbstractIterable.foreach(Iterable.scala:920)
        at scala.App.main(App.scala:73)
        at scala.App.main$(App.scala:71)
        at example.TestApp$.main(TestApp.scala:5)
        at example.TestApp.main(TestApp.scala)
Exception in thread "main" java.lang.RuntimeException: error reading Scala signature of example.TestApp: unsafe symbol B (child of package A) in runtime reflection universe
        at scala.reflect.internal.pickling.UnPickler.unpickle(UnPickler.scala:48)
        at scala.reflect.runtime.JavaMirrors$JavaMirror.unpickleClass(JavaMirrors.scala:661)
        at scala.reflect.runtime.SymbolLoaders$TopClassCompleter.$anonfun$complete$3(SymbolLoaders.scala:37)
        at scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.scala:18)
        at scala.reflect.internal.SymbolTable.slowButSafeEnteringPhaseNotLaterThan(SymbolTable.scala:318)
        at scala.reflect.runtime.SymbolLoaders$TopClassCompleter.complete(SymbolLoaders.scala:34)
        at scala.reflect.internal.Symbols$Symbol.completeInfo(Symbols.scala:1555)
        at scala.reflect.internal.Symbols$Symbol.info(Symbols.scala:1518)
        at scala.reflect.runtime.SynchronizedSymbols$SynchronizedSymbol$$anon$8.scala$reflect$runtime$SynchronizedSymbols$SynchronizedSymbol$$super$info(SynchronizedSymbols.scala:206)
        at scala.reflect.runtime.SynchronizedSymbols$SynchronizedSymbol.info(SynchronizedSymbols.scala:158)
        at scala.reflect.runtime.SynchronizedSymbols$SynchronizedSymbol.info$(SynchronizedSymbols.scala:158)
        at scala.reflect.runtime.SynchronizedSymbols$SynchronizedSymbol$$anon$8.info(SynchronizedSymbols.scala:206)
        at scala.reflect.runtime.JavaMirrors$JavaMirror.coreLookup$1(JavaMirrors.scala:1038)
        at scala.reflect.runtime.JavaMirrors$JavaMirror.lookupClass$1(JavaMirrors.scala:1044)
        at scala.reflect.runtime.JavaMirrors$JavaMirror.classToScala1(JavaMirrors.scala:1049)
        at scala.reflect.runtime.JavaMirrors$JavaMirror.$anonfun$classToScala$1(JavaMirrors.scala:1026)
        at scala.reflect.runtime.JavaMirrors$JavaMirror.$anonfun$toScala$1(JavaMirrors.scala:138)
        at scala.reflect.runtime.TwoWayCaches$TwoWayCache.toScala(TwoWayCaches.scala:50)
        at scala.reflect.runtime.JavaMirrors$JavaMirror.toScala(JavaMirrors.scala:136)
        at scala.reflect.runtime.JavaMirrors$JavaMirror.classToScala(JavaMirrors.scala:1026)
        at scala.reflect.runtime.JavaMirrors$JavaMirror.classSymbol(JavaMirrors.scala:239)
        at scala.reflect.runtime.JavaMirrors$JavaMirror.classSymbol(JavaMirrors.scala:70)
        at example.TestApp$.delayedEndpoint$example$TestApp$1(TestApp.scala:10)
        at example.TestApp$delayedInit$body.apply(TestApp.scala:5)
        at scala.Function0.apply$mcV$sp(Function0.scala:39)
        at scala.Function0.apply$mcV$sp$(Function0.scala:39)
        at scala.runtime.AbstractFunction0.apply$mcV$sp(AbstractFunction0.scala:17)
        at scala.App.$anonfun$main$1(App.scala:73)
        at scala.App.$anonfun$main$1$adapted(App.scala:73)
        at scala.collection.IterableOnceOps.foreach(IterableOnce.scala:553)
        at scala.collection.IterableOnceOps.foreach$(IterableOnce.scala:551)
        at scala.collection.AbstractIterable.foreach(Iterable.scala:920)
        at scala.App.main(App.scala:73)
        at scala.App.main$(App.scala:71)
        at example.TestApp$.main(TestApp.scala:5)
        at example.TestApp.main(TestApp.scala)