[GROOVY-9385] Access to outer class private field from closure leads to ClassCastException (@CompileStatic) - ASF JIRA

Details

Type: Bug
Status: Closed
Priority: Major
Resolution: Fixed
Affects Version/s: 3.0.0-rc-3
Fix Version/s: 4.0.0-alpha-1, 3.0.1, 2.5.16
Component/s: Static compilation
Labels:
None
Environment:

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openjdk version "11.0.5" 2019-10-15 LTS
OpenJDK Runtime Environment Zulu11.35+15-CA (build 11.0.5+10-LTS)
OpenJDK 64-Bit Server VM Zulu11.35+15-CA (build 11.0.5+10-LTS, mixed mode)
Gradle 6.1.1
Windows 10
JAVA_TOOL_OPTIONS: "-XX:+UsePerfData" "-Duser.language=en" "-Duser.country=US" "-Duser.timezone=UTC" "-Dfile.encoding=UTF-8"
ASM 7.3.1

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openjdk version "11.0.5" 2019-10-15 LTS OpenJDK Runtime Environment Zulu11.35+15-CA (build 11.0.5+10-LTS) OpenJDK 64-Bit Server VM Zulu11.35+15-CA (build 11.0.5+10-LTS, mixed mode) Gradle 6.1.1 Windows 10 JAVA_TOOL_OPTIONS: "-XX:+UsePerfData" "-Duser.language=en" "-Duser.country=US" "-Duser.timezone=UTC" "-Dfile.encoding=UTF-8" ASM 7.3.1

Description

Given the following code:

package org.example

import groovy.transform.CompileStatic
import org.objectweb.asm.ClassReader
import org.objectweb.asm.util.TraceClassVisitor

@CompileStatic
class OuterClass {
    private int counter

    void call() {
        { ->
            def closureClassName = new Throwable().stackTrace[0].className
            counter++

            printClass(closureClassName)
        }.call()
    }

    static void printClass(String className) {
        new ClassReader(className).accept(new TraceClassVisitor(new PrintWriter(System.err)), ClassReader.EXPAND_FRAMES)
    }

    static void main(String[] args) {
        try {
            new OuterClass().call()
        } catch (ClassCastException e) {
            printClass(e.stackTrace[0].className)
            throw e
        }
    }
}

Groovy 3.0.0-rc-3

Compilation OK
Runtime ClassCastException

Exception in thread "main" java.lang.ClassCastException: class org.example.OuterClass$_call_closure1 cannot be cast to class org.example.OuterClass (org.example.OuterClass$_call_closure1 and org.example.OuterClass are in unnamed module of loader 'app')
	at org.example.OuterClass$_call_closure1.doCall(OuterClass.groovy:14)
	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 org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:107)
	at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:323)
	at org.codehaus.groovy.runtime.metaclass.ClosureMetaClass.invokeMethod(ClosureMetaClass.java:263)
	at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1027)
	at groovy.lang.Closure.call(Closure.java:412)
	at groovy.lang.Closure.call(Closure.java:406)
	at org.example.OuterClass.call(OuterClass.groovy:12)
	at org.example.OuterClass.main(OuterClass.groovy:26)

Execution failed for task ':OuterClass.main()'.
> Process 'command 'C:/Program Files/Java/zulu11.35.15-ca-jdk11.0.5-win_x64/bin/java.exe'' finished with non-zero exit value 1

Disassembled view from ASM (preceding the exception):

// class version 55.0 (55)
// access flags 0x31
public final class org/example/OuterClass$_call_closure1 extends groovy/lang/Closure implements org/codehaus/groovy/runtime/GeneratedClosure {

  // compiled from: OuterClass.groovy
  OUTERCLASS org/example/OuterClass call ()V
  // access flags 0x11
  public final INNERCLASS org/example/OuterClass$_call_closure1 null _call_closure1

  // access flags 0x100A
  private static synthetic Lorg/codehaus/groovy/reflection/ClassInfo; $staticClassInfo

  // access flags 0x1089
  public static transient synthetic Z __$stMC

  // access flags 0x1
  public <init>(Ljava/lang/Object;Ljava/lang/Object;)V
   L0
    ALOAD 0
    ALOAD 1
    ALOAD 2
    INVOKESPECIAL groovy/lang/Closure.<init> (Ljava/lang/Object;Ljava/lang/Object;)V
   L1
    RETURN
    LOCALVARIABLE this Lorg/example/OuterClass$_call_closure1; L0 L1 0
    LOCALVARIABLE _outerInstance Ljava/lang/Object; L0 L1 1
    LOCALVARIABLE _thisObject Ljava/lang/Object; L0 L1 2
    MAXSTACK = 3
    MAXLOCALS = 3

  // access flags 0x1
  public doCall()Ljava/lang/Object;
   L0
    LINENUMBER 13 L0
    NEW java/lang/Throwable
    DUP
    INVOKESPECIAL java/lang/Throwable.<init> ()V
    INVOKEVIRTUAL java/lang/Throwable.getStackTrace ()[Ljava/lang/StackTraceElement;
    ICONST_0
    INVOKESTATIC org/codehaus/groovy/runtime/BytecodeInterface8.objectArrayGet ([Ljava/lang/Object;I)Ljava/lang/Object;
    CHECKCAST java/lang/StackTraceElement
    INVOKEVIRTUAL java/lang/StackTraceElement.getClassName ()Ljava/lang/String;
    ASTORE 1
   L1
    ALOAD 1
    POP
   L2
    LINENUMBER 14 L2
    ALOAD 0
    CHECKCAST org/example/OuterClass
    LDC "counter"
    INVOKEINTERFACE groovy/lang/GroovyObject.getProperty (Ljava/lang/String;)Ljava/lang/Object; (itf)
    DUP
    ASTORE 2
    INVOKESTATIC org/codehaus/groovy/runtime/typehandling/DefaultTypeTransformation.intUnbox (Ljava/lang/Object;)I
    ICONST_1
    IADD
    DUP
    INVOKESTATIC java/lang/Integer.valueOf (I)Ljava/lang/Integer;
    LDC Lorg/example/OuterClass$_call_closure1;.class
    ALOAD 0
    LDC "counter"
    CHECKCAST java/lang/String
    INVOKESTATIC org/codehaus/groovy/runtime/ScriptBytecodeAdapter.setGroovyObjectProperty (Ljava/lang/Object;Ljava/lang/Class;Lgroovy/lang/GroovyObject;Ljava/lang/String;)V
    POP
    ALOAD 2
    POP
   L3
    LINENUMBER 16 L3
    ALOAD 1
    INVOKESTATIC org/example/OuterClass.printClass (Ljava/lang/String;)V
    ACONST_NULL
    ARETURN
   L4
   FRAME FULL [] [java/lang/Throwable]
    NOP
    ATHROW
    LOCALVARIABLE this Lorg/example/OuterClass$_call_closure1; L0 L4 0
    LOCALVARIABLE closureClassName Ljava/lang/String; L1 L4 1
    MAXSTACK = 5
    MAXLOCALS = 3

  // access flags 0x1004
  protected synthetic $getStaticMetaClass()Lgroovy/lang/MetaClass;
    ALOAD 0
    INVOKEVIRTUAL java/lang/Object.getClass ()Ljava/lang/Class;
    LDC Lorg/example/OuterClass$_call_closure1;.class
    IF_ACMPEQ L0
    ALOAD 0
    INVOKESTATIC org/codehaus/groovy/runtime/ScriptBytecodeAdapter.initMetaClass (Ljava/lang/Object;)Lgroovy/lang/MetaClass;
    ARETURN
   L0
   FRAME FULL [org/example/OuterClass$_call_closure1] []
    GETSTATIC org/example/OuterClass$_call_closure1.$staticClassInfo : Lorg/codehaus/groovy/reflection/ClassInfo;
    ASTORE 1
    ALOAD 1
    IFNONNULL L1
    ALOAD 0
    INVOKEVIRTUAL java/lang/Object.getClass ()Ljava/lang/Class;
    INVOKESTATIC org/codehaus/groovy/reflection/ClassInfo.getClassInfo (Ljava/lang/Class;)Lorg/codehaus/groovy/reflection/ClassInfo;
    DUP
    ASTORE 1
    PUTSTATIC org/example/OuterClass$_call_closure1.$staticClassInfo : Lorg/codehaus/groovy/reflection/ClassInfo;
   L1
   FRAME FULL [org/example/OuterClass$_call_closure1 org/codehaus/groovy/reflection/ClassInfo] []
    ALOAD 1
    INVOKEVIRTUAL org/codehaus/groovy/reflection/ClassInfo.getMetaClass ()Lgroovy/lang/MetaClass;
    ARETURN
    MAXSTACK = 2
    MAXLOCALS = 2
}

Groovy 2.5.9

Compilation OK
No runtime exception

Disassembled view of the closure

// class version 55.0 (55)
// access flags 0x31
public final class org/example/OuterClass$_call_closure1 extends groovy/lang/Closure implements org/codehaus/groovy/runtime/GeneratedClosure {

  // compiled from: OuterClass.groovy
  OUTERCLASS org/example/OuterClass call ()V
  // access flags 0x11
  public final INNERCLASS org/example/OuterClass$_call_closure1 null _call_closure1

  // access flags 0x100A
  private static synthetic Lorg/codehaus/groovy/reflection/ClassInfo; $staticClassInfo

  // access flags 0x1089
  public static transient synthetic Z __$stMC

  // access flags 0x1
  public <init>(Ljava/lang/Object;Ljava/lang/Object;)V
   L0
    ALOAD 0
    ALOAD 1
    ALOAD 2
    INVOKESPECIAL groovy/lang/Closure.<init> (Ljava/lang/Object;Ljava/lang/Object;)V
   L1
    RETURN
    LOCALVARIABLE this Lorg/example/OuterClass$_call_closure1; L0 L1 0
    LOCALVARIABLE _outerInstance Ljava/lang/Object; L0 L1 1
    LOCALVARIABLE _thisObject Ljava/lang/Object; L0 L1 2
    MAXSTACK = 3
    MAXLOCALS = 3

  // access flags 0x1
  public doCall()Ljava/lang/Object;
   L0
    LINENUMBER 13 L0
    NEW java/lang/Throwable
    DUP
    INVOKESPECIAL java/lang/Throwable.<init> ()V
    INVOKEVIRTUAL java/lang/Throwable.getStackTrace ()[Ljava/lang/StackTraceElement;
    ICONST_0
    INVOKESTATIC org/codehaus/groovy/runtime/BytecodeInterface8.objectArrayGet ([Ljava/lang/Object;I)Ljava/lang/Object;
    CHECKCAST java/lang/StackTraceElement
    INVOKEVIRTUAL java/lang/StackTraceElement.getClassName ()Ljava/lang/String;
    ASTORE 1
   L1
    ALOAD 1
    POP
   L2
    LINENUMBER 14 L2
    ALOAD 0
    INVOKEVIRTUAL groovy/lang/Closure.getThisObject ()Ljava/lang/Object;
    CHECKCAST org/example/OuterClass
    INVOKESTATIC org/example/OuterClass.pfaccess$0 (Lorg/example/OuterClass;)I
    DUP
    ISTORE 2
    ICONST_1
    IADD
    DUP
    INVOKESTATIC java/lang/Integer.valueOf (I)Ljava/lang/Integer;
    LDC Lorg/example/OuterClass$_call_closure1;.class
    ALOAD 0
    LDC "counter"
    CHECKCAST java/lang/String
    INVOKESTATIC org/codehaus/groovy/runtime/ScriptBytecodeAdapter.setGroovyObjectProperty (Ljava/lang/Object;Ljava/lang/Class;Lgroovy/lang/GroovyObject;Ljava/lang/String;)V
    POP
    ILOAD 2
    POP
   L3
    LINENUMBER 16 L3
    ALOAD 1
    INVOKESTATIC org/example/OuterClass.printClass (Ljava/lang/String;)V
    ACONST_NULL
    ARETURN
   L4
   FRAME FULL [] [java/lang/Throwable]
    NOP
    ATHROW
    LOCALVARIABLE this Lorg/example/OuterClass$_call_closure1; L0 L4 0
    LOCALVARIABLE closureClassName Ljava/lang/String; L1 L4 1
    MAXSTACK = 5
    MAXLOCALS = 3

  // access flags 0x1004
  protected synthetic $getStaticMetaClass()Lgroovy/lang/MetaClass;
    ALOAD 0
    INVOKEVIRTUAL java/lang/Object.getClass ()Ljava/lang/Class;
    LDC Lorg/example/OuterClass$_call_closure1;.class
    IF_ACMPEQ L0
    ALOAD 0
    INVOKESTATIC org/codehaus/groovy/runtime/ScriptBytecodeAdapter.initMetaClass (Ljava/lang/Object;)Lgroovy/lang/MetaClass;
    ARETURN
   L0
   FRAME FULL [org/example/OuterClass$_call_closure1] []
    GETSTATIC org/example/OuterClass$_call_closure1.$staticClassInfo : Lorg/codehaus/groovy/reflection/ClassInfo;
    ASTORE 1
    ALOAD 1
    IFNONNULL L1
    ALOAD 0
    INVOKEVIRTUAL java/lang/Object.getClass ()Ljava/lang/Class;
    INVOKESTATIC org/codehaus/groovy/reflection/ClassInfo.getClassInfo (Ljava/lang/Class;)Lorg/codehaus/groovy/reflection/ClassInfo;
    DUP
    ASTORE 1
    PUTSTATIC org/example/OuterClass$_call_closure1.$staticClassInfo : Lorg/codehaus/groovy/reflection/ClassInfo;
   L1
   FRAME FULL [org/example/OuterClass$_call_closure1 org/codehaus/groovy/reflection/ClassInfo] []
    ALOAD 1
    INVOKEVIRTUAL org/codehaus/groovy/reflection/ClassInfo.getMetaClass ()Lgroovy/lang/MetaClass;
    ARETURN
    MAXSTACK = 2
    MAXLOCALS = 2
}

It seems the call to getThisObject is missing (not sure whether Groovy 3 expects that part to change):

Groovy 3.0.0-rc-3

    LINENUMBER 14 L2
    ALOAD 0
    CHECKCAST org/example/OuterClass

Groovy 2.5.9

    LINENUMBER 14 L2
    ALOAD 0
    INVOKEVIRTUAL groovy/lang/Closure.getThisObject ()Ljava/lang/Object;
    CHECKCAST org/example/OuterClass

Access to outer class private field from closure leads to ClassCastException (@CompileStatic)

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