JDK-5011080 : A constructor call to an inner class that extends Enum crashes javac.
  • Type: Bug
  • Component: tools
  • Sub-Component: javac
  • Affected Version: 5.0
  • Priority: P4
  • Status: Closed
  • Resolution: Duplicate
  • OS: linux
  • CPU: x86
  • Submitted: 2004-03-10
  • Updated: 2004-03-10
  • Resolved: 2004-03-10
Related Reports
Duplicate :  
Description

Name: rmT116609			Date: 03/10/2004


FULL PRODUCT VERSION :
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0-beta-b32c)
Java HotSpot(TM) Client VM (build 1.5.0-beta-b32c, mixed mode)

ADDITIONAL OS VERSION INFORMATION :
Linux localhost.localdomain 2.4.20-8 #1 Thu Mar 13 17:54:28 EST 2003 i686 i686
i386 GNU/Linux

A DESCRIPTION OF THE PROBLEM :
A programmer can write an inner class that subclasses the type java.lang.Enum
(itself illegal!). A statement to instantiate this class, e.g. by calling the no-arg public constructor, will cause the compiler to crash. Specifically the constructor statement must come prior to the declaration of the inner class (the compiler will produce a correct error message if the constructor statement comes after).


STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
see code example.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
An error message from javac such as 'enum types may not be instantiated'.

ACTUAL -
javac crashes (see error message).

ERROR MESSAGES/STACK TRACES THAT OCCUR :
[alexis@localhost examples]$ javac -source 1.5 -target 1.5 Outer.java
An exception has occurred in the compiler (1.5.0-beta). Please file a bug at the Java
Developer Connection (http://java.sun.com/cgi-bin/bugreport.cgi)  after checking the
  Bug Parade for duplicates. Include your program and the following diagnostic in your
report.  Thank you.
java.lang.NullPointerException
        at com.sun.tools.javac.comp.Lower.boxArgs(Lower.java:2312)
        at com.sun.tools.javac.comp.Lower.visitNewClass(Lower.java:2095)
        at com.sun.tools.javac.tree.Tree$NewClass.accept(Tree.java:841)
        at com.sun.tools.javac.comp.Lower.translate(Lower.java:1739)
        at com.sun.tools.javac.comp.Lower.translate(Lower.java:1751)
        at com.sun.tools.javac.comp.Lower.visitVarDef(Lower.java:2708)
        at com.sun.tools.javac.tree.Tree$VarDef.accept(Tree.java:511)
        at com.sun.tools.javac.comp.Lower.translate(Lower.java:1739)
        at com.sun.tools.javac.comp.Lower.visitClassDef(Lower.java:1821)
        at com.sun.tools.javac.tree.Tree$ClassDef.accept(Tree.java:438)
        at com.sun.tools.javac.comp.Lower.translate(Lower.java:1739)
        at com.sun.tools.javac.comp.Lower.translate(Lower.java:1759)
        at com.sun.tools.javac.comp.Lower.translateTopLevelClass(Lower.java:2830)
        at com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:455)
        at com.sun.tools.javac.main.Main.compile(Main.java:593)
        at com.sun.tools.javac.main.Main.compile(Main.java:545)
        at com.sun.tools.javac.Main.compile(Main.java:44)
        at com.sun.tools.javac.Main.main(Main.java:35)


REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
public class Outer {
    // The line below will crash the compiler:
    Inner inner = new Inner();
    // The line below is an illegal declaration (but the compiler allows it):
    class Inner extends Enum {
    }
}


---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
Do not write inner classes that extend java.lang.Enum (this is illegal anyway).
(Incident Review ID: 242873) 
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