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https://issues.apache.org/jira/browse/BCEL-4?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13511614#comment-13511614
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Emmanuel Bourg edited comment on BCEL-4 at 4/24/14 10:05 AM:
-------------------------------------------------------------
This is not a "simple" bug. Interfaces implemented directly are NOT forgotten.
{code}
import org.apache.bcel.*;
import org.apache.bcel.classfile.*;
public class Test {
public static void main(String[] args) {
JavaClass a = Repository.lookupClass("A");
JavaClass c = Repository.lookupClass("B");
System.out.println(a.implementationOf(c));
}
}
{code}
This program prints "true"; and JavaClass.implementationOf() is what the static
Repository methods are mapped to. The original test program lets the VERIFIER
fail, it has a bug in its pass 3b implementation:
{code}
Pass 3b, method number 0 ['void <init>()']:VERIFIED_REJECTED
Constraint violated in method 'void <init>()':Instruction INVOKESPECIAL
constraint violated: The 'objref' item '<UNINITIALIZED OBJECT OF TYPE 'A'>'
does not implement 'java.lang.Object' as expected.InstructionHandle:
1: invokespecial[183](3) 1
Execution Frame:
Local Variables:0: <UNINITIALIZED OBJECT OF TYPE 'A'>
OperandStack:
Slots used: 1
MaxStack: 1.<UNINITIALIZED OBJECT OF TYPE 'A'> (Size: 1)
Execution flow:
0: aload_0 [InstructionContext]
1: invokespecial 1 [InstructionContext]
{code}
Problem is that the JVM spec 4.9.4 mentions UNINITIALIZED objects as a special
type, and this type indeed does not implement any interfaces.
was (Author: [email protected]):
This is not a "simple" bug. Interfaces implemented directly are
NOTforgotten.---------import org.apache.bcel.*;import
org.apache.bcel.classfile.*; public class Test{public static void main(String[]
args){ JavaClass a = Repository.lookupClass("A"); JavaClass c =
Repository.lookupClass("B");
System.out.println(a.implementationOf(c));}}-------This program prints "true";
and JavaClass.implementationOf()is what the static Repository methods are
mapped to.The original test program lets the VERIFIER fail, it hasa bug in its
pass 3b implementation:----------------Pass 3b, method number 0 ['void
<init>()']:VERIFIED_REJECTEDConstraint violated in method 'void
<init>()':Instruction INVOKESPECIAL constraint violated: The 'objref' item
'<UNINITIALIZED OBJECT OF TYPE 'A'>' does not implement 'java.lang.Object' as
expected.InstructionHandle: 1: invokespecial[183](3) 1 Execution Frame:Local
Variables:0: <UNINITIALIZED OBJECT OF TYPE 'A'>OperandStack:Slots used: 1
MaxStack: 1.<UNINITIALIZED OBJECT OF TYPE 'A'> (Size: 1)Execution flow: 0:
aload_0 [InstructionContext] 1: invokespecial 1
[InstructionContext]-----------------Problem is that the JVM spec 4.9.4
mentions UNINITIALIZEDobjects as a special type, and this type indeed does
notimplement any interfaces.
> Pass3b Verifier is corrupted
> ----------------------------
>
> Key: BCEL-4
> URL: https://issues.apache.org/jira/browse/BCEL-4
> Project: Commons BCEL
> Issue Type: Bug
> Components: Main
> Affects Versions: 5.0
> Environment: Operating System: All
> Platform: All
> Reporter: Peter Schneider
> Assignee: Apache Commons Developers
>
> The Repostiroty method
> public static boolean implementationOf(JavaClass clazz, JavaClass inter);
> Isn't working correctly. Therefore the Cast checks performed in the Pass3b
> verifier are wrong.
> With this simple program the verifcation fails.
> (tested with jdk1.4.0 W32)
> <code>
> class A implements B{
> static C temp;
> public static void main(String[] args){
> temp = new A();
> }
> }
> interface B extends C{
> }
> interface C{
> }
> </code>
> The reason is simple. Interfaces are checked only directly. Interfaces
> inherited indirectly are forgotten.
> There is another version of this bug, where even direct implemented
> interfaces
> are not recognized, but i wasn't able to reduce it to a simple example.
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