[jboss-jira] [JBoss JIRA] Created: (JASSIST-51) Editing a NewExpr results in a VerifyError (inconsistent stack height)
Editing a NewExpr results in a VerifyError (inconsistent stack height)
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Key: JASSIST-51
URL: http://jira.jboss.com/jira/browse/JASSIST-51
Project: Javassist
Issue Type: Bug
Environment: Javassist 3.7, JDK 1.6.0_03 on WinXP
Reporter: Yanic Inghelbrecht
Assigned To: Shigeru Chiba
The code below is the simplest case I could find that reproduces the error. The code
contains two classes : Client and Main. Client is the class that gets instrumented, Main
does the instrumenting. The error that result is :
Exception in thread "main" java.lang.VerifyError: (class: test_try_catch/Client,
method: instrumentMe signature: ()V) Inconsistent stack height 0 != 1
at java.lang.Class.getDeclaredConstructors0(Native Method)
at java.lang.Class.privateGetDeclaredConstructors(Unknown Source)
at java.lang.Class.getConstructor0(Unknown Source)
at java.lang.Class.newInstance0(Unknown Source)
at java.lang.Class.newInstance(Unknown Source)
at test_try_catch.Main.main(Main.java:30)
Javassist somehow messes up on instrumenting the NewExpr in method Client#instrumentMe
The weird thing about this bug is, the verifyError only occurs when the method containing
the NewExpr also contains a try/catch block!
For me this is a show stopper, not using try/catch blocks is not really an option :o)
I hope you agree this is a high priority issue, because our project cannot be released
because of this.
Best regards,
Yanic
--------- source code for Client.java below
package test_try_catch;
import java.util.ArrayList;
public class Client {
public void instrumentMe() {
// we need a 'new' expression to instrument, the exact type is not important
new Object();
// if the try/catch block below is removed, the error does not occur
try {
System.out.println();
} catch (Throwable t) {
//
}
}
}
--------- source code for Main.java below
package test_try_catch;
import java.lang.reflect.Method;
import javassist.CannotCompileException;
import javassist.ClassPool;
import javassist.CtClass;
import javassist.CtMethod;
import javassist.Loader;
import javassist.NotFoundException;
import javassist.Translator;
import javassist.expr.ExprEditor;
import javassist.expr.NewExpr;
public class Main {
public static void main(String[] args) throws Exception {
ClassPool pool = new ClassPool(true);
Loader cl = new Loader();
try {
cl.addTranslator(pool, new MyTranslator());
} catch (Exception e) {
e.printStackTrace();
return;
}
// load the Client class
Class clientClass=cl.loadClass("test_try_catch.Client");
// create an instance
Object client=clientClass.newInstance();
// execute Client#instrumentMe
Method callMethod=clientClass.getMethod("instrumentMe", new Class[]{});
callMethod.invoke(client, new Object[]{});
}
static public class MyTranslator extends ExprEditor implements Translator {
public void onLoad(ClassPool pool, String classname) throws NotFoundException,
CannotCompileException {
CtClass cc = pool.get(classname);
modify(cc);
}
public void modify(CtClass c) throws CannotCompileException {
for (CtMethod m : c.getMethods()) {
m.instrument(this);
}
}
@Override
public void edit(NewExpr m) throws CannotCompileException {
// no changes, for simplicity's sake
String block = "{$_=$proceed($$);}";
m.replace(block);
}
public void start(ClassPool pool) throws NotFoundException, CannotCompileException {
// do nothing
}
}
}
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