[jboss-jira] [JBoss JIRA] Resolved: (JASSIST-51) Editing a NewExpr results in a VerifyError (inconsistent stack height)

Editing a NewExpr results in a VerifyError (inconsistent stack height) ---------------------------------------------------------------------- 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 } } }