[jboss-jira] [JBoss JIRA] Closed: (JASSIST-52) VerifyError (inconsistent stack height) through MethodCall#replace when block includes a try/catch block

VerifyError (inconsistent stack height) through MethodCall#replace when block includes a try/catch block -------------------------------------------------------------------------------------------------------- Key: JASSIST-52 URL: http://jira.jboss.com/jira/browse/JASSIST-52 Project: Javassist Issue Type: Bug Environment: javassist 3.7.1 (from cvs HEAD), jdk 1.6.0_03 on winXP Reporter: Yanic Inghelbrecht Assigned To: Shigeru Chiba Attachments: supplement_to_jassist-52.zip Included is the simplest test case I could find that reproduces the error, it consists of two classes : Client (to be instrumented) and Main (does the instrumentation). When run, it produces the following exception trace : Exception in thread "main" java.lang.VerifyError: (class: test_verify_error_with_try_catch_in_replace/Client, method: instrumentMe signature: ()V) Inconsistent stack height 0 != 2 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_verify_error_with_try_catch_in_replace.Main.main(Main.java:30) The error disappears in all of the following cases (so it must be related to them I guess) : - when the try/catch block is removed from the replacement block - when the string concatenation happens without using two local variables - when the string concatenation is removed but the local variables are kept This is related (for me at least) to JIRA JAVASSIST 51, where a similar error occurred for NewExpr (and was quickly fixed, thanks again for that!!). Just like issue 51, it is a show stopper for our project since it all ties in with the support for exceptions in the development tool we're creating, so I hope you will again regard it as an urgent issue. Thanks in advance. Best regards, Yanic -- source code for client.java package test_verify_error_with_try_catch_in_replace; public class Client { public void instrumentMe() throws Exception { // the error is somehow related to the string concatenation and local variables, // when the code below is replaced with something else, the error does not occur. String s1 = "a"; String s2 = s1 + "b"; } } -- source code for Main.java package test_verify_error_with_try_catch_in_replace; 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.MethodCall; 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_verify_error_with_try_catch_in_replace.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(MethodCall mc) throws CannotCompileException { // simple proceed surrounded by a try/catch block String block = "{try{$_=$proceed($$);} catch(Throwable t) {}}"; mc.replace(block); } public void start(ClassPool pool) throws NotFoundException, CannotCompileException { // do nothing } } }