6:13 a.m.
VerifyError (constructor must call super() or this()) through ConstructorCall#replace when
block includes a try/catch block
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Key: JASSIST-53
URL: http://jira.jboss.com/jira/browse/JASSIST-53
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
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_for_constructor_call/Client, method:
<init> signature: ()V) Constructor must call super() or this()
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_for_constructor_call.Main.main(Main.java:31)
Also, when the replacement block uses $0 (the constructed object), for example :
String block = "{try {$_=$proceed($$);} catch (Throwable t)
{System.out.println($0);}}";
the error message changes to :
Exception in thread "main" java.lang.VerifyError: (class:
test_verify_error_with_try_catch_in_replace_for_constructor_call/Client, method:
<init> signature: ()V) Register 1 contains wrong type
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_for_constructor_call.Main.main(Main.java:31)
Again, this is related (for me at least) to JIRA JAVASSIST 51 and 52, since those also
deal with adding a try/catch block using replace in an ExprEditor#edit method.
So far I've reported three issues all related to adding try/catch block with a replace
in ExprEditor#edit :
51 for NewExpr
52 for MethodCall
53 for ConstructorCall
I don't use the other ExprEditor#edit methods (i.e. edit(Handler), edit(FieldAccess),
...), so I don't expect to report any similar issues. However, you may want to check
them to see if they suffer from the same problem.
I hope it's an easy fix for you!
Best regards,
Yanic
-- source for Client.java
package test_verify_error_with_try_catch_in_replace_for_constructor_call;
public class Client {
//
}
-- source for Main.java
package test_verify_error_with_try_catch_in_replace_for_constructor_call;
import java.lang.reflect.Method;
import javassist.CannotCompileException;
import javassist.ClassPool;
import javassist.CtBehavior;
import javassist.CtClass;
import javassist.CtMethod;
import javassist.Loader;
import javassist.NotFoundException;
import javassist.Translator;
import javassist.expr.ConstructorCall;
import javassist.expr.ExprEditor;
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_for_constructor_call.Client");
// create an instance
Object client=clientClass.newInstance();
}
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 (CtBehavior b : c.getDeclaredBehaviors()) {
b.instrument(this);
}
}
@Override
public void edit(ConstructorCall cc) throws CannotCompileException {
// simple proceed surrounded by a try/catch block
// each block gives a different VerifyError
String block = "{try {$_=$proceed($$);} catch (Throwable t) {}}";
// String block = "{try {$_=$proceed($$);} catch (Throwable t)
{System.out.println($0);}}";
cc.replace(block);
}
public void start(ClassPool pool) throws NotFoundException, CannotCompileException {
// do nothing
}
}
}
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