MethodCall.replace() throws inconsistent stack height in certain scenarios -------------------------------------------------------------------------- Key: JASSIST-210 URL: https://issues.jboss.org/browse/JASSIST-210 Project: Javassist Issue Type: Bug Affects Versions: 3.16.1-GA, 3.18.1-GA Reporter: Patson Luk Assignee: Shigeru Chiba Tested on 3.16.1-GA This is similar to https://issues.jboss.org/browse/JASSIST-52, but the try-catch block usage is different (not wrapping the $proceed($$)) Based on the javassist tutorial, the substituted code for MethodCall.replace(): {{Note that the substituted code is not an expression but a statement or a block. It cannot be or contain a try-catch statement.}} However in the case that try-catch does not wrap the $_=$proceed($$); It seems to work properly. For example: ctClass.instrument(new ExprEditor() { public void edit(MethodCall m) throws CannotCompileException { if (m.getMethodName().equals("testMethod2")) { String newBlock = "{ try { System.out.println(\"injected\"); } catch (Exception e) { e.printStackTrace(); } $_ = $proceed($$); }"; m.replace(newBlock); } } }); {{which ctClass is class TestReplace, which has code as below:}} public class TestReplace { public static void main(String[] args) { RefClass ref = new RefClass(); ref.testMethod2(); } } class RefClass { public void testMethod1(Object o) {} public Object testMethod2() { return null; } } {{running TestReplace with the modified bytecode correctly prints "injected" to the screen. However if I add one more line to the TestReplace's main() method}} ref.testMethod1(ref.testMethod2()); {{It throws exception as below}} javassist.bytecode.BadBytecode: inconsistent stack height -1 javassist.bytecode.stackmap.Tracer.doOpcode(Tracer.java:106) *So is try-catch acceptable if it does not wrap the $_=$proceed($$)? If so, is it a bug if it does not work properly for method invocation within another method invocation?* Many thanks in advance!