[jboss-user] [Javassist] - VerifyError with complex Javassist instrumentation

[Matt Benson]

Matt Benson [https://community.jboss.org/people/mbenson] created the discussion

"VerifyError with complex Javassist instrumentation"

To view the discussion, visit: https://community.jboss.org/message/805734#805734

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Hi, I'm working on a new OSS project to allow Java developers to declaratively handle the Java AccessController APIs.  One of our features is the concept of "method blueprinting" whereby the code requiring privileges is housed in a security-agnostic static implementation method.  Calls to such methods are translated to calls to local, cloned methods.  This basic concept is all working great with Javassist.  The problem occurs when such a "blueprint method" references a field.  I have created code to handle field accesses using reflection (as opposed to copying the field, which might then not be initialized, etc.).  I am by no means a bytecode expert, but I am familiar with recursive-descent parsers and I have stepped through the code that compiles my replacement statements; this all looks fine.  I have compared the bytecode Javassist is generating with the bytecode generated by javac to do the same type of field reflection and I (from my inexpert POV) cannot see anything that appears significant.  When I try to run my instrumented code I get VerifyError "Incompatible argument to function".  I am at a complete loss.  I would be highly appreciative if any experts were able to offer further advice on how to proceed.  If anyone is interested, the current code can be viewed at  http://svn.apache.org/repos/asf/commons/sandbox/weaver/branches/fields http://svn.apache.org/repos/asf/commons/sandbox/weaver/branches/fields .  Probably the easiest way to test is `mvn -DskipTests clean install` then `cd example; mvn test` to see the problem.

TIA,
Matt
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