[LOG4J2-3609] javac error when PluginProcessor (log4j-core jar) is in the classpath and annotation is not

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 2.19.0
• Component/s: Core

Environment

The problem seems to be reproducible in every JDK. I tested with JDK 8, 11, 19, and 19.

• Assignee: Matt Sicker
• Reporter: Stamatis Zampetakis
• Created: 27/Sep/22 12:04
• Updated: 21/Oct/22 19:29

Description

Java compilation (javac) fails to compile a class when the following conditions hold:

• the class transitively depends on an annotation;
• the annotation is not in the classpath;
• the log4j annotation processor (PluginProcessor) is in the classpath.

Assuming that MyAnnotation.class is not in the classpath the error is the one shown below.

error: cannot access MyAnnotation
  class file for MyAnnotation not found
1 error

I admit that not including the annotation in the classpath could be considered a problem in general but there is no reason why the compilation should fail only when the log4j jar is in the classpath.

It is pretty clear that the problem is related to the annotation processor present in log4j-core jar (PluginProcessor) cause removing the respective entries from the jar allows compilation to complete sucessfully.

From the JDK perspective, it seems that this scenario was considered as a bug and was fixed somewhere in JDK6 allowing compilation to proceed even when annotations are missing from the classpath:
https://bugs.java.com/bugdatabase/view_bug.do?bug_id=6365854

I will upload a minimal scenario with exact steps to reproduce the problem in a few minutes.

Issue Links

• is related to: CALCITE-5300 Cannot access org.immutables.value.Value error when extending standard rules
• is related to: SOLR-16443 Upgrade Jackson bom to 2.13.4.20221013