[slf4j-dev] [JIRA] (SLF4J-487) module-info.class must be in root of jar, not META-INF/versions/9

[QOS.CH (JIRA)]

Joakim Erdfelt created SLF4J-487:
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             Summary: module-info.class must be in root of jar, not META-INF/versions/9
                 Key: SLF4J-487
                 URL: https://jira.qos.ch/browse/SLF4J-487
             Project: SLF4J
          Issue Type: Bug
          Components: Core API
    Affects Versions: 2.0.0-alpha1
         Environment: Also reported here [https://github.com/qos-ch/slf4j/commit/fb418db538a4990#r37662713]

This triggers build warnings on javac.

The {{module-info.class}} shouldn't be in the {{META-INF/versions/9}} in the jar file, it should be in the root of the jar file.

Yes, I'm aware of -SLF4J-456-, but that's a bug in websphere's annotation parsing (a similar bug that *all* web containers have had to fix since [JEP238|https://openjdk.java.net/jeps/238] became a reality).

>From maven (Eclipse Jetty 10.x is migrating to Slf4j 2.0.0-alpha1 btw).

{noformat}
 [INFO] — maven-compiler-plugin:3.8.1:compile (default-compile) @ jetty-slf4j-impl —
 [INFO] Changes detected - recompiling the module!
 [INFO] Compiling 9 source files to /home/joakim/code/jetty/jetty.project-10.0.x/jetty-slf4j-impl/target/classes
 [WARNING] /home/joakim/code/jetty/jetty.project-10.0.x/jetty-slf4j-impl/src/main/java/module-info.java:[26,28] requires transitive directive for an automatic module
{noformat}

Using {{javac -Xlint:all ...}} on a project using {{slf4j-api-2.0.0-alpha1.jar}} with it's own {{module-info.class}} will show the above warning.

If you want a small example project, I'll be happy to make one for you.

The warning is because the {{module-info.class}} is not present at the root of the jar file (where it must be, despite the jigsaw devs brief suggestion in 2018 that {{META-INF/versions/9}} could be a solution for bytecode scanning problems, other tooling in the JDK hasn't caught up yet to that suggestion, even in JDK 14, even including {{javac}}).

javac sees {{slf4j-api-2.0.0-alpha1.jar}} as having no {{module-info.class}} and is instead using the jar as one with an automatic module name.

Manually repackaging {{slf4j-api-2.0.0-alpha1.jar}} with the {{module-info.class}} in the root fixes the javac warnings.
            Reporter: Joakim Erdfelt
            Assignee: SLF4J developers list






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