[jira] Commented: (MCOMPILER-97) META-INF/services/javax.annotation.processing.Processor copied before compilation and causes error

["Kohsuke Kawaguchi (JIRA)" <ji...@codehaus.org>]

    [ https://jira.codehaus.org/browse/MCOMPILER-97?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=272516#comment-272516 ] 

Kohsuke Kawaguchi commented on MCOMPILER-97:
--------------------------------------------

The original description of the issue says "when using -source 1.6 or higher" in the end, but that doesn't make sense. The question is if the build is using JDK6 or above to compile, not whether it's producing 1.6 compatible files or 1.5 compatible files. JSR-269 still kicks in with -source 1.5.

Note that the problem is beyond just the maven-compiler-plugin. IDEs are also affected by this --- for example when IntelliJ IDEA compiles a subset of source files that are updated, it automatically adds the class file folder to classpath, and you get the same problem.

I wonder if this calls for a change in javac --- perhaps it shouldn't look for its own output directory to look for annotation processors. I can't think of a valid use case for doing that.

> META-INF/services/javax.annotation.processing.Processor copied before compilation and causes error
> --------------------------------------------------------------------------------------------------
>
>                 Key: MCOMPILER-97
>                 URL: https://jira.codehaus.org/browse/MCOMPILER-97
>             Project: Maven 2.x Compiler Plugin
>          Issue Type: Bug
>    Affects Versions: 2.0.2
>         Environment: Ubuntu 8.10, JDK 6.
>            Reporter: Jesse Glick
>         Attachments: maven-6647998-test.zip
>
>
> It is tricky to compile a Maven module which defines a (269-compliant) annotation processor. If you write the code for the processor in src/main/java and register it in src/main/resources, META-INF/services/javax.annotation.processing.Processor is copied to target/classes first, and then javac is run. But javac is given target/classes in -classpath, so it tries to load the processor, which of course has not been compiled yet - a chicken-and-egg problem.
> The most straightforward workaround is to specify <compilerArgument>-proc:none</compilerArgument> in your POM. This will only work, however, if the module does not use any annotation processors defined in dependencies. If it does, there may be some other trick involving -processorpath and Maven variable substitution to insert the dependency classpath.
> Switching the order of resources:resources and compiler:compile would help - at least a clean build would work - though it could still cause problems in incremental builds. Better would be for the compiler plugin to pass -processorpath based on the dependency classpath (i.e. -classpath minus target/classes) when using -source 1.6 or higher.

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