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Posted to log4j-dev@logging.apache.org by "ASF GitHub Bot (JIRA)" <ji...@apache.org> on 2016/04/27 04:45:13 UTC

[jira] [Commented] (LOG4J2-1157) log4j2 exception covers real compiler error (PR on GitHub)

    [ https://issues.apache.org/jira/browse/LOG4J2-1157?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15259436#comment-15259436 ] 

ASF GitHub Bot commented on LOG4J2-1157:
----------------------------------------

Github user asfgit closed the pull request at:

    https://github.com/apache/logging-log4j2/pull/14


> log4j2 exception covers real compiler error (PR on GitHub)
> ----------------------------------------------------------
>
>                 Key: LOG4J2-1157
>                 URL: https://issues.apache.org/jira/browse/LOG4J2-1157
>             Project: Log4j 2
>          Issue Type: Bug
>    Affects Versions: 2.4
>            Reporter: Norbert Bartels
>            Assignee: Matt Sicker
>             Fix For: 2.5
>
>
> There's already a Pull Request on Github: https://github.com/apache/logging-log4j2/pull/14
> *Explanation:*
> If you have a project you use log4j2 as logging framework and you have a class which is annotated with the log4j2 {{Plugin}} annotation and you have a different class with a not existing annotation, you can not compile the project. (You can run in that problem by forget a dependency or delete a jar, where the annotation is defined in.) This is rather normal, but the java compiler produces a "wrong" error message. The problem - the not existing annotation - is covered by a log4j2 error message and so you get something like:
> {code}
> java.lang.NullPointerException: Plugin annotation is null.
>     at java.util.Objects.requireNonNull(Objects.java:226)
>     at org.apache.logging.log4j.core.config.plugins.processor.PluginProcessor$PluginElementVisitor.visitType(PluginProcessor.java:126)
>     at org.apache.logging.log4j.core.config.plugins.processor.PluginProcessor$PluginElementVisitor.visitType(PluginProcessor.java:116)
>     at com.sun.tools.javac.code.Symbol$ClassSymbol.accept(Symbol.java:892)
>     at org.apache.logging.log4j.core.config.plugins.processor.PluginProcessor.collectPlugins(PluginProcessor.java:95)
>     at org.apache.logging.log4j.core.config.plugins.processor.PluginProcessor.process(PluginProcessor.java:73)
>     at com.sun.tools.javac.processing.JavacProcessingEnvironment.callProcessor(JavacProcessingEnvironment.java:793)
>     at com.sun.tools.javac.processing.JavacProcessingEnvironment.discoverAndRunProcs(JavacProcessingEnvironment.java:722)
>     at com.sun.tools.javac.processing.JavacProcessingEnvironment.access$1700(JavacProcessingEnvironment.java:97)
>     at com.sun.tools.javac.processing.JavacProcessingEnvironment$Round.run(JavacProcessingEnvironment.java:1029)
>     at com.sun.tools.javac.processing.JavacProcessingEnvironment.doProcessing(JavacProcessingEnvironment.java:1163)
>     at com.sun.tools.javac.main.JavaCompiler.processAnnotations(JavaCompiler.java:1108)
>     at com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:824)
>     at com.sun.tools.javac.main.Main.compile(Main.java:439)
>     at com.sun.tools.javac.main.Main.compile(Main.java:353)
>     at com.sun.tools.javac.main.Main.compile(Main.java:342)
>     at com.sun.tools.javac.main.Main.compile(Main.java:333)
>     at com.sun.tools.javac.Main.compile(Main.java:94)
>     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
>     at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
>     at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
>     at java.lang.reflect.Method.invoke(Method.java:606)
>     at org.codehaus.plexus.compiler.javac.JavacCompiler.compileInProcess(JavacCompiler.java:554)
>     at org.codehaus.plexus.compiler.javac.JavacCompiler.compile(JavacCompiler.java:161)
>     at org.apache.maven.plugin.AbstractCompilerMojo.execute(AbstractCompilerMojo.java:605)
>     at org.apache.maven.plugin.CompilerMojo.execute(CompilerMojo.java:128)
>     at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:101)
>     at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:209)
>     at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:153)
>     at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:145)
>     at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:84)
>     at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:59)
>     at org.apache.maven.lifecycle.internal.LifecycleStarter.singleThreadedBuild(LifecycleStarter.java:183)
>     at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:161)
>     at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:320)
>     at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:156)
>     at org.apache.maven.cli.MavenCli.execute(MavenCli.java:537)
>     at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:196)
>     at org.apache.maven.cli.MavenCli.main(MavenCli.java:141)
>     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
>     at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
>     at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
>     at java.lang.reflect.Method.invoke(Method.java:606)
>     at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:290)
>     at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:230)
>     at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:409)
>     at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:352)
> {code}
> But the correct error message should be:
> {code}
> COMPILATION ERROR : 
> -------------------------------------------------------------
> xxx/SomeClass.java:[3,1] error: cannot find symbol
> xxx/SomeClass.java:[3,1] error: cannot find symbol
> {code}
> The problem is the {{RoundEnvironment}}. Because it returns an element in the list ({{getElementsAnnotatedWith}}) that's {{null}}, so the {{collectPlugins}} method in the {{PluginProcessor}} tries to call accept on {{null}} and we get a NPE. A simple check for null solves the issue and the compiler error is shown again.



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