Norbert Bartels created LOG4J2-1157:
---------------------------------------
Summary: log4j2 exception covers real compiler error
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
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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