META-INF/services/javax.annotation.processing.Processor copied before compilation and causes error

I also hit this issue. My scenario is that the my Maven project provides an annotation processor, and tests for this project use this processor. So when compiling sources, I do not need to run annotation processors; when compiling tests, they need to be compiled. The workaround I found (based on Jesse's straightforward workaround above) is to configure maven-compiler-plugin as follows:

<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>2.0.2</version>
<executions>
<execution>
<id>default-compile</id>
<configuration>
<compilerArgument>-proc:none</compilerArgument>
<source>1.6</source>
<target>1.6</target>
</configuration>
</execution>
<execution>
<id>default-testCompile</id>
<configuration>
<source>1.6</source>
<target>1.6</target>
</configuration>
</execution>
</executions>
</plugin>

Sorry, what I meant is "when compiling tests, processors need to be run".

See: http://maven.apache.org/guides/mini/guide-default-execution-ids.html

I used a variation of the above workaround, in my case I needed the outputs from the annotation processing to be packaged in the final jar not just generated for the testing phase. I added the following to my pom:

 
<plugin>
 <groupId>org.apache.maven.plugins</groupId>
 <artifactId>maven-compiler-plugin</artifactId>
 <version>2.1</version>
 <configuration>
  <source>1.6</source>
  <target>1.6</target>
 </configuration>
 <executions>
  <execution>
   <id>default-compile</id>
   <configuration>
    <compilerArgument>-proc:none</compilerArgument>
    <includes>
     <include>path/to/annotation/processor/**</include>
     <include>path/to/annotation/processor/dependencies/**</include>
    </includes>
   </configuration>
  </execution>
  <execution>
   <id>compile-everything-else</id>
   <phase>compile</phase>
   <goals>
    <goal>compile</goal>
   </goals>
  </execution>
 </executions>
</plugin>

more detail on this approach here

I needed to do something similar.

I have a Unit Test which actually runs my Processor by calling the JavaCompiler.

@Test
    public void fullComprehensiveTest() {


       ...
        
        // Get an instance of java compiler
        JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();

        // Get a new instance of the standard file manager implementation
        StandardJavaFileManager fileManager = compiler.getStandardFileManager(null, null, null);
        List<String> options = new ArrayList<String>();
        options.add("-d");
        File outputDir = new File("target", "processor-test");
        outputDir.mkdirs();
        options.add(outputDir.getAbsolutePath());

        options.add("-s");
        options.add(outputDir.getAbsolutePath());

        // Get the list of java file objects
        SrcFilesTestClass srcFiles = new SrcFilesTestClass();

        System.out.println(">> testing: files to run annotation test on (only some have annotations): ");
        for (String f : srcFiles.srcFiles()) {
            System.out.println(f);
        }

        Iterable<? extends JavaFileObject> compilationUnits1 = fileManager.getJavaFileObjects(srcFiles.srcFiles());

        StringWriter output = new StringWriter();
        CompilationTask task = compiler.getTask(output, fileManager, null, options, null, compilationUnits1);

        // Create a list to hold annotation processors
        LinkedList<AbstractProcessor> processors = new LinkedList<AbstractProcessor>();

        // Add an annotation processor to the list
        processors.add(new VannitationOneToOneProcessor());
        processors.add(new VannitationManyToOneProcessor());

        // Set the annotation processor to the compiler task
        task.setProcessors(processors);

        // Perform the compilation task.
        // the compiler will return false for us because the files we are
        // creating won't compile as
        // we don't have the required fields.
        task.call();

        // now some tests .. we will just validate that
        ...

     }

So .. to ensure that the processor does not run in my package from maven, and that I control it (maven via surefire runs it), I -proc:none on the compile test also.

<plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-compiler-plugin</artifactId>
        <version>2.3.2</version>
        <executions>
          <execution>
            <id>default-compile</id>
            <configuration>
              <compilerArgument>-proc:none</compilerArgument>
              <source>1.6</source>
              <target>1.6</target>
            </configuration>
          </execution>
          <execution>
            <id>default-testCompile</id>
            <configuration>
              <compilerArgument>-proc:none</compilerArgument>
              <source>1.6</source>
              <target>1.6</target>
            </configuration>
          </execution>
        </executions>
      </plugin>

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.

Regarding -source 1.5: it is unsafe to pass -processorpath in this case, since the target javac might in fact be from JDK 5 and not recognize this option. (If the compiler plugin went through JSR 199, with javac on the plugin classpath, this would not be an issue.)

Regarding a change in javac's behavior: I would not hold my breath. After all, you passed -classpath target/classes:... so that is where it is looking. It is really the responsibility of the invoker to make sure the processor path is correct.

Complete example project working around this problem; for the main sources the processorpath is set to the Maven classpath, so that processors in dependencies can still be used.

For test sources, the default behavior is left alone, which is usually OK since tests would not likely define their own processors; processors from dependencies and main sources are still run over test sources.

My workaround is to define a separate Maven module (D) and defines a dummy do-nothing processor of the same fully-qualifled class name. This D module is then added as an optional dependency to my real project (R), so that D won't pollute other projects depending on R.

This has the added benefit of making IDEs happy, but the downside is that the test code won't be subject to the annotation processing (which is OK in my case, but may not be OK for others.)