Many warning messages related to errorprone "CompatibleWith"

[enwired]

When compiling code that depends on Guava 21.0, [Edit: I mistakenly said 20.0 originally] using Maven, I get many warning messages like this:

Cannot find annotation method 'value()' in type 'com.google.errorprone.annotations.CompatibleWith': class file for com.google.errorprone.annotations.CompatibleWith not found

I do not use the errorprone library in my code, so this error message is due to its use by Guava.

Obviously, these are only warning messages and are not critical.

[cpovirk]

The reason is that we don't make the Error Prone annotations available to our users at compile time. We could maybe change that, but our understanding has been that it shouldn't be necessary. Do you know if you're using any Maven plugins that might be plugging into the compiler (annotation processors, mainly)?

[enwired]

These warnings are happening even in some pretty simple packages where there are no exotic maven plugins.

It does not happen on all of my modules that use Guava. But I haven't narrowed-down which Guava class is involved.

The warnings happen during the "default-compile" step from maven-compiler-plugin. I've tried version 3.3 and 3.6 of that plugin.

The warnings appear even if I set <showWarnings>false</showWarnings>

[enwired]

Ok. So this is related to annotation processors of some basic sort. My standard build involves this:

<build>
  <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-compiler-plugin</artifactId>
        <version>3.3</version>
        <configuration>
          <source>1.8</source>
          <target>1.8</target>
          <compilerArgs>
            <arg>-Xlint:all</arg>
            <arg>-Xlint:-serial</arg>
          </compilerArgs>
          <showWarnings>true</showWarnings>
          <showDeprecation>true</showDeprecation>
        </configuration>
      </plugin>
  </plugins>
</build>

The warnings are shown only when I include Xlint along with either of showWarnings or showDeprecation.

Then 9 identical warnings appear if my java code contains one single line like this:
ImmutableTable.Builder<?,?,?> builder = ImmutableTable.builder();

So, I don't know if there is a bug in maven compiler plugin, or in Guava's ImmutableTable or what. But I really shouldn't be seeing these warnings.

Again, not a bug in the program operation, just an annoying set of warning messages.

[stevenschlansker]

We ran into this attempting to upgrade the jdbi3 project to Guava 21:
jdbi/jdbi#697

We also don't do anything super fancy with Maven plugins, but we do attempt to set "warnings as errors" everywhere. That said, despite being logged at ERROR level, it doesn't fail the build.

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.5.1:
testCompile (default-testCompile) on project jdbi3-sqlobject: Compilation failure

[ERROR] /home/travis/.m2/repository/com/google/guava/guava/21.0/guava-21.0.jar(com/google/common/collect/Multimap.class):
warning: Cannot find annotation method 'value()' in type 'CompatibleWith': 
class file for com.google.errorprone.annotations.CompatibleWith not found

[cpovirk]

Thanks. I tried pulling the jdbi3 and running mvn clean install. It successes without the CompatibleWith message. Is there a different command I should use or a different commit I should check out?

[stevenschlansker]

No, sorry, an earlier version of this comment incorrectly stated the build failed.

The actual problem is that the javac output all gets logged at the maximum error level -- so the WARNING that this emits will be represented as an ERROR if there are other build errors, which is confusing. Once you fix the other unrelated build errors this message then gets downgraded to a WARNING. So it does not actually break out build, but it does introduce warnings -- which as soon as "warnings as errors" gets fixed (someday 🤞) it will then actually fail the build

[PhilippWendler]

I am also seeing this, on a standard javac -Xlint -Werror build with ant.
The messages are

    [javac] .../guava.jar(com/google/common/collect/Multiset.class): warning: Cannot find annotation method 'value()' in type 'CompatibleWith': class file for com.google.errorprone.annotations.CompatibleWith not found
    [javac] .../guava.jar(com/google/common/collect/Multiset.class): warning: Cannot find annotation method 'value()' in type 'CompatibleWith'
    [javac] error: warnings found and -Werror specified

Because we want to use -Werror, this breaks our build and prevents us from upgrading Guava.

[enwired]

@PhilippWendler thanks for trying javac. Which JDK version is it?

I have found that I can eliminate the warning message in a Maven build by using this flag for the maven-compiler-plugin: <forceJavacCompilerUse>true</forceJavacCompilerUse>. That should make Maven use the javac command in my jdk, which is 1.8.0_66. I don't exactly understand why that removes the warning.

[PhilippWendler]

I tested with javac 1.8.0_111 from OpenJDK.

[cpovirk]

Running mvn clean install on jdbi3 didn't give me any output that mentions "CompatibleWith" anywhere. I tried with -Dmaven.compiler.forceJavacCompilerUse=true, and I tried introducing a compile error into a file that uses Multimap, and I still don't see it.

If anyone can point me to a repository and a command that I can use to reproduce this, that would be a big help. There's definitely something wrong, but I need to figure out where to point the finger (which might be at us -- I'm not just not sure yet).

[cpovirk]

In the meantime, as a workaround, you can probably add an explicit dependency on:

    <groupId>com.google.errorprone</groupId>
    <artifactId>error_prone_annotations</artifactId>
    <version>2.0.15</version>

[Stephan202]

^ And if you declare that dependency <scope>provided</scope>, then it shouldn't end up in your final aggregate build artifact (WAR, Uber JAR, etc.), meaning there should be no downside to doing so.

[PhilippWendler]

You should be able to reproduce the problem in branch guava21 of sosy-lab/java-common-lib. You can start a build with javac with ant clean build-project. The definition of the ant target that calls javac is in build/build-compile.xml, you can see the compiler options there.

The problem is reproducible with this branch on AppVeyor (log) and Travis (log).

Btw, we are even using error-prone already (though I disabled it in that branch for easier debugging) and want to upgrade to 2.0.15 at some point anyway, but I think that it would still be good if Guava would not have this problem.

The Eclipse Java Compiler builds our project just fine (ant clean build-project-ecj).

[enwired]

@cpovirk To reproduce the problem in Maven you must use both Xlint and showWarnings or showDeprecation. @PhilippWendler did something similar with javac -Xlint -Werror. So it may be that the problem is related to lint.

You can then reproduce it with a project containing one single java class like this:

public class GuavaTest {
  private ImmutableTable.Builder table = ImmutableTable.builder();
}