Using source 1.8 triggers a Java 9 dependency and fails compilation

[acisternino]

I tried using Java 8 features in the Java classes of my mixed Java/Groovy project and now the compilation fails.

Here you can see a minimal project that replicates the error: groovy-java8-bug.

The pom is configured according to the instructions in the wiki.

Tested with Maven 3.5.2:

Apache Maven 3.5.2 (138edd61fd100ec658bfa2d307c43b76940a5d7d; 2017-10-18T09:58:13+02:00)
Maven home: /opt/apache-maven-3.5.2
Java version: 1.8.0_144, vendor: Oracle Corporation
Java home: /usr/lib/jvm/java-8-openjdk/jre
Default locale: en_GB, platform encoding: UTF-8
OS name: "linux", version: "4.14.3-1-arch", arch: "amd64", family: "unix"

The error is triggered by adding:

<source>1.8</source>
<target>1.8</target>

to the maven-compiler-plugin configuration. Without those entries everything works but I can't use Java 8 features because it seems that source and target levels are set at 1.5.

Something tries to load the javax.lang.model.element.ModuleElement class that is only available in Java 9.

Full error log:

[INFO] Scanning for projects...
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] Building groovy-java8-bug 1.0-SNAPSHOT
[INFO] ------------------------------------------------------------------------
[INFO]
[INFO] --- maven-clean-plugin:2.5:clean (default-clean) @ groovy-java8-bug ---
[INFO]
[INFO] --- maven-resources-plugin:2.6:resources (default-resources) @ groovy-java8-bug ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] skip non existing resourceDirectory /home/anci8360/Private/temp/groovy-mvn-test/src/main/resources
[INFO]
[INFO] --- maven-compiler-plugin:3.7.0:compile (default-compile) @ groovy-java8-bug ---
[INFO] Changes detected - recompiling the module!
[INFO] Using Groovy-Eclipse compiler to compile both Java and Groovy files
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 1.176 s
[INFO] Finished at: 2017-12-06T12:10:16+01:00
[INFO] Final Memory: 14M/355M
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.7.0:compile (default-compile) on project groovy-java8-bug: Execution default-compile of goal org.apache.maven.plugins:maven-compiler-plugin:3.7.0:compile failed: A required class was missing while executing org.apache.maven.plugins:maven-compiler-plugin:3.7.0:compile: javax/lang/model/element/ModuleElement
[ERROR] -----------------------------------------------------
[ERROR] realm =    plugin>org.apache.maven.plugins:maven-compiler-plugin:3.7.0
[ERROR] strategy = org.codehaus.plexus.classworlds.strategy.SelfFirstStrategy
[ERROR] urls[0] = file:/home/anci8360/.m2/repository/org/apache/maven/plugins/maven-compiler-plugin/3.7.0/maven-compiler-plugin-3.7.0.jar
[ERROR] urls[1] = file:/home/anci8360/.m2/repository/org/codehaus/groovy/groovy-eclipse-compiler/2.9.2-03/groovy-eclipse-compiler-2.9.2-03.jar
[ERROR] urls[2] = file:/home/anci8360/.m2/repository/org/apache/xbean/xbean-reflect/3.7/xbean-reflect-3.7.jar
[ERROR] urls[3] = file:/home/anci8360/.m2/repository/com/google/collections/google-collections/1.0/google-collections-1.0.jar
[ERROR] urls[4] = file:/home/anci8360/.m2/repository/org/codehaus/groovy/groovy-eclipse-batch/2.4.13-01/groovy-eclipse-batch-2.4.13-01.jar
[ERROR] urls[5] = file:/home/anci8360/.m2/repository/org/sonatype/sisu/sisu-inject-bean/1.4.2/sisu-inject-bean-1.4.2.jar
[ERROR] urls[6] = file:/home/anci8360/.m2/repository/org/sonatype/sisu/sisu-guice/2.1.7/sisu-guice-2.1.7-noaop.jar
[ERROR] urls[7] = file:/home/anci8360/.m2/repository/org/codehaus/plexus/plexus-utils/2.0.4/plexus-utils-2.0.4.jar
[ERROR] urls[8] = file:/home/anci8360/.m2/repository/org/sonatype/aether/aether-util/1.7/aether-util-1.7.jar
[ERROR] urls[9] = file:/home/anci8360/.m2/repository/org/codehaus/plexus/plexus-interpolation/1.14/plexus-interpolation-1.14.jar
[ERROR] urls[10] = file:/home/anci8360/.m2/repository/org/codehaus/plexus/plexus-component-annotations/1.6/plexus-component-annotations-1.6.jar
[ERROR] urls[11] = file:/home/anci8360/.m2/repository/org/sonatype/plexus/plexus-sec-dispatcher/1.3/plexus-sec-dispatcher-1.3.jar
[ERROR] urls[12] = file:/home/anci8360/.m2/repository/org/sonatype/plexus/plexus-cipher/1.4/plexus-cipher-1.4.jar
[ERROR] urls[13] = file:/home/anci8360/.m2/repository/org/apache/maven/shared/maven-shared-utils/3.1.0/maven-shared-utils-3.1.0.jar
[ERROR] urls[14] = file:/home/anci8360/.m2/repository/commons-io/commons-io/2.5/commons-io-2.5.jar
[ERROR] urls[15] = file:/home/anci8360/.m2/repository/org/apache/maven/shared/maven-shared-incremental/1.1/maven-shared-incremental-1.1.jar
[ERROR] urls[16] = file:/home/anci8360/.m2/repository/org/codehaus/plexus/plexus-java/0.9.2/plexus-java-0.9.2.jar
[ERROR] urls[17] = file:/home/anci8360/.m2/repository/org/ow2/asm/asm/6.0_BETA/asm-6.0_BETA.jar
[ERROR] urls[18] = file:/home/anci8360/.m2/repository/com/thoughtworks/qdox/qdox/2.0-M7/qdox-2.0-M7.jar
[ERROR] urls[19] = file:/home/anci8360/.m2/repository/org/codehaus/plexus/plexus-compiler-api/2.8.2/plexus-compiler-api-2.8.2.jar
[ERROR] urls[20] = file:/home/anci8360/.m2/repository/org/codehaus/plexus/plexus-compiler-manager/2.8.2/plexus-compiler-manager-2.8.2.jar
[ERROR] urls[21] = file:/home/anci8360/.m2/repository/org/codehaus/plexus/plexus-compiler-javac/2.8.2/plexus-compiler-javac-2.8.2.jar
[ERROR] Number of foreign imports: 1
[ERROR] import: Entry[import  from realm ClassRealm[maven.api, parent: null]]
[ERROR]
[ERROR] -----------------------------------------------------: javax.lang.model.element.ModuleElement
[ERROR] -> [Help 1]
[ERROR]
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR]
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/PluginContainerException

[eric-milles]

This stems from JDT bug 514471 (https://bugs.eclipse.org/bugs/show_bug.cgi?id=514471). When Eclipse Oxygen 4.7.2 is released on Dec 20th, I will release an updated batch compiler artifact (2.4.13-02).

[eric-milles]

There is a little java9api.jar embedded in Eclipse JDT APT support that you can add as a dependency to your compiler if you want to keep testing before the 20th.

[acisternino]

Thanks Eric,

Copying the jar to a local lib folder and adding the following entry to the maven-compiler-plugin dependencies works perfectly.

<dependency>
    <groupId>eclipse.jdt.core</groupId>
    <artifactId>java9api</artifactId>
    <version>1.0</version>
    <scope>system</scope>
    <systemPath>${project.basedir}/lib/java9api.jar</systemPath>
</dependency>

The file could be currently downloaded from
https://github.com/eclipse/eclipse.jdt.core/tree/master/org.eclipse.jdt.compiler.tool/lib

[acisternino]

Closing waiting for Oxygen 4.7.2.