JDK version determined incorrectly by Gradle on JDK 10

[sdavids]

https://github.com/policeman-tools/forbidden-apis/wiki/BundledSignatures
"Gradle automatically add the compile Java version"

forbiddenApis {
  bundledSignatures = ['jdk-internal']
}

Error:
Parsing signatures failed: Invalid bundled signature reference (JDK version is invalid): jdk-internal-1.10

Workaround:

forbiddenApis {
  bundledSignatures = ['jdk-internal-10']
}

[sdavids]

org.gradle.api.JavaVersion

    // Since Java 9, version should be X instead of 1.X
    // However, to keep backward compatibility, we change from 11

Possible fix:

def javaVersion = JavaVersion.current()

def fixed = javaVersion.java9Compatible ? javaVersion.majorVersion : javaVersion

[uschindler]

This is not a bug. The version should anyways be defined in the project setup, checking against the current version is wrong anyways.

[sdavids]

https://docs.gradle.org/current/userguide/java_plugin.html#other_convention_properties

Neither setting sourceCompatibility nor targetCompatibility is not recommended but allowed.

Both sourceCompatibility and targetCompatibility are of type org.gradle.api.JavaVersion.

JavaVersion.VERSION_1_10 => jdk-internal-1.10 => does not work
JavaVersion.valueOf("1.10") => jdk-internal-1.10 => does not work
JavaVersion.valueOf("10") => No enum constant JavaVersion.10 => does not work
JavaVersion.toVersion("1.10") => jdk-internal-1.10 => does not work
JavaVersion.toVersion("10") => No enum constant JavaVersion.10 => does not work

[uschindler]

Actually this is a serious bug in Gradle. The forbiddenapis backend solely uses official version numbers, as accepted by javac. Javac does not accept "1.[9|10|11]" as version for the new -release parameter, so i have no idea, how the compile task handles that internally. Forbiddenapis enforces full version numbers for Java versions >=9, for previous versions it accepts both variants ("1.8" and "8"), but normalizes them (to "1.8").
Nevertheless, the targetCompatibility property of the forbiddenapis task is of type String (for good reason), so you can simply specify it as a string in the task config, no need to rely on shitty Gradle enum constants.
I am not sure If I should add a hack for this because the forbiddenapis main task is about correctness, so I'd like to enforce correctness - also in Gradle. It works correctly in Maven and Ant, only Gradle is broken (as always).

[uschindler]

Neither setting sourceCompatibility nor targetCompatibility is not recommended but allowed.

For build reproducibility it is required to be set. Otherwise the project build depends on the actually used Java version and produces artifacts solely working with this Java version. This may also cause compile errors, as the source code parsing uses an undefined Java version.

[dweiss]

Sadly even setting source/target doesn't always help (for example, covariants on ByteBuffer.flip() can cause incompatibilities if compiled under java 9 with 1.8 as the target).

[sdavids]

Actually this is a serious bug in Gradle

https://github.com/gradle/gradle/blob/master/subprojects/base-services/src/main/java/org/gradle/api/JavaVersion.java#L46

For build reproducibility it is required to be set.

I know but some people like pain 😳

[sdavids]

This line should be modified:

https://github.com/policeman-tools/forbidden-apis/blob/master/src/main/resources/de/thetaphi/forbiddenapis/gradle/plugin-init.groovy#L63

[uschindler]

@dweiss Of course you should set "release 8", which compiles against the Java 8 symbols. That's what I said before. Maven supports this, no idea about Gradle.

[uschindler]

@sdavids I can add a fix there, but I would do it only for the 2 enum entries (Java 9 and Java 10). Starting with Java 11, Gradle behaves correct. So it would apply the setting as-is, but for Java 9 and Java 10 it would set it to "9" and "10" manually.

[uschindler]

My fix would be (just workaround the 2 bogus versions):

// Define our tasks (one for each SourceSet):
project.sourceSets.all{ sourceSet ->
  def getSourceSetClassesDirs = { sourceSet.output.hasProperty('classesDirs') ? sourceSet.output.classesDirs : project.files(sourceSet.output.classesDir) }
  project.tasks.create(sourceSet.getTaskName(FORBIDDEN_APIS_TASK_NAME, null), CheckForbiddenApis.class) { task ->
    description = "Runs forbidden-apis checks on '${sourceSet.name}' classes.";
    conventionMapping.with{
      extensionProps.each{ key ->
        map(key, { extension[key] });
      }
      classesDirs = { getSourceSetClassesDirs() }
      classpath = { sourceSet.compileClasspath }
      targetCompatibility = { EnumSet.of(JavaVersion.VERSION_1_9,JavaVersion.VERSION_1_10).contains(project.targetCompatibility) ? project.targetCompatibility.majorVersion : project.targetCompatibility?.toString() }
    }
    // add dependency to compile task after evaluation, if the classesDirs collection has overlaps with our SourceSet:
    project.afterEvaluate{
      def sourceSetDirs = getSourceSetClassesDirs().files;
      if (classesDirs.any{ sourceSetDirs.contains(it) }) {
        task.dependsOn(sourceSet.output);
      }
    }
    forbiddenTask.dependsOn(task);
  }
}