Scala not builds on Java 10 - scala

Question

while building through Intellij Idea, I got the following message:
Error:scalac: 'jvm-1.10' is not a valid choice for '-target'
Error:scalac: bad option: '-target:jvm-1.10'
later, after a Java upgrade
Build, Execution, Deployment -> Build Tools -> Gradle -> Gradle JVM:
1.8 Build, Execution, Deployment -> Complier -> Scala Complier -> Scala Compile Server -> JDK: 1.8
in build.gradle
compileScala.targetCompatibility = 1.8
ScalaCompileOptions.metaClass.useAnt = false
Nothing helps!
upd:
this helps: in build.gradle
tasks.withType(ScalaCompile) {
scalaCompileOptions.useAnt = false
}
not needed:
compileScala.targetCompatibility = 1.8
ScalaCompileOptions.metaClass.useAnt = false

Answer 1

"Error:scalac: 'jvm-1.10' is not a valid choice for '-target' Error:scalac: bad option: '-target:jvm-1.10'"
In the JDK compatibility notes as mentioned below, it also indicates
that the Java 10 is not fully supporting Scala 2.12.6 JDK 9 & 10
compatibility notes
As you were saying you build this through IntelliJ IDEA, I suspect
you haven't configure your java version (Java 10) or scala version
(2.12.6) inside running configuration project settings.
And also please try out building/compile your application through
commandline in order to check whether you are getting the same error
with that (Otherwise this is just bad configuration in IDEA tht you
need to change)
JDK 9 & 10 compatibility notes (Mentioned in Scala Docs)
JDK 9 & 10 compatibility notes
As of Scala 2.12.6 and 2.11.12, JDK 9 & 10 support is incomplete. Notably, scalac will not enforce the restrictions of the Java Platform Module System, which means that code that typechecks may incur linkage errors at runtime.
JDK 9 & 10 support requires minimum sbt version 1.1.0, or 0.13.17 in the 0.13.x series.
For more information on JDK 9 & 10 compatibility, watch the “Support JDK 9” issue on GitHub.

Answer 2

The same issue can happen with mixed multi-module gradle projects that use java 11 and scala 2.12.10.
In that case, it may help to reconfigure IntelliJ (2019.2) via
Settings > Build, Execution, Deployment > Scala Compiler
by removing the targets defined in Additional compiler options for the affected scala modules.

Answer 3

I stumbled over this issue when having the same problem with Java 11. The reconfiguration comment of Roland Ewald solved the problem. It is important to mention, that this reconfiguration has to be made for all modules of the project (at least for me this was necessary) as well as that IntelliJ sometimes hides parts of the Additional compiler options, so be sure to click on expand even if they seem empty or correct.