add JDK 12 community build

[SethTisue]

JDK 12 "overall feature set is frozen" (according to https://openjdk.java.net/projects/jdk/12/) as of Feb 13 2019)

we might as well install an early-access JDK 12 build and try it, see what happens, perhaps it will turn up something we ought to do something about

ea builds are here: https://jdk.java.net/12/

behemoth 1 has the lightest community build load at present

[SethTisue]

using
#742 (comment) as a guide,

curl -O -L 'https://download.java.net/java/early_access/jdk12/31/GPL/openjdk-12+31_linux-x64_bin.tar.gz'
sudo mv openjdk-12+31_linux-x64_bin.tar.gz /usr/lib/jvm
cd /usr/lib/jvm
sudo tar xzf openjdk-12+31_linux-x64_bin.tar.gz
sudo rm openjdk-12+31_linux-x64_bin.tar.gz
sudo mv jdk-12 java-12-openjdk-x64
sudo update-alternatives --install /usr/bin/java java /usr/lib/jvm/java-12-openjdk-x64/bin/java 1
sudo update-alternatives --install /usr/bin/javac javac /usr/lib/jvm/java-12-openjdk-x64/bin/javac 1

[SethTisue]

went to https://scala-ci.typesafe.com/view/scala-2.12.x/newJob and cloned the scala-2.12.x-jdk11-integrate-community-build job to scala-2.12.x-jdk12-integrate-community-build , changing jvmVersion to 12 and assigning it to behemoth 1

https://scala-ci.typesafe.com/view/scala-2.12.x/job/scala-2.12.x-jdk12-integrate-community-build/

first run: https://scala-ci.typesafe.com/view/scala-2.12.x/job/scala-2.12.x-jdk12-integrate-community-build/1/consoleFull

Java home: /usr/lib/jvm/java-12-openjdk-x64 👍

note to self: do this for 2.13 too, but I'll probably want to get the whole 2.12 build extracting first

[SethTisue]

EXTRACTION FAILED (failed: scala-async, scala-collection-compat, scala-continuations, scala-java8-compat, scala-partest, scala-swing)

darn those third-party libraries and their flaky builds! oh, wait... who, us?

[scala-async] java.lang.RuntimeException: No Scala version for Java major version 12. Change your Java version or adjust `scalaVersionsByJvm` in build.sbt.
[scala-async] 	at com.lightbend.tools.scalamoduleplugin.ScalaModulePlugin$$anonfun$buildSettings$2.apply(ScalaModulePlugin.scala:50)
[scala-async] 	at com.lightbend.tools.scalamoduleplugin.ScalaModulePlugin$$anonfun$buildSettings$2.apply(ScalaModulePlugin.scala:23)

• scala-async Scala + JDK version bumps scala-async#211
• scala-collection-compat scala/scala-collection-compat@7b3516c
• scala-continuations assorted version bumps scala-continuations#42
• scala-java8-compat version bumps scala-java8-compat#129
• scala-partest scala/scala-partest@39e7516
• scala-swing version bumps (sbt, JDK) scala-swing#92

[SethTisue]

https://scala-ci.typesafe.com/view/scala-2.12.x/job/scala-2.12.x-jdk12-integrate-community-build/6/

[SethTisue]

everything extracts now except:

[scala-java8-compat] [info] Compiling 1 Scala source to /home/jenkins/workspace/scala-2.12.x-jdk12-integrate-community-build/target-0.9.16/extraction/c0e9c74dc16863433bdc5fecff58e5dee33e2e27/projects/3279f8989166aa618f4fd2839ee335743e05f4e2/project/target/scala-2.10/sbt-0.13/classes...
[scala-java8-compat] [error] Class sun.invoke.empty.Empty not found - continuing with a stub.
[scala-java8-compat] [error] Class sun.invoke.empty.Empty not found - continuing with a stub.
[scala-java8-compat] [error] two errors found
[scala-java8-compat] [error] (compile:compileIncremental) Compilation failed
[scala-java8-compat] Project loading failed: (r)etry, (q)uit, (l)ast, or (i)gnore? 
[scala-java8-compat:error] java.lang.RuntimeException: 
[scala-java8-compat:error] 	at scala.sys.package$.error(package.scala:27)
[scala-java8-compat:error] 	at com.typesafe.dbuild.support.sbt.SbtRunner.com$typesafe$dbuild$support$sbt$SbtRunner$$processCommand(SbtRunner.scala:94)
[scala-java8-compat:error] 	at com.typesafe.dbuild.support.sbt.SbtRunner$$anonfun$run$1$$anonfun$apply$2$$anonfun$apply$3.apply(SbtRunner.scala:75)
[scala-java8-compat:error] 	at com.typesafe.dbuild.support.sbt.SbtRunner$$anonfun$run$1$$anonfun$apply$2$$anonfun$apply$3.apply(SbtRunner.scala:75)
[scala-java8-compat:error] 	at com.typesafe.dbuild.support.sbt.SbtRunner$$anonfun$run$1.apply(SbtRunner.scala:75)

I'll have to come back to this.

[SethTisue]

outside of dbuild, if I build scala-java8-compat on JDK 12, it works fine. I see error while loading String, class file '/Library/Java/JavaVirtualMachines/jdk-12.jdk/Contents/Home(java/lang/String.class)' is broken but sbt keeps on trucking, and test passes (on Scala 2.12.8)

back in the community build context, I note that warning: Class sun.invoke.empty.Empty not found - continuing with a stub. is also printed when loading the genjavadoc and scala-xml build definitions

in scala-java8-compat, project/plugins.sbt has scalacOptions += "-Xfatal-warnings" (applying to the build definition itself, not to project code), so I think that's our culprit, we just need to disable that in this context? not sure why the results would be different inside or outside dbuild, but perhaps we don't need to get to the bottom of that

EDIT: scala/scala-java8-compat#131 should fix it

[SethTisue]

queued:
https://scala-ci.typesafe.com/view/scala-2.12.x/job/scala-2.12.x-jdk12-integrate-community-build/8/

[SethTisue]

everything extracts now 🎉

we can track further progress at #796

[xuwei-k]

I see error while loading String, class file '/Library/Java/JavaVirtualMachines/jdk-12.jdk/Contents/Home(java/lang/String.class)' is broken but sbt keeps on trucking, and test passes (on Scala 2.12.8)

scala/bug#11381

[SethTisue]

in the first runs, 98 projects are green. that's encouraging, it means nothing catastrophic is wrong. about 10 projects fail that didn’t fail on JDK 11. I’ll gradually investigate them. usually it’s just that some silly thing in the build isn’t expecting a “12”. occasionally it’s something more substantial

[SethTisue]

now tracking any further progress at #796