JRuby 9.1.7.0 fails to start on Java 9

[jordansissel]

Environment

• JRuby: jruby 9.1.7.0 (2.3.1) 2017-01-11 68056ae OpenJDK 64-Bit Server VM 9-Debian+0-9b161-1 on 9-Debian+0-9b161-1 +jit [linux-x86_64]
• Java: OpenJDK 64-Bit Server VM (build 9-Debian+0-9b161-1, mixed mode)

Other environmentals:

Docker image "openjdk:9-jdk" (shortest path for me to try Java 9)

Reproducing.

# ruby -e 'puts "Hello"'

Result:

2017-04-07T02:25:41.459Z [main] ERROR JavaProxyClassFactory : could not use ClassLoader.defineClass method
java.lang.reflect.InaccessibleObjectException: Unable to make protected final java.lang.Class java.lang.ClassLoader.defineClass(java.lang.String,byte[],int,int,java.security.ProtectionDomain) throws java.lang.ClassFormatError accessible: module java.base does not "opens java.lang" to unnamed module @396a51ab

        at java.base/java.lang.reflect.AccessibleObject.checkCanSetAccessible(AccessibleObject.java:335)
        at java.base/java.lang.reflect.AccessibleObject.checkCanSetAccessible(AccessibleObject.java:278)
        at java.base/java.lang.reflect.Method.checkCanSetAccessible(Method.java:196)
        at java.base/java.lang.reflect.Method.setAccessible(Method.java:190)
        at org.jruby.javasupport.proxy.JavaProxyClassFactory$1.run(JavaProxyClassFactory.java:219)
        at org.jruby.javasupport.proxy.JavaProxyClassFactory$1.run(JavaProxyClassFactory.java:212)
        at java.base/java.security.AccessController.doPrivileged(Native Method)
        at org.jruby.javasupport.proxy.JavaProxyClassFactory.<clinit>(JavaProxyClassFactory.java:212)
        at org.jruby.javasupport.proxy.JavaProxyClass.<clinit>(JavaProxyClass.java:89)
        at org.jruby.javasupport.Java.createJavaModule(Java.java:163)
        at org.jruby.javasupport.Java.load(Java.java:103)
        at org.jruby.runtime.load.LoadService.reflectedLoad(LoadService.java:590)
        at org.jruby.ext.LateLoadingLibrary.load(LateLoadingLibrary.java:48)
        at org.jruby.runtime.load.LibrarySearcher$FoundLibrary.load(LibrarySearcher.java:34)
        at org.jruby.runtime.load.LoadService.tryLoadingLibraryOrScript(LoadService.java:887)
        at org.jruby.runtime.load.LoadService.smartLoadInternal(LoadService.java:527)
        at org.jruby.runtime.load.LoadService.require(LoadService.java:398)
        at org.jruby.ext.jruby.JRubyLibrary.load(JRubyLibrary.java:57)
        at org.jruby.runtime.load.LoadService.reflectedLoad(LoadService.java:590)
        at org.jruby.ext.LateLoadingLibrary.load(LateLoadingLibrary.java:48)
        at org.jruby.runtime.load.LibrarySearcher$FoundLibrary.load(LibrarySearcher.java:34)
        at org.jruby.runtime.load.LoadService.tryLoadingLibraryOrScript(LoadService.java:887)
        at org.jruby.runtime.load.LoadService.smartLoadInternal(LoadService.java:527)
        at org.jruby.runtime.load.LoadService.require(LoadService.java:398)
        at org.jruby.Ruby.init(Ruby.java:1203)
        at org.jruby.Ruby.newInstance(Ruby.java:334)
        at org.jruby.Main.internalRun(Main.java:271)
        at org.jruby.Main.run(Main.java:232)
        at org.jruby.Main.main(Main.java:204)
NameError: missing class or uppercase package name (`java.lang.String'), caused by Unable to make public int java.lang.String$CaseInsensitiveComparator.compare(java.lang.String,java.lang.String) accessible: module java.base does not "opens java.lang" to unnamed module @396a51ab
   method_missing at org/jruby/javasupport/JavaPackage.java:259
     <class:Ruby> at file:/usr/local/rvm/rubies/jruby-9.1.7.0/lib/jruby.jar!/jruby/jruby.rb:43
  singleton class at file:/usr/local/rvm/rubies/jruby-9.1.7.0/lib/jruby.jar!/jruby/jruby.rb:42
   <module:JRuby> at file:/usr/local/rvm/rubies/jruby-9.1.7.0/lib/jruby.jar!/jruby/jruby.rb:2
           <main> at file:/usr/local/rvm/rubies/jruby-9.1.7.0/lib/jruby.jar!/jruby/jruby.rb:1

[jordansissel]

Workaround: Add some --add-opens flags:

% ruby -J--add-opens=java.base/{java.lang,java.security,java.util,java.security.cert}=ALL-UNNAMED -e 'puts 123'
123

So far at least 4 packages need to be added for opens. Possibly more I haven't found yet.

[iignatev]

there is a new introduced --permit-illegal-access Java option which relax access checks, so you still can setAccessible, JVM will also prints warnings, so you are able to track your illegal access.

please be informed that the option will be removed in JDK 10, hence it an be used only as an indeed temporary workaround.

[headius]

JRuby 9.1.8.0 should start up fine on Java 9, though for this example there's obviously some rogue output (stty?):

$ rvm jruby-9.1.8.0 do ruby -e 'puts "hello"'
speed 38400 baud; line = 0;
-brkint -imaxbel iutf8
hello

I'll look into that output separately.

[headius]

JRuby master does not appear to have the stty output.