JRUBY_OPTS=--1.9 jirb
jruby-1.7.19 :001 > %i[]
SyntaxError: (irb):1: unknown type of %string
%i[]
  ^
    from org/jruby/RubyKernel.java:1107:in `eval'
    from org/jruby/RubyKernel.java:1507:in `loop'
    from org/jruby/RubyKernel.java:1270:in `catch'
    from org/jruby/RubyKernel.java:1270:in `catch'
    from /Users/rejeep/.rvm/rubies/jruby-1.7.19/bin/jirb:13:in `(root)'

JRUBY_OPTS=--2.0 jirb
jruby-1.7.19 :001 > %i[]
Java::JavaLang::ClassCastException: org.jruby.ast.ZArrayNode cannot be cast to org.jruby.ast.ListNode
    from org.jruby.parser.Ruby20Parser$180.execute(Ruby20Parser.java:2863)
    from org.jruby.parser.Ruby20Parser.yyparse(Ruby20Parser.java:1575)
    from org.jruby.parser.Ruby20Parser.yyparse(Ruby20Parser.java:1466)
    from org.jruby.parser.Ruby20Parser.parse(Ruby20Parser.java:4640)
    from org.jruby.parser.Parser.parse(Parser.java:114)
    from org.jruby.parser.Parser.parse(Parser.java:84)
    from org.jruby.parser.Parser.parse(Parser.java:76)
    from org.jruby.Ruby.parseEval(Ruby.java:2711)
    from org.jruby.evaluator.ASTInterpreter.evalWithBinding(ASTInterpreter.java:176)
    from org.jruby.RubyKernel.evalCommon(RubyKernel.java:1144)
    from org.jruby.RubyKernel.eval19(RubyKernel.java:1107)
    from org.jruby.RubyKernel$INVOKER$s$0$3$eval19.call(RubyKernel$INVOKER$s$0$3$eval19.gen)
    from org.jruby.internal.runtime.methods.DynamicMethod.call(DynamicMethod.java:180)
    from org.jruby.runtime.callsite.CachingCallSite.cacheAndCall(CachingCallSite.java:296)
    from org.jruby.runtime.callsite.CachingCallSite.call(CachingCallSite.java:72)
    from org.jruby.ast.FCallManyArgsNode.interpret(FCallManyArgsNode.java:60)
... 117 levels...
    from org.jruby.ast.BlockNode.interpret(BlockNode.java:71)
    from org.jruby.evaluator.ASTInterpreter.INTERPRET_METHOD(ASTInterpreter.java:74)
    from org.jruby.internal.runtime.methods.InterpretedMethod.call(InterpretedMethod.java:182)
    from org.jruby.internal.runtime.methods.DefaultMethod.call(DefaultMethod.java:203)
    from org.jruby.runtime.callsite.CachingCallSite.cacheAndCall(CachingCallSite.java:326)
    from org.jruby.runtime.callsite.CachingCallSite.call(CachingCallSite.java:170)
    from Users.rejeep.$_dot_rvm.rubies.jruby_minus_1_dot_7_dot_19.bin.jirb.__file__(/Users/rejeep/.rvm/rubies/jruby-1.7.19/bin/jirb:13)
    from Users.rejeep.$_dot_rvm.rubies.jruby_minus_1_dot_7_dot_19.bin.jirb.load(/Users/rejeep/.rvm/rubies/jruby-1.7.19/bin/jirb)
    from org.jruby.Ruby.runScript(Ruby.java:866)
    from org.jruby.Ruby.runScript(Ruby.java:859)
    from org.jruby.Ruby.runNormally(Ruby.java:728)
    from org.jruby.Ruby.runFromMain(Ruby.java:577)
    from org.jruby.Main.doRunFromMain(Main.java:395)
    from org.jruby.Main.internalRun(Main.java:290)
    from org.jruby.Main.run(Main.java:217)
    from org.jruby.Main.main(Main.java:197)jruby-1.7.19 :002 >