JRuby 9.2 with unified Integer raises ClassCastException

[headius]

We have been working on our Ruby 2.4 support for a release in the next couple months. Rubhy 2.4 unified Fixnum and Bignum into Integer, which means some APIs that only expected to get Fixnum or Bignum before might need to adapt to support both.

It appears that the JRuby extension has not been updated for that change yet. I get the following error in MRI's test_json.rb:

[ 3/32] TestJSON#test_big_integers = 0.01 s
  1) Error:
TestJSON#test_big_integers:
Java::JavaLang::ClassCastException: org.jruby.RubyBignum cannot be cast to org.jruby.RubyFixnum
    json.ext.Generator$2.generate(Generator.java:224)
    json.ext.Generator$4.generate(Generator.java:292)
    json.ext.Generator$4.generate(Generator.java:249)
    json.ext.Generator$Handler.generateNew(Generator.java:171)
    json.ext.Generator.generateJson(Generator.java:57)
    json.ext.GeneratorState.generate(GeneratorState.java:209)
    json.ext.GeneratorState$INVOKER$i$1$0$generate.call(GeneratorState$INVOKER$i$1$0$generate.gen)

Any place that assumes it will only receive Fixnums should probably be audited. I can help, but I assume this work was already done for the C ext, and the changes should be very similar for the Java ext.

[headius]

See jruby/jruby#4293 for ongoing Ruby 2.4 work. The branch is ruby-2.4.

[skarmakar]

Seems like related

jruby-9.2.5.0 :010 > {"a" => 1, "b" => 12345678901234567890}.to_json
Traceback (most recent call last):
       16: from org.jruby.ir.interpreter.InterpreterEngine.processCall(InterpreterEngine.java:346)
       15: from org.jruby.runtime.callsite.CachingCallSite.call(CachingCallSite.java:141)
       14: from org.jruby.runtime.callsite.CachingCallSite.cacheAndCall(CachingCallSite.java:325)
       13: from org.jruby.internal.runtime.methods.DynamicMethod.call(DynamicMethod.java:191)
       12: from org.jruby.internal.runtime.methods.JavaMethod$JavaMethodN.call(JavaMethod.java:793)
       11: from json.ext.GeneratorMethods$RbHash$INVOKER$s$0$0$to_json_DBG.call(GeneratorMethods$RbHash$INVOKER$s$0$0$to_json_DBG.gen)
       10: from json.ext.GeneratorMethods$RbHash.to_json(GeneratorMethods.java:70)
        9: from json.ext.Generator.generateJson(Generator.java:35)
        8: from json.ext.Generator$Handler.generateNew(Generator.java:171)
        7: from json.ext.Generator$5.generate(Generator.java:306)
        6: from json.ext.Generator$5.generate(Generator.java:333)
        5: from org.jruby.RubyHash.visitAll(RubyHash.java:2725)
        4: from org.jruby.RubyHash.visitLimited(RubyHash.java:690)
        3: from org.jruby.RubyHash$Visitor.visit(RubyHash.java:668)
        2: from json.ext.Generator$5$1.visit(Generator.java:354)
        1: from json.ext.Generator$2.generate(Generator.java:224)
Java::JavaLang::ClassCastException (org.jruby.RubyBignum cannot be cast to org.jruby.RubyFixnum)

which works perfectly with jruby 9.1.8, json (1.8.3 java)

jruby-9.1.8.0 :002 > {"a" => 1, "b" => 12345678901234567890}.to_json
 => "{\"a\":1,\"b\":12345678901234567890}" 

[anup1710]

Seems like this issue is not fully fixed.

require 'json'
JSON({"a": 1, "b": 23886820000238866000})

The above code causes same issue while parsing the hash into JSON. See the exception screenshot below.

@headius / @kares - I think this needs to be fixed.

[headius]

We did not update json in time for the JRuby 9.2.7 release; please try to install the json gem. We will update it for 9.2.8.