bson 5.2.0-java raises Java::JavaLang::InstantiationError on JRuby 10.1.2.0 (Ruby 4.0.0) when using BSON::ByteBuffer. This blocks our application's migration to JRuby 10.1.

Reproduction

With JRuby 10.1.2.0 and bson 5.2.0 installed:

require "bson"
b = BSON::ByteBuffer.new
b.put_int32(5)
p BSON::ByteBuffer.new(b.to_s).get_int32

Expected: 5

Actual:

Java::JavaLang::InstantiationError: org.jruby.RubyFixnum

Our application also encounters this error at org.bson_ruby.ByteBuf.getLength(ByteBuf.java:156).

Cause

JRuby 10.1 made org.jruby.RubyFixnum abstract as part of its LongFixnum/ShortFixnum implementation. The constructors remain declared, so existing compiled extensions link but fail when they attempt direct instantiation.

src/main/org/bson_ruby/ByteBuf.java directly constructs RubyFixnum at seven sites. The same calls are present in bson 5.2.0 and the inspected master source.

Proposed fix

Replace all seven constructor calls with the public RubyFixnum.newFixnum factory. For example:

// Before
return new RubyFixnum(context.runtime, getLengthInternal());

// After
return RubyFixnum.newFixnum(context.runtime, getLengthInternal());

RubyFixnum.newFixnum(Ruby, long) is also present in JRuby 9.2.9.0, 9.3.13.0 and 9.4.8.0.

Verification

We recompiled the patched ByteBuf against JRuby 10.1.2.0 and inserted it into the released bson 5.2.0 Java artifact.

Our Rails application's unit suite then passed: 4112 examples, 0 failures. With the unpatched artifact, the suite aborts before running examples.