Here's the living checklist of changes needed to support Ruby 2.3.

These changes will go on the 2.3 branch at https://github.com/jruby/jruby/tree/ruby-2.3 and then we will merge to master when we're ready to release 2.3 support in JRuby 9.1.0.0.

Pull requests should be made against the ruby-2.3 branch please!

This list is currently based on https://github.com/ruby/ruby/blob/v2_3_0_preview2/NEWS.

Language changes

• frozen-string-literal pragma:
  • new pragma, frozen-string-literal has been experimentally introduced. (https://bugs.ruby-lang.org/issues/8976)
  • besides, --enable/--disable=frozen-string-literal options also have been introduced. (https://bugs.ruby-lang.org/issues/8976)
  • command line options --debug or --debug=frozen-string-literal enable additional debugging mode which shows created location with at frozen object error (RuntimeError). (https://bugs.ruby-lang.org/issues/11725)
• safe navigation operator:
  • new method call syntax, object&.foo', method #foo is called onobject' if it is not nil.
    this is similar to `try!' in Active Support, except:
    • method name is syntactically required
      obj.try! {} # valid
      obj&. {} # syntax error
    • arguments are evaluated only if a call is made:
      obj.try!(:foo, bar()) # bar() is always evaluated
      obj&.foo(bar()) # bar() is conditionally evaluated
    • attribute assignment is valid
      obj&.attr += 1
    • (https://bugs.ruby-lang.org/issues/11537)
• indented here document:
  • new string literal, here document starts with <<~. refer doc/syntax/literals.rdoc for more details. (https://bugs.ruby-lang.org/issues/9098)
• Additional parser changes
  • class Foo end is no longer a syntax error (see tagged specs in 0304cc7).
• Changes in how super works for methods copied from parent to child. See https://bugs.ruby-lang.org/issues/3351 and RSpec mocks isn't properly rolling back stubbed any_instance methods with ruby 2.3.0-preview2 rspec/rspec-mocks#1042

Core classes updates (outstanding ones only)

• ARGF
  • ARGF.read_nonblock supports `exception: false' like IO#read_nonblock.
    (https://bugs.ruby-lang.org/issues/11358)
• Array
  • Array#bsearch_index (https://bugs.ruby-lang.org/issues/10730)
  • Array#dig (https://bugs.ruby-lang.org/issues/11643) needs rubyspec update (see Ruby 2.3's #dig #3458)
• Enumerable
  • Enumerable#grep_v is added as inverse version of Enumerable#grep.
    (https://bugs.ruby-lang.org/issues/11049)
  • Enumerable#chunk_while (https://bugs.ruby-lang.org/issues/10769)
• File
  • File.mkfifo (https://bugs.ruby-lang.org/issues/11536) (4a79bca)
  • Add File::TMPFILE corresponding to O_TMPFILE (876445b)
• Hash
  • Hash#fetch_values (https://bugs.ruby-lang.org/issues/10017)
  • Hash#dig (https://bugs.ruby-lang.org/issues/11643) needs rubyspec update (see Ruby 2.3's #dig #3458)
  • Hash#<=, Hash#<, Hash#>=, Hash#> (https://bugs.ruby-lang.org/issues/10984)
  • Hash#to_proc (https://bugs.ruby-lang.org/issues/11653)
• IO
  • new mode flag File::SHARE_DELETE is available.
    this flag means to permit deleting opened file on Windows, but currently
    this affect only files opened as binary. (https://bugs.ruby-lang.org/issues/11218)
  • new option parameter `flags' is added.
    this parameter is bitwise-ORed to oflags generated by normal mode argument.
    (https://bugs.ruby-lang.org/issues/11253)
• Kernel
  • Kernel#loop, when stopped by a StopIteration exception, returns
    what the enumerator has returned instead of nil. (https://bugs.ruby-lang.org/issues/11498)
• Module
  • Module#deprecate_constant (https://bugs.ruby-lang.org/issues/11398)
• NameError
  • NameError#receiver is added to take the receiver object. (https://bugs.ruby-lang.org/issues/10881) (Added in f7088b9)
• Numeric
  • Numeric#positive? and Numeric#negative? are added, which return
    true when the receiver is positive and negative respectively.
    (https://bugs.ruby-lang.org/issues/11151)
• Proc
  • Proc#call (and also #[], #===, #yield) are optimized.
    Backtrace doesn't show each methods (show block lines directly).
    • TracePoint also ignore these calls. (https://bugs.ruby-lang.org/issues/11569)
    • Testing
• Queue (Thread::Queue)
  • Queue#close is added to notice a termination. (https://bugs.ruby-lang.org/issues/10600) (Added in 2531143)
  • Benchmark modified Queue and SizedQueue implementations from 2531143. (New impls contributed in [Ruby 2.3] Concurrency improvements to Queue/SizedQueue  #3553 based on blocking queues we used to use)
  • Reconcile tests that do not seem correct (https://bugs.ruby-lang.org/issues/11822)
• Regexp/String: Updated Unicode version from 7.0.0 to 8.0.0
  • Ensure manual change in jruby/jcodings@4bcfdc3#diff-63b6d8b6c8616d7df068493913a90413R136 is preserved during update
• String
  • String#+@ and String#-@ are added to get mutable/frozen strings. (https://bugs.ruby-lang.org/issues/11782)
  • String.new now accepts new option parameter `encoding'. (https://bugs.ruby-lang.org/issues/11785)
• Struct
  • Struct#dig (https://bugs.ruby-lang.org/issues/11688)
• Thread
  • Thread#name, Thread#name= are added to handle thread names (https://bugs.ruby-lang.org/issues/11251)

Core classes compatibility issues (excluding feature bug fixes)

• Array
  • Array#select!, Array#keep_if, Array#reject!, and Array#delete_if
    no longer changes the receiver array instantly every time the
    block is called. (https://bugs.ruby-lang.org/issues/10714)
  • Array#flatten and Array#flatten! no longer try to call #to_ary
    method on elements beyond the given level. (https://bugs.ruby-lang.org/issues/10748)
  • Array#inspect doesn't raise error even if its content returns
    a string which is not compatible with Encoding.default_external
    as inspected result. (https://bugs.ruby-lang.org/issues/11801) 7f47946
• Enumerable
  • Enumerable#chunk and Enumerable#slice_before no longer takes the
    initial_state argument. (https://bugs.ruby-lang.org/issues/10958)
    Use a local variable instead to maintain a state. remove "initial_state" argument of Enumerable#{slice_before,chunk} #3490
• File::Stat
  • On Windows File::Stat#ino always returned 0, but now returns
    BY_HANDLE_FILE_INFORMATION.nFileIndexHigh/Low.
• Hash
  • Hash#inspect doesn't raise error even if its content returns
    a string which is not compatible with Encoding.default_external
    as inspected result. (https://bugs.ruby-lang.org/issues/11801) 7f47946
• IO
  • IO#close doesn't raise when the IO object is closed. (https://bugs.ruby-lang.org/issues/10718)
  • IO#each_codepoint raises an exception at incomplete character
    before EOF when conversion takes place. (https://bugs.ruby-lang.org/issues/11444) (866c248)
• Module
  • Module#define_method and Object.define_singleton_method now
    require method body, Proc, Method, or a block, and raise
    ArgumentError if no block is given directly. (https://bugs.ruby-lang.org/issues/11283)
• StringIO
  • StringIO#set_encoding sets an internal encoding - String only affected when writeable (https://bugs.ruby-lang.org/issues/11827)
• pack/unpack (Array/String)
  • j and J directives for pointer width integer type. (https://bugs.ruby-lang.org/issues/11215)

Stdlib updates (outstanding ones only)

Only items relevant to JRuby

• Update .rb parts of stdlib to 2.3 (delay until 2.3.0 final, probably) 66570f0
• Bundle did_you_mean gem Bundle did_you_mean gem #3480
• Socket
  • Socket#connect_nonblock, Socket#accept_nonblock,
    TCPServer#accept_nonblock, UNIXServer#accept_nonblock,
    BasicSocket#recv_nonblock, BasicSocket#recvmsg_nonblock,
    BasicSocket#sendmsg_nonblock all support exception: false to return
    :wait_readable or :wait_writable symbols instead of raising
    IO::WaitReadable or IO::WaitWritable exceptions (b27a2b0)
  • BasicSocket#recv and BasicSocket#recv_nonblock allow an output
    String buffer argument like IO#read and IO#read_nonblock to reduce
    GC overhead
• OpenSSL
  • OpenSSL::SSL::SSLSocket#accept_nonblock and
    OpenSSL::SSL::SSLSocket#connect_nonblock supports exception: false.
  • update OpenSSL's .rb parts to match changes in 2.3
  • test & update jruby-openssl to be >= 0.9.13 (to incorporate above updates)
• Pathname
  • Pathname#descend and Pathname#ascend supported blockless form.
    (https://bugs.ruby-lang.org/issues/11052)
• io/wait
  • IO#wait_readable no longer checks FIONREAD, it may be used for
    non-bytestream IO such as listen sockets. (975dcc7 and 64638d0)
• timeout
  • Object#timeout is now warned as deprecated when called. (a042a39)

Stdlib compatibility issues (excluding feature bug fixes)

Only items relevant to JRuby

• ext/coverage/coverage.c
  • Coverage.peek_result: new method to allow coverage to be captured without
    stopping the coverage tool. implement Coverage.peek_result #3481