This bug tracks the remaining items from CRuby 2.5's NEWS file that we have not yet implemented in JRuby.

This issue will track Ruby 2.5 support for JRuby. This will be released in JRuby 9.3.0.0 or JRuby 10.

As with previous releases, we will base our checklist on MRI's NEWS file: https://github.com/ruby/ruby/blob/trunk/NEWS
This bug will track all NEWS items new in Ruby 2.5. This list is based off https://github.com/ruby/ruby/blob/trunk/NEWS.

Only changes relevant to JRuby are listed here. MRI-specific internal changes and features are not included.

Language changes

• refinements take place in string interpolations. Feature #13812

Core classes updates (outstanding ones only)

File

• :newline option to File.open implies text mode now. Bug #13350

IO

• IO#pread Feature #4532
• IO#pwrite Feature #4532
• IO#copy_stream tries copy offload with copy_file_range(2) Feature #13867

Process

• Precision of Process.times is improved if getrusage(2) exists. Feature #11952

Range

• Range#initialize no longer rescue exceptions when comparing begin and
  end with #<=> and raise a "bad value for range" ArgumentError
  but instead let the exception from the #<=> call go through.
  Feature #7688

Regexp

• Update to Onigmo 6.1.1.
• Support absent operator Implement Absent Operator k-takata/Onigmo#82

Compatibility issues (excluding feature bug fixes)

BasicSocket

• BasicSocket#read_nonblock and BasicSocket#write_nonblock no longer sets the O_NONBLOCK file description flag as side effect (on Linux only) Feature #13362

Implementation improvements

(Probably not JRuby-relevant.)

• This might not be a "user visible feature change" but) Hash class's
  hash function is now SipHash13. Feature #13017
• SecureRandom now prefers OS-provided sources than OpenSSL. Bug #9569
• Mutex rewritten to be smaller and faster Feature #13517
• Performance of block passing using block parameters is improved by lazy Proc allocation Feature #14045
• Dynamic instrumentation for TracePoint hooks instead of using "trace" instruction to avoid overhead Feature #14104

Miscellaneous changes

• Print backtrace and error message in reverse order if STDERR is unchanged and a tty. Feature #8661 [experimental] (Started in Reverse the order in which we print out the backtrace. #4876 #5094)
• Print error message in bold/underlined text if STDERR is unchanged and a tty. Feature #14140 [experimental] (Started in Reverse the order in which we print out the backtrace. #4876 #5094)