ruby/NEWS.md

NEWS for Ruby 3.3.0

This document is a list of user-visible feature changes since the 3.2.0 release, except for bug fixes.

Note that each entry is kept to a minimum, see links for details.

Language changes

Command line options

• A new performance warning category was introduced. They are not displayed by default even in verbose mode. Turn them on with -W:performance or Warning[:performance] = true. [Feature #19538]

Core classes updates

Note: We're only listing outstanding class updates.

• Array

  • Array#pack now raises ArgumentError for unknown directives. [Bug #19150]

• Dir

  • Dir.for_fd added for returning a Dir object for the directory specified by the provided directory file descriptor. [Feature #19347]
  • Dir.fchdir added for changing the directory to the directory specified by the provided directory file descriptor. [Feature #19347]
  • Dir#chdir added for changing the directory to the directory specified by the provided Dir object. [Feature #19347]

• MatchData

  • MatchData#named_captures now accepts optional symbolize_names keyword. [Feature #19591]

• String

  • String#unpack now raises ArgumentError for unknown directives. [Bug #19150]
  • String#bytesplice now accepts new arguments index/length or range of the source string to be copied. [Feature #19314]

• ObjectSpace::WeakKeyMap

  • New core class to build collections with weak references. The class use equality semantic to lookup keys like a regular hash, but it doesn't hold strong references on the keys. [Feature #18498]

Stdlib updates

The following default gems are updated.

• RubyGems 3.5.0.dev
• bigdecimal 3.1.4
• bundler 2.5.0.dev
• csv 3.2.7
• fiddle 1.1.2
• fileutils 1.7.1
• irb 1.7.0
• nkf 0.1.3
• optparse 0.4.0.pre.1
• psych 5.1.0
• reline 0.3.5
• stringio 3.0.8
• strscan 3.0.7
• syntax_suggest 1.1.0
• time 0.2.2
• timeout 0.3.2
• uri 0.12.1

The following bundled gems are updated.

• minitest 5.18.0
• test-unit 3.6.0
• rbs 3.1.0
• typeprof 0.21.7
• debug 1.8.0

The following default gem is now bundled.

• racc 1.7.0

See GitHub releases like Logger or changelog for details of the default gems or bundled gems.

Supported platforms

Compatibility issues

Stdlib compatibility issues

• racc is promoted bundled gems.
  • You need to add racc to your Gemfile if you use racc under bundler environment.
• ext/readline is retired
  • We have reline that is pure Ruby implementation compatible with ext/readline API. We rely on reline in the future. If you need to use ext/readline, you can install ext/readline via rubygems.org with gem install readline-ext.
  • We no longer need to install libraries like libreadline or libedit.

C API updates

Implementation improvements

• defined?(@ivar) is optimized with Object Shapes.

YJIT

• Significant performance improvements over 3.2
  • Splat and rest arguments support has been improved.
  • Registers are allocated for stack operations of the virtual machine.
  • More calls with optional arguments are compiled.
  • Integer#!=, String#!=, Kernel#block_given?, Kernel#is_a?, Kernel#instance_of?, Module#=== are specially optimized.
  • Instance variables no longer exit to the interpreter with megamorphic Object Shapes.
• Metadata for compiled code uses a lot less memory.
• Improved code generation on ARM64
• Option to start YJIT in paused mode and then later enable it manually
  • --yjit-pause and RubyVM::YJIT.resume
  • This can be used to enable YJIT only once your application is done booting
• Exit tracing option now supports sampling
  • --trace-exits-sample-rate=N
• Multiple bug fixes

RJIT

• Introduced a pure-Ruby JIT compiler RJIT and replaced MJIT.
  • RJIT supports only x86_64 architecture on Unix platforms.
  • Unlike MJIT, it doesn't require a C compiler at runtime.
• RJIT exists only for experimental purposes.
  • You should keep using YJIT in production.