# 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]] * The `RUBY_GC_HEAP_INIT_SLOTS` environment variable has been deprecated and removed. Environment variables `RUBY_GC_HEAP_%d_INIT_SLOTS` should be used instead. [[Feature #19785]] ## 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]] * Module * Module#set_temporary_name added for setting a temporary name for a module. [[Feature #19521]] * 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]] * Proc * Now Proc#dup and Proc#clone call `#initialize_dup` and `#initialize_clone` hooks respectively. [[Feature #19362]] * Process.warmup * Notify the Ruby virtual machine that the boot sequence is finished, and that now is a good time to optimize the application. This is useful for long running applications. The actual optimizations performed are entirely implementation specific and may change in the future without notice. [[Feature #18885]] * Process::Status * Process::Status#& and Process::Status#>> are deprecated. [[Bug #19868]] * Range * Range#reverse_each can now process beginless ranges with an Integer endpoint. [[Feature #18515]] * Refinement * Add Refinement#target as an alternative of Refinement#refined_class. Refinement#refined_class is deprecated and will be removed in Ruby 3.4. [[Feature #19714]] * 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]] ## Stdlib updates * RubyGems and Bundler warn if users require gem that is scheduled to become the bundled gems in the future version of Ruby. [[Feature #19351]] [[Feature #19776]] [[Feature #19843]] Targeted libraries are: * abbrev * base64 * bigdecimal * csv * drb * getoptlong * mutex_m * nkf * observer * resolv-replace * rinda * syslog * Socket#recv and Socket#recv_nonblock returns `nil` instead of an empty string on closed connections. Socket#recvmsg and Socket#recvmsg_nonblock returns `nil` instead of an empty packet on closed connections. [[Bug #19012]] * Random::Formatter#alphanumeric is extended to accept optional `chars` keyword argument. [[Feature #18183]] The following default gem is added. * prism 0.16.0 The following default gems are updated. * RubyGems 3.5.0.dev * bigdecimal 3.1.5 * bundler 2.5.0.dev * csv 3.2.8 * erb 4.0.3 * etc 1.4.3.dev.1 * fiddle 1.1.2 * fileutils 1.7.1 * io-console 0.6.1.dev * irb 1.8.3 * nkf 0.1.3 * openssl 3.2.0 * optparse 0.4.0.pre.1 * psych 5.1.1.1 * reline 0.3.9 * stringio 3.0.9 * strscan 3.0.7 * syntax_suggest 1.1.0 * time 0.2.2 * timeout 0.4.0 * uri 0.12.2 The following bundled gem is promoted from default gems. * racc 1.7.1 The following bundled gems are updated. * minitest 5.20.0 * rake 13.1.0 * test-unit 3.6.1 * rexml 3.2.6 * rss 0.3.0 * net-imap 0.4.3 * net-smtp 0.4.0 * rbs 3.2.2 * typeprof 0.21.8 * debug 1.8.0 See GitHub releases like [Logger](https://github.com/ruby/logger/releases) or changelog for details of the default gems or bundled gems. ## Supported platforms ## Compatibility issues ## Stdlib compatibility issues * `racc` is promoted to 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 * Major performance improvements over 3.2 * Support for splat and rest arguments has been improved. * Registers are allocated for stack operations of the virtual machine. * More calls with optional arguments are compiled. * Exception handlers are also compiled. * Instance variables no longer exit to the interpreter with megamorphic object shapes. * Unsupported call types no longer exit to the interpreter. * `Integer#!=`, `String#!=`, `Kernel#block_given?`, `Kernel#is_a?`, `Kernel#instance_of?`, `Module#===` are specially optimized. * Now more than 3x faster than the interpreter on optcarrot! * Significantly improved memory usage over 3.2 * Metadata for compiled code uses a lot less memory. * Generate more compact code on ARM64 * Compilation speed is now slightly faster than 3.2. * Add `RubyVM::YJIT.enable` that can enable YJIT later * You can start YJIT without modifying command-line arguments or environment variables. * This can also be used to enable YJIT only once your application is done booting. `--yjit-disable` can be used if you want to use other YJIT options while disabling YJIT at boot. * Option to disable code GC and treat `--yjit-exec-mem-size` as a hard limit * Can produce better copy-on-write behavior on servers using unicorn and forking * `ratio_in_yjit` stat produced by `--yjit-stats` is now avaiable in release builds, a special stats or dev build is no longer required to access most stats. * Exit tracing option now supports sampling * `--trace-exits-sample-rate=N` * More thorough testing and multiple bug fixes * `--yjit-stats=quiet` is added to avoid printing stats on exit. * `--yjit-perf` is added to facilitate profiling with Linux perf. ### MJIT * MJIT is removed. * `--disable-jit-support` is removed. Consider using `--disable-yjit --disable-rjit` instead. ### RJIT * Introduced a pure-Ruby JIT compiler RJIT. * 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. [Feature #18183]: https://bugs.ruby-lang.org/issues/18183 [Feature #18498]: https://bugs.ruby-lang.org/issues/18498 [Feature #18515]: https://bugs.ruby-lang.org/issues/18515 [Feature #18885]: https://bugs.ruby-lang.org/issues/18885 [Bug #19012]: https://bugs.ruby-lang.org/issues/19012 [Bug #19150]: https://bugs.ruby-lang.org/issues/19150 [Feature #19314]: https://bugs.ruby-lang.org/issues/19314 [Feature #19347]: https://bugs.ruby-lang.org/issues/19347 [Feature #19351]: https://bugs.ruby-lang.org/issues/19351 [Feature #19362]: https://bugs.ruby-lang.org/issues/19362 [Feature #19521]: https://bugs.ruby-lang.org/issues/19521 [Feature #19538]: https://bugs.ruby-lang.org/issues/19538 [Feature #19591]: https://bugs.ruby-lang.org/issues/19591 [Feature #19714]: https://bugs.ruby-lang.org/issues/19714 [Feature #19776]: https://bugs.ruby-lang.org/issues/19776 [Feature #19785]: https://bugs.ruby-lang.org/issues/19785 [Feature #19843]: https://bugs.ruby-lang.org/issues/19843 [Bug #19868]: https://bugs.ruby-lang.org/issues/19868