NEWS for Ruby 3.4.0¶ ↑

This document is a list of user-visible feature changes since the 3.3.0 release, except for bug fixes.

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

Language changes¶ ↑

• String literals in files without a frozen_string_literal comment now emit a deprecation warning when they are mutated. These warnings can be enabled with -W:deprecated or by setting Warning[:deprecated] = true. To disable this change, you can run Ruby with the --disable-frozen-string-literal command line argument. [Feature #20205]

• it is added to reference a block parameter. [Feature #18980]

• Keyword splatting nil when calling methods is now supported. **nil is treated similarly to **{}, passing no keywords, and not calling any conversion methods. [{Bug #20064}[https://bugs.ruby-lang.org/issues/20064]]

• Block passing is no longer allowed in index assignment (e.g. a[0, &b] = 1). [Bug #19918]

• Keyword arguments are no longer allowed in index assignment (e.g. a[0, kw: 1] = 2). [Bug #20218]

Core classes updates¶ ↑

Note: We’re only listing outstanding class updates.

• Exception

  • Exception#set_backtrace now accepts arrays of Thread::Backtrace::Location. Kernel#raise, Thread#raise and Fiber#raise also accept this new format. [Feature #13557]

• GC

  • GC.config added to allow setting configuration variables on the Garbage Collector. [Feature #20443]

  • GC configuration parameter rgengc_allow_full_mark introduced. When false GC will only mark young objects. Default is true. [Feature #20443]

• Hash

  • Hash.new now accepts an optional capacity: argument, to preallocate the hash with a given capacity. This can improve performance when building large hashes incrementally by saving on reallocation and rehashing of keys. [Feature #19236]

• Fiber::Scheduler

  • An optional Fiber::Scheduler#blocking_operation_wait hook allows blocking operations to be moved out of the event loop in order to reduce latency and improve multi-core processor utilization. [Feature #20876]

• IO::Buffer

  • IO::Buffer#copy can release the GVL, allowing other threads to run while copying data. [Feature #20902]

• Integer

  • Integer#** used to return Float::INFINITY when the return value is large, but now returns an Integer. If the return value is extremely large, it raises an exception. [Feature #20811]

• MatchData

  • MatchData#bytebegin and MatchData#byteend have been added. [Feature #20576]

• Ractor

  • require in Ractor is allowed. The requiring process will be run on the main Ractor. Ractor._require(feature) is added to run requiring process on the main Ractor. [Feature #20627]

  • Ractor.main? is added. [Feature #20627]

  • Ractor.[] and Ractor.[]= are added to access the ractor local storage of the current Ractor. [Feature #20715]

• Range

  • Range#size now raises TypeError if the range is not iterable. [Misc #18984]

  • Range#step now consistently has a semantics of iterating by using + operator for all types, not only numerics. [Feature #18368]

    (Time.utc(2022, 2, 24)..).step(24*60*60).take(3)
    #=> [2022-02-24 00:00:00 UTC, 2022-02-25 00:00:00 UTC, 2022-02-26 00:00:00 UTC]
    

• Rational

  • Rational#** used to return Float::INFINITY or Float::NAN when the numerator of the return value is large, but now returns an Integer. If it is extremely large, it raises an exception. [Feature #20811]

• Refinement

  • Removed deprecated method Refinement#refined_class. [Feature #19714]

• RubyVM::AbstractSyntaxTree

  • Add RubyVM::AbstractSyntaxTree::Node#locations method which returns location objects associated with the AST node. [Feature #20624]

  • Add RubyVM::AbstractSyntaxTree::Location class which holds location information. [Feature #20624]

• Time

  • On Windows, now Time#zone encodes the system timezone name in UTF-8 instead of the active code page, if it contains non-ASCII characters. [Bug #20929]

• Warning

  • Add Warning.categories method which returns a list of possible warning categories. [Feature #20293]

Stdlib updates¶ ↑

• Tempfile

  • The keyword argument anonymous: true is implemented for Tempfile.create. Tempfile.create(anonymous: true) removes the created temporary file immediately. So applications don’t need to remove the file. [Feature #20497]

• win32/sspi.rb

  • This library is now extracted from the Ruby repository to ruby/net-http-sspi. [Feature #20775]

The following default gem is added.

• win32-registry 0.1.0

The following default gems are updated.

• RubyGems 3.6.0.dev

• benchmark 0.4.0

• bundler 2.6.0.dev

• date 3.4.1

• delegate 0.4.0

• did_you_mean 2.0.0

• digest 3.2.0.pre0

• erb 4.0.4

• error_highlight 0.7.0

• etc 1.4.5

• fcntl 1.2.0

• fiddle 1.1.6.dev

• fileutils 1.7.3

• io-console 0.8.0

• io-nonblock 0.3.1

• ipaddr 1.2.7

• irb 1.14.1

• json 2.9.0

• logger 1.6.2

• net-http 0.6.0

• open-uri 0.5.0

• optparse 0.6.0

• ostruct 0.6.1

• pathname 0.4.0

• pp 0.6.2

• prism 1.0.0

• pstore 0.1.4

• psych 5.2.1

• rdoc 6.8.1

• reline 0.5.12

• resolv 0.5.0

• securerandom 0.4.0

• set 1.1.1

• shellwords 0.2.1

• singleton 0.3.0

• stringio 3.1.2.dev

• strscan 3.1.1.dev

• syntax_suggest 2.0.2

• tempfile 0.3.1

• time 0.4.1

• timeout 0.4.2

• tmpdir 0.3.0

• uri 1.0.2

• win32ole 1.9.0

• yaml 0.4.0

• zlib 3.2.0

The following bundled gem is added.

• repl_type_completor 0.1.7

The following bundled gems are updated.

• minitest 5.25.4

• power_assert 2.0.4

• rake 13.2.1

• test-unit 3.6.4

• rexml 3.3.9

• rss 0.3.1

• net-ftp 0.3.8

• net-imap 0.5.1

• net-smtp 0.5.0

• prime 0.1.3

• rbs 3.7.0

• typeprof 0.21.11

• debug 1.9.2

• racc 1.8.1

The following bundled gems are promoted from default gems.

• mutex_m 0.3.0

• getoptlong 0.2.1

• base64 0.2.0

• bigdecimal 3.1.8

• observer 0.1.2

• abbrev 0.1.2

• resolv-replace 0.1.1

• rinda 0.2.0

• drb 2.2.1

• nkf 0.2.0

• syslog 0.2.0

• csv 3.3.0

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

Supported platforms¶ ↑

Compatibility issues¶ ↑

• Error messages and backtrace displays have been changed.

  • Use a single quote instead of a backtick as an opening quote. [Feature #16495]

  • Display a class name before a method name (only when the class has a permanent name). [Feature #19117]

  • Extra rescue/ensure frames are no longer available on the backtrace. [Feature #20275]

  • Kernel#caller, Thread::Backtrace::Location’s methods, etc. are also changed accordingly.

    Old:

    test.rb:1:in `foo': undefined method `time' for an instance of Integer
            from test.rb:2:in `<main>'

    New:

    test.rb:1:in 'Object#foo': undefined method 'time' for an instance of Integer
            from test.rb:2:in '<main>'

• Hash#inspect rendering have been changed. [Bug #20433]

  • Symbol keys are displayed using the modern symbol key syntax: "{user: 1}"

  • Other keys now have spaces around =>: '{"user" => 1}', while previously they didn't: '{"user"=>1}'

• Kernel#Float() now accepts a decimal string with decimal part omitted. [Feature #20705] Float("1.") #=> 1.0 (previously, an ArgumentError was raised) Float("1.E-1") #=> 0.1 (previously, an ArgumentError was raised)

• String#to_f now accepts a decimal string with decimal part omitted. [Feature #20705] Note that the result changes when an exponent is specified. "1.".to_f #=> 1.0 "1.E-1".to_f #=> 0.1 (previously, 1.0 was returned)

• Object#singleton_method now returns methods in modules prepended to or included in the receiver’s singleton class. [Bug #20620] o = Object.new o.extend(Module.new{def a = 1}) o.singleton_method(:a).call #=> 1

Stdlib compatibility issues¶ ↑

• DidYouMean

  • DidYouMean::SPELL_CHECKERS[]= and DidYouMean::SPELL_CHECKERS.merge! are removed.

• Net::HTTP

  • Removed the following deprecated constants: Net::HTTP::ProxyMod Net::NetPrivate::HTTPRequest Net::HTTPInformationCode Net::HTTPSuccessCode Net::HTTPRedirectionCode Net::HTTPRetriableCode Net::HTTPClientErrorCode Net::HTTPFatalErrorCode Net::HTTPServerErrorCode Net::HTTPResponseReceiver Net::HTTPResponceReceiver

  These constants were deprecated from 2012.

• Timeout

  • Reject negative values for Timeout.timeout. [Bug #20795]

• URI

  • Switched default parser to RFC 3986 compliant from RFC 2396 compliant. [Bug #19266]

C API updates¶ ↑

• rb_newobj and rb_newobj_of (and corresponding macros RB_NEWOBJ, RB_NEWOBJ_OF, NEWOBJ, NEWOBJ_OF) have been removed. [Feature #20265]

• Removed deprecated function rb_gc_force_recycle. [Feature #18290]

Implementation improvements¶ ↑

• The default parser is now Prism. To use the conventional parser, use the command-line argument --parser=parse.y. [Feature #20564]

• Happy Eyeballs version 2 (RFC8305) is used in Socket.tcp. To disable it, use the keyword argument fast_fallback: false. [Feature #20108]

• Happy Eyeballs version 2 (RFC8305) is implemented in TCPSocket.new. To enable it, use the keyword argument fast_fallback: true. (This entry is temporary. It should be merged with the above entry after it becomes settled) [Feature #20782]

• Array#each is rewritten in Ruby for better performance [Feature #20182].

• Alternative garbage collector (GC) implementations can be loaded dynamically through the modular garbage collector feature. To enable this feature, configure Ruby with --with-modular-gc at build time. GC libraries can be loaded at runtime using the environment variable RUBY_GC_LIBRARY. [Feature #20351]

• Ruby's built-in garbage collector has been split into a separate file at gc/default/default.c and interacts with Ruby using an API defined in gc/gc_impl.h. The built-in garbage collector can now also be built as a library using make modular-gc MODULAR_GC=default and enabled using the environment variable RUBY_GC_LIBRARY=default. [Feature #20470]

• An experimental GC library is provided based on MMTk. This GC library can be built using make modular-gc MODULAR_GC=mmtk and enabled using the environment variable RUBY_GC_LIBRARY=mmtk. This requires the Rust toolchain on the build machine. [Feature #20860]

JIT¶ ↑

Miscellaneous changes¶ ↑

• Passing a block to a method which doesn't use the passed block will show a warning on verbose mode (-w). [Feature #15554]

• Redefining some core methods that are specially optimized by the interpreter and JIT like String#freeze or Integer#+ now emits a performance class warning (-W:performance or Warning[:performance] = true). [Feature #20429]