ruby/NEWS.md

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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]

  • 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]

  • 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]

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]
  • Range

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

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]

The following default gems are updated.

  • RubyGems 3.6.0.dev
  • bundler 2.6.0.dev
  • erb 4.0.4
  • fiddle 1.1.3
  • io-console 0.7.2
  • irb 1.14.0
  • json 2.7.2
  • net-http 0.4.1
  • optparse 0.5.0
  • prism 0.30.0
  • rdoc 6.7.0
  • reline 0.5.9
  • resolv 0.4.0
  • stringio 3.1.2
  • strscan 3.1.1

The following bundled gems are updated.

  • minitest 5.24.1
  • rake 13.2.1
  • test-unit 3.6.2
  • rexml 3.3.2
  • net-ftp 0.3.7
  • net-imap 0.4.14
  • net-smtp 0.5.0
  • rbs 3.5.2
  • typeprof 0.21.11
  • debug 1.9.2
  • racc 1.8.0

The following bundled gems are promoted from default gems.

  • mutex_m 0.2.0
  • 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 0.1.2
  • 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 a opening quote. [Feature #16495]
    • Display a class name before a method name (only when the class has a permanent name). [Feature #19117]
    • 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>'
    

Stdlib compatibility issues

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

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

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]