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 behave as if they were frozen. If they are mutated a deprecation warning is emitted. 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. [Bug #19918]

• Keyword arguments are no longer allowed in index. [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]

• Range

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

Stdlib updates

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 1.12.0
• json 2.7.2
• net-http 0.4.1
• optparse 0.5.0
• prism 0.26.0
• rdoc 6.6.3.1
• reline 0.5.3
• resolv 0.4.0
• stringio 3.1.1
• strscan 3.1.1

The following bundled gems are updated.

• minitest 5.22.3
• rake 13.2.1
• test-unit 3.6.2
• net-ftp 0.3.4
• net-imap 0.4.10
• net-smtp 0.5.0
• rbs 3.4.4
• typeprof 0.21.11
• debug 1.9.2

The following bundled gems are promoted from default gems.

• mutex_m 0.2.0
• getoptlong 0.2.1
• base64 0.2.0
• bigdecimal 3.1.7
• 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:infoo': undefined method time' for an instance of Integer from test.rb:2:in
    '

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

## 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 interpeter
  and JIT like {String.freeze} or {Integer#+} now emits a performance class
  warning (`-W:performance` or `Warning[:performance] = true`).
  [[Feature #20429]]