F40 Change Proposal: Ruby 3.3 (System-Wide)

[Aoife Moloney]

This document represents a proposed Change. As part of the Changes
process, proposals are publicly announced in order to receive
community feedback. This proposal will only be implemented if approved
by the Fedora Engineering Steering Committee.

Wiki: https://fedoraproject.org/wiki/Changes/Ruby_3.3

= Ruby 3.3 =

== Summary ==

Ruby 3.3 is the latest stable version of Ruby. Many new features and
improvements are included for the increasingly diverse and expanding
demands for Ruby. With this major update from Ruby 3.2 in Fedora 39 to
Ruby 3.3 in Fedora 40, Fedora becomes the superior Ruby development
platform.

== Owner ==

* Name: [[User:vondruch| Vít Ondruch]]

* Email: [e-mail]
* Name: [[User:mtasaka| Mamoru Tasaka]]

* Email: [e-mail]

== Detailed Description ==

Ruby 3.3 is upstream's new major release of Ruby. Ruby 3.3 adds a new
pure-Ruby JIT compiler named RJIT, uses Lrama as a parser generator,
and many performance improvements especially YJIT.

=== 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.

=== Use Lrama instead of Bison ===

* Replace Bison with Lrama LALR parser generator

=== 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!
* Metadata for compiled code uses a lot less memory.
* Generate more compact code 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
* `ratio_in_yjit` stat produced by `--yjit-stats` is now available in
release builds, a special stats or dev build is no longer required.
* Exit tracing option now supports sampling
** `--trace-exits-sample-rate=N`
* More thorough testing and multiple bug fixes

=== Other notable changes since 3.2 ===

* Performance improvements
** `defined?(@ivar)` is optimized with Object Shapes.
* IRB has received several enhancements, including but not limited to:
** Advanced `irb:rdbg` integration that provides an equivalent
debugging experience to `pry-byebug`.
** Pager support for commands like `ls` and `show_cmds`.
** More accurate and helpful information provided by the `ls` and
`show_source` commands.
* ext/readline is retired
** Replaced by `reline` that is pure Ruby implementation compatible
with `ext/readline` API.
* RubyGems and Bundler warn if users require gem that is scheduled to
become the bundled gems in the future version of Ruby.

== Feedback ==

== Benefit to Fedora ==

With a latest release, Ruby language is supporting the newest language
features, which enables even faster and easier development of Ruby
applications.

== Scope ==
* Proposal owners:
** Finish packaging of Ruby 3.3. Current changes available in PR
https://src.fedoraproject.org/rpms/ruby/pull-request/159
** Rebuilding of Ruby packages providing native extensions (i.e.
packages which depends on libruby).

* Other developers:
** Rebuild of packages with binary extensions (i.e. packages which
depends on libruby) will be handled automatically, but some packages
might need fixes/updates to support Ruby 3.3 properly.

* Release engineering: [https://pagure.io/releng/issue/11753 #11753] <
** The packages are going to be rebuild in side-tag, but that does not
need releng involvement nowadays.

* Policies and guidelines: N/A (not needed for this Change)

* Trademark approval: N/A (not needed for this Change)

* Alignment with Community Initiatives:

== Upgrade/compatibility impact ==

* User specific Ruby binary extensions need to be rebuild.
* Ruby packages/application dependencies might need to be adjusted if
newly bundled gems are used.

== How To Test ==

* No special hardware is needed.
* To test, install Ruby 3.3. The test builds are published in PR or on
Ruby-SIG ML
* Try to locally rebuild your packages using Ruby 3.3.
* Use the packages with your applications previously written in Ruby.
* If something doesn't work as it should, let us know.

== User Experience ==

The Ruby programs/scripts should behave as they were used to.

== Dependencies ==

<pre>
$ dnf repoquery --disablerepo=* --enablerepo=rawhide
--enablerepo=rawhide-source --arch=src --whatrequires 'ruby-devel' |
sort | uniq | wc -l
134
</pre>

== Contingency Plan ==

* Contingency mechanism: We would like to get a special buildroot tag
to be able to rebuild necessary the packages with Ruby 3.3. If
anything goes wrong, the tag could be easily dropped and previous
version of Ruby 3.2 and its dependencies stays intact. The tag would
be merged into F40 after everything is rebuild.
* Contingency deadline: Mass Rebuild
* Blocks release? No

== Documentation ==

* [http://www.ruby-doc.org/ Help and documentation for the Ruby
programming language]
* [https://github.com/ruby/ruby/blob/master/NEWS.md Ruby 3.3.0 NEWS]
* [https://www.ruby-lang.org/en/news/2023/09/14/ruby-3-3-0-preview2-released/
Ruby 3.3.0-preview2 release announcement]

== Release Notes ==

* The Ruby 3.3 bumps soname, therefore Ruby packages, which use binary
extensions, should be rebuilt. Nevertheless, since upstream paid great
attention to source compatibility, no changes to your code are needed.

https://github.com/ruby/ruby/blob/master/NEWS.md