Ruby 3.2.0 Preview 3 Released (2025)

Posted by naruse on 11 Nov 2022

We are pleased to announce the release of Ruby 3.2.0-preview3. Ruby 3.2 adds many features and performance improvements.

WASI based WebAssembly support

This is an initial port of WASI based WebAssembly support. This enables a CRuby binary to be available on Web browser, Serverless Edge environment, and other WebAssembly/WASI embedders. Currently this port passes basic and bootstrap test suites not using Thread API.

Background

WebAssembly (Wasm) is originally introduced to run programs safely and fast in web browsers. But its objective - running programs efficinently with security on various environment - is long wanted not only by web but also by general applications.

WASI (The WebAssembly System Interface) is designed for such use cases. Though such applications need to communicate with operating systems, WebAssembly runs on a virtual machine which didn’t have a system interface. WASI standardizes it.

WebAssembly/WASI Support in Ruby intends to leverage those projects. It enables Ruby developers to write applications which runs on such promised platform.

Use case

This support encourages developers can utilize CRuby in WebAssembly environment. An example use case of it is TryRuby playground’s CRuby support. Now you can try original CRuby in your web browser.

Technical points

Today’s WASI and WebAssembly itself has some missing features to implement Fiber, exception, and GC because it’s still evolving and also for security reasons. So CRuby fills the gap by using Asyncify, which is a binary transformation technique to control execution in userland.

In addition, we built a VFS on top of WASI so that we can easily pack Ruby apps into a single .wasm file. This makes distribution of Ruby apps a bit easier.

Regexp improvements against ReDoS

It is known that Regexp matching may take unexpectedly long. If your code attempts to match an possibly inefficient Regexp against an untrusted input, an attacker may exploit it for efficient Denial of Service (so-called Regular expression DoS, or ReDoS).

We have introduced two improvements that significantly mitigate ReDoS.

Improved Regexp matching algorithm

Since Ruby 3.2, Regexp’s matching algorithm has been greatly improved by using memoization technique.

# This matching takes 10 sec. in Ruby 3.1, and does 0.003 sec. in Ruby 3.2/^a*b?a*$/ =~ "a" * 50000 + "x"

The improved matching algorithm allows most of Regexp matching (about 90% in our experiments) to be completed in linear time.

(For preview users: this optimization may consume memory proportional to the input length for each matching. We expect no practical problems to arise because this memory allocation is usually delayed, and a normal Regexp matching should consume at most 10 times as much memory as the input length. If you run out of memory when matching Regexps in a real-world application, please report it.)

Regexp timeout

The optimization above cannot be applied to some kind of regular expressions, such as including advanced features (e.g., back-references or look-around), or with huge fixed number of repetitions. As a fallback measure, a timeout feature for Regexp matching is also introduced.

Regexp.timeout = 1.0/^a*b?a*()\1$/ =~ "a" * 50000 + "x"#=> Regexp::TimeoutError is raised in one second

Note that Regexp.timeout is a global configuration. If you want to use different timeout settings for some special Regexps, you may want to use timeout keyword for Regexp.new.

Regexp.timeout = 1.0# This regexp has no timeoutlong_time_re = Regexp.new('^a*b?a*()\1$', timeout: Float::INFINITY)long_time_re =~ "a" * 50000 + "x" # never interrupted

The original proposal is https://bugs.ruby-lang.org/issues/17837

Other Notable New Features

No longer bundle 3rd party sources

We no longer bundle 3rd party sources like libyaml, libffi.
- libyaml source has been removed from psych. You may need to install libyaml-dev with Ubuntu/Debian platform. The package name is different each platforms.
- bundled libffi source is also removed from fiddle

Language

Anonymous rest and keyword rest arguments can now be passed asarguments, instead of just used in method parameters.[Feature #18351]
```
 def foo(*) bar(*) end def baz(**) quux(**) end
```
A proc that accepts a single positional argument and keywords willno longer autosplat. [Bug #18633]
```
proc{|a, **k| a}.call([1, 2])# Ruby 3.1 and before# => 1# Ruby 3.2 and after# => [1, 2]
```
Constant assignment evaluation order for constants set on explicitobjects has been made consistent with single attribute assignmentevaluation order. With this code:
```
 foo::BAR = baz
```
foo is now called before baz. Similarly, for multiple assignmentsto constants, left-to-right evaluation order is used. With thiscode:
```
 foo1::BAR1, foo2::BAR2 = baz1, baz2
```
The following evaluation order is now used:
1. foo1
2. foo2
3. baz1
4. baz2
[Bug #15928]
Find pattern is no longer experimental.[Feature #18585]
Methods taking a rest parameter (like *args) and wishing to delegate keywordarguments through foo(*args) must now be marked with ruby2_keywords(if not already the case). In other words, all methods wishing to delegatekeyword arguments through *args must now be marked with ruby2_keywords,with no exception. This will make it easier to transition to other ways ofdelegation once a library can require Ruby 3+. Previously, the ruby2_keywordsflag was kept if the receiving method took *args, but this was a bug and aninconsistency. A good technique to find the potentially-missing ruby2_keywordsis to run the test suite, for where it fails find the last method which mustreceive keyword arguments, use puts nil, caller, nil there, and check eachmethod/block on the call chain which must delegate keywords is correctly markedas ruby2_keywords. [Bug #18625] [Bug #16466]
```
 def target(**kw) end # Accidentally worked without ruby2_keywords in Ruby 2.7-3.1, ruby2_keywords # needed in 3.2+. Just like (*args, **kwargs) or (...) would be needed on # both #foo and #bar when migrating away from ruby2_keywords. ruby2_keywords def bar(*args) target(*args) end ruby2_keywords def foo(*args) bar(*args) end foo(k: 1)
```

Performance improvements

YJIT

Support arm64 / aarch64 on UNIX platforms.
Building YJIT requires Rust 1.58.1+. [Feature #18481]

Other notable changes since 3.1

Hash
- Hash#shift now always returns nil if the hash isempty, instead of returning the default value orcalling the default proc. [Bug #16908]
MatchData
- MatchData#byteoffset has been added. [Feature #13110]
Module
- Module.used_refinements has been added. [Feature #14332]
- Module#refinements has been added. [Feature #12737]
- Module#const_added has been added. [Feature #17881]
Proc
- Proc#dup returns an instance of subclass. [Bug #17545]
- Proc#parameters now accepts lambda keyword. [Feature #15357]
Refinement
- Refinement#refined_class has been added. [Feature #12737]
RubyVM::AbstractSyntaxTree
- Add error_tolerant option for parse, parse_file and of. [Feature #19013]
Set
- Set is now available as a builtin class without the need for require "set". [Feature #16989]It is currently autoloaded via the Set constant or a call to Enumerable#to_set.
String
- String#byteindex and String#byterindex have been added. [Feature #13110]
- Update Unicode to Version 14.0.0 and Emoji Version 14.0. [Feature #18037](also applies to Regexp)
- String#bytesplice has been added. [Feature #18598]
Struct
- A Struct class can also be initialized with keyword argumentswithout keyword_init: true on Struct.new [Feature #16806]

Compatibility issues

Note: Excluding feature bug fixes.

Removed constants

The following deprecated constants are removed.

Fixnum and Bignum [Feature #12005]
Random::DEFAULT [Feature #17351]
Struct::Group
Struct::Passwd

Removed methods

The following deprecated methods are removed.

Dir.exists? [Feature #17391]
File.exists? [Feature #17391]
Kernel#=~ [Feature #15231]
Kernel#taint, Kernel#untaint, Kernel#tainted?[Feature #16131]
Kernel#trust, Kernel#untrust, Kernel#untrusted?[Feature #16131]

Stdlib compatibility issues

Psych no longer bundles libyaml sources.Users need to install the libyaml library themselves via the packagesystem. [Feature #18571]

C API updates

Updated C APIs

The following APIs are updated.

PRNG updaterb_random_interface_t updated and versioned.Extension libraries which use this interface and built for older versions.Also init_int32 function needs to be defined.

Removed C APIs

The following deprecated APIs are removed.

rb_cData variable.
“taintedness” and “trustedness” functions. [Feature #16131]

Standard libraries updates

SyntaxSuggest
- The feature of syntax_suggest formerly dead_end is integrated in Ruby.[Feature #18159]
ErrorHighlight
- Now it points an argument(s) of TypeError and ArgumentError

test.rb:2:in `+': nil can't be coerced into Integer (TypeError)sum = ary[0] + ary[1] ^^^^^^

The following default gems are updated.
- RubyGems 3.4.0.dev
- bigdecimal 3.1.2
- bundler 2.4.0.dev
- cgi 0.3.2
- date 3.2.3
- error_highlight 0.4.0
- etc 1.4.0
- io-console 0.5.11
- io-nonblock 0.1.1
- io-wait 0.3.0.pre
- ipaddr 1.2.4
- json 2.6.2
- logger 1.5.1
- net-http 0.2.2
- net-protocol 0.1.3
- ostruct 0.5.5
- psych 5.0.0.dev
- reline 0.3.1
- securerandom 0.2.0
- set 1.0.3
- stringio 3.0.3
- syntax_suggest 0.0.1
- timeout 0.3.0
The following bundled gems are updated.
- minitest 5.16.3
- net-imap 0.2.3
- rbs 2.6.0
- typeprof 0.21.3
- debug 1.6.2
The following default gems are now bundled gems.

See NEWSor commit logsfor more details.

With those changes, 2719 files changed, 191269 insertions(+), 120315 deletions(-)since Ruby 3.1.0!

Download

https://cache.ruby-lang.org/pub/ruby/3.2/ruby-3.2.0-preview3.tar.gz

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https://cache.ruby-lang.org/pub/ruby/3.2/ruby-3.2.0-preview3.tar.xz

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https://cache.ruby-lang.org/pub/ruby/3.2/ruby-3.2.0-preview3.zip

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What is Ruby

Ruby was first developed by Matz (Yukihiro Matsumoto) in 1993,and is now developed as Open Source. It runs on multiple platformsand is used all over the world especially for web development.