January 2026 - ruby-core - ml.ruby-lang.org

[ruby-core:123731] [Ruby Bug#21674] Possible regression in return case in statement
by jandudulski (Jan Dudulski) 16 Mar '26

16 Mar '26

Issue #21674 has been reported by jandudulski (Jan Dudulski). ---------------------------------------- Bug #21674: Possible regression in return case in statement https://bugs.ruby-lang.org/issues/21674 * Author: jandudulski (Jan Dudulski) * Status: Open * ruby -v: 3.4.6 * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- Suddenly my code started failing in Ruby 3.4.6 and 3.4.7. Shortest code example: ``` ruby args = [:increased] context = Data.define(:event).new(:decreased) case args in [event] context.event in ^event end ``` In Ruby prior to 3.4.6 in returns `false` (as expected) but in 3.4.6 and 3.4.7 it returns `:decreased`. `context.event in ^event` still returns `false`. -- https://bugs.ruby-lang.org/

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[ruby-core:120819] [Ruby master Bug#21097] `x = a rescue b in c` and `def f = a rescue b in c` parsed differently between parse.y and prism
by tompng (tomoya ishida) 16 Mar '26

16 Mar '26

Issue #21097 has been reported by tompng (tomoya ishida). ---------------------------------------- Bug #21097: `x = a rescue b in c` and `def f = a rescue b in c` parsed differently between parse.y and prism https://bugs.ruby-lang.org/issues/21097 * Author: tompng (tomoya ishida) * Status: Open * ruby -v: ruby 3.5.0dev (2025-01-27T08:19:32Z master c3c7300b89) +YJIT +MN +PRISM [arm64-darwin22] * Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- ~~~ruby x = a rescue b in c (x = (a rescue b)) in c # parse.y, prism(ruby 3.4) x = (a rescue (b in c)) # prism(ruby 3.5) ~~~ ~~~ruby def f = a rescue b in c #=> true(parse.y), :f(prism) (def f = (a rescue b)) in c # parse.y def f = (a rescue (b in c)) # prism ~~~ There is no difference between prism and parse.y parsing these codes ~~~ruby a rescue b in c # a rescue (b in c) x = a rescue b # x = (a rescue b) x = b in c # (x = b) in c def f = a rescue b # def f = (a rescue b) def f = b in c # (def f = a) in b ~~~ -- https://bugs.ruby-lang.org/

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[ruby-core:124443] [Ruby Bug#21828] An incorrect warning message related to `benchmark` is shown when using `benchmark-ips`
by y-yagi (Yuji Yaginuma) 16 Mar '26

16 Mar '26

Issue #21828 has been reported by y-yagi (Yuji Yaginuma). ---------------------------------------- Bug #21828: An incorrect warning message related to `benchmark` is shown when using `benchmark-ips` https://bugs.ruby-lang.org/issues/21828 * Author: y-yagi (Yuji Yaginuma) * Status: Open * ruby -v: ruby 4.0.0 (2025-12-25 revision 553f1675f3) +PRISM [x86_64-linux] * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN, 4.0: UNKNOWN ---------------------------------------- ## Descrition When using `benchmark-ips` gem with Ruby 4.0.0, the warning related to `benchmark` gem is shown. ## Step to reproduce ```ruby # Gemfile # frozen_string_literal: true source "https://rubygems.org" gem "benchmark-ips" ``` ```ruby # script.rb require "benchmark/ips" ``` ```text $ bundle exec ruby -v script.rb ruby 4.0.0 (2025-12-25 revision 553f1675f3) +PRISM [x86_64-linux] script.rb:1: warning: benchmark/ips is found in benchmark, which is not part of the default gems since Ruby 4.0.0. You can add benchmark to your Gemfile or gemspec to fix this error. ``` ## Expected behavior The warning for `benchmark` isn't shown when using `benchmark-ips`. -- https://bugs.ruby-lang.org/

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[ruby-core:116589] [Ruby master Misc#20238] Use prism for mk_builtin_loader.rb
by kddnewton (Kevin Newton) 13 Mar '26

13 Mar '26

Issue #20238 has been reported by kddnewton (Kevin Newton). ---------------------------------------- Misc #20238: Use prism for mk_builtin_loader.rb https://bugs.ruby-lang.org/issues/20238 * Author: kddnewton (Kevin Newton) * Status: Open * Priority: Normal ---------------------------------------- I would like to propose that we use prism for mk_builtin_loader.rb. Right now the Ruby syntax that you can use in builtin classes is restricted to the base Ruby version (2.7). This means you can't use a lot of the nicer syntax that Ruby has shipped in the last couple of years. If we switch to using prism to parse the builtin files instead of using ripper, then we can always use the latest version of Ruby syntax. A pull request for this is here: https://github.com/kddnewton/ruby/pull/65. The approach for the PR is taken from how RJIT bindgen works. -- https://bugs.ruby-lang.org/

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[ruby-core:123871] [Ruby Feature#21700] `IO::Buffer.map`: offset argument is "broken" and needs to be made more useful
by trinistr (Alexander Bulancov) 11 Mar '26

11 Mar '26

Issue #21700 has been reported by trinistr (Alexander Bulancov). ---------------------------------------- Feature #21700: `IO::Buffer.map`: offset argument is "broken" and needs to be made more useful https://bugs.ruby-lang.org/issues/21700 * Author: trinistr (Alexander Bulancov) * Status: Open ---------------------------------------- *This was supposed to be a bug report, but it turned into a feature request halfway through.* `IO::Buffer.map` supports `size` and `offset` arguments to localize buffer to a specific part of mapped file. While `size` works fine, specifying `offset` as anything but 0 is a recipe for disaster. 1. It is practically undocumented. This is it currently: "Optional size and offset of mapping can be specified." While `size` can be whatever user desires, `offset` can only be set to specific values. It was *very* surprising when I started testing it, as I expected it to behave similar to size and offset of a slice. Which values are allowed? That's the next point. 2. Possible values for `offset` are highly platform-dependent. - On Linux it must be a multiple of page size. (https://www.man7.org/linux/man-pages/man2/mmap.2.html) - On macOS it can be any value? manpage doesn't specify exactly. (https://developer.apple.com/library/archive/documentation/System/Conceptual… (I looked at the manpage on a mac, seems to be the same.)) - On Windows it must be a multiple of some value that *isn't* page size and page size doesn't work here. StackOverflow says it's 64 kB, but that didn't work for me. (See dwFileOffsetLow in https://learn.microsoft.com/en-us/windows/win32/api/memoryapi/nf-memoryapi-…) - On other systems? Who knows. 3. On macOS, a buffer successfully created with an offset crashes on read. I don't know why, it's exactly the same file, size and offset that works on Ubuntu, and the read is bounded. 4. Currently, offset doesn't change the buffer's size if unspecified, leading to crashes. I will be making a PR addressing this but still. 5. All of this makes offset unpractical to test, leading to all kinds of problems. So the problem is: this argument is a very low-level detail that requires significant knowledge of all platforms your code may be ever deployed to, even if strictly Ruby is used (no C API), with unexpectedly high footgun potential. I understand that IO::Buffer is a lower-level class, but this seems too much. I propose to make `offset` argument into a convenience for users, allowing any reasonable value (i.e inside the file). Behind the scenes, we can use the native offset for efficieny, on platforms where it works well, but the user API would be decoupled from this. However, I'm not particularly familiar with Ruby internals, so I can't tell how viable this is. -- https://bugs.ruby-lang.org/

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[ruby-core:123992] [Ruby Bug#21760] Ruby::Box: a couple of require-related problems
by zverok (Victor Shepelev) 09 Mar '26

09 Mar '26

Issue #21760 has been reported by zverok (Victor Shepelev). ---------------------------------------- Bug #21760: Ruby::Box: a couple of require-related problems https://bugs.ruby-lang.org/issues/21760 * Author: zverok (Victor Shepelev) * Status: Open * ruby -v: 4.0.0dev (2025-12-03T05:16:03Z master 4762f429f4) +PRISM [x86_64-linux] * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- I am not sure whether all the problems have the same nature, but putting them together for now. **1. Enabling box breaks `gem`+`require`** Minimal reproducible example: `test.rb`: ```ruby gem 'faraday', '= 2.14.0' require 'faraday' p Faraday::VERSION ``` (Note that there is no explicit use of `Ruby::Box`) Running it with and without `RUBY_BOX`: ```sh $ ruby test.rb "2.14.0" $ RUBY_BOX=1 ruby test.rb ruby: warning: Ruby::Box is experimental, and the behavior may change in the future! See doc/box.md for known issues, etc. test.rb:2:in 'Kernel#require': cannot load such file -- faraday (LoadError) from test.rb:2:in 'Ruby::Box::Loader#require' from test.rb:2:in '<main>' test.rb:2:in 'Kernel#require': cannot load such file -- faraday (LoadError) from test.rb:2:in 'Ruby::Box::Loader#require' from test.rb:2:in '<main>' ``` (sic, the error is printed twice) **2. requiring the same gem from `Box`-loaded file and the main file** `box.rb`: ```ruby require 'faraday' p "In a box: #{Faraday::VERSION}" ``` `main.rb` ```ruby b = Ruby::Box.new b.load('box.rb') require 'faraday' ``` ```sh $ RUBY_BOX=1 ruby main.rb ruby: warning: Ruby::Box is experimental, and the behavior may change in the future! See doc/box.md for known issues, etc. "In a box: 2.14.0" main.rb:5:in 'Kernel#require': cannot load such file -- faraday (LoadError) from main.rb:5:in 'Ruby::Box::Loader#require' from main.rb:5:in '<main>' main.rb:5:in 'Kernel#require': cannot load such file -- faraday (LoadError) from main.rb:5:in 'Ruby::Box::Loader#require' from main.rb:5:in '<main>' ``` **3. `Box#require` seem to not be aware of gems** In the example above, we see that Box-loaded file can require a gem. This also works: ```ruby b = Ruby::Box.new b.eval(<<~RUBY) require "faraday" p Faraday::VERSION RUBY ``` (prints "2.14.0" as expected) But this doesn't: ```ruby b = Ruby::Box.new b.require('faraday') ``` ```sh $ RUBY_BOX=1 ruby test.rb ruby: warning: Ruby::Box is experimental, and the behavior may change in the future! See doc/language/box.md for known issues, etc. test.rb:3:in 'Ruby::Box#require': cannot load such file -- faraday (LoadError) from test.rb:3:in '<main>' ``` -- https://bugs.ruby-lang.org/

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[ruby-core:123913] [Ruby Bug#21711] Prism and parse.y parses private endless method definition with block differently
by tompng (tomoya ishida) 06 Mar '26

06 Mar '26

Issue #21711 has been reported by tompng (tomoya ishida). ---------------------------------------- Bug #21711: Prism and parse.y parses private endless method definition with block differently https://bugs.ruby-lang.org/issues/21711 * Author: tompng (tomoya ishida) * Status: Open * ruby -v: ruby 4.0.0dev (2025-11-26T06:41:42Z master 43ed35de6c) +YJIT +MN +PRISM [arm64-darwin24] * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- In the following code, `do end` block is passed to `private` in Prism but passed to `tap` in parse.y ~~~ruby private def f = tap do end f # different result(prism: LocalJumpError, parsey: returns main) ~~~ According to https://bugs.ruby-lang.org/issues/17398#note-10, `private def hello = puts "Hello" do expr end` should be parsed as `private (def hello = puts "Hello") do expr end`. This is correctly implemented in both Prism and parse.y, but when rhs is `tap do end`, there is a discrepancy. Another example. Prism: parse success, parse.y: syntax error. ~~~ruby private def f = 1 do end ~~~ -- https://bugs.ruby-lang.org/

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[ruby-core:121627] [Ruby Feature#21264] Extract Date library from Ruby repo in the future
by hsbt (Hiroshi SHIBATA) 06 Mar '26

06 Mar '26

Issue #21264 has been reported by hsbt (Hiroshi SHIBATA). ---------------------------------------- Feature #21264: Extract Date library from Ruby repo in the future https://bugs.ruby-lang.org/issues/21264 * Author: hsbt (Hiroshi SHIBATA) * Status: Open ---------------------------------------- Note: This is not for Ruby 3.5. `Date` and `DateTime` has no primary maintainer in 10+ years. I would like to deprecate `date` via bundled gems for reducing our maintenance time especially @nobu. But `Time.prase` and `Time.strptime` are widely used now. How do we deprecate `date` library? 1. Migrate `Date._strptime`, `Date.strptime` and `Date._parse` to `Time`. The current `Date` is migrated as bundled gems. 2. Migrate `Date` to the bundled gems. `Time.parse` and `Time.strptime` warns if `date` is not found. 3. Keep the current situation 4. ... Does anyone have another idea? -- https://bugs.ruby-lang.org/

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[ruby-core:124419] [Ruby Bug#21827] Deprecating Ripper
by Eregon (Benoit Daloze) 03 Mar '26

03 Mar '26

Issue #21827 has been reported by Eregon (Benoit Daloze). ---------------------------------------- Bug #21827: Deprecating Ripper https://bugs.ruby-lang.org/issues/21827 * Author: Eregon (Benoit Daloze) * Status: Open * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN, 4.0: UNKNOWN ---------------------------------------- I think it is time to consider deprecating `Ripper`. [Matz has agreed that going forward the official parser API for Ruby will be the Prism API](https://railsatscale.com/2024-04-16-prism-in-2024/) so it's clear the official Ruby parsing API is the Prism API. `Ripper` while being currently supported on CRuby, JRuby and TruffleRuby (partially) has a significant maintenance overhead. For CRuby, it roughly doubles the number of lines in `parse.y` and adds lots of `#ifdef RIPPER`/`#ifndef RIPPER` which makes it really hard to follow. For JRuby it's many thousands of lines of code to maintain just for that: https://github.com/jruby/jruby/tree/master/core/src/main/java/org/jruby/ext… For TruffleRuby, `ripper` is by far the most difficult C extension to support as it relies on many internal functions. When an internal function is used by ripper is missing it kills the entire process. On every update of `RUBY_VERSION` in TruffleRuby, the biggest amount of time is spent dealing with Ripper, which feels as a result like a major hack. It could be possible to implement Ripper based on Prism, in fact there is [some support for that](https://github.com/ruby/prism/blob/main/docs/ripper_translation.md), but the fact the Ripper API is rather unstable means it's hard to be compatible, and currently the translation layer [relies on original ripper for some things](https://github.com/ruby/prism/blob/e0e5e68acbed98a6b4e4e77b9b52b448…. It's also worth noting that [`Ripper.sexp` is 2.75x slower than `Prism.parse`](https://eregon.me/blog/2024/10/27/benchmarking-ruby-parsers.html#parsing-and-not-walking), while providing a much worse API (widely recognized as such, e.g. `Ripper.sexp("def m = 42")` vs `Prism.parse("def m = 42")`, lots of `nil` with unclear meaning in `Ripper`). So from a new code perspective there seems to be very little value to use `Ripper`. `Ripper` has lexing via `Ripper.lex`, which can be replaced by `Prism::lex_compat`. I think we should start to deprecate `Ripper`. The advantages of deprecating it are: * Make it clear that this API should not be used in new code * Encourage the usages to migrate to the Prism API, which is stable, officially supported, designed with many people to be usable and convenient for every parsing/tooling usage, etc. * Improve portability of Ruby code between Ruby implementations (given Ripper is not fully compatible between Ruby implementations) I propose to deprecate Ripper in 4.1. I'm not sure when it would be appropriate to remove it given it's a more established API, maybe in 4.2, 4.3? -- https://bugs.ruby-lang.org/

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[ruby-core:123894] [Ruby Bug#21709] Inconsistent encoding by Regexp.escape
by thyresias (Thierry Lambert) 26 Feb '26

26 Feb '26

Issue #21709 has been reported by thyresias (Thierry Lambert). ---------------------------------------- Bug #21709: Inconsistent encoding by Regexp.escape https://bugs.ruby-lang.org/issues/21709 * Author: thyresias (Thierry Lambert) * Status: Open * ruby -v: ruby 3.4.7 (2025-10-08 revision 7a5688e2a2) +PRISM [x64-mingw-ucrt] * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- ```ruby %w(foo être).each do |s| puts "string: #{s.inspect} -> #{s.encoding}" puts "escaped: #{Regexp.escape(s).inspect} -> #{Regexp.escape(s).encoding}" end ``` Output: ``` string: "foo" -> UTF-8 escaped: "foo" -> US-ASCII string: "être" -> UTF-8 escaped: "être" -> UTF-8 ``` The result should always match the encoding of the argument. -- https://bugs.ruby-lang.org/

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