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

[ruby-core:124861] [Ruby Feature#17056] Array#index: Allow specifying the position to start search as in String#index
by Earlopain (Earlopain _) 21 Feb '26

21 Feb '26

Issue #17056 has been updated by Earlopain (Earlopain _). I often use the offset parameter from `String#byteindex` and was a bit surprised there is not yet something for arrays. It's a bit unfortunate with the ambiguity between block/noblock usage but a keyword argument `offset` seems like a perfectly fine solution for that. ---------------------------------------- Feature #17056: Array#index: Allow specifying the position to start search as in String#index https://bugs.ruby-lang.org/issues/17056#change-116515 * Author: TylerRick (Tyler Rick) * Status: Open ---------------------------------------- I have a use case of finding the first matching line within a given section in a file. After finding the line number of the start of the section, I want to find the first match after that line. My workaround for now is to use `with_index`: ```ruby lines = pathname.read.lines section_start_line = lines.index {|line| line.start_with?(/#* #{section_name}/) } lines.index.with_index {|line, i| i > section_start_line && line.include?(sought) } ``` I'd like to do it in a more concise way using a feature of `Array#index` that I propose here, which is analogous to `String#index`. If the second parameter of `String#index` is present, it specifies the position in the string to begin the search: ```ruby 'abcabc'.index('a') # => 0 'abcabc'.index('a',2) # => 3 ``` I would expect to also be able to do: ```ruby 'abcabc'.chars.index('a') # => 0 'abcabc'.chars.index('a', 2) ``` Using such feature, I would be able to do: ```ruby lines.index(sought, section_start_line) ``` This would give Ruby better parity with other programming languages like Python: ```python >>> list('abcabc') ['a', 'b', 'c', 'a', 'b', 'c'] >>> list('abcabc').index('a') 0 >>> list('abcabc').index('a', 2) 3 ``` ## End index We can further think of an optional parameter to specify the position to end the search. The following languages allow specifying both start and end indexes: - [Python](https://docs.python.org/3/tutorial/datastructures.html) - [C#](https://docs.microsoft.com/en-us/dotnet/api/system.array.indexof?view=n… Ruby's `String#index` does not have one, so we could make a separate proposal to add `end` to both methods at the same time. -- https://bugs.ruby-lang.org/

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[ruby-core:124855] [Ruby Bug#21920] LIBRUBYARG_SHARED contains -lgmp and other libraries for static linking
by larskanis (Lars Kanis) 21 Feb '26

21 Feb '26

Issue #21920 has been reported by larskanis (Lars Kanis). ---------------------------------------- Bug #21920: LIBRUBYARG_SHARED contains -lgmp and other libraries for static linking https://bugs.ruby-lang.org/issues/21920 * Author: larskanis (Lars Kanis) * Status: Open * ruby -v: ruby 4.1.0dev (2026-02-21 master e730ac41be) +PRISM [aarch64-mingw-ucrt] * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN, 4.0: UNKNOWN ---------------------------------------- That recent commit introduced `MAINLIBS` into `LIBRUBYARG_SHARED`: https://github.com/ruby/ruby/commit/d256629bf9e194838d1837be74dcc0b8ff0bcfd6 Before that commit: ``` CONFIG["LIBRUBYARG_SHARED"] = "-l$(RUBY_SO_NAME)" CONFIG["LIBRUBYARG_STATIC"] = "-l$(RUBY_SO_NAME)-static $(MAINLIBS)" RbConfig::CONFIG["LIBRUBYARG_SHARED"] # => "-laarch64-ucrt-ruby410" ``` After that commit: ``` CONFIG["LIBRUBYARG_SHARED"] = "-l$(RUBY_SO_NAME) $(MAINLIBS)" CONFIG["LIBRUBYARG_STATIC"] = "-l$(RUBY_SO_NAME)-static $(MAINLIBS)" RbConfig::CONFIG["LIBRUBYARG_SHARED"] # => "-laarch64-ucrt-ruby410 -lgmp -lshell32 -lws2_32 -liphlpapi -limagehlp -lshlwapi -lbcrypt" ``` To my understanding `MAINLIBS` are only for static linking and these libraries are not necessary for shared linking. This breaks RubyInstaller for Windows, since all C extensions are linked with `LIBRUBYARG_SHARED` and the RubyInstaller distribution ships `libgmp-10.dll` only but not related the `libgmp.a` file. The same happens on x86_64. It is probably an issue on other operating systems as well. A CI failure log is here: https://github.com/oneclick/rubyinstaller2/actions/runs/22238372563/job/643… -- https://bugs.ruby-lang.org/

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[ruby-core:124646] [Ruby Bug#21855] Bundle `win32-registry` or implement it without `fiddle`
by Earlopain (Earlopain _) 20 Feb '26

20 Feb '26

Issue #21855 has been reported by Earlopain (Earlopain _). ---------------------------------------- Bug #21855: Bundle `win32-registry` or implement it without `fiddle` https://bugs.ruby-lang.org/issues/21855 * Author: Earlopain (Earlopain _) * Status: Open * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN, 4.0: UNKNOWN ---------------------------------------- `win32-registry` (a default gem), is currently implemented via `fiddle` (a bundled gem). This makes it impossible to use under bundler without adding `fiddle` to the gemfile. In the past it has lead to issues like https://bugs.ruby-lang.org/issues/21645. It was solved by simply not using `win32-registry` anymore in `resolv` and implementing it via C (https://github.com/ruby/resolv/pull/110) although the overarching issue is still present. There is also a report for this for rubygems https://github.com/ruby/rubygems/issues/9277. This should be solved by updating the vendored `resolv` version I think. Still, the dependecy relation between `win32-registry` and `fiddle` is pretty incompatible. A default gem can't depend on a bundled gem without breaking dependency resolution. To solve this it would have to be implemented without using `fiddle`, similar to how `resolv` did it. But now that `resolv` doesn't use `win32-registry`, I don't think anything in ruby uses it anymore. So moving it to a bundled gem could also be a solution without rewriting the whole thing. Here is an issue about this in the `win32-registry` repo: https://github.com/ruby/win32-registry/issues/11 -- https://bugs.ruby-lang.org/

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[ruby-core:124851] [Ruby Bug#21918] fiber scheduler: fiber interrupt triggers for IOs that haven't been closed
by chucke (Tiago Cardoso) 19 Feb '26

19 Feb '26

Issue #21918 has been reported by chucke (Tiago Cardoso). ---------------------------------------- Bug #21918: fiber scheduler: fiber interrupt triggers for IOs that haven't been closed https://bugs.ruby-lang.org/issues/21918 * Author: chucke (Tiago Cardoso) * 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 ---------------------------------------- I've been chasing an issue, which I believe is to with the recent introduction of the `fiber_interrupt` hook in ruby 4. As a reproduction I have the following snippet: ```ruby require "socket" require_relative "test/fiber/scheduler" # use the one defined here: https://github.com/ruby/ruby/blob/master/test/fiber/scheduler.rb udp = UDPSocket.new(Socket::AF_INET) tcp = Socket.new(Socket::AF_INET, :STREAM, 0) tcp.connect(Socket.sockaddr_in(80, "nghttp2")) t = Thread.start do Thread.current.abort_on_exception = true scheduler = Scheduler.new Fiber.set_scheduler scheduler 5.times do Fiber.schedule do begin puts "#{Fiber.current.object_id} -> wait udp" udp.to_io.wait_readable(2) rescue IOError => e puts "#{Fiber.current.object_id} -> udp io error: #{e}" end begin puts "#{Fiber.current.object_id} -> closing udp" udp.close puts "#{Fiber.current.object_id} -> closed udp" puts "#{Fiber.current.object_id} -> wait tcp" tcp.to_io.wait_readable(2) puts "#{Fiber.current.object_id} -> done" rescue => e puts "#{Fiber.current.object_id} -> tcp io error: #{e}" else puts "#{Fiber.current.object_id} -> closing tcp" tcp.close end end end end t.join ``` This produces the following output to me: ``` 1472 -> wait udp 1488 -> wait udp 1496 -> wait udp 1504 -> wait udp 1512 -> wait udp 1472 -> closing udp 1488 -> closing udp 1488 -> closed udp 1488 -> wait tcp 1496 -> closing udp 1496 -> closed udp 1496 -> wait tcp 1504 -> closing udp 1504 -> closed udp 1504 -> wait tcp 1512 -> closing udp 1512 -> closed udp 1512 -> wait tcp 1512 -> tcp io error: stream closed in another thread 1504 -> tcp io error: stream closed in another thread 1496 -> tcp io error: stream closed in another thread 1488 -> tcp io error: stream closed in another thread 1472 -> closed udp 1472 -> wait tcp 1472 -> done 1472 -> closing tcp ``` The thing that makes this program very confusing is that the "stream closed in another thread" related to the udp socket is raised while waiting for read readiness on the tcp socket. In such a situation, I'd expect the error to relate to the actual socket being waited on, not something else that fiber does not care about anymore. One thing that could have helped would be to have the reference of which IO object the exception relates to in the exception (aka `IOError#io` would return the socket). Nevertheless, I'd still consider an issue that this triggers in the wrong "fiber.yield" moment. Therefore, I think there are two possible outcomes here: 1. all fibers stop on `udp.close` until it is in fact closed (and then IOError is raised before the "closed udp" message can be printed) 2. exceptions related to IOs not actively being monitored by the current fiber are ignored. -- https://bugs.ruby-lang.org/

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[ruby-core:124845] [Ruby Feature#18035] Introduce general model/semantic for immutability.
by Eregon (Benoit Daloze) 17 Feb '26

17 Feb '26

Issue #18035 has been updated by Eregon (Benoit Daloze). @ioquatix I think `deep_freeze` would be a clear solution for that, so probably best to add your comments/support to #21665 and potentially also add it to the dev meeting agenda. ---------------------------------------- Feature #18035: Introduce general model/semantic for immutability. https://bugs.ruby-lang.org/issues/18035#change-116498 * Author: ioquatix (Samuel Williams) * Status: Open ---------------------------------------- It would be good to establish some rules around mutability, immutability, frozen, and deep frozen in Ruby. I see time and time again, incorrect assumptions about how this works in production code. Constants that aren't really constant, people using `#freeze` incorrectly, etc. I don't have any particular preference but: - We should establish consistent patterns where possible, e.g. - Objects created by `new` are mutable. - Objects created by literal are immutable. We have problems with how `freeze` works on composite data types, e.g. `Hash#freeze` does not impact children keys/values, same for Array. Do we need to introduce `freeze(true)` or `#deep_freeze` or some other method? Because of this, frozen does not necessarily correspond to immutable. This is an issue which causes real world problems. I also propose to codify this where possible, in terms of "this class of object is immutable" should be enforced by the language/runtime, e.g. ```ruby module Immutable def new(...) super.freeze end end class MyImmutableObject extend Immutable def initialize(x) @x = x end def freeze return self if frozen? @x.freeze super end end o = MyImmutableObject.new([1, 2, 3]) puts o.frozen? ``` Finally, this area has an impact to thread and fiber safe programming, so it is becoming more relevant and I believe that the current approach which is rather adhoc is insufficient. I know that it's non-trivial to retrofit existing code, but maybe it can be done via magic comment, etc, which we already did for frozen string literals. Proposed PR: https://github.com/ruby/ruby/pull/4879 -- https://bugs.ruby-lang.org/

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[ruby-core:124841] [Ruby Feature#18035] Introduce general model/semantic for immutability.
by ioquatix (Samuel Williams) 16 Feb '26

16 Feb '26

Issue #18035 has been updated by ioquatix (Samuel Williams). Another example where immutability as a concept is useful - configurations that span across fibers and threads: https://github.com/ruby-i18n/i18n/issues/723 In general, it seems like `Fiber[]` for immutable values is a good idea. ---------------------------------------- Feature #18035: Introduce general model/semantic for immutability. https://bugs.ruby-lang.org/issues/18035#change-116462 * Author: ioquatix (Samuel Williams) * Status: Open ---------------------------------------- It would be good to establish some rules around mutability, immutability, frozen, and deep frozen in Ruby. I see time and time again, incorrect assumptions about how this works in production code. Constants that aren't really constant, people using `#freeze` incorrectly, etc. I don't have any particular preference but: - We should establish consistent patterns where possible, e.g. - Objects created by `new` are mutable. - Objects created by literal are immutable. We have problems with how `freeze` works on composite data types, e.g. `Hash#freeze` does not impact children keys/values, same for Array. Do we need to introduce `freeze(true)` or `#deep_freeze` or some other method? Because of this, frozen does not necessarily correspond to immutable. This is an issue which causes real world problems. I also propose to codify this where possible, in terms of "this class of object is immutable" should be enforced by the language/runtime, e.g. ```ruby module Immutable def new(...) super.freeze end end class MyImmutableObject extend Immutable def initialize(x) @x = x end def freeze return self if frozen? @x.freeze super end end o = MyImmutableObject.new([1, 2, 3]) puts o.frozen? ``` Finally, this area has an impact to thread and fiber safe programming, so it is becoming more relevant and I believe that the current approach which is rather adhoc is insufficient. I know that it's non-trivial to retrofit existing code, but maybe it can be done via magic comment, etc, which we already did for frozen string literals. Proposed PR: https://github.com/ruby/ruby/pull/4879 -- https://bugs.ruby-lang.org/

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[ruby-core:124840] [Ruby Bug#21883] IO::Buffer can be unlocked and freed by another thread during syscall
by hanazuki (Kasumi Hanazuki) 16 Feb '26

16 Feb '26

Issue #21883 has been reported by hanazuki (Kasumi Hanazuki). ---------------------------------------- Bug #21883: IO::Buffer can be unlocked and freed by another thread during syscall https://bugs.ruby-lang.org/issues/21883 * Author: hanazuki (Kasumi Hanazuki) * Status: Open * ruby -v: ruby 4.0.1 (2026-01-13 revision e04267a14b) +PRISM [x86_64-linux] * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN, 4.0: UNKNOWN ---------------------------------------- ```ruby # Assume this file is on a very slow device such as NFS. io = File.open('/mnt/slowfs/slow') buf = IO::Buffer.new(100) t1 = Thread.new do buf.locked do sleep 0.5 end buf.free end t2 = Thread.new do buf.read(io) # syscall takes 1 second # When the kernal writes to the memory, buf is already freed, thus use-after-free end t1.join t2.join ``` `io_buffer_blocking_region` skips taking a lock when the buffer is already locked, but this lock may be owned by another thread and can be unlocked during the syscall. -- https://bugs.ruby-lang.org/

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[ruby-core:124833] [Ruby Bug#21882] IO::Buffer#locked leaves the buffer locked when the block raises
by hanazuki (Kasumi Hanazuki) 16 Feb '26

16 Feb '26

Issue #21882 has been reported by hanazuki (Kasumi Hanazuki). ---------------------------------------- Bug #21882: IO::Buffer#locked leaves the buffer locked when the block raises https://bugs.ruby-lang.org/issues/21882 * Author: hanazuki (Kasumi Hanazuki) * Status: Open * ruby -v: ruby 4.0.1 (2026-01-13 revision e04267a14b) +PRISM [x86_64-linux] * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN, 4.0: UNKNOWN ---------------------------------------- `IO::Buffer#locked` should unlock the buffer even after the block raises an exception. ```ruby buf = IO::Buffer.new(100) buf.locked { fail } rescue nil buf.locked { p :ok } # expected to print :ok, but actually raises a LockedError ``` -- https://bugs.ruby-lang.org/

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[ruby-core:124824] [Ruby Bug#21879] SSLBypass
by sh2ll (Chmouel Taieb) 15 Feb '26

15 Feb '26

Issue #21879 has been reported by sh2ll (Chmouel Taieb). ---------------------------------------- Bug #21879: SSLBypass https://bugs.ruby-lang.org/issues/21879 * Author: sh2ll (Chmouel Taieb) * Status: Open * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN, 4.0: UNKNOWN ---------------------------------------- There is not enough space for photos upload ---Files-------------------------------- Critical SSL Verification Bypass Report.pdf (87.4 KB) ScriptsPOC.pdf (49.5 KB) -- https://bugs.ruby-lang.org/

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[ruby-core:115196] [Ruby master Feature#19979] Allow methods to declare that they don't accept a block via `&nil`
by ufuk (Ufuk Kayserilioglu) 15 Feb '26

15 Feb '26

Issue #19979 has been reported by ufuk (Ufuk Kayserilioglu). ---------------------------------------- Feature #19979: Allow methods to declare that they don't accept a block via `&nil` https://bugs.ruby-lang.org/issues/19979 * Author: ufuk (Ufuk Kayserilioglu) * Status: Open * Priority: Normal ---------------------------------------- ## Abstract This feature proposes new syntax to allow methods to explicitly declare that they don't accept blocks, and makes passing of a block to such methods an error. ## Background In #15554, it was proposed to automatically detect methods that do not use the block passed to them, and to error if a block was passed to such methods. As far as I can tell, it was later on closed since #10499 solved a large part of the problem. That proposal has, as part of the dev meeting discussion, a proposal from @matz to allow methods to use `&nil` to explicitly declare that they don't accept a block. At the time, the proposal was trying to solve a bigger problem, so this sub-proposal was never considered seriously. However, notes in the proposal say: > It is explicit, but it is tough to add this `&nil` parameter declaration to all of methods (do you want to add it to `def []=(i, e, &nil)`?). (I agree `&nil` is valuable on some situations) This proposal extracts that sub-proposal to make this a new language feature. ## Proposal In Ruby, it is always valid for the caller to pass a block to a method call, even if the callee is not expecting a block to be passed. This leads to subtle user errors, where the author of some code assumes a method call uses a block, but the block passed to the method call is silently ignored. The proposal is to introduce `&nil` at method declaration sites to mean "This method does not accept a block". This is symmetric to the ability to pass `&nil` at call sites to mean "I am not passing a block to this method call", which is sometimes useful when making `super` calls (since blocks are always implicitly passed). Explicitly, the proposal is to make the following behaviour be a part of Ruby: ```ruby def find(item = nil, &nil) # some implementation that doesn't call `yield` or `block_given?` end find { |i| i == 42 } # => ArgumentError: passing block to the method `find' that does not accept a block. ``` ## Implementation I assume the implementation would be a grammar change to make `&nil` valid at method declaration sites, as well as raising an `ArgumentError` for methods that are called with a block but are declared with `&nil`. ## Evaluation Since I don't have an implementation, I can't make a proper evaluation of the feature proposal. However, I would expect the language changes to be minimal with no runtime costs for methods that don't use the `&nil` syntax. ## Discussion This proposal has much smaller scope than #15554 so that the Ruby language can start giving library authors the ability to explicitly mark their methods as not accepting a block. This is fully backward compatible, since it is an opt-in behaviour and not an opt-out one. Future directions after this feature proposal could be a way to signal to the VM that any method in a file that doesn't explicitly use `yield`/`block_given?` or explicitly declared a block parameter should be treated as not accepting a block. This can be done via some kind of pragma similar to `frozen_string_literal`, or through other means. However, such future directions are beyond the scope of this proposal. ## Summary Adding the ability for methods to declare that they don't accept a block will make writing code against such methods safer and more resilient, and will prevent silently ignored behaviour that is often hard to catch or troubleshoot. -- https://bugs.ruby-lang.org/

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