August 2025 - ruby-core - ml.ruby-lang.org

[ruby-core:113430] [Ruby master Feature#19633] Allow passing block to `Kernel#autoload` as alternative to second `filename` argument
by shioyama (Chris Salzberg) 10 Jun '26

10 Jun '26

Issue #19633 has been reported by shioyama (Chris Salzberg). ---------------------------------------- Feature #19633: Allow passing block to `Kernel#autoload` as alternative to second `filename` argument https://bugs.ruby-lang.org/issues/19633 * Author: shioyama (Chris Salzberg) * Status: Open * Priority: Normal ---------------------------------------- `Kernel#autoload` takes two arguments, a symbol `module` representing the constant to be autoloaded, and a `filepath` to load the constant from (with `require`). Currently, Zeitwerk has to [monkeypatch `Kernel#require`](https://github.com/fxn/zeitwerk/blob/a7c4a983df0f4e4058f32c610dac1e8b99f687da/lib/zeitwerk/kernel.rb) to fetch the loader for the file being loaded, then run the original (aliased) `require`, then run autoload callbacks. In addition to the monkeypatch, this also requires a registry (`Zeitwerk::Registry`) to map file paths to loaders, to know which loader should be used for a given autoload-triggered `require`. In fact, Zeitwerk has to _assume_ that the monkey-patched `require` call came from an autoload trigger; there is no way to really be sure of the source. If Ruby allowed passing a block as an alternative to the explicit filepath, then I think this could be improved and would eliminate the need for a monkeypatch. So something like this: ```ruby autoload(:B) do require "lib/b" # trigger callback, etc end ``` I am implementing a gem called [Im](https://github.com/shioyama/im) which is a fork of Zeitwerk, and in the case of this gem, such a feature would be even more useful. Im implements autoloads on anonymous modules by registering an autoload and then "catching" the require and converting it into a `load`, passing the module as the second argument (see [here](https://github.com/shioyama/im/blob/44ce348639a1aae563a5be7a40602761e….) This is currently quite tricky because, again, it's hard to know _where_ a `require` came from. In addition to removing the monkeypatch (inherited from Zeitwerk), Im would further benefit from the block argument because then it could simply access the module via a closure, rather than pulling it from a registry: ```ruby mod.autoload(:Foo) do load "lib/foo.rb", mod end ``` I don't know how hard or easy this would be to implement, but if there is interest in this as a feature I'd be happy to look into implementing it. -- https://bugs.ruby-lang.org/

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[ruby-core:111146] [Ruby master Bug#19172] `ruby_thread_has_gvl_p` is innacurate sometimes -- document or change?
by ivoanjo (Ivo Anjo) 15 May '26

15 May '26

Issue #19172 has been reported by ivoanjo (Ivo Anjo). ---------------------------------------- Bug #19172: `ruby_thread_has_gvl_p` is innacurate sometimes -- document or change? https://bugs.ruby-lang.org/issues/19172 * Author: ivoanjo (Ivo Anjo) * Status: Open * Priority: Normal * ruby -v: (All Ruby versions) * Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN ---------------------------------------- Howdy 👋! I work for Datadog [on the ddtrace gem](https://github.com/DataDog/dd-trace-rb) and I found a... sharp edge on the internal `ruby_thread_has_gvl_p` API. I am aware that `ruby_thread_has_gvl_p` is documented an experimental API that is exported as a symbol but not present on the VM include files. ### Background In the ddtrace profiling component, we setup a signal handler and then periodically send SIGPROF signals to try to interrupt the running Ruby thread (e.g. the thread that is holding the global VM lock or equivalent). In the signal handler, we need to perform some API calls which are not safe to do without the GVL. So we need to check if the signal handler got called in the thread that has the GVL. ### The issue ```ruby int ruby_thread_has_gvl_p(void) { rb_thread_t *th = ruby_thread_from_native(); if (th && th->blocking_region_buffer == 0) { return 1; } else { return 0; } } ``` In its current implementation, `ruby_thread_has_gvl_p` only checks if the thread has a `blocking_region_buffer` or not. Unfortunately, this means that when called from a thread that lost the GVL but not due to blocking (e.g. via `rb_thread_schedule()`), it can still claim that a thread is holding the GVL when that is not the case. I ran into this issue in https://github.com/DataDog/dd-trace-rb/pull/2415, and needed to find a workaround. ### Next steps Since this is an internal VM API, I'm not sure you'd want to change the current behavior, so I was thinking of perhaps two options: * Is it worth changing `ruby_thread_has_gvl_p` to be accurate in the case I've listed? * If not, would you accept a PR to document its current limitations, so that others don't run into the same issue I did? -- https://bugs.ruby-lang.org/

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[ruby-core:117434] [Ruby master Bug#20409] Missing reporting some invalid breaks
by kddnewton (Kevin Newton) 13 May '26

13 May '26

Issue #20409 has been reported by kddnewton (Kevin Newton). ---------------------------------------- Bug #20409: Missing reporting some invalid breaks https://bugs.ruby-lang.org/issues/20409 * Author: kddnewton (Kevin Newton) * Status: Open * Backport: 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN ---------------------------------------- -- https://bugs.ruby-lang.org/

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[ruby-core:115241] [Ruby master Bug#19986] Win32: `HOME` is set to just `HOMEDRIVE` if `HOMEPATH` is unset
by nobu (Nobuyoshi Nakada) 10 May '26

10 May '26

Issue #19986 has been reported by nobu (Nobuyoshi Nakada). ---------------------------------------- Bug #19986: Win32: `HOME` is set to just `HOMEDRIVE` if `HOMEPATH` is unset https://bugs.ruby-lang.org/issues/19986 * Author: nobu (Nobuyoshi Nakada) * Status: Open * Priority: Normal * Backport: 3.0: REQUIRED, 3.1: REQUIRED, 3.2: REQUIRED ---------------------------------------- ``` $ env -u HOME -u USERPROFILE -u HOMEPATH HOMEDRIVE=no/such/home ./miniruby.exe -e 'p ENV["HOME"], Dir.home' "no/such/home" "no/such/home" ``` `HOMEDRIVE` should be ignored without `HOMEPATH`, and `HOME` should fallback to `CSIDL_PROFILE`. -- https://bugs.ruby-lang.org/

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[ruby-core:118940] [Ruby master Bug#20696] `IO.read` ignores `err:` option
by nobu (Nobuyoshi Nakada) 10 May '26

10 May '26

Issue #20696 has been reported by nobu (Nobuyoshi Nakada). ---------------------------------------- Bug #20696: `IO.read` ignores `err:` option https://bugs.ruby-lang.org/issues/20696 * Author: nobu (Nobuyoshi Nakada) * Status: Open * Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN ---------------------------------------- I expected the following code captures the error message, but `err:` option is ignored. ```shell-session $ ruby -e 'p IO.read("|ruby -e raise", err: %i[child out])' -e:1:in '<main>': unhandled exception "" ``` -- https://bugs.ruby-lang.org/

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[ruby-core:116382] [Ruby master Feature#20205] Enable `frozen_string_literal` by default
by byroot (Jean Boussier) 14 Apr '26

14 Apr '26

Issue #20205 has been reported by byroot (Jean Boussier). ---------------------------------------- Feature #20205: Enable `frozen_string_literal` by default https://bugs.ruby-lang.org/issues/20205 * Author: byroot (Jean Boussier) * Status: Open * Priority: Normal ---------------------------------------- ### Context The `frozen_string_literal: true` pragma was introduced in Ruby 2.3, and as far as I'm aware the plan was initially to make it the default for Ruby 3.0, but this plan was abandoned because it would be too much of a breaking change without any real further notice. According to Matz, he still wishes to enable `frozen_string_literal` by default in the future, but a reasonable migration plan is required. The main issue is backward compatibility, flipping the switch immediately would break a lot of code, so there must be some deprecation period. The usual the path forward for this kind of change is to emit deprecation warnings one of multiple versions in advance. One example of that was the Ruby 2.7 keyword argument deprecation. It was quite verbose, and some users were initially annoyed, but I think the community pulled through it and I don't seem to hear much about it anymore. So for frozen string literals, the first step would be to start warning when a string that would be frozen in the future is mutated. ### Deprecation Warning Implementation I implemented a quick proof of concept with @etienne in https://github.com/Shopify/ruby/pull/549 In short: - Files with `# frozen_string_literal: true` or `# frozen_string_literal: false` don't change in behavior at all. - Files with no `# frozen_string_literal` comment are compiled to use `putchilledstring` opcode instead of regular `putstring`. - This opcode mark the string with a user flag, when these strings are mutated, a warning is issued. Currently the proof of concept issue the warning at the mutation location, which in some case can make locating where the string was allocated a bit hard. But it is possible to improve it so the message also include the location at which the literal string was allocated, and learning from the keyword argument warning experience, we can record which warnings were already issued to avoid spamming users with duplicated warnings. As currently implemented, there is almost no overhead. If we modify the implementation to record the literal location, we'd incur a small memory overhead for each literal string in a file without an explicit `frozen_string_literal` pragma. But I believe we could do it in a way that has no overhead if `Warning[:deprecated] = false`. ### Timeline The migration would happen in 3 steps, each step can potentially last multiple releases. e.g. `R0` could be `3.4`, `R1` be `3.7` and `R2` be `4.0`. I don't have a strong opinion on the pace. - Release `R0`: introduce the deprecation warning (only if deprecation warnings enabled). - Release `R1`: make the deprecation warning show up regardless of verbosity level. - Release `R2`: make string literals frozen by default. ### Impact Given that `rubocop` is quite popular in the community and it has enforced the usage of `# frozen_string_literal: true` for years now, I suspect a large part of the actively maintained codebases in the wild wouldn't see any warnings. And with recent versions of `minitest` enabling deprecation warnings by default (and [potentially RSpec too](https://github.com/rspec/rspec-core/issues/2867)) the few that didn't migrate will likely be made compatible quickly. The real problem of course are the less actively developed libraries and applications. For such cases, any codebase can remain compatible by setting `RUBYOPT="--disable=frozen_string_literal"`, and so even after `R2` release. The flag would never be removed any legacy codebase can continue upgrading Ruby without changing a single line of cod by just flipping this flag. ### Workflow for library maintainers As a library maintainer, fixing the deprecation warnings can be as simple as prepending `# frozen_string_literal: false` at the top of all their source files, and this will keep working forever. Alternatively they can of course make their code compatible with frozen string literals. Code that is frozen string literal compatible doesn't need to explicitly declare it. Only code that need it turned of need to do so. ### Workflow for application owners For application owners, the workflow is the same than for libraries. However if they depend on a gem that hasn't updated, or that they can't upgrade it, they can run their application with `RUBYOPT="--disable=frozen_string_literal"` and it will keep working forever. Any user running into an incompatibility issue can set `RUBYOPT="--disable=frozen_string_literal"` forever, even in `4.x`, the only thing changing is the default value. And any application for which all dependencies have been made fully frozen string literal compatible can set `RUBYOPT="--enable=frozen_string_literal"` and start immediately removing magic comment from their codebase. -- https://bugs.ruby-lang.org/

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[ruby-core:122558] [Ruby Bug#21446] StackOverflow when changing visibility in reopened refinement
by luke-gru (Luke Gruber) 24 Mar '26

24 Mar '26

Issue #21446 has been reported by luke-gru (Luke Gruber). ---------------------------------------- Bug #21446: StackOverflow when changing visibility in reopened refinement https://bugs.ruby-lang.org/issues/21446 * Author: luke-gru (Luke Gruber) * Status: Open * ruby -v: 3.5.0 * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- ```ruby class A def a :a end end class B < A end module R refine B do private :a end end module R refine B do public :a end end using R B.new.a # StackOverflow ``` I would expect it to change the visibility, not to overflow the stack. -- https://bugs.ruby-lang.org/

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[ruby-core:121642] [Ruby Bug#21266] YJIT GC safety crash with proc objects as block argument
by alanwu (Alan Wu) 22 Mar '26

22 Mar '26

Issue #21266 has been reported by alanwu (Alan Wu). ---------------------------------------- Bug #21266: YJIT GC safety crash with proc objects as block argument https://bugs.ruby-lang.org/issues/21266 * Author: alanwu (Alan Wu) * Status: Open * Assignee: yjit * Backport: 3.2: DONTNEED, 3.3: REQUIRED, 3.4: REQUIRED ---------------------------------------- ```ruby # Run with --yjit-call-threshold=1 def foo(args) = bar(*args, &proc { _1 }) def bar(_, _, _, _, *rest) = yield rest GC.stress = true foo([1,2,3,4]) foo([1,2,3,4]) ``` The proc in these calls get collected on the yield to the GC to allocate the rest parameter arary. ``` ../vm_core.h:1668: Assertion Failed: vm_block_handler_type:rb_obj_is_proc(block_handler) ``` Or in release builds: ``` ../test.rb:1: [BUG] Segmentation fault at 0x0000000000000020 ruby 3.3.6 (2024-11-05 revision 75015d4c1f) +YJIT [arm64-darwin24] -- C level backtrace information ------------------------------------------- /Users/alan/.rubies/ruby-3.3.6/bin/ruby(rb_vm_bugreport+0xb4c) [0x104595590] /Users/alan/.rubies/ruby-3.3.6/bin/ruby(rb_bug_for_fatal_signal+0x100) [0x1043d6120] /Users/alan/.rubies/ruby-3.3.6/bin/ruby(sig_do_nothing+0x0) [0x1044fc4b0] /usr/lib/system/libsystem_platform.dylib(_sigtramp+0x38) [0x187572de4] /Users/alan/.rubies/ruby-3.3.6/bin/ruby(rb_vm_invokeblock+0x144) [0x10456b004] ``` -- https://bugs.ruby-lang.org/

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[ruby-core:122847] [Ruby Feature#21520] Feature Proposal: Enumerator::Lazy#peek
by nuzair46 (Nuzair Rasheed) 17 Mar '26

17 Mar '26

Issue #21520 has been reported by nuzair46 (Nuzair Rasheed). ---------------------------------------- Feature #21520: Feature Proposal: Enumerator::Lazy#peek https://bugs.ruby-lang.org/issues/21520 * Author: nuzair46 (Nuzair Rasheed) * Status: Open ---------------------------------------- # Abstract Add a #peek method to Enumerator::Lazy that allows observing each element in a lazy enumeration pipeline without modifying or consuming the stream. # Background Ruby provides Enumerator::Lazy for efficient lazy stream processing. However, unlike languages such as Java, it lacks a clean way to inspect intermediate elements during lazy evaluation. Currently, developers must misuse .map for side effects, example: ```rb (1..).lazy.map { |x| puts x; x }.select(&:even?).first(3) ``` This is semantically incorrect and confusing, since .map implies transformation, not observation. # Proposal Introduce Enumerator::Lazy#peek, which yields each item to a block and returns the item unmodified, similar to Object#tap, but in a lazy stream: ```rb (1..).lazy .peek { |x| puts "saw: #{x}" } .select(&:even?) .first(3) ``` This would be equivalent to: ```rb lazy.map { |x| block.call(x); x } ``` but with improved semantic clarity. # Use cases • Debugging lazy enumerators without breaking the chain • Logging or instrumentation in pipelines • Educational / demo use for showing lazy evaluation step-by-step • Cleaner replacement for map { puts x; x } hacks Example: ```rb data = (1..).lazy .peek { |x| puts "got #{x}" } .select(&:even?) .first(5) ``` result: ```rb got 1 got 2 got 3 got 4 got 5 ``` And return [2, 4, 6, 8, 10] # Discussion #peek is a minimal, non-breaking addition that improves clarity and idiomatic usage of Enumerator::Lazy. It avoids abusing .map for observation and is familiar to developers from other languages. #peek is also not needed for other enumerators where .tap or .each can do the job. It mirrors Java’s .stream().peek(...) and makes Ruby’s lazy enumeration more expressive and readable. # See also • [Java Stream.peek](https://docs.oracle.com/javase/8/docs/api/java/util/stream/Str… I would be glad to work on this and make a PR. Thank you. -- 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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