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

[ruby-core:124258] [Ruby Feature#21785] Add signed and unsigned LEB128 support to pack / unpack
by tenderlovemaking (Aaron Patterson) 12 Feb '26

12 Feb '26

Issue #21785 has been reported by tenderlovemaking (Aaron Patterson). ---------------------------------------- Feature #21785: Add signed and unsigned LEB128 support to pack / unpack https://bugs.ruby-lang.org/issues/21785 * Author: tenderlovemaking (Aaron Patterson) * Status: Open ---------------------------------------- Hi, I'd like to add signed and unsigned LEB128 support to the pack and unpack methods. LEB128 is a variable length encoding scheme for integers. You can read the wikipedia entry about it here: https://en.wikipedia.org/wiki/LEB128 LEB128 is used in DWARF, WebAssembly, MQTT, and Protobuf. I'm sure there are other formats, but these are the ones I'm familiar with. I sent a pull request here: https://github.com/ruby/ruby/pull/15589 I'm proposing `K` for the unsigned version and `k` for the signed version. I just picked `k` because it was available, I'm open to other format strings. Thanks for consideration! -- https://bugs.ruby-lang.org/

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[ruby-core:123449] [Ruby Bug#21633] A `rb_thread_call_without_gvl` loop can cause the fiber scheduler to ignore signals.
by ioquatix (Samuel Williams) 12 Feb '26

12 Feb '26

Issue #21633 has been reported by ioquatix (Samuel Williams). ---------------------------------------- Bug #21633: A `rb_thread_call_without_gvl` loop can cause the fiber scheduler to ignore signals. https://bugs.ruby-lang.org/issues/21633 * Author: ioquatix (Samuel Williams) * Status: Open * Assignee: ioquatix (Samuel Williams) * Backport: 3.3: REQUIRED, 3.4: REQUIRED ---------------------------------------- The gRPC gem calls `rb_thread_call_without_gvl` in a loop, and doesn't exit when interrupts are delivered if `Thread.handle_interrupt(::SignalException => :never)` is used by the scheduler to create a safe point for asynchronous signal handling. While this may not be considered a bug in any particular part of the system, the combination of the behaviour creates a situation where gRPC can hang for a long time and ignores SIGINT / SIGTERM. ## gRPC Failure Analysis From [`src/ruby/ext/grpc/rb_completion_queue.c`](https://github.com/samuel-williams-shopify/grpc/blob/debug/src/ruby/ext/grpc/rb_completion_queue.c): ```c static void unblock_func(void* param) { next_call_stack* const next_call = (next_call_stack*)param; next_call->interrupted = 1; // ← SIGINT causes this flag to be set } grpc_event rb_completion_queue_pluck(grpc_completion_queue* queue, void* tag, gpr_timespec deadline, const char* reason) { // ... do { next_call.interrupted = 0; // ← Reset flag rb_thread_call_without_gvl(grpc_rb_completion_queue_pluck_no_gil, (void*)&next_call, unblock_func, (void*)&next_call); if (next_call.event.type != GRPC_QUEUE_TIMEOUT) break; } while (next_call.interrupted); // ← The problem! If interrupted, LOOP AGAIN! return next_call.event; } ``` The loop explicitly retries after interruption, making SIGINT/SIGTERM ineffective. This might be considered the expected behaviour if `Thread.handle_interrupt` is used. However, the goal of `Thread.handle_interrupt` in the fiber scheduler is to create a safe point for signal handling, not to prevent them completely. Since this loop never yields back to the scheduler, no such chance exists, and the loop will continue indefinitely. As `rb_thread_call_without_gvl` invokes `vm_check_ints_blocking`, one solution is to yield to the scheduler in the case that there are pending interrupts. This gives the scheduler a chance to handle the incoming SIGINT / SIGTERM signals at the safe point. For a full reproduction of the issue using gRPC: https://github.com/samuel-williams-shopify/grpc-interrupt For the proposed fix: https://github.com/ruby/ruby/pull/14700 -- https://bugs.ruby-lang.org/

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[ruby-core:124553] [Ruby Misc#21839] DevMeeting-2026-02-12
by mame (Yusuke Endoh) 12 Feb '26

12 Feb '26

Issue #21839 has been reported by mame (Yusuke Endoh). ---------------------------------------- Misc #21839: DevMeeting-2026-02-12 https://bugs.ruby-lang.org/issues/21839 * Author: mame (Yusuke Endoh) * Status: Open ---------------------------------------- # The next dev meeting **Date: 2026/02/12 13:00-17:00** (JST) Log: *TBD* - Dev meeting *IS NOT* a decision-making place. All decisions should be done at the bug tracker. - Dev meeting is a place we can ask Matz, nobu, nurse and other developers directly. - Matz is a very busy person. Take this opportunity to ask him. If you can not attend, other attendees can ask instead of you (if attendees can understand your issue). - We will write a record of the discussion in the file or to each ticket in English. - All activities are best-effort (keep in mind that most of us are volunteer developers). - The date, time and place of the meeting are scheduled according to when/where we can reserve Matz's time. - *DO NOT* discuss then on this ticket, please. # Call for agenda items If you have a ticket that you want matz and committers to discuss, please post it into this ticket in the following format: ``` * [Ticket ref] Ticket title (your name) * Comment (A summary of the ticket, why you put this ticket here, what point should be discussed, etc.) ``` Example: ``` * [Feature #14609] `Kernel#p` without args shows the receiver (ko1) * I feel this feature is very useful and some people say :+1: so let discuss this feature. ``` - It is recommended to add a comment by 2026/02/09. We hold a preparatory meeting to create an agenda a few days before the dev-meeting. - The format is strict. We'll use [this script to automatically create an markdown-style agenda](https://gist.github.com/mame/b0390509ce1491b43610b9ebb665eb86). We may ignore a comment that does not follow the format. - Your comment is mandatory. We cannot read all discussion of the ticket in a limited time. We appreciate it if you could write a short summary and update from a previous discussion. -- https://bugs.ruby-lang.org/

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[ruby-core:124631] [Ruby Bug#21851] Performance difference between / operator and fdiv
by mbrown1intel (Michael Brown) 11 Feb '26

11 Feb '26

Issue #21851 has been reported by mbrown1intel (Michael Brown). ---------------------------------------- Bug #21851: Performance difference between / operator and fdiv https://bugs.ruby-lang.org/issues/21851 * Author: mbrown1intel (Michael Brown) * Status: Open * ruby -v: ruby 4.0.1 (2026-01-13 revision e04267a14b) +PRISM [x64-mingw-ucrt] * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN, 4.0: UNKNOWN ---------------------------------------- Benchmarking fdiv against the / operator, it seems like fdiv is significantly slower. As far as I'm aware there's no functional difference between these two methods. I first ran this on 2.6, and then checked against 4.0 to make sure it hadn't been fixed in the meantime, and saw the same results. ``` ruby require 'benchmark' n = 500_000_000 c = nil Benchmark.bm do |benchmark| benchmark.report("to_f ") do n.times do |i| c = n / i.to_f end end benchmark.report("fdiv ") do n.times do |i| c = n.fdiv(i) end end end ``` ``` user system total real to_f 37.672000 0.110000 37.782000 ( 38.714876) fdiv 113.016000 0.265000 113.281000 (116.428442) ``` -- https://bugs.ruby-lang.org/

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[ruby-core:124478] [Ruby Misc#21833] Switch default hash from SipHash13 to XXH3?
by samyron (Scott Myron) 11 Feb '26

11 Feb '26

Issue #21833 has been reported by samyron (Scott Myron). ---------------------------------------- Misc #21833: Switch default hash from SipHash13 to XXH3? https://bugs.ruby-lang.org/issues/21833 * Author: samyron (Scott Myron) * Status: Open ---------------------------------------- Has there been any consideration switching to some other hash implementation? I've searched through the issues and haven't found anything related to switching the default hash from SipHash13 to anything else. I created a [branch](https://github.com/ruby/ruby/compare/master...samyron:ruby:sm/xxh3) which switched `rb_memhash` from SipHash13 to [XXH3](https://github.com/Cyan4973/xxHash). I created a few simple benchmarks and ran them on my M1 Macbook Air. The results are very promising. ``` % cat ~/string_hash.yml prelude: | # Generate sets of short vs medium strings TINY_STRINGS = Array.new(100) { Array.new(3).map { (97 + rand(26)).chr }.join }.freeze SMALL_STRINGS = Array.new(100) { Array.new(8).map { (97 + rand(26)).chr }.join }.freeze MED_STRINGS = Array.new(100) { Array.new(20).map { (97 + rand(26)).chr }.join }.freeze LARGE_STRINGS = Array.new(100) { Array.new(200).map { (97 + rand(26)).chr }.join }.freeze HUGE_STRINGS = Array.new(100) { Array.new(65536).map { (97 + rand(26)).chr }.join }.freeze benchmark: tiny_strings: | TINY_STRINGS.each { |s| s.hash } small_strings: | SMALL_STRINGS.each { |s| s.hash } medium_strings: | MED_STRINGS.each { |s| s.hash } large_strings: | LARGE_STRINGS.each { |s| s.hash } huge_strings: | HUGE_STRINGS.each { |s| s.hash % benchmark-driver ~/string_hash.yml \ -e ruby-master::~/.rubies/ruby-master/bin/ruby \ -e ruby-xxhash::~/.rubies/ruby-xxhash/bin/ruby \ --output compare Warming up -------------------------------------- tiny_strings 262.513k i/s - 283.844k times in 1.081258s (3.81μs/i) small_strings 259.803k i/s - 280.445k times in 1.079454s (3.85μs/i) medium_strings 249.553k i/s - 267.531k times in 1.072041s (4.01μs/i) large_strings 116.426k i/s - 126.005k times in 1.082275s (8.59μs/i) huge_strings 498.481 i/s - 500.000 times in 1.003047s (2.01ms/i) Calculating ------------------------------------- ruby-master ruby-xxhash tiny_strings 264.070k 288.960k i/s - 787.538k times in 2.982305s 2.725421s small_strings 259.941k 286.229k i/s - 779.407k times in 2.998394s 2.723019s medium_strings 249.249k 283.952k i/s - 748.658k times in 3.003655s 2.636561s large_strings 116.572k 240.823k i/s - 349.278k times in 2.996244s 1.450351s huge_strings 500.164 5.296k i/s - 1.495k times in 2.989019s 0.282263s Comparison: tiny_strings ruby-xxhash: 288960.1 i/s ruby-master: 264070.2 i/s - 1.09x slower small_strings ruby-xxhash: 286229.0 i/s ruby-master: 259941.5 i/s - 1.10x slower medium_strings ruby-xxhash: 283952.5 i/s ruby-master: 249249.0 i/s - 1.14x slower large_strings ruby-xxhash: 240823.1 i/s ruby-master: 116571.9 i/s - 2.07x slower huge_strings ruby-xxhash: 5296.5 i/s ruby-master: 500.2 i/s - 10.59x slower ``` Running something a bit more real-world: ``` % cat ~/json_parse.yml prelude: | require 'json' activitypub_json_txt = File.read("/Users/scott/Development/json/benchmark/data/activitypub.json") twitter_json_txt = File.read("/Users/scott/Development/json/benchmark/data/twitter.json") citm_catalog_json_txt = File.read("/Users/scott/Development/json/benchmark/data/citm_catalog.json") ohai_json_txt = File.read("/Users/scott/Development/json/benchmark/data/ohai.json") benchmark: parse_activitypub_json: | JSON.parse(activitypub_json_txt) parse_twitter_json_txt: | JSON.parse(twitter_json_txt) parse_citm_catalog_json_txt: | JSON.parse(citm_catalog_json_txt) parse_ohai_json_txt: | JSON.parse(ohai_json_txt) % benchmark-driver ~/json_parse.yml \ -e ruby-master::~/.rubies/ruby-master/bin/ruby \ -e ruby-xxhash::~/.rubies/ruby-xxhash/bin/ruby \ --output compare Warming up -------------------------------------- parse_activitypub_json 10.969k i/s - 12.023k times in 1.096043s (91.16μs/i) parse_twitter_json_txt 1.169k i/s - 1.265k times in 1.082330s (855.60μs/i) parse_citm_catalog_json_txt 591.782 i/s - 600.000 times in 1.013887s (1.69ms/i) parse_ohai_json_txt 12.000k i/s - 12.782k times in 1.065168s (83.33μs/i) Calculating ------------------------------------- ruby-master ruby-xxhash parse_activitypub_json 10.986k 11.071k i/s - 32.908k times in 2.995440s 2.972542s parse_twitter_json_txt 1.162k 1.172k i/s - 3.506k times in 3.016331s 2.991486s parse_citm_catalog_json_txt 588.758 601.926 i/s - 1.775k times in 3.014820s 2.948868s parse_ohai_json_txt 10.747k 12.400k i/s - 35.999k times in 3.349753s 2.903138s Comparison: parse_activitypub_json ruby-xxhash: 11070.7 i/s ruby-master: 10986.0 i/s - 1.01x slower parse_twitter_json_txt ruby-xxhash: 1172.0 i/s ruby-master: 1162.3 i/s - 1.01x slower parse_citm_catalog_json_txt ruby-xxhash: 601.9 i/s ruby-master: 588.8 i/s - 1.02x slower parse_ohai_json_txt ruby-xxhash: 12400.0 i/s ruby-master: 10746.8 i/s - 1.15x slower ``` Admittedly, I'm not a hash expert nor a cryptographer. There doesn't seem to be any known vulnerabilities with XXH3 that I have found. -- https://bugs.ruby-lang.org/

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[ruby-core:124278] [Ruby Feature#21788] Promote Thread::Monitor to a core class
by byroot (Jean Boussier) 10 Feb '26

10 Feb '26

Issue #21788 has been reported by byroot (Jean Boussier). ---------------------------------------- Feature #21788: Promote Thread::Monitor to a core class https://bugs.ruby-lang.org/issues/21788 * Author: byroot (Jean Boussier) * Status: Open * Target version: 4.1 ---------------------------------------- `Monitor` is about as useful as `Mutex` and yet one is a core class and the other is a "stdlib" extension. I propose to promote `Thread::Monitor` as a core class convenience. ### The rest of `monitor.rb` The `monitor` stdlib also contains `MonitorMixin`, but I think this part can remain in `lib/monitor.rb` (or even be moved to `lib/monitor_mixin.rb`. One more questionable part is `Monitor#new_cond`, as it returns a `::MonitorMixin::ConditionVariable` so it would also need to remain in the stdlib. ### Performance benefit By being a core class, Monitor can also be implemented more efficiently, as it is no longer constrained to the public C API. On my branch, monitor is approximately 15% faster (but there might be some more optimizations to be found). `master`: ``` ruby 4.0.0dev (2025-12-17T07:21:34Z core-monitor 32815a1bc4) +YJIT +PRISM [arm64-darwin25] Warming up -------------------------------------- Mutex 1.975M i/100ms Monitor 1.936M i/100ms Calculating ------------------------------------- Mutex 25.213M (± 0.4%) i/s (39.66 ns/i) - 126.407M in 5.013728s Monitor 24.099M (± 0.1%) i/s (41.50 ns/i) - 121.992M in 5.062092s ``` core monitor: ``` ruby 4.0.0dev (2025-12-17T07:16:32Z master 54d3945ee5) +YJIT +PRISM [arm64-darwin25] Warming up -------------------------------------- Mutex 1.952M i/100ms Monitor 1.775M i/100ms Calculating ------------------------------------- Mutex 25.102M (± 0.4%) i/s (39.84 ns/i) - 126.884M in 5.054731s Monitor 21.189M (± 0.1%) i/s (47.19 ns/i) - 106.485M in 5.025493s ``` Proposed implementation: https://github.com/ruby/ruby/pull/15538 -- https://bugs.ruby-lang.org/

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[ruby-core:124552] [Ruby Bug#21838] Rails seeding degradation (20% slowdown) related to Revision 079ef92b "Implement global allocatable slots and empty pages" (from Sep 5 2024)
by bluz71 (Dennis B) 09 Feb '26

09 Feb '26

Issue #21838 has been reported by bluz71 (Dennis B). ---------------------------------------- Bug #21838: Rails seeding degradation (20% slowdown) related to Revision 079ef92b "Implement global allocatable slots and empty pages" (from Sep 5 2024) https://bugs.ruby-lang.org/issues/21838 * Author: bluz71 (Dennis B) * Status: Open * ruby -v: ruby 3.4.0dev (2024-09-09T14:15:21Z v3_4_0_preview2~545 079ef92b5e) * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN, 4.0: UNKNOWN ---------------------------------------- Hello, I noticed a performance degradation with Ruby 3.4 when seeding my Rails application, which does image derivation via the Shrine Gem and `libvips` image library. I skipped Ruby 3.4 hoping that 4.0 would magically solve my performance issue. Alas not. My degradation when doing `rails db:reset` (aka database seeding) was about 20% as compared with Ruby 3.3. The last couple of days I looked at this issue more closely and with the help of `git bisect` I believe this commit: https://bugs.ruby-lang.org/projects/ruby-master/repository/git/revisions/07… is the cause of my regression. That commit implements global allocatable slots and empty pages. The revision before is fast when seeding my Rails application. This revision however slows down my Rails seeding by about 20%, from 30 seconds to 40 seconds consistently. I created a minimal Rails application as the reproducible test case: https://github.com/bluz71/rails_app_ruby_slowdown Steps to reproduce: 1. `git clone https://github.com/bluz71/rails_app_ruby_slowdown` 2. `cd rails_app_ruby_slowdown` 3. `bundle config set force_ruby_platform true` 4. `bundle install` 5. `bundle exec rails db:create` 6. `RUBY_YJIT_ENABLE=0 time bundle exec rails db:reset` Note, `libvips` needs to be installed at the system level, for example `sudo apt install libvips`, libvips is the image processing library used by Shrine which in turn is used in this Rails application when seeding. Use Ruby 3.3 and 3.4 to compare, or use Revision de7ac11a (https://bugs.ruby-lang.org/projects/ruby-master/repository/git/revisions/de…) and Revision 079ef92b (https://bugs.ruby-lang.org/projects/ruby-master/repository/git/revisions/07…) to compare. I hope this is reproducible, if so, I also hope this performance loss can be minimised in future. Best regards. -- https://bugs.ruby-lang.org/

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[ruby-core:124604] [Ruby Bug#21847] Backport `syntax_suggest` 2.0.3 to supported branches
by Earlopain (Earlopain _) 09 Feb '26

09 Feb '26

Issue #21847 has been reported by Earlopain (Earlopain _). ---------------------------------------- Bug #21847: Backport `syntax_suggest` 2.0.3 to supported branches https://bugs.ruby-lang.org/issues/21847 * Author: Earlopain (Earlopain _) * Status: Open * Backport: 3.2: DONTNEED, 3.3: REQUIRED, 3.4: REQUIRED, 4.0: REQUIRED ---------------------------------------- Prism contains a translation layer for ripper, which until very recently didn't emit `on_sp` tokens. This has now been implemented to improve compatibility. However right after merging some `syntax_suggest` tests started failing: https://gist.github.com/schneems/834c75345b2085bda54dab69d913bcc0. `syntax_suggest` is using the ripper translation layer and is working around the missing `on_sp` tokens. Now that they are correctly created by prism, `syntax_suggest` is not able to handle these. For prism this is just a bugfix but I do not want to break `syntax_suggest` unnecessarily. I asked @schneems and this is what he had to say about it: https://github.com/ruby/syntax_suggest/pull/243#issuecomment-3779113958 Backport PRs: -- https://bugs.ruby-lang.org/

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[ruby-core:124579] [Ruby Bug#21842] Encoding of rb_interned_str
by herwin (Herwin W) 09 Feb '26

09 Feb '26

Issue #21842 has been reported by herwin (Herwin W). ---------------------------------------- Bug #21842: Encoding of rb_interned_str https://bugs.ruby-lang.org/issues/21842 * Author: herwin (Herwin W) * Status: Open * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN, 4.0: UNKNOWN ---------------------------------------- This is one of the API methods to get an fstring. The documentation in the source says the following: ```c /** * Identical to rb_str_new(), except it returns an infamous "f"string. What is * a fstring? Well it is a special subkind of strings that is immutable, * deduped globally, and managed by our GC. It is much like a Symbol (in fact * Symbols are dynamic these days and are backended using fstrings). This * concept has been silently introduced at some point in 2.x era. Since then * it gained wider acceptance in the core. Starting from 3.x extension * libraries can also generate ones. * * @param[in] ptr A memory region of `len` bytes length. * @param[in] len Length of `ptr`, in bytes, not including the * terminating NUL character. * @exception rb_eArgError `len` is negative. * @return A found or created instance of ::rb_cString, of `len` bytes * length, of "binary" encoding, whose contents are identical to * that of `ptr`. * @pre At least `len` bytes of continuous memory region shall be * accessible via `ptr`. */ VALUE rb_interned_str(const char *ptr, long len); ``` I tried to create some specs for them (https://github.com/ruby/spec/pull/1327) but instead of binary encoding, the string is actually encoded as US-ASCII. This may result is some weird behaviour if the input contains bytes that are not valid in US-ASCII (the following is more an observation of the current behaviour) ```ruby it "support binary strings that are invalid in ASCII encoding" do str = "foo\x81bar\x82baz".b result = @s.rb_interned_str(str, str.bytesize) result.encoding.should == Encoding::US_ASCII result.should == str.dup.force_encoding(Encoding::US_ASCII) result.should_not.valid_encoding? end ``` So it seems to me like either the implementation of the documentation is incorrect. (`rb_interned_str_cstr` has the same behaviour, it's pretty much the same thing except using a null terminator instead of an explicit length argument). -- https://bugs.ruby-lang.org/

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[ruby-core:123966] [Ruby Bug#21723] `binding.irb` raises a LoadError under `bundle exec`
by osyoyu (Daisuke Aritomo) 09 Feb '26

09 Feb '26

Issue #21723 has been reported by osyoyu (Daisuke Aritomo). ---------------------------------------- Bug #21723: `binding.irb` raises a LoadError under `bundle exec` https://bugs.ruby-lang.org/issues/21723 * Author: osyoyu (Daisuke Aritomo) * Status: Open * ruby -v: ruby 4.0.0preview2 (2025-11-17 master 4fa6e9938c) +PRISM [arm64-darwin24] * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- In Ruby 4.0, `binding.irb` raises a LoadError when some unknown condition is met. ```ruby # main.rb binding.irb ``` ``` main.rb:1: warning: irb used to be loaded from the standard library, but is not part of the default gems since Ruby 4.0.0. You can add irb to your Gemfile or gemspec to fix this error. Failed to activate irb, please install it with 'gem install irb' /Users/osyoyu/.rbenv/versions/master/lib/ruby/4.0.0+0/bundled_gems.rb:60:in 'Kernel.require': cannot load such file -- irb (LoadError) Did you mean? erb from /Users/osyoyu/.rbenv/versions/master/lib/ruby/4.0.0+0/bundled_gems.rb:60:in 'block (2 levels) in Kernel#replace_require' from main.rb:1:in 'Binding#irb' from main.rb:1:in '<main>' /Users/osyoyu/.rbenv/versions/master/lib/ruby/4.0.0+0/bundled_gems.rb:60:in 'Kernel.require': cannot load such file -- irb (LoadError) Did you mean? erb from /Users/osyoyu/.rbenv/versions/master/lib/ruby/4.0.0+0/bundled_gems.rb:60:in 'block (2 levels) in Kernel#replace_require' from main.rb:1:in 'Binding#irb' from main.rb:1:in '<main>' ``` While irb has been changed to a bundle gem in #20309, it is agreed that `binding.irb` shall work under `bundle exec` without adding `irb` in Gemfile. Thus, I've considered this behavior as an bug and created a ticket here. One condition I have discovered is when the Gemfile contains a `gem` reference with a `path:` option. I have created a repro repository in https://github.com/osyoyu/irbfail for that case. -- https://bugs.ruby-lang.org/

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