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

[ruby-core:125161] [Ruby Bug#21974] Cannot inspect RubyVM::AST for CDECL
by kddnewton (Kevin Newton) 02 Apr '26

02 Apr '26

Issue #21974 has been reported by kddnewton (Kevin Newton). ---------------------------------------- Bug #21974: Cannot inspect RubyVM::AST for CDECL https://bugs.ruby-lang.org/issues/21974 * Author: kddnewton (Kevin Newton) * Status: Open * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN, 4.0: UNKNOWN ---------------------------------------- ``` ./ruby -e 'pp RubyVM::AbstractSyntaxTree.parse("::Foo = 1")' ``` and ``` ./ruby -e 'p RubyVM::AbstractSyntaxTree.parse("::Foo = 1").children[2].children' ``` both crash -- https://bugs.ruby-lang.org/

2 1

[ruby-core:125156] [Ruby Feature#21972] Add Date.birthday and Date.age to track Ruby's milestones
by jinroq (Jinroq SAITOH) 01 Apr '26

01 Apr '26

Issue #21972 has been reported by jinroq (Jinroq SAITOH). ---------------------------------------- Feature #21972: Add Date.birthday and Date.age to track Ruby's milestones https://bugs.ruby-lang.org/issues/21972 * Author: jinroq (Jinroq SAITOH) * Status: Open ---------------------------------------- Since its inception in 1993, Ruby has grown beyond a mere programming language to become a rich culture beloved by developers worldwide. However, the standard `date` library surprisingly lacks a formal interface to commemorate Ruby's own historical milestones. The fact that developers cannot programmatically reference Ruby’s heritage is a missed opportunity to foster affection and respect for the language's identity. To rectify this historical oversight, I propose adding the following methods to reference Ruby's key anniversaries and calculate the elapsed years. #### New Features * **`Date.birthday(version = nil)`** Returns the "birthday" of significant moments in Ruby's history. * `nil` (default): **1993-02-24** (The day the name "Ruby" was decided). * `0.95`: **1995-12-21** (The first public release date). * `1.0`: **1996-12-25** (The first stable release date). * **`Date.age(version = nil)`** Calculates the current age (in full years) based on today's date and the specified milestone. * `Date.age`: Years since the name "Ruby" was born. * `Date.age(0.95)`: Years since Ruby was first introduced to the public as OSS. * `Date.age(1.0)`: Years since Ruby began its journey as a stable language. #### Usage Example ```ruby # Check the "age" of each edition puts "Name age: #{Date.age}" # => 33 (as of 2026) puts "OSS age: #{Date.age(0.95)}" # => 30 puts "Stable: #{Date.age(1.0)}" # => 29 # Perform a special action on a specific anniversary if Date.today == Date.birthday(1.0) celebrate_stable_anniversary! end ``` #### Implementation and Testing The attached patch (`birthday_and_age.patch`) includes the implementation of these methods along with a rigorous test suite (`test/date/test_date_birthday.rb`). The tests cover argument dispatching, `ArgumentError` for invalid inputs, and edge cases for age calculation (e.g., boundaries before and after the actual birthday), ensuring production-level quality. Equipping Ruby with the intelligence to reflect upon its own origins is a vital step toward the next 30 or 40 years of its evolution. (Note: This proposal was submitted on a special day that encourages looking at our history with both deep respect and a touch of creative imagination, as is traditional for such a significant date in the calendar.) ---Files-------------------------------- birthday_and_age.patch (8.08 KB) -- https://bugs.ruby-lang.org/

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[ruby-core:120488] [Ruby master Feature#21005] Update the source location method to include line start/stop and column start/stop details
by bkuhlmann (Brooke Kuhlmann) 01 Apr '26

01 Apr '26

Issue #21005 has been reported by bkuhlmann (Brooke Kuhlmann). ---------------------------------------- Feature #21005: Update the source location method to include line start/stop and column start/stop details https://bugs.ruby-lang.org/issues/21005 * Author: bkuhlmann (Brooke Kuhlmann) * Status: Open ---------------------------------------- ## Why 👋 Hello. After discussing with Kevin Newton and Benoit Daloze in [Feature 20999](https://bugs.ruby-lang.org/issues/20999), I'd like to propose adding line start/stop and column start/stop information to the `#source_location` method for the following objects: - [Binding](https://docs.ruby-lang.org/en/master/Binding.html) - [Proc](https://docs.ruby-lang.org/en/master/Proc.html) - [Method](https://docs.ruby-lang.org/en/master/Method.html) - [UnboundMethod](https://docs.ruby-lang.org/en/master/UnboundMethod.html) At the moment, when using `#source_location`, you only get the following information: ``` ruby def demo = "A demonstration." # From disk. method(:demo).source_location # ["/Users/bkuhlmann/Engineering/Misc/demo", 15] # From memory. method(:demo).source_location # ["(irb)", 3] ``` Notice, when asking for the source location, we only get the path/location as the first element and the line number as the second element but I'd like to obtain a much richer set of data which includes line start/stop and column start/stop so I can avoid leaning on the `RubyVM` for this information. Example: ``` ruby def demo = "A demonstration." # From disk. instructions = RubyVM::InstructionSequence.of method(:demo) puts [instructions.absolute_path, *instructions.to_a.dig(4, :code_location)] [ "/Users/bkuhlmann/Engineering/Misc/demo", # Source path. 15, # Line start. 0, # Column start. 15, # Line stop. 29 # Column stop. ] # From memory. instructions = RubyVM::InstructionSequence.of method(:demo) puts instructions.script_lines [ "def demo = \"A demonstration.\"\n", "" ] ``` By having access to the path (or lack thereof in case of IRB), line start/stop, and column start/stop, this means we could avoid using the RubyVM to obtain raw source code for any of these objects. This would not only enhance debugging situations but also improve Domain Specific Languages that wish to leverage this information for introducing new features and/or new debugging capabilities to the language. ## How Building upon the examples provided above, I'd like to see `Binding`, `Proc`, `Method`, and `UnboundMethod` respond to `#source_location` as follows: ``` ruby [ "/Users/bkuhlmann/Engineering/Misc/demo", # Source path. 15, # Line start. 15, # Line stop. 0, # Column start. 29 # Column stop. ] ``` Notice, for data grouping purposes, I changed the array structure to always start with the path as the first element, followed by line information, and ending with column information. Alternatively, it could might be nice to improve upon the above by answering a hash each time, instead, for a more self-describing data structure. Example: ``` ruby { path: "/Users/bkuhlmann/Engineering/Misc/demo", line_start: 15, line_stop: 15, column_start: 0, column_stop: 29 } ``` For in-memory, situations like IRB, it would be nice to answer the equivalent of `RubyVM::InstructionSequence#script_lines` which would always be an `Array` with no line or column information since only the source code is necessary. Example: ``` ruby [ "def demo = \"A demonstration.\"\n", "" ] ``` From a pattern matching perspective, this could provide the best of both worlds especially if information is answered as either a `Hash` or and `Array`. Example: ``` def demo = "A demonstration." case method(:demo).source_location in Hash then puts "Source information obtained from disk." in Array then puts "Source obtained from memory." else fail TypeError, "Unrecognized source location type." end ``` This above is only a simple example but there's a lot we could do with this information if the above pattern match was enhanced to deal with the extraction and formatting of the actual source code! ## Notes This feature request is related to the following discussions in case more context is of help: - [Feature 6012](https://bugs.ruby-lang.org/issues/6012) - [Feature 20999](https://bugs.ruby-lang.org/issues/20999) -- https://bugs.ruby-lang.org/

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[ruby-core:125157] [Ruby Feature#21973] Smile argument
by kinoppyd (Yasuhiro Kinoshita) 31 Mar '26

31 Mar '26

Issue #21973 has been reported by kinoppyd (Yasuhiro Kinoshita). ---------------------------------------- Feature #21973: Smile argument https://bugs.ruby-lang.org/issues/21973 * Author: kinoppyd (Yasuhiro Kinoshita) * Status: Open ---------------------------------------- Ruby makes us smile. So I want Ruby to smile too, and that is why I would like to propose this feature. The smile argument makes Ruby smile by allowing a method call to end its argument list with `:)`. smile_method(arg, :) This syntax implicitly supplies keyword arguments by matching the names of local variables in the current scope with the names of the method’s keyword parameters. For example, if a method has the following signature: ```ruby some_method(arg, smile:, hugging:) ``` then these two calls would be equivalent: ```ruby arg = "hello" smile = "smile" hugging = "hugging" some_method(arg, smile:, hugging:) ``` ```ruby arg = "hello" smile = "smile" hugging = "hugging" some_method(arg, :) ``` The motivation behind this feature is the assumption that names used in a method signature are often also used at the call site. For instance, if a library method defines keyword arguments like `(from:, to:)`, I expect that code using that method would often have local variables named `from` and `to` holding the actual values before passing them along. In real application development, when developers adopt a new library, they will usually look at the argument list of the method they want to call. If they intend to use that method as designed, it seems natural that they may also choose the same variable names as those in the method signature. This idea was inspired by Scala’s implicit parameters. It is not exactly the same feature, but as a lazy person, I find the idea of context-driven currying quite appealing. In any case, the real purpose is to make Ruby smile. Happy Ruby! And happy April Fools' Day! -- https://bugs.ruby-lang.org/

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[ruby-core:125141] [Ruby Bug#21967] `vm_call_cfunc: cfp consistency error` while requiring `nkf.so`
by byroot (Jean Boussier) 30 Mar '26

30 Mar '26

Issue #21967 has been reported by byroot (Jean Boussier). ---------------------------------------- Bug #21967: `vm_call_cfunc: cfp consistency error` while requiring `nkf.so` https://bugs.ruby-lang.org/issues/21967 * Author: byroot (Jean Boussier) * Status: Open * ruby -v: ruby 4.0.2 (2026-03-17 revision d3da9fec82) +PRISM [aarch64-linux] * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN, 4.0: UNKNOWN ---------------------------------------- I'm unfortunately unable to reproduce this consistently. It does happen a few times a day on our production servers, and I have a few core dumps around for investigation if needed. The crash is always while loading `nknf.so`. I'm unfortunately not familiar enough with `cfp` to investigate this much further myself. ``` <PATH>/vendor/bundle/ruby/4.0.0/gems/nkf-0.2.0/lib/nkf.so: [BUG] vm_call_cfunc: cfp consistency error (0x0000ffff80779830, 0x0000ffff807797f8) ruby 4.0.2 (2026-03-17 revision d3da9fec82) +PRISM [aarch64-linux] -- Control frame information ----------------------------------------------- c:0032 p:---- s:0172 e:000171 l:y b:0001 TOP [FINISH] c:0031 p:---- s:0169 e:000168 l:y b:---- CFUNC :require c:0030 p:0033 s:0164 e:000163 l:n b:---- BLOCK <PATH>/vendor/ruby-4.0.2/lib/ruby/4.0.0/bu c:0029 p:0145 s:0158 e:000157 l:y b:0001 METHOD <PATH>/vendor/bundle/ruby/4.0.0/gems/boots c:0028 p:0026 s:0149 e:000148 l:y b:0001 TOP <PATH>/vendor/bundle/ruby/4.0.0/gems/nkf-0 [FINISH] c:0027 p:---- s:0146 e:000145 l:y b:---- CFUNC :require c:0026 p:0033 s:0141 e:000140 l:n b:---- BLOCK <PATH>/vendor/ruby-4.0.2/lib/ruby/4.0.0/bu c:0025 p:0145 s:0135 e:000134 l:y b:0001 METHOD <PATH>/vendor/bundle/ruby/4.0.0/gems/boots c:0024 p:0011 s:0126 e:000125 l:y b:0001 TOP <PATH>/vendor/bundle/ruby/4.0.0/gems/mecha [FINISH] c:0023 p:---- s:0123 e:000122 l:y b:---- CFUNC :require c:0022 p:0033 s:0118 e:000117 l:n b:---- BLOCK <PATH>/vendor/ruby-4.0.2/lib/ruby/4.0.0/bu c:0021 p:0145 s:0112 e:000111 l:y b:0001 METHOD <PATH>/vendor/bundle/ruby/4.0.0/gems/boots c:0020 p:0265 s:0103 e:000102 l:y b:0001 TOP <PATH>/vendor/bundle/ruby/4.0.0/gems/mecha [FINISH] c:0019 p:---- s:0100 e:000099 l:y b:---- CFUNC :require c:0018 p:0011 s:0095 e:000094 l:y b:0001 METHOD <internal:<PATH>/vendor/ruby-4.0.2/lib/rub c:0017 p:0033 s:0089 e:000088 l:n b:---- BLOCK <PATH>/vendor/ruby-4.0.2/lib/ruby/4.0.0/bu c:0016 p:0024 s:0083 e:000082 l:n b:---- BLOCK <PATH>/vendor/bundle/ruby/4.0.0/gems/bundl [FINISH] c:0015 p:---- s:0077 e:000076 l:y b:---- CFUNC :each c:0014 p:0027 s:0073 e:000072 l:n b:---- BLOCK <PATH>/vendor/bundle/ruby/4.0.0/gems/bundl [FINISH] c:0013 p:---- s:0069 e:000068 l:y b:---- CFUNC :each c:0012 p:0042 s:0065 e:000064 l:y b:0001 METHOD <PATH>/vendor/bundle/ruby/4.0.0/gems/bundl c:0011 p:0013 s:0059 e:000058 l:y b:0001 METHOD <PATH>/vendor/bundle/ruby/4.0.0/gems/bundl c:0010 p:0117 s:0054 e:000053 l:y b:0001 TOP <PATH>/config/application.rb:25 [FINISH] c:0009 p:---- s:0051 e:000050 l:y b:---- CFUNC :require_relative c:0008 p:0005 s:0046 e:000045 l:y b:0001 TOP <PATH>/config/environment.rb:2 [FINISH] c:0007 p:---- s:0043 e:000042 l:y b:---- CFUNC :require c:0006 p:0033 s:0038 e:000037 l:n b:---- BLOCK <PATH>/vendor/ruby-4.0.2/lib/ruby/4.0.0/bu c:0005 p:0145 s:0032 e:000031 l:y b:0001 METHOD <PATH>/vendor/bundle/ruby/4.0.0/gems/boots c:0004 p:0011 s:0023 e:000022 l:y b:0001 TOP <PATH>/gems/intercom-sqs/exe/intercom-sqs: [FINISH] c:0003 p:---- s:0011 e:000010 l:y b:---- CFUNC :load c:0002 p:0017 s:0006 e:000005 l:n b:---- EVAL bin/intercom-sqs:6 [FINISH] c:0001 p:0000 s:0003 E:001b40 l:y b:---- DUMMY [FINISH] -- Ruby level backtrace information ---------------------------------------- bin/intercom-sqs:6:in '<main>' bin/intercom-sqs:6:in 'load' <PATH>/gems/intercom-sqs/exe/intercom-sqs:6:in '<main>' <PATH>/vendor/bundle/ruby/4.0.0/gems/bootsnap-1.22.0/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:33:in 'require' <PATH>/vendor/ruby-4.0.2/lib/ruby/4.0.0/bundled_gems.rb:60:in 'block (2 levels) in replace_require' <PATH>/vendor/ruby-4.0.2/lib/ruby/4.0.0/bundled_gems.rb:60:in 'require' <PATH>/config/environment.rb:2:in '<main>' <PATH>/config/environment.rb:2:in 'require_relative' <PATH>/config/application.rb:25:in '<main>' <PATH>/vendor/bundle/ruby/4.0.0/gems/bundler-4.0.8/lib/bundler.rb:213:in 'require' <PATH>/vendor/bundle/ruby/4.0.0/gems/bundler-4.0.8/lib/bundler/runtime.rb:52:in 'require' <PATH>/vendor/bundle/ruby/4.0.0/gems/bundler-4.0.8/lib/bundler/runtime.rb:52:in 'each' <PATH>/vendor/bundle/ruby/4.0.0/gems/bundler-4.0.8/lib/bundler/runtime.rb:58:in 'block in require' <PATH>/vendor/bundle/ruby/4.0.0/gems/bundler-4.0.8/lib/bundler/runtime.rb:58:in 'each' <PATH>/vendor/bundle/ruby/4.0.0/gems/bundler-4.0.8/lib/bundler/runtime.rb:63:in 'block (2 levels) in require' <PATH>/vendor/ruby-4.0.2/lib/ruby/4.0.0/bundled_gems.rb:60:in 'block (2 levels) in replace_require' <internal:<PATH>/vendor/ruby-4.0.2/lib/ruby/4.0.0/rubygems/core_ext/kernel_require.rb>:37:in 'require' <internal:<PATH>/vendor/ruby-4.0.2/lib/ruby/4.0.0/rubygems/core_ext/kernel_require.rb>:37:in 'require' <PATH>/vendor/bundle/ruby/4.0.0/gems/mechanize-2.10.0/lib/mechanize.rb:1387:in '<main>' <PATH>/vendor/bundle/ruby/4.0.0/gems/bootsnap-1.22.0/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:33:in 'require' <PATH>/vendor/ruby-4.0.2/lib/ruby/4.0.0/bundled_gems.rb:60:in 'block (2 levels) in replace_require' <PATH>/vendor/ruby-4.0.2/lib/ruby/4.0.0/bundled_gems.rb:60:in 'require' <PATH>/vendor/bundle/ruby/4.0.0/gems/mechanize-2.10.0/lib/mechanize/util.rb:3:in '<main>' <PATH>/vendor/bundle/ruby/4.0.0/gems/bootsnap-1.22.0/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:33:in 'require' <PATH>/vendor/ruby-4.0.2/lib/ruby/4.0.0/bundled_gems.rb:60:in 'block (2 levels) in replace_require' <PATH>/vendor/ruby-4.0.2/lib/ruby/4.0.0/bundled_gems.rb:60:in 'require' <PATH>/vendor/bundle/ruby/4.0.0/gems/nkf-0.2.0/lib/nkf.rb:5:in '<main>' <PATH>/vendor/bundle/ruby/4.0.0/gems/bootsnap-1.22.0/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:33:in 'require' <PATH>/vendor/ruby-4.0.2/lib/ruby/4.0.0/bundled_gems.rb:60:in 'block (2 levels) in replace_require' <PATH>/vendor/ruby-4.0.2/lib/ruby/4.0.0/bundled_gems.rb:60:in 'require' -- Threading information --------------------------------------------------- Total ractor count: 1 Ruby thread count for this ractor: 1 -- C level backtrace information ------------------------------------------- <PATH>/vendor/ruby-4.0.2/bin/ruby(rb_print_backtrace+0x8) [0xaaaab1d0964c] /ruby-4.0.2/vm_dump.c:1105 <PATH>/vendor/ruby-4.0.2/bin/ruby(rb_vm_bugreport) /ruby-4.0.2/vm_dump.c:1450 <PATH>/vendor/ruby-4.0.2/bin/ruby(rb_bug_without_die_internal+0x70) [0xaaaab1821640] /ruby-4.0.2/error.c:1098 <PATH>/vendor/ruby-4.0.2/bin/ruby(rb_bug) /ruby-4.0.2/error.c:1116 <PATH>/vendor/ruby-4.0.2/bin/ruby(rb_vm_check_ints+0x0) [0xaaaab19edc54] /ruby-4.0.2/vm_insnhelper.c:3904 <PATH>/vendor/ruby-4.0.2/bin/ruby(rb_vm_check_ints) /ruby-4.0.2/vm_core.h:2256 <PATH>/vendor/ruby-4.0.2/bin/ruby(vm_pop_frame) /ruby-4.0.2/vm_insnhelper.c:452 <PATH>/vendor/ruby-4.0.2/bin/ruby(rb_vm_pop_frame) /ruby-4.0.2/vm_insnhelper.c:461 <PATH>/vendor/ruby-4.0.2/bin/ruby(vm_call_cfunc_with_frame_) /ruby-4.0.2/vm_insnhelper.c:3906 <PATH>/vendor/ruby-4.0.2/bin/ruby(vm_call_symbol+0x32c) [0xaaaab19fed34] /ruby-4.0.2/vm_insnhelper.c:4403 <PATH>/vendor/ruby-4.0.2/bin/ruby(vm_sendish+0xc4) [0xaaaab19f3750] /ruby-4.0.2/vm_insnhelper.c:6124 <PATH>/vendor/ruby-4.0.2/bin/ruby(vm_exec_core+0xa4) [0xaaaab1a0b994] /ruby-4.0.2/insns.def:904 <PATH>/vendor/ruby-4.0.2/bin/ruby(vm_exec_loop+0x68) [0xaaaab19fc734] /ruby-4.0.2/vm.c:2825 <PATH>/vendor/ruby-4.0.2/bin/ruby(rb_vm_exec) /ruby-4.0.2/vm.c:2804 <PATH>/vendor/ruby-4.0.2/bin/ruby(load_iseq_eval+0x3c) [0xaaaab18a1b44] /ruby-4.0.2/load.c:774 <PATH>/vendor/ruby-4.0.2/bin/ruby(require_internal) /ruby-4.0.2/load.c:1341 <PATH>/vendor/ruby-4.0.2/bin/ruby(rb_require_string_internal+0x3c) [0xaaaab18a1f8c] /ruby-4.0.2/load.c:1451 <PATH>/vendor/ruby-4.0.2/bin/ruby(rb_require_string) /ruby-4.0.2/load.c:1437 <PATH>/vendor/ruby-4.0.2/bin/ruby(rb_f_require) /ruby-4.0.2/load.c:1048 <PATH>/vendor/ruby-4.0.2/bin/ruby(vm_cfp_consistent_p+0x0) [0xaaaab19edb00] /ruby-4.0.2/vm_insnhelper.c:3902 <PATH>/vendor/ruby-4.0.2/bin/ruby(vm_call_cfunc_with_frame_) /ruby-4.0.2/vm_insnhelper.c:3904 <PATH>/vendor/ruby-4.0.2/bin/ruby(vm_call_symbol+0x32c) [0xaaaab19fed34] /ruby-4.0.2/vm_insnhelper.c:4403 <PATH>/vendor/ruby-4.0.2/bin/ruby(vm_sendish+0xc4) [0xaaaab19f3750] /ruby-4.0.2/vm_insnhelper.c:6124 <PATH>/vendor/ruby-4.0.2/bin/ruby(vm_exec_core+0xa4) [0xaaaab1a0b994] /ruby-4.0.2/insns.def:904 <PATH>/vendor/ruby-4.0.2/bin/ruby(vm_exec_loop+0x68) [0xaaaab19fc734] /ruby-4.0.2/vm.c:2825 <PATH>/vendor/ruby-4.0.2/bin/ruby(rb_vm_exec) /ruby-4.0.2/vm.c:2804 <PATH>/vendor/ruby-4.0.2/bin/ruby(load_iseq_eval+0x3c) [0xaaaab18a1b44] /ruby-4.0.2/load.c:774 <PATH>/vendor/ruby-4.0.2/bin/ruby(require_internal) /ruby-4.0.2/load.c:1341 <PATH>/vendor/ruby-4.0.2/bin/ruby(rb_require_string_internal+0x3c) [0xaaaab18a1f8c] /ruby-4.0.2/load.c:1451 <PATH>/vendor/ruby-4.0.2/bin/ruby(rb_require_string) /ruby-4.0.2/load.c:1437 <PATH>/vendor/ruby-4.0.2/bin/ruby(rb_f_require) /ruby-4.0.2/load.c:1048 <PATH>/vendor/ruby-4.0.2/bin/ruby(vm_cfp_consistent_p+0x0) [0xaaaab19edb00] /ruby-4.0.2/vm_insnhelper.c:3902 <PATH>/vendor/ruby-4.0.2/bin/ruby(vm_call_cfunc_with_frame_) /ruby-4.0.2/vm_insnhelper.c:3904 <PATH>/vendor/ruby-4.0.2/bin/ruby(vm_call_symbol+0x32c) [0xaaaab19fed34] /ruby-4.0.2/vm_insnhelper.c:4403 <PATH>/vendor/ruby-4.0.2/bin/ruby(vm_sendish+0xc4) [0xaaaab19f3750] /ruby-4.0.2/vm_insnhelper.c:6124 <PATH>/vendor/ruby-4.0.2/bin/ruby(vm_exec_core+0xa4) [0xaaaab1a0b994] /ruby-4.0.2/insns.def:904 <PATH>/vendor/ruby-4.0.2/bin/ruby(vm_exec_loop+0x68) [0xaaaab19fc734] /ruby-4.0.2/vm.c:2825 <PATH>/vendor/ruby-4.0.2/bin/ruby(rb_vm_exec) /ruby-4.0.2/vm.c:2804 <PATH>/vendor/ruby-4.0.2/bin/ruby(load_iseq_eval+0x3c) [0xaaaab18a1b44] /ruby-4.0.2/load.c:774 <PATH>/vendor/ruby-4.0.2/bin/ruby(require_internal) /ruby-4.0.2/load.c:1341 <PATH>/vendor/ruby-4.0.2/bin/ruby(rb_require_string_internal+0x3c) [0xaaaab18a1f8c] /ruby-4.0.2/load.c:1451 <PATH>/vendor/ruby-4.0.2/bin/ruby(rb_require_string) /ruby-4.0.2/load.c:1437 <PATH>/vendor/ruby-4.0.2/bin/ruby(rb_f_require) /ruby-4.0.2/load.c:1048 <PATH>/vendor/ruby-4.0.2/bin/ruby(vm_cfp_consistent_p+0x0) [0xaaaab19edb00] /ruby-4.0.2/vm_insnhelper.c:3902 <PATH>/vendor/ruby-4.0.2/bin/ruby(vm_call_cfunc_with_frame_) /ruby-4.0.2/vm_insnhelper.c:3904 <PATH>/vendor/ruby-4.0.2/bin/ruby(vm_call_alias+0x8c) [0xaaaab19fe90c] /ruby-4.0.2/vm_insnhelper.c:4297 <PATH>/vendor/ruby-4.0.2/bin/ruby(vm_sendish+0xc4) [0xaaaab19f3750] /ruby-4.0.2/vm_insnhelper.c:6124 <PATH>/vendor/ruby-4.0.2/bin/ruby(vm_exec_core+0xa4) [0xaaaab1a0b994] /ruby-4.0.2/insns.def:904 <PATH>/vendor/ruby-4.0.2/bin/ruby(rb_vm_exec+0x188) [0xaaaab19fc3f0] /ruby-4.0.2/vm.c:2798 <PATH>/vendor/ruby-4.0.2/bin/ruby(rb_yield+0xd0) [0xaaaab1a0131c] /ruby-4.0.2/vm.c:1871 <PATH>/vendor/ruby-4.0.2/bin/ruby(RB_FL_TEST_RAW+0x0) [0xaaaab1bf8968] /ruby-4.0.2/array.c:2754 <PATH>/vendor/ruby-4.0.2/bin/ruby(RB_FL_ANY_RAW) ./include/ruby/internal/fl_type.h:514 <PATH>/vendor/ruby-4.0.2/bin/ruby(rb_array_len) ./include/ruby/internal/core/rarray.h:259 <PATH>/vendor/ruby-4.0.2/bin/ruby(rb_ary_each) /ruby-4.0.2/array.c:2753 <PATH>/vendor/ruby-4.0.2/bin/ruby(vm_cfp_consistent_p+0x0) [0xaaaab19edb00] /ruby-4.0.2/vm_insnhelper.c:3902 <PATH>/vendor/ruby-4.0.2/bin/ruby(vm_call_cfunc_with_frame_) /ruby-4.0.2/vm_insnhelper.c:3904 <PATH>/vendor/ruby-4.0.2/bin/ruby(vm_sendish+0xc4) [0xaaaab19f3750] /ruby-4.0.2/vm_insnhelper.c:6124 <PATH>/vendor/ruby-4.0.2/bin/ruby(vm_exec_core+0x108) [0xaaaab1a0b9f8] /ruby-4.0.2/insns.def:856 <PATH>/vendor/ruby-4.0.2/bin/ruby(vm_exec_loop+0x68) [0xaaaab19fc734] /ruby-4.0.2/vm.c:2825 <PATH>/vendor/ruby-4.0.2/bin/ruby(rb_vm_exec) /ruby-4.0.2/vm.c:2804 <PATH>/vendor/ruby-4.0.2/bin/ruby(rb_yield+0xd0) [0xaaaab1a0131c] /ruby-4.0.2/vm.c:1871 <PATH>/vendor/ruby-4.0.2/bin/ruby(RB_FL_TEST_RAW+0x0) [0xaaaab1bf8968] /ruby-4.0.2/array.c:2754 <PATH>/vendor/ruby-4.0.2/bin/ruby(RB_FL_ANY_RAW) ./include/ruby/internal/fl_type.h:514 <PATH>/vendor/ruby-4.0.2/bin/ruby(rb_array_len) ./include/ruby/internal/core/rarray.h:259 <PATH>/vendor/ruby-4.0.2/bin/ruby(rb_ary_each) /ruby-4.0.2/array.c:2753 <PATH>/vendor/ruby-4.0.2/bin/ruby(vm_cfp_consistent_p+0x0) [0xaaaab19edb00] /ruby-4.0.2/vm_insnhelper.c:3902 <PATH>/vendor/ruby-4.0.2/bin/ruby(vm_call_cfunc_with_frame_) /ruby-4.0.2/vm_insnhelper.c:3904 <PATH>/vendor/ruby-4.0.2/bin/ruby(vm_sendish+0xc4) [0xaaaab19f3750] /ruby-4.0.2/vm_insnhelper.c:6124 <PATH>/vendor/ruby-4.0.2/bin/ruby(vm_exec_core+0x108) [0xaaaab1a0b9f8] /ruby-4.0.2/insns.def:856 <PATH>/vendor/ruby-4.0.2/bin/ruby(vm_exec_loop+0x68) [0xaaaab19fc734] /ruby-4.0.2/vm.c:2825 <PATH>/vendor/ruby-4.0.2/bin/ruby(rb_vm_exec) /ruby-4.0.2/vm.c:2804 <PATH>/vendor/ruby-4.0.2/bin/ruby(load_iseq_eval+0x3c) [0xaaaab18a1b44] /ruby-4.0.2/load.c:774 <PATH>/vendor/ruby-4.0.2/bin/ruby(require_internal) /ruby-4.0.2/load.c:1341 <PATH>/vendor/ruby-4.0.2/bin/ruby(rb_require_string_internal+0x58) [0xaaaab18a1e20] /ruby-4.0.2/load.c:1451 <PATH>/vendor/ruby-4.0.2/bin/ruby(vm_cfp_consistent_p+0x0) [0xaaaab19edb00] /ruby-4.0.2/vm_insnhelper.c:3902 <PATH>/vendor/ruby-4.0.2/bin/ruby(vm_call_cfunc_with_frame_) /ruby-4.0.2/vm_insnhelper.c:3904 <PATH>/vendor/ruby-4.0.2/bin/ruby(vm_sendish+0xc4) [0xaaaab19f3750] /ruby-4.0.2/vm_insnhelper.c:6124 <PATH>/vendor/ruby-4.0.2/bin/ruby(vm_exec_core+0xa4) [0xaaaab1a0b994] /ruby-4.0.2/insns.def:904 <PATH>/vendor/ruby-4.0.2/bin/ruby(rb_vm_exec+0x188) [0xaaaab19fc3f0] /ruby-4.0.2/vm.c:2798 <PATH>/vendor/ruby-4.0.2/bin/ruby(load_iseq_eval+0x3c) [0xaaaab18a1b44] /ruby-4.0.2/load.c:774 <PATH>/vendor/ruby-4.0.2/bin/ruby(require_internal) /ruby-4.0.2/load.c:1341 <PATH>/vendor/ruby-4.0.2/bin/ruby(rb_require_string_internal+0x3c) [0xaaaab18a1f8c] /ruby-4.0.2/load.c:1451 <PATH>/vendor/ruby-4.0.2/bin/ruby(rb_require_string) /ruby-4.0.2/load.c:1437 <PATH>/vendor/ruby-4.0.2/bin/ruby(rb_f_require) /ruby-4.0.2/load.c:1048 <PATH>/vendor/ruby-4.0.2/bin/ruby(vm_cfp_consistent_p+0x0) [0xaaaab19edb00] /ruby-4.0.2/vm_insnhelper.c:3902 <PATH>/vendor/ruby-4.0.2/bin/ruby(vm_call_cfunc_with_frame_) /ruby-4.0.2/vm_insnhelper.c:3904 <PATH>/vendor/ruby-4.0.2/bin/ruby(vm_call_symbol+0x32c) [0xaaaab19fed34] /ruby-4.0.2/vm_insnhelper.c:4403 <PATH>/vendor/ruby-4.0.2/bin/ruby(vm_sendish+0xc4) [0xaaaab19f3750] /ruby-4.0.2/vm_insnhelper.c:6124 <PATH>/vendor/ruby-4.0.2/bin/ruby(vm_exec_core+0xa4) [0xaaaab1a0b994] /ruby-4.0.2/insns.def:904 <PATH>/vendor/ruby-4.0.2/bin/ruby(vm_exec_loop+0x68) [0xaaaab19fc734] /ruby-4.0.2/vm.c:2825 <PATH>/vendor/ruby-4.0.2/bin/ruby(rb_vm_exec) /ruby-4.0.2/vm.c:2804 <PATH>/vendor/ruby-4.0.2/bin/ruby(raise_load_if_failed+0x0) [0xaaaab18a108c] /ruby-4.0.2/load.c:851 <PATH>/vendor/ruby-4.0.2/bin/ruby(rb_load_internal) /ruby-4.0.2/load.c:853 <PATH>/vendor/ruby-4.0.2/bin/ruby(rb_f_load+0x84) [0xaaaab18a112c] /ruby-4.0.2/load.c:893 <PATH>/vendor/ruby-4.0.2/bin/ruby(vm_cfp_consistent_p+0x0) [0xaaaab19edb00] /ruby-4.0.2/vm_insnhelper.c:3902 <PATH>/vendor/ruby-4.0.2/bin/ruby(vm_call_cfunc_with_frame_) /ruby-4.0.2/vm_insnhelper.c:3904 <PATH>/vendor/ruby-4.0.2/bin/ruby(vm_sendish+0xc4) [0xaaaab19f3750] /ruby-4.0.2/vm_insnhelper.c:6124 <PATH>/vendor/ruby-4.0.2/bin/ruby(vm_exec_core+0xa4) [0xaaaab1a0b994] /ruby-4.0.2/insns.def:904 <PATH>/vendor/ruby-4.0.2/bin/ruby(rb_vm_exec+0x188) [0xaaaab19fc3f0] /ruby-4.0.2/vm.c:2798 <PATH>/vendor/ruby-4.0.2/bin/ruby(rb_ec_exec_node+0x8c) [0xaaaab1824c4c] /ruby-4.0.2/eval.c:283 <PATH>/vendor/ruby-4.0.2/bin/ruby(ruby_run_node+0x3c) [0xaaaab182716c] /ruby-4.0.2/eval.c:321 <PATH>/vendor/ruby-4.0.2/bin/ruby(main+0x70) [0xaaaab1821b30] ./main.c:42 ``` -- https://bugs.ruby-lang.org/

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[ruby-core:125148] [Ruby Bug#21969] fork() + Socket.getaddrinfo() triggers SIGSEGV/SIGABRT via libsystem_trace.dylib on macOS 26 (darwin25) x86_64 and ARM64
by saurabhpandit (Saurabh Pandit) 30 Mar '26

30 Mar '26

Issue #21969 has been reported by saurabhpandit (Saurabh Pandit). ---------------------------------------- Bug #21969: fork() + Socket.getaddrinfo() triggers SIGSEGV/SIGABRT via libsystem_trace.dylib on macOS 26 (darwin25) x86_64 and ARM64 https://bugs.ruby-lang.org/issues/21969 * Author: saurabhpandit (Saurabh Pandit) * Status: Open * ruby -v: 4.0.1 * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN, 4.0: UNKNOWN ---------------------------------------- On macOS 26 (darwin25), forked child processes crash with SIGSEGV (x86_64) or SIGABRT (ARM64) when calling `Socket.getaddrinfo` after the parent process has established `libsystem_trace.dylib` os_log shared-memory state through prior DNS activity. This is distinct from [#21790](https://bugs.ruby-lang.org/issues/21790) (NAT64 hang/crash in `_gai_nat64_second_pass`). The crash site here is `_os_log_preferences_refresh` and `os_log_type_enabled` inside `libsystem_trace.dylib` — the OS logging subsystem, not the DNS resolver. The stale shared-memory pointer for os_log preferences is inherited across `fork()` and dereferenced in the child, causing the fault. ### Ruby -v x86_64 ~ root# /opt/puppetlabs/puppet/bin/ruby -v ruby 4.0.1 (2026-01-13 revision e04267a14b) +PRISM [x86_64-darwin25] arm64 ~ root# /opt/puppetlabs/puppet/bin/ruby -v ruby 4.0.1 (2026-01-13 revision e04267a14b) +PRISM [arm64-darwin25] ### Crash stack (x86_64, Ruby 4.0.1 embedded — same frames observed on 3.x) ``` [BUG] Segmentation fault at 0x0000000101fd0863 ruby 4.0.1 (2025-02-26 revision ???) [x86_64-darwin25] -- C level backtrace information ------------------------------------------- _os_log_preferences_refresh + 0x2f (libsystem_trace.dylib) _os_log_preferences_check_extended (libsystem_trace.dylib) _os_log_type_enabled (libsystem_trace.dylib) ... (DNS resolution internals) Socket.getaddrinfo (ext/socket) ``` Apple's crash reporter (`asi`) confirms: "crashed on child side of fork pre-exec". ### Signal asymmetry between architectures | Architecture | Signal | Reason | |-----------|---------|---------| | x86_64 | SIGSEGV (11) | Ruby's `sigsegv` handler re-delivers the signal; child exits 11 | | ARM64 | SIGABRT (6) | Ruby's `sigabrt` handler calls `abort();` child exits 6 | Both architectures crash identically — the signal number differs only due to Ruby's signal handler behaviour. Monitoring that watches only for `termsig == 11` **will miss all ARM64 crashes** . ### Reproducer ```ruby #!/usr/bin/env ruby # frozen_string_literal: true # # Minimal Ruby-only fork reproducer for macOS 26 segfault. # Only configurable option: TRIALS=<n> # # Run: ruby reproducer.rb # Crash expected within ~10–20 trials on a primed x86_64 system. # ARM64: may crash on trial 1; check for termsig 6 (SIGABRT) not just 11. require 'socket' TRIALS = Integer(ENV.fetch('TRIALS', '50')) HOST = 'api.segment.io' PORT = 443 PRIME_THREADS = 8 SIGSEGV_NUM = 11 SIGABRT_NUM = 6 # Keep parent DNS activity running while children fork to increase race # likelihood — this primes the os_log shared-memory state in libsystem_trace. def start_prime_threads(host, port, thread_count) stop = false threads = Array.new(thread_count) do Thread.new do until stop begin Socket.getaddrinfo(host, port, nil, :STREAM) rescue nil end end end end [threads, proc { stop = true }] end puts '=== Minimal Ruby fork reproducer ===' puts "Ruby #{RUBY_VERSION} (#{RUBY_PLATFORM})" puts "Host=#{HOST} Port=#{PORT} Trials=#{TRIALS}" puts prime_threads, stop_primers = start_prime_threads(HOST, PORT, PRIME_THREADS) sleep 0.2 puts 'Priming active' puts crash_count = 0 begin TRIALS.times do |trial| pid = fork do Socket.getaddrinfo(HOST, PORT, nil, :STREAM) exit 0 rescue exit 0 end _, status = Process.waitpid2(pid) if status.signaled? && [SIGSEGV_NUM, SIGABRT_NUM].include?(status.termsig) crash_count += 1 puts "[Trial #{trial + 1}] CRASH signal=#{status.termsig}" else print '.' end end ensure stop_primers.call prime_threads.each(&:join) end puts puts '=== Summary ===' puts "CRASH: #{crash_count} / #{TRIALS}" exit(crash_count.positive? ? 1 : 0) ``` ### Observed output (x86_64-darwin25) ``` === Minimal Ruby fork reproducer === Ruby 3.4.1 (x86_64-darwin25) Host=api.segment.io Port=443 Trials=50 Priming active ......[Trial 7] CRASH signal=11 ......[Trial 14] CRASH signal=11 ... === Summary === CRASH: 8 / 50 ``` On ARM64, signal=6 (SIGABRT) is reported instead of 11. ### Conditions required 1. Parent process runs continuous `Socket.getaddrinfo` threads before forking (primes `libsystem_trace.dylib` os_log shared-memory) 2. Child calls `Socket.getaddrinfo` — this triggers `os_log_type_enabled` → `_os_log_preferences_refresh` → stale pointer dereference 3. macOS 26 (darwin25) only — not reproducible on macOS 14/15 ---Files-------------------------------- ruby_fork_resolv_getaddrinfo_prime1_x86_64.log (197 KB) ruby_fork_resolv_getaddrinfo_prime1_ARM64.log (202 KB) -- https://bugs.ruby-lang.org/

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[ruby-core:125136] [Ruby Bug#21965] cross compile with out-of-source build is broken
by hsbt (Hiroshi SHIBATA) 30 Mar '26

30 Mar '26

Issue #21965 has been reported by hsbt (Hiroshi SHIBATA). ---------------------------------------- Bug #21965: cross compile with out-of-source build is broken https://bugs.ruby-lang.org/issues/21965 * Author: hsbt (Hiroshi SHIBATA) * Status: Open * Assignee: kddnewton (Kevin Newton) * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN, 4.0: UNKNOWN ---------------------------------------- cross compile with out-of-source build is broken since 14th. I created simple cross-compile workflow with out-of-source build at https://github.com/ruby/ruby/pull/16545 because our CI suite is not covered that case. `ruby_4_0` branch is working fine: https://github.com/ruby/ruby/actions/runs/23571659532/job/68635350261 `master` branch is broken: https://github.com/ruby/ruby/actions/runs/23574018376/job/68642526668 ``` ... making ../src/warning.rbinc making ../src/gc.rbinc ./dump_ast: 1: ELF�@[@��5@8: not found ./dump_ast: 1: %@@@��888,�: not found ./dump_ast: 2: ,�: not found ./dump_ast: 3: ��: not found ... ``` @nobu try to fix that at https://github.com/ruby/ruby/pull/16456 -- https://bugs.ruby-lang.org/

1 1

[ruby-core:124634] [Ruby Feature#21852] New improved allocator function interface
by byroot (Jean Boussier) 27 Mar '26

27 Mar '26

Issue #21852 has been reported by byroot (Jean Boussier). ---------------------------------------- Feature #21852: New improved allocator function interface https://bugs.ruby-lang.org/issues/21852 * Author: byroot (Jean Boussier) * Status: Open ---------------------------------------- When implementing native types with the `TypedData` API, You have to define an allocator function. That function receive the class to allocate and is supposed to return a new instance. ```c /** * This is the type of functions that ruby calls when trying to allocate an * object. It is sometimes necessary to allocate extra memory regions for an * object. When you define a class that uses ::RTypedData, it is typically the * case. On such situations define a function of this type and pass it to * rb_define_alloc_func(). * * @param[in] klass The class that this function is registered. * @return A newly allocated instance of `klass`. */ typedef VALUE (*rb_alloc_func_t)(VALUE klass); ``` ### Current API shortcomings There are a few limitations with the current API. #### Hard to disallow `.allocate` without breaking `#dup` and `#clone`. First, it is frequent for extensions to want to disable `Class#allocate` for their native types via `rb_undef_alloc_func`, as very often allowing uninitialized object would lead to bugs. The problem with `rb_undef_alloc_func` is that the alloc func is also used internally by `dup` and `clone`, so most types that undefine the allocator also prevent object copy without necessarily realizing it. If you want to both disable `Class#allocate` yet still allow copying, you need to entirely implement the `#dup` and `#clone` methods, which is non-trivial and very few types do. One notable exception is `Binding`, which has to implement these two methods: https://github.com/ruby/ruby/blob/bea48adbcacc29cce9536977e15ceba0d65c8a02/… This works for Ruby code, however it doesn't work with C-level `rb_obj_dup(VALUE)`, as used by the Ractor logic to copy objects across ractors. In the case of `Binding` we probably wouldn't allow it anyway, but for other types it may be a problem. #### Can't support objects of variable width When duping or cloning an object of variable width, you need access to the original object to be able to allocate the right slot size. An example of that is `Thread::Backtrace` objects, as evidenced by [Bug #21818]. To support sending exception objects across ractors, we'd need to make `rb_obj_dup()` work for `Thread::Backtrace`, but to correctly duplicate a backtrace, the allocator needs to know the size. ### Proposed new API I'd like to propose a new API for defining allocators: ```ruby typedef VALUE (*rb_copy_alloc_func_t)(VALUE klass, VALUE other); ``` In addition to the class to allocate, the function also receives the instance to copy. When called by `Class#allocate`, the `other` argument is set to `Qundef`. Example usage: ```c static VALUE backtrace_alloc(VALUE klass, VALUE other) { rb_backtrace_t *bt; if (UNDEF_P(other)) { // Regular alloc return TypedData_Make_Struct(klass, rb_backtrace_t, &backtrace_data_type, bt); } else { // Copy rb_backtrace_t *other_bt; TypedData_Get_Struct(other, rb_backtrace_t, &backtrace_data_type, other_bt); VALUE self = backtrace_alloc_capa(other_bt->backtrace_size, &bt); bt->backtrace_size = other_bt->backtrace_size; MEMCPY(bt->backtrace, other_bt->backtrace, rb_backtrace_location_t, other_bt->backtrace_size); return self; } } ``` ### Backward compatibility Older-style allocator can keep being supported as long as we wish. The one backward potential compatibility concern is third party code that calls `rb_alloc_func_t rb_get_alloc_func(VALUE klass);`. As its documentation suggest, there's not much valid use case for it, but regardless we can keep supporting it by returning a "jump function". See `copy_allocator_adapter`: https://github.com/ruby/ruby/pull/15795/changes#diff-884a5a8a369ef1b4c7597e… ### Opportunity for more changes? I was discussing this new interface with @ko1 and it appears that the current allocator interface may also be a limitation for Ractors and Ractor local GC. i.e. it might be useful to let the allocator function know that we're copying from one Ractor to another. But I know to little about Ractor local GC to make a proposition here, so I will let @ko1 make suggestions. ### Implementation I implemented this idea in https://github.com/ruby/ruby/pull/15795, to solve [Bug #21818]. It could remain a purely private API, but I think it would make sense to expose it. -- https://bugs.ruby-lang.org/

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[ruby-core:125144] [Ruby Feature#6012] Proc#source_location also return the column
by Eregon (Benoit Daloze) 27 Mar '26

27 Mar '26

Issue #6012 has been updated by Eregon (Benoit Daloze). Status changed from Closed to Rejected Revert PR: https://github.com/ruby/ruby/pull/16582 I'll mark this issue as rejected to reflect the revert. ---------------------------------------- Feature #6012: Proc#source_location also return the column https://bugs.ruby-lang.org/issues/6012#change-116873 * Author: rogerdpack (Roger Pack) * Status: Rejected * Assignee: nobu (Nobuyoshi Nakada) ---------------------------------------- As originally suggested in http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-core/42418 Suggestion/feature request: have #source_location also return the beginning column where it was defined. ["test.rb", 8, 33] Thanks! -roger- -- https://bugs.ruby-lang.org/

1 0

[ruby-core:117658] [Ruby master Feature#20448] Make coverage event hooking C API public
by ms-tob (Matt S) 27 Mar '26

27 Mar '26

Issue #20448 has been reported by ms-tob (Matt S). ---------------------------------------- Feature #20448: Make coverage event hooking C API public https://bugs.ruby-lang.org/issues/20448 * Author: ms-tob (Matt S) * Status: Open ---------------------------------------- # Abstract Gathering code coverage information is a well-known goal within software engineering. It is most commonly used to assess code coverage during automated testing. A lesser known use-case is coverage-guided fuzz testing, which will be the primary use-case presented in this issue. This issue exists to request that Ruby coverage event hooking be made part of its official, public C API. # Background Ruby currently provides a number of avenues for hooking events *or* gathering coverage information: 1. The [Coverage](https://ruby-doc.org/3.3.0/exts/coverage/Coverage.html) module 2. The [TracePoint](https://ruby-doc.org/3.3.0/TracePoint.html) module 3. The [rb_add_event_hook](https://ruby-doc.org/3.3.0/extension_rdoc.html#label-Hoo… extension function Unfortunately, none of these pieces of functionality solve this issue's specific use-case. The `Coverage` module is not a great fit for real-time coverage analysis with an unknown start and stop point. Coverage-guided fuzz testing requires this. The `TracePoint` module and `rb_add_event_hook` are not able to hook branch and line coverage events. Coverage-guided fuzz testing typically tracks branch events. # Proposal The ultimate goal is to enable Ruby C extensions to process coverage events in real-time. I did some cursory investigation into the Ruby C internals to determine what it would take to achieve this, but I'm by no means an expert, so my list may be incomplete. The good news is that much of this functionality already exists, but it's part of the private, internal-only C API. 1. Make `RUBY_EVENT_COVERAGE_LINE` and `RUBY_EVENT_COVERAGE_BRANCH` public: https://github.com/ruby/ruby/blob/v3_3_0/vm_core.h#L2182-L2184 a. This would be an addition to the current public event types: https://github.com/ruby/ruby/blob/v3_3_0/include/ruby/internal/event.h#L32-… 2. Allow initializing global coverage state so that coverage tracking can be fully enabled a. Currently, if `Coverage.setup` or `Coverage.start` is not called, then coverage events cannot be hooked. I do not fully understand why this is, but I believe it has something to do with `rb_get_coverages` and `rb_set_coverages`. If calls to `rb_get_coverages` return `NULL` (https://github.com/ruby/ruby/blob/v3_3_0/iseq.c#L641-L647, https://github.com/ruby/ruby/blob/v3_3_0/iseq.c#L864-L868) then coverage hooking will not be enabled. I believe the `Coverage` module initializes that state via a `rb_set_coverages` call here: https://github.com/ruby/ruby/blob/v3_3_0/ext/coverage/coverage.c#L112-L120. b. So, to achieve this goal, a C extension would need to be able to call `rb_set_coverages` or somehow initialize the global coverage state. I've actually been able to achieve this functionality by calling undocumented features and defining `RUBY_EVENT_COVERAGE_BRANCH`: ```c #include <ruby.h> #include <ruby/debug.h> #define RUBY_EVENT_COVERAGE_BRANCH 0x020000 // ... rb_event_flag_t events = RUBY_EVENT_COVERAGE_BRANCH; rb_event_hook_flag_t flags = ( RUBY_EVENT_HOOK_FLAG_SAFE | RUBY_EVENT_HOOK_FLAG_RAW_ARG ); rb_add_event_hook2( (rb_event_hook_func_t) event_hook_branch, events, counter_hash, flags ); ``` If I call `Coverage.setup(branches: true)`, and add this event hook, then branch hooking works as expected. `rb_add_event_hook2` will still respect the `RUBY_EVENT_COVERAGE_BRANCH` value if its passed. But it would be better if I could rely on official functionality rather than undocumented features. The above two points would be requirements for this functionality, but there's an additional nice-to-have: 3. Extend the public `tracearg` functionality to include additional coverage information a. Currently, `tracearg` offers information like `rb_tracearg_lineno` and `rb_tracearg_path`. It would be helpful if it also provided additional coverage information like `coverage.c`'s column information and a unique identifier for each branch. Currently, I can only use `(path, lineno)` as a unique identifier for a branch because that's what's offered by the public API, but more information like column number would be helpful for uniquely identify branches. Since there can be multiple `if` statements on a single line, this can provide ambiguous identification for a branch event. # Use cases This use-case was born out of a new coverage-guided Ruby fuzzer: https://github.com/trailofbits/ruzzy. You can read more about its implementation details here: https://blog.trailofbits.com/2024/03/29/introducing-ruzzy-a-coverage-guided…. You can also find the Ruby C extension code behind its implementation here: https://github.com/trailofbits/ruzzy/blob/v0.7.0/ext/cruzzy/cruzzy.c#L220-L…. So, the primary use-case here is enabling real-time, coverage-guided fuzz testing of Ruby code. However, as mentioned in the abstract, gathering code coverage information is useful in many domains. For example, it could enable new workflows in standard unit/integration test coverage. It could also enable gathering coverage information in real-time as an application is running. I see this as the most generalized form of gathering code coverage information, and something like the `Coverage` module as a specialized implementation. Another example, https://bugs.ruby-lang.org/issues/20282 may be solved by this more generalized solution. We are tracking this request downstream here: https://github.com/trailofbits/ruzzy/issues/9 # Discussion Fuzz testing is another tool in a testers toolbelt. It is an increasingly common way to improve software's robustness. Go has it built in to the standard library, Python has Atheris, Java has Jazzer, JavaScript has Jazzer.js, etc. OSS-Fuzz has helped identify and fix over 10,000 vulnerabilities and 36,000 bugs [using fuzzing](https://google.github.io/oss-fuzz/#trophies). Ruby deserves a good fuzzer, and improving coverage gathering would help achieve that goal. The `Coverage` module, `TracePoint` module, and `rb_add_event_hook` function seem like they could fulfill this goal. However, after deeper investigation, none of them fit the exact requirements for this use-case. # See also - https://bugs.ruby-lang.org/issues/20282 - https://github.com/google/atheris - https://security.googleblog.com/2020/12/how-atheris-python-fuzzer-works.html - https://github.com/CodeIntelligenceTesting/jazzer/ - https://www.code-intelligence.com/blog/java-fuzzing-with-jazzer - https://go.dev/doc/security/fuzz/ -- https://bugs.ruby-lang.org/

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