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

[ruby-core:116028] [Ruby master Feature#20152] mkmf / extconf: Add a proper way to not compile the extension
by byroot (Jean Boussier) 06 Feb '26

06 Feb '26

Issue #20152 has been reported by byroot (Jean Boussier). ---------------------------------------- Feature #20152: mkmf / extconf: Add a proper way to not compile the extension https://bugs.ruby-lang.org/issues/20152 * Author: byroot (Jean Boussier) * Status: Open * Priority: Normal ---------------------------------------- ### Context There are various gems that ship with a native extension as a way to speedup part of the gem, but also ship with a pure Ruby version of these methods as a fallback. So they only want to compile the extension if the platform supports it, and if not, just fallback to the slightly slower Ruby version. Right now users rely on one of two hacks to do this. Either they create an empty Makefile, but then still depend on `make` being available, or publish platform specific packages without any extension in them. Examples: - [`bootsnap` skip compilation if not on MRI or TruffleRuby](https://github.com/Shopify/bootsnap/blob/070151f1305f23102365d… - [`erb` has an extension for MRI but then need to publish a `java` version of the gem that doesn't actually contain Java code, just to skip compilation on JRuby](https://github.com/ruby/erb/issues/52) - [`hiredis-client` skips the compilation for Windows and non-MRI rubies](https://github.com/redis-rb/redis-client/blob/1ab081c1d0e47df5d55e0… ### Feature It would be very useful to have some proper first class API to skip compiling the extension. Something like: ```ruby require "mkmf" if RUBY_ENGINE != "ruby" || RUBY_PLATFORM.match?(/mswin/) skip_compilation else # ... end ``` cc @k0kubun @headius -- https://bugs.ruby-lang.org/

10 21

[ruby-core:124359] [Ruby Misc#21804] Getting setup-ruby Earlier
by koic (Koichi ITO) 03 Feb '26

03 Feb '26

Issue #21804 has been reported by koic (Koichi ITO). ---------------------------------------- Misc #21804: Getting setup-ruby Earlier https://bugs.ruby-lang.org/issues/21804 * Author: koic (Koichi ITO) * Status: Open ---------------------------------------- ruby/setup-ruby is commonly used for development in OSS projects and real-world Rails applications. https://github.com/ruby/setup-ruby This is not specific to Ruby 4.0.0. There is often a delay between a Ruby release and the availability of the corresponding version in setup-ruby. setup-ruby is maintained by the ruby organization and may take a few days to become available after a Ruby release. In contrast, ruby-build is maintained by the rbenv organization and tends to become available shortly after a Ruby release. This makes it easier to start using new Ruby versions immediately. If setup-ruby maintained by the ruby organization were released shortly after a Ruby release, users could start using new Ruby versions sooner. It is difficult to determine whether this issue should be registered on bugs.ruby-lang.org. Since setup-ruby is maintained by the ruby organization, this issue is being opened to raise awareness of the situation. If this is not appropriate, please feel free to close it. Thank you for your continued maintenance and for releasing Ruby. -- https://bugs.ruby-lang.org/

9 17

[ruby-core:123681] [Ruby Bug#21669] Thoroughly implement void value expression check
by mame (Yusuke Endoh) 03 Feb '26

03 Feb '26

Issue #21669 has been reported by mame (Yusuke Endoh). ---------------------------------------- Bug #21669: Thoroughly implement void value expression check https://bugs.ruby-lang.org/issues/21669 * Author: mame (Yusuke Endoh) * Status: Open * Assignee: prism * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- A void-value-expression check is a syntax check that raises a `SyntaxError` if an expression that cannot grammatically return a value (a "void value expression," such as a `return` expression) appears in a context where a value is expected (e.g., the right-hand side of an assignment, the argument of a method call, etc.). A typical example rejected by this check is `x = return`. However, it has become clear that this check is incomplete. This ticket summarizes the results of a discussion with @matz at the hackathon before RubyWorld Conference today. ## 1\. Expressions containing branches @matz said that an expression containing branches should be considered a void value expression only if it can be grammatically determined that all possible branches do not return a value. Based on this, both parse.y and prism currently reject the following code with a "void value expression" `SyntaxError`, but it should be accepted: ```ruby x = begin raise return rescue "OK" else return end # Expected: Code parses and executes successfully. # Actual: Rejected with "unexpected void value expression" SyntaxError. ``` Reason: The `rescue` clause can return a value ("OK"), so the entire `begin` expression is not void. Conversely, the following code is currently accepted by both parse.y and prism, but it should be rejected: ```ruby x = begin foo rescue return else return end # Expected: Rejected with SyntaxError. # Actual: Code parses and executes. ``` Reason: This expression always does `return`, so it is void whether `foo` raises an exception or not. Furthermore, `case` expressions must also be rejected similarly when all branches are void: ```ruby x = case when 1; return when 2; return else return end # Expected: Rejected with SyntaxError. # Actual: Code parses and executes. ``` Note that `if` expressions appear to be implemented correctly as intended: ```ruby x = if rand < 0.5 return else return end # Expected: Rejected with SyntaxError. # Actual: Rejected. (OK!) ``` ## 2\. Statement lists containing a void value expression @matz also said that if a statements node contains a void value expression, the entire statement list should be treated as a void value expression, even if the void expression is not the last one. Therefore, the following code is currently accepted but should be rejected: ```ruby x = begin return "NG" end # Expected: Rejected with SyntaxError. # Actual: Code parses and executes. ``` The same applies to branches within other expressions: ```ruby x = if rand < 0.5 return "NG" else return end # Expected: Rejected with SyntaxError. # Actual: Code parses and executes. ``` Note that if a return statement is inside a branch, that statement cannot be considered a void value expression, so the entire expression also cannot be a void value expression. ```ruby x = begin return if true "NG" end # Expected: Code parses and executes. # Actual: Code parses and executes as expected. (OK!) ``` --- This is considered a bug, but if it causes practical compatibility issues, it may be necessary to plan a migration path or revisit the specifications. (Both prism and parse.y need to be fixed, but I'll assign it to the prism team for now.) -- https://bugs.ruby-lang.org/

6 15

[ruby-core:123920] [Ruby Bug#21715] Miscompilation on x86-64-v2 due to undefined behavior in search_nonascii in string.c
by mjacob (Manuel Jacob) 25 Jan '26

25 Jan '26

Issue #21715 has been reported by mjacob (Manuel Jacob). ---------------------------------------- Bug #21715: Miscompilation on x86-64-v2 due to undefined behavior in search_nonascii in string.c https://bugs.ruby-lang.org/issues/21715 * Author: mjacob (Manuel Jacob) * Status: Open * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- Building the following Dockerfile fails on a x86-64 machine in the last step (running `make` command): ``` FROM opensuse/leap:16.0 RUN zypper --non-interactive install wget make gcc RUN wget 'https://cache.ruby-lang.org/pub/ruby/3.4/ruby-3.4.7.tar.gz' RUN tar xaf ruby-3.4.7.tar.gz WORKDIR ruby-3.4.7/build RUN ../configure RUN make ``` The failing command (during `make`) is: `./miniruby -I../lib -I. -I.ext/common ../tool/mkconfig.rb -arch=x86_64-linux -version=3.4.7 -install_name=ruby -so_name=ruby -unicode_version=15.0.0 -unicode_emoji_version=15.0 > rbconfig.tmp` Excerpt from the crash report: ``` ../tool/mkconfig.rb: [BUG] Segmentation fault at 0x0000000000000000 ruby 3.4.7 (2025-10-08 revision 7a5688e2a2) +PRISM [x86_64-linux] -- Control frame information ----------------------------------------------- c:0001 p:0000 s:0003 E:000ec0 DUMMY [FINISH] -- Threading information --------------------------------------------------- Total ractor count: 1 Ruby thread count for this ractor: 1 -- Machine register context ------------------------------------------------ RIP: 0x0000556c2da74760 RBP: 0x0000000000000027 RSP: 0x00007ffd24a195f0 RAX: 0x0000000000000028 RBX: 0x0000556c64acc420 RCX: 0x0000000000000000 RDX: 0x0000000000000000 RDI: 0x0000000000000014 RSI: 0x00007f49f7d6c123 R8: 0x46ea57707c6b1df2 R9: 0x00007f49f7d6c123 R10: 0x2afb945fcb545f01 R11: 0x0000556c2dc3fe50 R12: 0x00007f49f7d6c263 R13: 0x00007f49f7d6c11b R14: 0x0000556c64bdaa48 R15: 0x00007f49f7d6c25c EFL: 0x0000000000010256 -- C level backtrace information ------------------------------------------- /ruby-3.4.7/build/miniruby(rb_print_backtrace+0x5) [0x556c2db2c1b6] ../vm_dump.c:823 /ruby-3.4.7/build/miniruby(rb_vm_bugreport) ../vm_dump.c:1155 /ruby-3.4.7/build/miniruby(rb_bug_for_fatal_signal+0xf7) [0x556c2d8cdc47] ../error.c:1130 /ruby-3.4.7/build/miniruby(sigsegv+0x42) [0x556c2da58482] ../signal.c:934 /lib64/libc.so.6(__restore_rt+0x0) [0x7f49f7eb2090] /ruby-3.4.7/build/miniruby(search_nonascii+0xcb) [0x556c2da74760] ../string.c:729 /ruby-3.4.7/build/miniruby(coderange_scan) ../string.c:767 /ruby-3.4.7/build/miniruby(rbimpl_fl_unset_raw_raw+0x0) [0x556c2da76874] ../string.c:895 /ruby-3.4.7/build/miniruby(RB_FL_UNSET_RAW) ../include/ruby/internal/fl_type.h:669 /ruby-3.4.7/build/miniruby(RB_ENC_CODERANGE_SET) ../include/ruby/internal/encoding/coderange.h:131 /ruby-3.4.7/build/miniruby(enc_coderange_scan) ../string.c:911 /ruby-3.4.7/build/miniruby(rb_enc_str_coderange) ../string.c:910 /ruby-3.4.7/build/miniruby(is_ascii_string+0x8) [0x556c2da7697e] ../internal/string.h:151 /ruby-3.4.7/build/miniruby(str_do_hash) ../string.c:393 /ruby-3.4.7/build/miniruby(register_fstring) ../string.c:554 /ruby-3.4.7/build/miniruby(rb_enc_literal_str+0x87) [0x556c2da94bb7] ../string.c:12546 /ruby-3.4.7/build/miniruby(parse_static_literal_string+0x38) [0x556c2d875991] ../prism_compile.c:312 /ruby-3.4.7/build/miniruby(pm_compile_node) ../prism_compile.c:10321 /ruby-3.4.7/build/miniruby(pm_compile_node+0x2e65) [0x556c2d875aa5] ../prism_compile.c:10309 /ruby-3.4.7/build/miniruby(pm_compile_conditional+0x18c) [0x556c2d88cfcc] ../prism_compile.c:1053 /ruby-3.4.7/build/miniruby(pm_compile_node+0x42e1) [0x556c2d876f21] ../prism_compile.c:9355 /ruby-3.4.7/build/miniruby(pm_setup_args_core+0xe4) [0x556c2d884304] ../prism_compile.c:1792 /ruby-3.4.7/build/miniruby(pm_setup_args+0x98) [0x556c2d884e98] ../prism_compile.c:1979 /ruby-3.4.7/build/miniruby(pm_compile_call+0x307) [0x556c2d885cf7] ../prism_compile.c:3673 /ruby-3.4.7/build/miniruby(pm_compile_call_node+0x2c6) [0x556c2d872326] ../prism_compile.c:7403 /ruby-3.4.7/build/miniruby(pm_compile_node+0x39dc) [0x556c2d87661c] ../prism_compile.c:8775 /ruby-3.4.7/build/miniruby(pm_compile_node+0x2e65) [0x556c2d875aa5] ../prism_compile.c:10309 /ruby-3.4.7/build/miniruby(pm_compile_conditional+0x18c) [0x556c2d88cfcc] ../prism_compile.c:1053-march=x86-64-v2 /ruby-3.4.7/build/miniruby(pm_compile_node+0x42e1) [0x556c2d876f21] ../prism_compile.c:9355 /ruby-3.4.7/build/miniruby(pm_compile_node+0x2e3a) [0x556c2d875a7a] ../prism_compile.c:10307 /ruby-3.4.7/build/miniruby(pm_compile_scope_node+0x104a) [0x556c2d88f5da] ../prism_compile.c:6991 /ruby-3.4.7/build/miniruby(pm_compile_node+0x35c9) [0x556c2d876209] ../prism_compile.c:10180 /ruby-3.4.7/build/miniruby(APPEND_LIST+0x0) [0x556c2d891e60] ../prism_compile.c:10481 /ruby-3.4.7/build/miniruby(pm_iseq_compile_node) ../prism_compile.c:10485 /ruby-3.4.7/build/miniruby(pm_iseq_new_with_opt_try+0x10) [0x556c2d94c790] ../iseq.c:1042 /ruby-3.4.7/build/miniruby(rb_protect+0xd6) [0x556c2d8db9c6] ../eval.c:1054 /ruby-3.4.7/build/miniruby(pm_iseq_new_with_opt+0x177) [0x556c2d9525c7] ../iseq.c:1095 /ruby-3.4.7/build/miniruby(pm_iseq_new_main+0x85) [0x556c2d952895] ../iseq.c:943 /ruby-3.4.7/build/miniruby(process_options+0x12fd) [0x556c2da519cd] ../ruby.c:2616 /ruby-3.4.7/build/miniruby(ruby_process_options+0x157) [0x556c2da52657] ../ruby.c:3174 /ruby-3.4.7/build/miniruby(ruby_options+0x97) [0x556c2d8da977] ../eval.c:117 /ruby-3.4.7/build/miniruby(rb_main+0x19) [0x556c2d7eb578] ../prism/prism.c:21769 /ruby-3.4.7/build/miniruby(main) ../main.c:68 /lib64/libc.so.6(__libc_start_call_main+0x82) [0x7f49f7e9b340] /lib64/libc.so.6(__libc_start_main+0x8b) [0x7f49f7e9b409] /ruby-3.4.7/build/miniruby(_start+0x25) [0x556c2d7eb5c5] ../main.c:69 ``` The failing instruction at 0x556c2da74760 is: `movdqa xmm0, XMMWORD PTR [rsi+rcx*1]`. At this place, register `rsi` contains 0x7f49f7d6c123, which is the value 0x7f49f7d6c11b of parameter `p` of the function `search_nonascii` + 8, and register `rcx` contains 0. So, the whole instruction means “[move aligned packed integer values](https://www.felixcloutier.com/x86/movdqa:vmovdqa32:vmovdqa64) from memory at 0x7f49f7d6c123 to register `xmm0`”. The segmentation fault happened because the address is expected to be aligned on a 16-byte boundary, but it is not. The instruction is part of a loop at https://github.com/ruby/ruby/blob/v3_4_7/string.c#L728 that gets auto-vectorized by GCC. On x86-64, * `UNALIGNED_WORD_ACCESS` is `1` * `p` doesn’t get aligned to anything because of `#if !UNALIGNED_WORD_ACCESS` in line 700 * `aligned_ptr(value)` is expanded to `(uintptr_t *)(value)` according to line 723 * `p` is therefore casted to type `uintptr_t *` in line 725 * `uintptr_t` is typedefed to `unsigned long int`, which has alignment of 8 bytes In result, a pointer `p` to potentially unaligned memory is casted to a pointer to a type with alignment of 8 bytes. That is undefined behavior according to C99 6.3.2.3p7: “A pointer to an object or incomplete type may be converted to a pointer to a different object or incomplete type. If the resulting pointer is not correctly aligned for the pointed-to type, the behavior is undefined.”. Compilers can utilize this rule to make the assumption that the pointed-to memory has alignment of 8 bytes. In this case, the GCC loop auto-vectorizer adds code to align the assumedly 8 bytes aligned address to 16 bytes alignment. A subsequent instruction assuming 16 bytes alignment can therefore fail. I could reproduce this crash only on openSUSE Leap 16.0, but not openSUSE Leap 15.6, openSUSE Tumbleweed or Arch Linux, because only the former configured GCC to default to emitting code requiring x86-64-v2. When passing `-march=x86-64-v2` in CFLAGS, the crash happens on all these distributions. -- https://bugs.ruby-lang.org/

6 9

[ruby-core:124366] [Ruby Bug#21807] ArgumentError is reported when forwarding arguments to method with intermediate optional arguments
by taichi730 (Taichi Ishitani) 25 Jan '26

25 Jan '26

Issue #21807 has been reported by taichi730 (Taichi Ishitani). ---------------------------------------- Bug #21807: ArgumentError is reported when forwarding arguments to method with intermediate optional arguments https://bugs.ruby-lang.org/issues/21807 * Author: taichi730 (Taichi Ishitani) * Status: Open * ruby -v: 3.4.8 * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN, 4.0: UNKNOWN ---------------------------------------- In Ruby 3.4.x, @ArgumentError@ is reported when forwarding arguments to a method with intermediate optional arguments. How to reproduce: Execute sample below. ``` ruby class Foo def foo(a = nil, b) p a, b end end class Bar def initialize @foo = Foo.new end def bar(...) @foo.foo(...) @foo.foo(...) end end class Baz def initialize @bar = Bar.new end def baz(_a, ...) @bar.bar(...) end end puts RUBY_VERSION baz = Baz.new baz.baz(0, 1) ``` output: <pre> $ RBENV_VERSION=3.4.8 ruby test.rb 3.4.8 nil 1 test.rb:2:in 'foo': wrong number of arguments (given 0, expected 1..2) (ArgumentError) from test.rb:14:in 'Bar#bar' from test.rb:24:in 'Baz#baz' </pre> <pre> $ RBENV_VERSION=3.4.1 ruby test.rb 3.4.1 nil 1 test.rb:2:in 'foo': wrong number of arguments (given 0, expected 1..2) (ArgumentError) from test.rb:14:in 'Bar#bar' from test.rb:24:in 'Baz#baz' </pre> For other Ruby verions (e.g. 4.0.0, 3.3.0), no error is reported. <pre> $ RBENV_VERSION=4.0.0 ruby test.rb 4.0.0 nil 1 nil 1 </pre> <pre> $ RBENV_VERSION=3.3.0 ruby test.rb 3.3.0 nil 1 nil 1 </pre> -- https://bugs.ruby-lang.org/

3 3

[ruby-core:121993] [Ruby Bug#21326] Instruction generation differences between parse.y and prism for `def a(x, ...); b(...); end`
by zenspider (Ryan Davis) 25 Jan '26

25 Jan '26

Issue #21326 has been reported by zenspider (Ryan Davis). ---------------------------------------- Bug #21326: Instruction generation differences between parse.y and prism for `def a(x, ...); b(...); end` https://bugs.ruby-lang.org/issues/21326 * Author: zenspider (Ryan Davis) * Status: Open * ruby -v: ruby 3.5.0dev * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- Diff instructions using: ```sh DUMP="puts RubyVM::InstructionSequence.compile(ARGV.first).disasm.gsub(/^\d+ /, '')" RUBY="def a(x, ...); b(...); end" env -u RUBYOPT \ diff -U99 \ <(./build/ruby -v --parser=parse.y -e "$DUMP" "$RUBY" 2>/dev/null) \ <(./build/ruby -v --parser=prism -e "$DUMP" "$RUBY" 2>/dev/null) ``` shows: ```diff --- /dev/fd/63 2025-05-10 14:46:37 +++ /dev/fd/62 2025-05-10 14:46:37 @@ -1,17 +1,18 @@ -ruby 3.5.0dev (2025-05-10T17:32:21Z master 98667f82d2) +GC [arm64-darwin24] +ruby 3.5.0dev (2025-05-10T17:32:21Z master 98667f82d2) +PRISM +GC [arm64-darwin24] == disasm: #<ISeq:<compiled>@<compiled>:1 (1,0)-(1,26)> definemethod :a, a ( 1)[Li] putobject :a leave == disasm: #<ISeq:a@<compiled>:1 (1,0)-(1,26)> local table (size: 5, argc: 1 [opts: 0, rest: 1, post: 0, block: 3, kw: -1@-1, kwrest: 2]) [ 5] x@0<Arg> [ 4] "*"@1<AnonRest>[ 3] "**"@2<AnonKwrest>[ 2] "&"@3<Block>[ 1] "..."@4 putself ( 1)[LiCa] getlocal_WC_0 "*"@1 -splatarray false +splatarray true getlocal_WC_0 "**"@2 getblockparamproxy "&"@3, 0 splatkw -send <calldata!mid:b, argc:2, ARGS_SPLAT|ARGS_BLOCKARG|FCALL|KW_SPLAT>, nil +splatkw +send <calldata!mid:b, argc:2, ARGS_SPLAT|ARGS_SPLAT_MUT|ARGS_BLOCKARG|FCALL|KW_SPLAT>, nil leave [Re] ``` PR here: https://github.com/ruby/ruby/pull/13299 goes back to at least 3.4. -- https://bugs.ruby-lang.org/

3 2

[ruby-core:116935] [Ruby master Bug#18743] Enumerator#next / peek re-use each others stacktraces
by nagachika (Tomoyuki Chikanaga) 22 Jan '26

22 Jan '26

Issue #18743 has been updated by nagachika (Tomoyuki Chikanaga). Backport changed from 3.0: REQUIRED, 3.1: REQUIRED, 3.2: REQUIRED to 3.0: REQUIRED, 3.1: REQUIRED, 3.2: DONE ruby_3_2 5e4606423da96c2e26b00981c22bddfce0d970bf merged revision(s) f15123c34ce80f3928612befe2a9aaf4c9d27fda. ---------------------------------------- Bug #18743: Enumerator#next / peek re-use each others stacktraces https://bugs.ruby-lang.org/issues/18743#change-106970 * Author: sos4nt (Stefan Schüßler) * Status: Closed * Assignee: ko1 (Koichi Sasada) * Backport: 3.0: REQUIRED, 3.1: REQUIRED, 3.2: DONE ---------------------------------------- I encountered an odd behavior. If I rescue the `StopIteration` exception from `peek` and call `next` afterwards: (or vice-versa) ```ruby # enum.rb # 1 # 2 enum = [].each # 3 enum.peek rescue nil # 4 enum.next # 5 ``` it will show the stacktrace from the rescued `peek` call: ``` $ ruby enum.rb enum.rb:4:in `peek': iteration reached an end (StopIteration) from enum.rb:4:in `<main>' ``` Whereas the error should refer to `next` on line number 5. The same happens when calling `peek` after `next` or when having muliple `peek` / `next` calls: ```ruby # enum.rb # 1 # 2 enum = [].each # 3 enum.peek rescue nil # 4 enum.next rescue nil # 5 enum.peek rescue nil # 6 puts "line #{__LINE__}" # 7 enum.next # 8 ``` The stacktrace from the first (rescued) `peek` or `next` call will be shown which doesn't reflect the actual error location: ``` $ ruby enum.rb line 7 enum.rb:4:in `peek': iteration reached an end (StopIteration) from enum.rb:4:in `<main>' ``` This is very confusing when debugging code. ---Files-------------------------------- 01-Recreate-stacktrace-enumerator.patch (1.29 KB) -- https://bugs.ruby-lang.org/

2 1

[ruby-core:123414] [Ruby Bug#21629] Ruby-3.4.7 fails to build using clang / llvm
by debo (David Bohman) 22 Jan '26

22 Jan '26

Issue #21629 has been reported by debo (David Bohman). ---------------------------------------- Bug #21629: Ruby-3.4.7 fails to build using clang / llvm https://bugs.ruby-lang.org/issues/21629 * Author: debo (David Bohman) * Status: Open * ruby -v: ruby 3.4.6 (2025-09-16 revision dbd83256b1) +PRISM [x86_64-darwin16] * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- Here is the error I encountered. This is using clang version 21.1.3 as the compiler toolchain on Darwin. ``` DYLD_LIBRARY_PATH=.:../../.. ASAN_OPTIONS=detect_leaks=0 "clang -I../../../.ext/include/x86_64-darwin16 -I../../../../ruby-3.4.7/include -I../../../../ruby-3.4.7/ext/-test-/public_header_warnings -I/usr/local/include -D_XOPEN_SOURCE -D_DARWIN_C_SOURCE -D_DARWIN_UNLIMITED_SELECT -D_REENTRANT -fstack-protector-strong -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 -fdeclspec -O3 -fno-fast-math -ggdb3 -Wall -Wextra -Wextra-tokens -Wdeprecated-declarations -Wdivision-by-zero -Wdiv-by-zero -Wimplicit-function-declaration -Wimplicit-int -Wpointer-arith -Wshorten-64-to-32 -Wwrite-strings -Wold-style-definition -Wmissing-noreturn -Wno-cast-function-type -Wno-constant-logical-operand -Wno-long-long -Wno-missing-field-initializers -Wno-overlength-strings -Wno-parentheses-equality -Wno-self-assign -Wno-tautological-compare -Wno-unused-parameter -Wno-unused-value -Wunused-variable -Wmisleading-indentation -Wundef -fno-common -pipe -D_TEST_OK -Werror -c conftest.c" In file included from conftest.c:1: In file included from ../../../../ruby-3.4.7/include/ruby.h:38: In file included from ../../../../ruby-3.4.7/include/ruby/ruby.h:28: In file included from ../../../../ruby-3.4.7/include/ruby/internal/arithmetic.h:24: In file included from ../../../../ruby-3.4.7/include/ruby/internal/arithmetic/char.h:29: ../../../../ruby-3.4.7/include/ruby/internal/core/rstring.h:398:24: error: default initialization of an object of type 'struct RString' with const member leaves the object uninitialized [-Werror,-Wdefault-const-init-field-unsafe] 398 | struct RString retval; | ^ ../../../../ruby-3.4.7/include/ruby/internal/core/rbasic.h:86:17: note: member 'klass' declared 'const' here 86 | const VALUE klass; | ^ 1 error generated. checked program was: /* begin */ 1: #include "ruby.h" 2: 3: int main(int argc, char **argv) 4: { 5: return !!argv[argc]; 6: } /* end */ ``` The configuration is the following: ``` CC=clang CXX=clang++ CPPFLAGS=-I/usr/local/include LDFLAGS=-L/usr/local/lib ../ruby-3.4.7/configure --enable-shared --with-rdoc=ri,html ``` -- https://bugs.ruby-lang.org/

5 18

[ruby-core:123923] [Ruby Bug#21716] YJIT panic: "all PendingBranchRefs should be unique" in net/http response reading (infinite unwind loop)
by angelim＠angelim.com.br (Alexandre Angelim) 22 Jan '26

22 Jan '26

Issue #21716 has been reported by angelim(a)angelim.com.br (Alexandre Angelim). ---------------------------------------- Bug #21716: YJIT panic: "all PendingBranchRefs should be unique" in net/http response reading (infinite unwind loop) https://bugs.ruby-lang.org/issues/21716 * Author: angelim(a)angelim.com.br (Alexandre Angelim) * Status: Open * ruby -v: ruby 3.4.7 * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- We encountered a YJIT panic in production that caused the process to enter an infinite logging loop for several hours. The panic occurs within `yjit/src/core.rs` when handling branch references. The trigger appears to be in `net/http`, specifically when reading a response body (possibly involving chunked encoding or zlib) inside a Datadog trace transport flush. Key Observations: The Panic: YJIT fails with all PendingBranchRefs should be unique when ready to construct a Block. The Loop: After the panic, the process fails to exit and instead logs `rust_begin_unwind` and `try_fold` iterator errors repeatedly, filling logs for hours. System Configuration Ruby Version: ruby 3.4.7 (2025-10-08 revision 7a5688e2a2) +YJIT +PRISM [aarch64-linux] Environment: Linux aarch64 (AWS Graviton/ARM) Reproduction Context While we cannot provide a standalone reproduction script yet, the crash happens intermittently during a Net::HTTP request initiated by datadog-ruby (v2.17.0) to flush traces to a Unix socket, which is wrapped by sentry-ruby (v5.26.0). Ruby Location: `/gems/net-http-0.6.0/lib/net/http/response.rb:604` Rust Location: `./yjit/src/core.rs:2403:27` Backtrace & Logs ``` ruby: YJIT has panicked. More info to follow... thread '<unnamed>' panicked at 'all PendingBranchRefs should be unique when ready to construct a Block', ./yjit/src/core.rs:2403:27 stack backtrace: 0: rust_begin_unwind at /rustc/.../library/std/src/panicking.rs:578:5 ... 28: yjit::core::branch_stub_hit at /workspace/ruby-3.4.7/yjit/src/core.rs:3492:9 /gems/net-http-0.6.0/lib/net/http/response.rb:604: [BUG] YJIT: panicked at 'all PendingBranchRefs should be unique when ready to construct a Block', ./yjit/src/core.rs:2403:27 -- Control frame information ----------------------------------------------- c:0047 p:0049 s:0248 e:000247 BLOCK /gems/net-http-0.6.0/lib/net/http/response.rb:604 c:0046 p:0098 s:0243 e:000242 METHOD /gems/net-http-0.6.0/lib/net/http/response.rb:588 c:0045 p:0004 s:0235 e:000234 METHOD /gems/net-http-0.6.0/lib/net/http/response.rb:593 ... c:0039 p:0033 s:0196 e:000195 BLOCK /gems/sentry-ruby-5.26.0/lib/sentry/net/http.rb:44 ... c:0033 p:0023 s:0158 e:000157 METHOD /gems/datadog-2.17.0/lib/datadog/core/transport/http/adapters/unix_socket.rb:43 c:0032 p:0066 s:0152 e:000151 METHOD /gems/datadog-2.17.0/lib/datadog/core/transport/http/adapters/net.rb:77 ``` The stack suggests the crash happens during `branch_stub_hit` resolution. The presence of sentry-ruby and datadog suggests complex interaction with Net::HTTP patching. The infinite loop of logs following the crash looks like this (repeated): ``` /usr/lib/libruby.so.3.4(try_fold<alloc::vec::into_iter::IntoIter<alloc::rc::Rc<yjit::core::PendingBranch> ... `` This suggests the panic handler itself is tripping over the corrupted `PendingBranch` state. We encountered a YJIT panic in production that caused the process to enter an infinite logging loop for several hours. The panic occurs within `yjit/src/core.rs` when handling branch references. The trigger appears to be in `net/http`, specifically when reading a response body (possibly involving chunked encoding or zlib) inside a Datadog trace transport flush. -- https://bugs.ruby-lang.org/

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[ruby-core:124408] [Ruby Bug#21816] iseq code_location miss calculated indent
by zzak (zzak _) 16 Jan '26

16 Jan '26

Issue #21816 has been reported by zzak (zzak _). ---------------------------------------- Bug #21816: iseq code_location miss calculated indent https://bugs.ruby-lang.org/issues/21816 * Author: zzak (zzak _) * Status: Open * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN, 4.0: UNKNOWN ---------------------------------------- TBH, I'm not really sure if that title matches the problem here, but I can produce this issue with the following test: ```ruby # bug.rb # note the indentation of the callable callable = -> { puts "Hello, World!" } iseq = RubyVM::InstructionSequence.of(callable) pp iseq.to_a pp iseq.to_a[4] pp iseq.to_a[4][:code_location][1] ``` Ruby 4.0.0: ``` $ ruby -v bug.rb ruby 4.0.0 (2025-12-25 revision 553f1675f3) +PRISM [x86_64-linux] ["YARVInstructionSequence/SimpleDataFormat", 4, 0, 1, {arg_size: 0, local_size: 0, stack_max: 2, node_id: 7, code_location: [1, 15, 1, 40], node_ids: [4, 5, 4, 7], parser: :prism}, "block in <main>", "bug.rb", "/tmp/tmp.Fbq5WA0GnO/bug.rb", 1, :block, [], {}, [], [1, :RUBY_EVENT_LINE, :RUBY_EVENT_B_CALL, [:putself], [:putchilledstring, "Hello, World!"], [:opt_send_without_block, {mid: :puts, flag: 20, orig_argc: 1}], :RUBY_EVENT_B_RETURN, [:leave]]] {arg_size: 0, local_size: 0, stack_max: 2, node_id: 7, code_location: [1, 15, 1, 40], node_ids: [4, 5, 4, 7], parser: :prism} 15 ``` Ruby 4.1.0: ``` $ ruby -v bug.rb ruby 4.1.0dev (2025-12-30T18:02:00Z master 9d37155cfc) +PRISM [x86_64-linux] ["YARVInstructionSequence/SimpleDataFormat", 4, 1, 1, {arg_size: 0, local_size: 0, stack_max: 2, node_id: 7, code_location: [1, 13, 1, 40], node_ids: [4, 5, 4, 7], parser: :prism}, "block in <main>", "bug.rb", "/tmp/tmp.Fbq5WA0GnO/bug.rb", 1, :block, [], {}, [], [1, :RUBY_EVENT_LINE, :RUBY_EVENT_B_CALL, [:putself], [:putchilledstring, "Hello, World!"], [:opt_send_without_block, {mid: :puts, flag: 20, orig_argc: 1}], :RUBY_EVENT_B_RETURN, [:leave]]] {arg_size: 0, local_size: 0, stack_max: 2, node_id: 7, code_location: [1, 13, 1, 40], node_ids: [4, 5, 4, 7], parser: :prism} 13 ``` For context: This second value being 13 instead of 15 is causing Rails tests to fail: https://buildkite.com/rails/rails-nightly/builds/3447#019b710f-e78a-405f-82… We want: ``` { @object.num } ``` But we get: ``` -> { @object.num } ``` I am pretty sure using the same version of `prism`: ``` /tmp/tmp.Fbq5WA0GnO => rbenv shell 4.1.0 /tmp/tmp.Fbq5WA0GnO => gem list | grep prism prism (1.7.0) /tmp/tmp.Fbq5WA0GnO => rbenv shell 4.0.0 /tmp/tmp.Fbq5WA0GnO => gem list | grep prism prism (1.7.0) ``` We use this data to get the original source string of a block we use to decorate the `assert_difference` assertion: https://github.com/rails/rails/blob/3d31d593e6cf0f82fa9bd0338b635af2f30d627… https://api.rubyonrails.org/classes/ActiveSupport/Testing/Assertions.html#m… -- https://bugs.ruby-lang.org/

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