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

[ruby-core:122798] [Ruby Bug#21516] Segfault in String#succ! on 32-bit i686
by leahneukirchen (Leah Neukirchen) 26 Nov '25

26 Nov '25

Issue #21516 has been reported by leahneukirchen (Leah Neukirchen). ---------------------------------------- Bug #21516: Segfault in String#succ! on 32-bit i686 https://bugs.ruby-lang.org/issues/21516 * Author: leahneukirchen (Leah Neukirchen) * Status: Open * ruby -v: 3.4.5 * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- I noticed segfaults in the test suite of Ruby 3.4.5, related to String#succ! A very easy reproducer is: ./miniruby -e 'puts "ZZZZ999".succ!' $ ./miniruby -e 'puts "ZZZZ999".succ!' -e:1: [BUG] Segmentation fault at 0x9e968041 ruby 3.4.5 (2025-07-16 revision 20cda200d3) +PRISM [x86_64-linux-x32] -- Control frame information ----------------------------------------------- c:0003 p:---- s:0011 e:000010 CFUNC :succ! c:0002 p:0005 s:0007 e:000005 EVAL -e:1 [FINISH] c:0001 p:0000 s:0003 E:0017b8 DUMMY [FINISH] -- Ruby level backtrace information ---------------------------------------- -e:1:in '<main>' -e:1:in 'succ!' -- Threading information --------------------------------------------------- Total ractor count: 1 Ruby thread count for this ractor: 1 -- Machine register context ------------------------------------------------ GS: 0x00000063 FS: 0x00000000 ES: 0x0000002b DS: 0x0000002b EDI: 0x9e968049 ESI: 0x9e968041 EBP: 0x5896c1a0 ESP: 0xff97d638 EBX: 0x9e968046 EDX: 0x9e968049 ECX: 0x5896c1a0 EAX: 0x9e968041 TRA: 0x0000000e ERR: 0x00000004 EIP: 0x5681ea07 CS: 0x00000023 EFL: 0x00010293 UES: 0xff97d638 SS: 0x0000002b -- C level backtrace information ------------------------------------------- /builddir/ruby/ruby/miniruby(rb_print_backtrace+0x14) [0x568ae631] /builddir/ruby/ruby/vm_dump.c:823 /builddir/ruby/ruby/miniruby(rb_vm_bugreport) /builddir/ruby/ruby/vm_dump.c:1155 /builddir/ruby/ruby/miniruby(rb_bug_for_fatal_signal+0x86) [0x566e4ee6] /builddir/ruby/ruby/error.c:1130 /builddir/ruby/ruby/miniruby(sigsegv+0x4f) [0x5680e98f] /builddir/ruby/ruby/signal.c:934 linux-gate.so.1(__kernel_rt_sigreturn+0x0) [0xf7f475a0] /builddir/ruby/ruby/miniruby(search_nonascii+0x17) [0x5681ea07] /builddir/ruby/ruby/string.c:728 /builddir/ruby/ruby/miniruby(coderange_scan+0x59) [0x56821d09] /builddir/ruby/ruby/string.c:767 /builddir/ruby/ruby/miniruby(rbimpl_fl_unset_raw_raw+0x0) [0x56824715] /builddir/ruby/ruby/string.c:895 /builddir/ruby/ruby/miniruby(RB_FL_UNSET_RAW) ./include/ruby/internal/fl_type.h:669 /builddir/ruby/ruby/miniruby(RB_ENC_CODERANGE_SET) ./include/ruby/internal/encoding/coderange.h:131 /builddir/ruby/ruby/miniruby(rb_enc_str_coderange) /builddir/ruby/ruby/string.c:911 /builddir/ruby/ruby/miniruby(str_succ+0x69c) [0x5682545c] /builddir/ruby/ruby/string.c:5364 /builddir/ruby/ruby/miniruby(rb_str_succ_bang+0x15) [0x56829f85] /builddir/ruby/ruby/string.c:5380 /builddir/ruby/ruby/miniruby(vm_call_cfunc_with_frame_+0x106) [0x568860e6] /builddir/ruby/ruby/vm_insnhelper.c:3794 /builddir/ruby/ruby/miniruby(vm_call_method_each_type+0x76) [0x56894636] /builddir/ruby/ruby/vm_insnhelper.c:4772 /builddir/ruby/ruby/miniruby(vm_sendish+0xa2) [0x5689fecb] /builddir/ruby/ruby/vm_insnhelper.c:5961 /builddir/ruby/ruby/miniruby(vm_exec_core) /builddir/ruby/ruby/insns.def:898 /builddir/ruby/ruby/miniruby(vm_exec_loop+0x38) [0x56893d68] /builddir/ruby/ruby/vm.c:2622 /builddir/ruby/ruby/miniruby(rb_vm_exec) /builddir/ruby/ruby/vm.c:2598 /builddir/ruby/ruby/miniruby(rb_ec_exec_node+0x7f) [0x566eb0ef] /builddir/ruby/ruby/eval.c:281 /builddir/ruby/ruby/miniruby(ruby_run_node+0x58) [0x566ee558] /builddir/ruby/ruby/eval.c:319 /builddir/ruby/ruby/miniruby(main+0x70) [0x56648460] ./main.c:43 -- Other runtime information ----------------------------------------------- * Loaded script: -e * Loaded features: 0 enumerator.so 1 thread.rb 2 fiber.so 3 rational.so 4 complex.so 5 ruby2_keywords.rb * Process memory map: 56622000-56642000 r--p 00000000 fe:02 9210459 /builddir/ruby/ruby/miniruby 56642000-56941000 r-xp 00020000 fe:02 9210459 /builddir/ruby/ruby/miniruby 56941000-56b4c000 r--p 0031f000 fe:02 9210459 /builddir/ruby/ruby/miniruby 56b4c000-56b54000 r--p 0052a000 fe:02 9210459 /builddir/ruby/ruby/miniruby 56b54000-56b55000 rw-p 00532000 fe:02 9210459 /builddir/ruby/ruby/miniruby 56b55000-56b5e000 rw-p 00000000 00:00 0 58967000-58abb000 rw-p 00000000 00:00 0 [heap] f43b8000-f5a48000 r--s 00000000 fe:02 9210459 /builddir/ruby/ruby/miniruby f5a48000-f5a4b000 r--p 00000000 fe:02 11307369 /usr/lib/libgcc_s.so.1 f5a4b000-f5a79000 r-xp 00003000 fe:02 11307369 /usr/lib/libgcc_s.so.1 f5a79000-f5a7e000 r--p 00031000 fe:02 11307369 /usr/lib/libgcc_s.so.1 f5a7e000-f5a7f000 r--p 00035000 fe:02 11307369 /usr/lib/libgcc_s.so.1 f5a7f000-f5a80000 rw-p 00036000 fe:02 11307369 /usr/lib/libgcc_s.so.1 f5a80000-f5ab0000 rw-p 00000000 00:00 0 [anon:Ruby:GC:default:heap_page_body_allocate] f5abf000-f5ac0000 ---p 00000000 00:00 0 [anon:Ruby:fiber_pool_allocate_memory] f5ac0000-f5b11000 rw-p 00000000 00:00 0 [anon:Ruby:fiber_pool_allocate_memory] f5b11000-f5b12000 ---p 00000000 00:00 0 [anon:Ruby:fiber_pool_allocate_memory] f5b12000-f5b63000 rw-p 00000000 00:00 0 [anon:Ruby:fiber_pool_allocate_memory] f5b63000-f5b64000 ---p 00000000 00:00 0 [anon:Ruby:fiber_pool_allocate_memory] f5b64000-f5bb5000 rw-p 00000000 00:00 0 [anon:Ruby:fiber_pool_allocate_memory] f5bb5000-f5bb6000 ---p 00000000 00:00 0 [anon:Ruby:fiber_pool_allocate_memory] f5bb6000-f5c07000 rw-p 00000000 00:00 0 [anon:Ruby:fiber_pool_allocate_memory] f5c07000-f5c08000 ---p 00000000 00:00 0 [anon:Ruby:fiber_pool_allocate_memory] f5c08000-f5c59000 rw-p 00000000 00:00 0 [anon:Ruby:fiber_pool_allocate_memory] f5c59000-f5c5a000 ---p 00000000 00:00 0 [anon:Ruby:fiber_pool_allocate_memory] f5c5a000-f5cab000 rw-p 00000000 00:00 0 [anon:Ruby:fiber_pool_allocate_memory] f5cab000-f5cac000 ---p 00000000 00:00 0 [anon:Ruby:fiber_pool_allocate_memory] f5cac000-f5cfd000 rw-p 00000000 00:00 0 [anon:Ruby:fiber_pool_allocate_memory] f5cfd000-f5cfe000 ---p 00000000 00:00 0 [anon:Ruby:fiber_pool_allocate_memory] f5cfe000-f5d4f000 rw-p 00000000 00:00 0 [anon:Ruby:fiber_pool_allocate_memory] f5d4f000-f5d50000 ---p 00000000 00:00 0 f5d50000-f6550000 rw-p 00000000 00:00 0 f6550000-f6590000 rw-p 00000000 00:00 0 [anon:Ruby:GC:default:heap_page_body_allocate] f659f000-f759f000 rw-p 00000000 00:00 0 [anon:Ruby:Init_default_shapes:shape_cache] f759f000-f765f000 rw-p 00000000 00:00 0 [anon:Ruby:Init_default_shapes:shape_list] f765f000-f7690000 rw-p 00000000 00:00 0 f7690000-f76a0000 rw-p 00000000 00:00 0 [anon:Ruby:GC:default:heap_page_body_allocate] f76a9000-f772a000 rw-p 00000000 00:00 0 f772a000-f79a4000 r--p 00074000 fe:02 11307480 /usr/lib/locale/locale-archive f79a4000-f7ba4000 r--p 00000000 fe:02 11307480 /usr/lib/locale/locale-archive f7ba4000-f7ba6000 rw-p 00000000 00:00 0 f7ba6000-f7bc9000 r--p 00000000 fe:02 11307064 /usr/lib/libc.so.6 f7bc9000-f7d69000 r-xp 00023000 fe:02 11307064 /usr/lib/libc.so.6 f7d69000-f7dc5000 r--p 001c3000 fe:02 11307064 /usr/lib/libc.so.6 f7dc5000-f7dc7000 r--p 0021f000 fe:02 11307064 /usr/lib/libc.so.6 f7dc7000-f7dc8000 rw-p 00221000 fe:02 11307064 /usr/lib/libc.so.6 f7dc8000-f7dd2000 rw-p 00000000 00:00 0 f7dd2000-f7de0000 r--p 00000000 fe:02 11307059 /usr/lib/libm.so.6 f7de0000-f7ead000 r-xp 0000e000 fe:02 11307059 /usr/lib/libm.so.6 f7ead000-f7edf000 r--p 000db000 fe:02 11307059 /usr/lib/libm.so.6 f7edf000-f7ee0000 r--p 0010c000 fe:02 11307059 /usr/lib/libm.so.6 f7ee0000-f7ee1000 rw-p 0010d000 fe:02 11307059 /usr/lib/libm.so.6 f7ee1000-f7ee2000 r--p 00000000 fe:02 11307767 /usr/lib/libcrypt.so.2.0.0 f7ee2000-f7efe000 r-xp 00001000 fe:02 11307767 /usr/lib/libcrypt.so.2.0.0 f7efe000-f7f18000 r--p 0001d000 fe:02 11307767 /usr/lib/libcrypt.so.2.0.0 f7f18000-f7f19000 r--p 00036000 fe:02 11307767 /usr/lib/libcrypt.so.2.0.0 f7f19000-f7f1a000 rw-p 00037000 fe:02 11307767 /usr/lib/libcrypt.so.2.0.0 f7f1a000-f7f22000 rw-p 00000000 00:00 0 f7f22000-f7f24000 r--p 00000000 fe:02 11307365 /usr/lib/libz.so.1.3.1 f7f24000-f7f34000 r-xp 00002000 fe:02 11307365 /usr/lib/libz.so.1.3.1 f7f34000-f7f3a000 r--p 00012000 fe:02 11307365 /usr/lib/libz.so.1.3.1 f7f3a000-f7f3b000 r--p 00017000 fe:02 11307365 /usr/lib/libz.so.1.3.1 f7f3b000-f7f3c000 rw-p 00018000 fe:02 11307365 /usr/lib/libz.so.1.3.1 f7f41000-f7f43000 rw-p 00000000 00:00 0 f7f43000-f7f45000 r--p 00000000 00:00 0 [vvar] f7f45000-f7f47000 r--p 00000000 00:00 0 [vvar_vclock] f7f47000-f7f49000 r-xp 00000000 00:00 0 [vdso] f7f49000-f7f4a000 r--p 00000000 fe:02 11307070 /usr/lib/ld-linux.so.2 f7f4a000-f7f72000 r-xp 00001000 fe:02 11307070 /usr/lib/ld-linux.so.2 f7f72000-f7f7d000 r--p 00029000 fe:02 11307070 /usr/lib/ld-linux.so.2 f7f7d000-f7f7f000 r--p 00034000 fe:02 11307070 /usr/lib/ld-linux.so.2 f7f7f000-f7f80000 rw-p 00036000 fe:02 11307070 /usr/lib/ld-linux.so.2 ff95d000-ff97e000 rw-p 00000000 00:00 0 [stack] Segmentation fault Backtrace in gdb: Thread 1 "miniruby" received signal SIGSEGV, Segmentation fault. search_nonascii (p=<optimized out>, e=0xb3b91049 <error: Cannot access memory at address 0xb3b91049>) at string.c:729 729 if (*s & NONASCII_MASK) { (gdb) bt #0 search_nonascii (p=<optimized out>, e=0xb3b91049 <error: Cannot access memory at address 0xb3b91049>) at string.c:729 #1 0x56754d09 in coderange_scan (p=0xb3b91041 <error: Cannot access memory at address 0xb3b91041>, len=8, enc=0x56a961a0) at string.c:767 #2 0x56757715 in enc_coderange_scan (str=4122077840, enc=<optimized out>) at ./include/ruby/internal/core/rstring.h:430 #3 rb_enc_str_coderange (str=4122077840) at string.c:910 #4 0x5675845c in str_succ (str=str@entry=4122077840) at string.c:5364 #5 0x5675cf85 in rb_str_succ_bang (str=4122077840) at string.c:5380 #6 0x567b90e6 in vm_call_cfunc_with_frame_ (ec=0x56a9598c, reg_cfp=0xf77a6fd8, calling=<optimized out>, argc=0, argv=0xf7727030, stack_bottom=0xf772702c) at /builddir/ruby/ruby/vm_insnhelper.c:3794 #7 0x567c7636 in vm_call_method_each_type (ec=0x56a9598c, cfp=0xf77a6fd8, calling=0xffffd9e8) at /builddir/ruby/ruby/vm_insnhelper.c:4772 #8 0x567d2ecb in vm_sendish (ec=<optimized out>, reg_cfp=<optimized out>, cd=<optimized out>, block_handler=<optimized out>, method_explorer=<optimized out>) at /builddir/ruby/ruby/vm_callinfo.h:415 #9 vm_exec_core (ec=0xb3b91041, ec@entry=0x56a9598c) at /builddir/ruby/ruby/insns.def:898 #10 0x567c6d68 in vm_exec_loop (ec=<optimized out>, state=<optimized out>, tag=<optimized out>, result=10) at vm.c:2622 #11 rb_vm_exec (ec=0x56a9598c) at vm.c:2598 #12 0x5661e0ef in rb_ec_exec_node (ec=ec@entry=0x56a9598c, n=n@entry=0xf5b1eaf4) at eval.c:281 #13 0x56621558 in ruby_run_node (n=0xf5b1eaf4) at eval.c:319 #14 0x5657b460 in rb_main (argc=5, argv=0xffffdc34) at ./main.c:43 #15 main (argc=<optimized out>, argv=<optimized out>) at ./main.c:68 I can trigger this with "./configure CFLAGS="-O2 -g" The -O2 is important. With -flto=auto it goes away, with -O0 or -O3 too. I use gcc (GCC) 14.2.1 20250405 on Void Linux with glibc 2.41. On 64-bit x86_64 it works fine with same versions. I have bisected the issue to https://github.com/ruby/ruby/commit/14d154076876 but I don't see how this can introduce the bug. I assume it's some undefined behavior that is potentially triggered. (However reverting that patch works...) I think the behavior is related to the embedded string being expanded into a proper string, but my internal-fu isn't good enough. I hope this helps to debug the issue. -- https://bugs.ruby-lang.org/

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[ruby-core:123889] [Ruby Bug#21707] Destructuring assignment of SimpleDelegator wrapped array bug with YJIT
by tompng (tomoya ishida) 26 Nov '25

26 Nov '25

Issue #21707 has been reported by tompng (tomoya ishida). ---------------------------------------- Bug #21707: Destructuring assignment of SimpleDelegator wrapped array bug with YJIT https://bugs.ruby-lang.org/issues/21707 * Author: tompng (tomoya ishida) * Status: Open * ruby -v: ruby 4.0.0dev (2025-11-08T15:08:09Z master 75d25a42e6) +PRISM [x86_64-linux] * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- Destructuring assignment does not work after a few iterations if YJIT is enabled. Happens in ruby 3.4.1 and 4.0.0dev. ~~~ root@05305c0005f4:/# ruby -v ruby 4.0.0dev (2025-11-23T19:10:29Z master 8d73a18187) +PRISM [x86_64-linux] root@05305c0005f4:/# ruby --enable-yjit -rdelegate -e "p 40.times.map { x, = SimpleDelegator.new([1,2,3]); x }" [1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, [1, 2, 3], [1, 2, 3], [1, 2, 3], [1, 2, 3], [1, 2, 3], [1, 2, 3], [1, 2, 3], [1, 2, 3], [1, 2, 3], [1, 2, 3], [1, 2, 3]] ~~~ Works perfectly if yjit is disabled or zjit is enabled. ~~~ root@05305c0005f4:/# ruby --disable-yjit -rdelegate -e "p 40.times.map { x, = SimpleDelegator.new([1,2,3]); x }" [1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1] root@05305c0005f4:/# ruby --enable-zjit -rdelegate -e "p 40.times.map { x, = SimpleDelegator.new([1,2,3]); x }" [1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1] ~~~ Found in a code like this: ~~~ruby code = '1;' * 100 lex_result = Prism.lex_compat(code) # Prism::LexCompat::Token is a subclass of SimpleDelegator lex_result.value.map do |(pos, kind, text, state)| p pos end ~~~ -- https://bugs.ruby-lang.org/

2 3

[ruby-core:123863] [Ruby Misc#21699] Updating CAPI docs
by stevo (Steve Savio) 25 Nov '25

25 Nov '25

Issue #21699 has been reported by stevo (Steve Savio). ---------------------------------------- Misc #21699: Updating CAPI docs https://bugs.ruby-lang.org/issues/21699 * Author: stevo (Steve Savio) * Status: Open ---------------------------------------- Hello. How often are the CAPI docs hosted at https://docs.ruby-lang.org/capi/en/master/ refreshed? It looks like it's been more than 2 weeks since they were last refreshed. Last revision 4a3d8346a6d0e068508631541f6bc43e8b154ea1 is from 2025-11-03. The Ruby version still reads as 3.5.0dev instead of a Ruby 4 one. -- https://bugs.ruby-lang.org/

2 1

[ruby-core:122643] [Ruby Bug#21498] Windows - Ruby Overrides C Library APIs thus breaking them
by cfis (Charlie Savage) 24 Nov '25

24 Nov '25

Issue #21498 has been reported by cfis (Charlie Savage). ---------------------------------------- Bug #21498: Windows - Ruby Overrides C Library APIs thus breaking them https://bugs.ruby-lang.org/issues/21498 * Author: cfis (Charlie Savage) * Status: Open * ruby -v: *all* on windows (testing with ruby 3.4.3 (2025-04-14 revision d0b7e5b6a0) +PRISM [x64-mswin64_140]) * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- I am trying to wrap a simple C++ library, https://github.com/baderouaich/BitmapPlusPlus, as a Ruby extension. However when I use the extension to write a bitmap to disk the bitmap is corrupted. This is because the library uses std::ofstream which eventually uses the C API fclose to write the final bytes to the bitmap file and then closes it. The problem is that Ruby overrides `fclose` and replaces it with `rb_w32_fclose`. It then *exports* its custom version from from x64-vcruntime140-ruby340.dll. And the exported version is broken (at least from the standpoint of the C standard library). Note this has been a long standing issue. The first report I see is from 2013: https://bugs.ruby-lang.org/issues/8569 More recently in 2020 (which explains the issue very well): https://github.com/NREL/OpenStudio/issues/3942#issuecomment-610673401 I understand that Ruby is trying to provide a platform independent API. But the problem is this solution breaks any third party libraries that rely on these C APIs (which of course are very common). And there is no good workaround (see https://github.com/NREL/OpenStudio/issues/3942#issuecomment-611072774) So would it be possible for Ruby to stop exporting custom versions of basic C APIs? The code that does it is here: https://github.com/ruby/ruby/blob/master/win32/mkexports.rb#L41 Ruby of course could still use its custom versions of fclose, read, write etc within ruby.exe and x64-vcruntime140-ruby340.dll. But they should not be exported from x64-vcruntime140-ruby340.dll and thus be off limits to extensions. If a case comes up where an extension really needs access to rb_w32_fclose instead of fclose then an extension developer can use an `#ifdef _WIN32` to do so and work across platforms. That at least puts the developer in control versus now where I don't see any way I can to wrap the bitmap library for usage in Ruby. From my experience the biggest problem is the replacing of fclose with rb_w32_fclose. But I propose removing all such mappings, which include: FD_CLR=rb_w32_fdclr FD_ISSET=rb_w32_fdisset Sleep=rb_w32_Sleep accept=rb_w32_accept access=rb_w32_uaccess bind=rb_w32_bind close=rb_w32_close connect=rb_w32_connect dup2=rb_w32_dup2 fclose=rb_w32_fclose fstat=rb_w32_fstati128 get_osfhandle=rb_w32_get_osfhandle getcwd=rb_w32_ugetcwd getenv=rb_w32_ugetenv gethostbyaddr=rb_w32_gethostbyaddr gethostbyname=rb_w32_gethostbyname gethostname=rb_w32_gethostname getpeername=rb_w32_getpeername getpid=rb_w32_getpid getppid=rb_w32_getppid getprotobyname=rb_w32_getprotobyname getprotobynumber=rb_w32_getprotobynumber getservbyname=rb_w32_getservbyname getservbyport=rb_w32_getservbyport getsockname=rb_w32_getsockname getsockopt=rb_w32_getsockopt inet_ntop=rb_w32_inet_ntop inet_pton=rb_w32_inet_pton ioctlsocket=rb_w32_ioctlsocket isatty=rb_w32_isatty listen=rb_w32_listen lseek=rb_w32_lseek lstat=rb_w32_ulstati128 mkdir=rb_w32_umkdir mmap=rb_w32_mmap mprotect=rb_w32_mprotect munmap=rb_w32_munmap pipe=rb_w32_pipe pread=rb_w32_pread pwrite=rb_w32_pwrite read=rb_w32_read recv=rb_w32_recv recvfrom=rb_w32_recvfrom rename=rb_w32_urename rmdir=rb_w32_urmdir select=rb_w32_select send=rb_w32_send sendmsg sendto=rb_w32_sendto setsockopt=rb_w32_setsockopt shutdown=rb_w32_shutdown socket=rb_w32_socket stati128=rb_w32_ustati128 strcasecmp=msvcrt.stricmp strerror=rb_w32_strerror strncasecmp=msvcrt.strnicmp times=rb_w32_times unlink=rb_w32_uunlink utime=rb_w32_uutime utimensat=rb_w32_uutimensat utimes=rb_w32_uutimes write=rb_w32_write -- https://bugs.ruby-lang.org/

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[ruby-core:123890] [Ruby Bug#21708] Ruby 3.4 Forwardable: setter delegations trigger SyntaxError from forwardable/impl.rb
by jfi (James Inman) 24 Nov '25

24 Nov '25

Issue #21708 has been reported by jfi (James Inman). ---------------------------------------- Bug #21708: Ruby 3.4 Forwardable: setter delegations trigger SyntaxError from forwardable/impl.rb https://bugs.ruby-lang.org/issues/21708 * Author: jfi (James Inman) * Status: Open * ruby -v: 3.4.7 * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- - `forwardable`: 1.3.3 (bundled stdlib) - OS: Ubuntu 24.04 (also reproducible on macOS) - RUBYOPT / $DEBUG: default (but with $DEBUG=true or RUBYOPT=-d the errors are emitted) # Reproduction Script (minimal) ``` require "forwardable" class Host attr_accessor :scheme end class Delegator extend Forwardable def initialize @host = Host.new end def_delegator :@host, :scheme=, :scheme= def_delegator :@host, :scheme, :scheme end $DEBUG = true # force forwardable to log the SyntaxError d = Delegator.new d.scheme = "https" puts d.scheme ``` Output running with `ruby -d`: ``` Exception 'SyntaxError' at .../forwardable/impl.rb:6 - syntax errors found > 6 | BEGIN{throw tag}; ().scheme= | ^ expected an expression after `=` ``` Despite the `SyntaxError`, the program continues, but stderr is flooded whenever a setter is delegated. Similar errors appear for any delegated setter (`host=`, `port=`, etc.), causing noise in test runs and CI logs. # Expected behavior Delegating setter methods should not raise or log `SyntaxError`; `forwardable` should generate the delegator quietly, as in Ruby 3.3 and earlier. # Other reports - ruby/forwardable issue #35 shows the same SyntaxError output pattern on Ruby 3.4: https://github.com/ruby/forwardable/issues/35 -- https://bugs.ruby-lang.org/

2 1

[ruby-core:123888] [Ruby Feature#21706] Add SIMD optimizations for string comparison operations
by sebyx07 (Sebastian Buza) 23 Nov '25

23 Nov '25

Issue #21706 has been reported by sebyx07 (Sebastian Buza). ---------------------------------------- Feature #21706: Add SIMD optimizations for string comparison operations https://bugs.ruby-lang.org/issues/21706 * Author: sebyx07 (Sebastian Buza) * Status: Open ---------------------------------------- # Feature: SIMD-accelerated String Comparison (SSE2/NEON) **PR:** https://github.com/ruby/ruby/pull/15307 ## Summary SIMD optimizations for string comparison using SSE2 (x86_64) and NEON (ARM64). **17.2% average speedup** for strings e16 bytes, zero API changes, automatic fallback. - Backward compatible, all tests pass - Cross-platform (SSE2/NEON/memcmp fallback) - 1 new file (~400 lines), 2 files modified (5 lines total) ## Benchmark Results **Platform:** AMD EPYC 7282 16-Core, 47GB RAM, Ubuntu 24.04.3 LTS **Method:** Side-by-side master vs SIMD (5M iterations, default build) | Size | Operation | Master | SIMD | � | |------|-----------|--------|------|---| | 16B | `String#==` | 14.2M/s | 17.5M/s | **+23.3%** | | 16B | `String#eql?` | 11.1M/s | 14.8M/s | **+33.1%** | | 16B | `String#<=>` | 10.8M/s | 13.4M/s | **+23.8%** | | 64B | `String#==` | 14.0M/s | 16.4M/s | **+17.8%** | | 64B | `String#<=>` | 11.2M/s | 13.3M/s | **+18.5%** | | 256B | `String#==` | 14.0M/s | 15.2M/s | **+8.7%** | | 1KB | `String#==` | 12.5M/s | 14.9M/s | **+19.3%** | | 4KB | `String#==` | 9.0M/s | 10.4M/s | **+15.4%** | **Average:** +17.2% (range: +8.7% to +33.1%) ## Implementation ### Files Changed **`internal/string_simd.h`** (new, ~400 lines) - `rb_str_simd_memcmp(ptr1, ptr2, len)` - returns -1/0/+1 - `rb_str_simd_memeq(ptr1, ptr2, len)` - returns 0/1 - SSE2: `_mm_loadu_si128`, `_mm_cmpeq_epi8`, `_mm_movemask_epi8` - NEON: `vld1q_u8`, `vceqq_u8`, `vminvq_u8` - Threshold: 16-256 bytes (SIMD active), else memcmp - CPU detection: `__builtin_cpu_supports("sse2")` / ARM macros **`internal/string.h`** (2 lines) ```c #include "internal/string_simd.h" // rb_str_eql_internal: memcmp() � rb_str_simd_memeq() ``` **`string.c`** (3 lines) ```c #include "internal/string_simd.h" // rb_str_cmp: memcmp() � rb_str_simd_memcmp() // fstring_concurrent_set_cmp: memcmp() � rb_str_simd_memeq() ``` ### Optimized Functions (5 total) 1. `rb_str_cmp()` - `String#<=>`, sort 2. `rb_str_eql_internal()` - `String#==`, `#eql?` 3. `fstring_concurrent_set_cmp()` - frozen string dedup 4. `deleted_prefix_length()` - `String#start_with?`, `#delete_prefix` 5. `deleted_suffix_length()` - `String#end_with?`, `#delete_suffix` ### Technical Details **SSE2 (x86_64):** Processes 16 bytes/iteration, unrolled to 32 bytes in equality checks. Uses `__builtin_ctz()` for first-difference detection, `__restrict__` pointers, `LIKELY`/`UNLIKELY` branch hints. **NEON (ARM64):** 16 bytes/iteration using `uint8x16_t` vectors, horizontal min for difference detection. **Thresholds:** - `< 16 bytes` � standard memcmp (setup overhead) - `16-256 bytes` � SIMD - `> 256 bytes` � memcmp (cache effects dominate) **Type safety:** All pointers cast to `unsigned char*` (prevents signed comparison UB). ## Platform Support | Platform | Implementation | Fallback | |----------|----------------|----------| | x86_64 | SSE2 (universal since 2003) | memcmp | | ARM64 | NEON | memcmp | | Others | - | memcmp | Runtime detection, no special build flags required. ## Testing ```bash # Functional (all existing tests pass) make test-all # Performance ./ruby benchmark/string_comparison_simple.rb # Verify SSE2 instructions objdump -d ruby | grep -A5 "rb_str_cmp" | grep -E "movdqu|pcmpeqb|pmovmskb" ``` ## Design Rationale 1. **Pattern follows `ext/json/simd/simd.h`** - familiar to contributors 2. **Conservative start** - SSE2/NEON (universal), AVX2 is trivial add later 3. **unsigned char*** - matches memcmp semantics, prevents UB 4. **Inline + hot attributes** - compiler optimization hints 5. **Zero breaking changes** - drop-in memcmp replacement ## Future Extensions **Phase 2 (easy):** - AVX2: 32 bytes/iter (~50 LOC, `__builtin_cpu_supports("avx2")`) - `String#index`/`#rindex`: SIMD substring search - `String#casecmp`: case-insensitive SIMD **Phase 3 (advanced):** - UTF-8 validation, `upcase`/`downcase` transforms - SSE4.2 `pcmpistri` for substring search - POPCNT for `Integer#bit_count` ## Impact String comparison is in every Ruby program (hash lookups, routing, JSON, ORMs). This proves SIMD integration works and establishes pattern for future optimizations. **Real-world:** Rails apps, JSON APIs see 10-25% string operation speedup. **Prior art:** V8, Go, Rust, glibc, musl all use SIMD for string ops. --- **Developed with:** Claude Code (AI-assisted, ~3 hours) -- https://bugs.ruby-lang.org/

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[ruby-core:122296] [Ruby Bug#21374] FrozenError message is inconsistent when a singleton method is defined on a frozen object
by andrykonchin (Andrew Konchin) 23 Nov '25

23 Nov '25

Issue #21374 has been reported by andrykonchin (Andrew Konchin). ---------------------------------------- Bug #21374: FrozenError message is inconsistent when a singleton method is defined on a frozen object https://bugs.ruby-lang.org/issues/21374 * Author: andrykonchin (Andrew Konchin) * Status: Open * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- I would expect a message to contain an object class (e.g. `can't modify frozen <class>: <object#inspect>`) when an ordinary frozen object (non a module or class) is being modified. It works this way in the following example: ```ruby object = []; object.freeze; object.instance_variable_set(:@a, 42) # (irb):5:in `instance_variable_set': can't modify frozen Array: [] (FrozenError) ``` But it doesn't in the following example: ```ruby object = []; object.freeze; def object.x; end # (irb):4:in `<main>': can't modify frozen object: [] (FrozenError) ``` -- https://bugs.ruby-lang.org/

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[ruby-core:123737] [Ruby Feature#21675] Advent of Pattern Matching
by baweaver (Brandon Weaver) 19 Nov '25

19 Nov '25

Issue #21675 has been reported by baweaver (Brandon Weaver). ---------------------------------------- Feature #21675: Advent of Pattern Matching https://bugs.ruby-lang.org/issues/21675 * Author: baweaver (Brandon Weaver) * Status: Open ---------------------------------------- Ruby pattern matching is a very useful feature, but many of the core classes to not leverage it currently. Given this I would like to directly invest in opening PRs to add this functionality and see how many cases we can reasonably add as we approach Ruby 4.0. I have already started here: * `Gem::Version` - https://github.com/ruby/ruby/pull/15109 * `Net::HTTPResponse` - https://github.com/ruby/ruby/pull/15110 * `Net::HTTPGenericRequest` - https://github.com/ruby/ruby/pull/15111 But what I am currently considering looking at first are: * `Pathname` - Path manipulation is ubiquitous. Pattern matching on path components (dirname, basename, extname) would simplify file handling logic. * `URI::Generic` - URL routing and parsing would benefit from matching on scheme, host, port, and path components. * `IPAddr` - Network programming would benefit from matching on IP address components and families for filtering and routing logic. * `File::Stat` - File metadata inspection is common. Matching on size, mode, timestamps, and file type predicates would simplify permission and type checks. * `Process::Status` - Process exit status checking is verbose. Matching on exitstatus, signals, and success state would clarify intent. * `Addrinfo` - Socket programming would benefit from matching on address family, socket type, and IP address/port for connection handling. * `OpenSSL::X509::Certificate` - Certificate validation logic could be cleaner with matching on subject, issuer, and validity dates. * `OpenSSL::X509::Name` - Distinguished name parsing for certificate handling would benefit from component extraction. * `Gem::Requirement` - Complements Gem::Version for dependency management patterns. * `Gem::Specification` - Gem metadata inspection in tooling could benefit from structured matching. If this is of interest I will start looking for more areas as well. My goal is to make this a feature that is well supported throughout common libraries in Ruby. We can use this issue as a potential staging ground for discussion of what else might make sense. -- https://bugs.ruby-lang.org/

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[ruby-core:119239] [Ruby master Feature#20750] Expose ruby_thread_has_gvl_p in ruby/thread.h
by kbrock (Keenan Brock) 19 Nov '25

19 Nov '25

Issue #20750 has been reported by kbrock (Keenan Brock). ---------------------------------------- Feature #20750: Expose ruby_thread_has_gvl_p in ruby/thread.h https://bugs.ruby-lang.org/issues/20750 * Author: kbrock (Keenan Brock) * Status: Open ---------------------------------------- Hello All, I'm hoping we can make `ruby_thread_has_gvl_p` a public method and no longer experimental. I saw the following code in a gem that was not compiling with ruby 3.3: ``` c // int ruby_thread_has_gvl_p(void); // <== line of concern if (ruby_thread_has_gvl_p()) { method_call(&context); } else { rb_thread_call_with_gvl(method_call, &context); } ``` 400 unique projects on github added the line listed above to fix compilation. [1] Some of the projects detected the method first in `extconf.rb`, but a majority just referenced it. `ffi` used to have the detection code but dropped it since the method was in all supported ruby versions. It feels like this method is now part of the undocumented public interface. My suggestion is to add the method to the real public interface in `ruby/thread.h`. PR with possible solution: https://github.com/ruby/ruby/pull/11619 Also included a patch if that is easier Thank you for your consideration, Keenan Timeline: - Dec 30 2008 - `rb_thread_call_with_gvl` introduced via 9c04a06 [2] - Jan 12 2009 - `ruby_thread_has_gvl_p` introduced via 6f09fc2 [4] - Jul 18 2012 - `rb_thread_call_with_gvl` made public via e9a91d2 [3] Current references to code: `rb_thread_call_with_gvl` [5] `ruby_thread_has_gvl_p` [6]: [1]: https://github.com/search?q=ruby_thread_has_gvl_p+language%3AC++NOT+is%3Afo… [2]: https://github.com/ruby/ruby/commit/9c04a0647fb99f7554cb2e04385ddbb970631e02 [3]: https://github.com/ruby/ruby/commit/e9a91d2c95dfe22ad0487952f7a1053ef9a5fd16 [4]: https://github.com/ruby/ruby/commit/6f09fc2efd1915c4337ce6dded52a8a8771c3222 [5]: https://github.com/ruby/ruby/blob/master/thread.c#L1878 [6]: https://github.com/ruby/ruby/blob/master/thread.c#L1923 ---Files-------------------------------- 11618.patch (3.18 KB) -- https://bugs.ruby-lang.org/

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[ruby-core:123856] [Ruby Bug#21698] Should simple ArgumentError refer to Object?
by vo.x (Vit Ondruch) 19 Nov '25

19 Nov '25

Issue #21698 has been reported by vo.x (Vit Ondruch). ---------------------------------------- Bug #21698: Should simple ArgumentError refer to Object? https://bugs.ruby-lang.org/issues/21698 * Author: vo.x (Vit Ondruch) * Status: Open * ruby -v: ruby 4.0.0dev (2025-11-18 master 85abc59c32) +PRISM [x86_64-linux] * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- Having this simple test file: ~~~ $ cat test.rb def foo(x, y) end foo(1) ~~~ This is the Ruby 3.4 behavior: ~~~ $ ruby --disable-gems test.rb test.rb:1:in 'foo': wrong number of arguments (given 1, expected 2) (ArgumentError) from test.rb:4:in '<main>' $ ruby -v ruby 3.4.7 (2025-10-08 revision 7a5688e2a2) +PRISM [x86_64-linux] ~~~ While Ruby 4.0 refers to `Object` in the backtrace: ~~~ $ ruby --disable-gems test.rb test.rb:1:in 'Object#foo': wrong number of arguments (given 1, expected 2) (ArgumentError) from test.rb:4:in '<main>' $ ruby -v ruby 4.0.0dev (2025-11-18 master 85abc59c32) +PRISM [x86_64-linux] ~~~ While this is certainly correct, I also think it is a bit confusing, because the code does not explicitly refer to `Object`. This likely comes as a result of #21543, but I think that there the original proposal for such simple case was different. I am also not convinced that the `did_you_mean` output really helps: ~~~ $ ruby test.rb test.rb:1:in 'Object#foo': wrong number of arguments (given 1, expected 2) (ArgumentError) caller: test.rb:4 | foo(1) ^^^ callee: test.rb:1 | def foo(x, y) ^^^ from test.rb:4:in '<main>' ~~~ But maybe I should just get used to it 🤷 Just FTR, I have come here trying to fix the following Sass gem test suite error on Fedora: ~~~ 1) Failure: SassScriptTest#test_shallow_argument_error_unwrapped [test/sass/script_test.rb:704]: --- expected +++ actual @@ -1 +1,3 @@ -"wrong number of arguments (1 for 0) for `arg-error'" +# encoding: ASCII-8BIT +# valid: true +"wrong number of arguments (given 1, expected 0) for `arg-error'" ~~~ The problem there is that Sass is trying to parse the backtrace: https://github.com/sass/ruby-sass/blob/7a50eae567260a23d3bbf4d5aaf1a76db43d… and changes like these breaks the compatibility. We already had to apply some [changes for Ruby 3.4](https://src.fedoraproject.org/rpms/rubygem-sass/blob/rawhide/f/rubygem… and this is yet another breakage. This is the actual difference: ~~~ --- ruby-3.4 +++ ruby-4.0 @@ -1,3 +1,3 @@ > e.backtrace => -["/builddir/build/BUILD/rubygem-sass-3.7.4-build/sass-3.7.4/usr/share/gems/gems/sass-3.7.4/test/sass/script_test.rb:11:in 'arg_error'", +["/builddir/build/BUILD/rubygem-sass-3.7.4-build/sass-3.7.4/usr/share/gems/gems/sass-3.7.4/test/sass/script_test.rb:11:in 'Sass::Script::Functions::UserFunctions#arg_error'", ~~~ Contrary to my original point, in this case the backtrace might be better. Maybe this needs more polishing? -- https://bugs.ruby-lang.org/

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