Issue #21941 has been updated by nagachika (Tomoyuki Chikanaga). Backport changed from 3.2: DONTNEED, 3.3: DONTNEED, 3.4: REQUIRED, 4.0: DONE to 3.2: DONTNEED, 3.3: DONTNEED, 3.4: DONE, 4.0: DONE ruby_3_4 commit:8a434effcafaa4c2f32170a0003d3c1219110890 merged revision(s) commit:8f98abfc46d48c84db2b1408fc8f14b240ec05fd. ---------------------------------------- Bug #21941: Local variable becomes nil when YJIT enabled mid-method with fork/signal/ensure https://bugs.ruby-lang.org/issues/21941#change-117242 * Author: nicholasdower (Nick Dower) * Status: Closed * Assignee: jit * ruby -v: ruby 4.0.0 (2025-12-25 revision 553f1675f3) +PRISM [arm64-darwin25] * Backport: 3.2: DONTNEED, 3.3: DONTNEED, 3.4: DONE, 4.0: DONE ---------------------------------------- The following code results in the `read` local variable becoming nil, even though it is never reassigned: ``` def run fork_safe = ->(t) { t } RubyVM::YJIT.enable read, wakeup = IO.pipe Signal.trap("SIGCHLD") { wakeup.write("!") } begin while true begin fork { exit } next if read.wait_readable rescue Interrupt end end ensure end end run ``` Error: ``` repro.rb:13:in 'Object#run': undefined method 'wait_readable' for nil (NoMethodError) next if read.wait_readable ^^^^^^^^^^^^^^ from repro.rb:21:in '<main>' ``` See also: https://github.com/puma/puma/issues/3620 https://github.com/Shopify/ruby/issues/625 -- https://bugs.ruby-lang.org/