Issue #22320 has been reported by mreiche@adobe.com (Michael Reiche). ---------------------------------------- Misc #22320: Build fails with SIGSEGV in `miniruby` during `builtin_binary` on macOS 26 (Tahoe): `pipe2` declared by SDK but absent from libSystem at runtime https://bugs.ruby-lang.org/issues/22320 * Author: mreiche@adobe.com (Michael Reiche) * Status: Open ---------------------------------------- **Environment** - macOS 26.6.2 (Tahoe), Apple Silicon (arm64) - Apple clang 21.0.0 (clang-2100.3.34.2), target `arm64-apple-darwin25.6.0` - Ruby 3.4.10 (also reproduced on 4.0.7), built via ruby-build 20260915 / rbenv - Also reproduces with a plain `./configure && make` from the release tarball **Summary** On macOS 26, `make` dies with `Segmentation fault: 11` at the step that runs the freshly-linked `miniruby` to generate `builtin_binary.inc` (`builtin_binary.rbbin`). Every Ruby version fails identically, because `miniruby` segfaults *on launch* during interpreter init. ``` compiling enc/trans/newline.c linking miniruby make: *** [builtin_binary.inc] Segmentation fault: 11 ``` **Root cause** macOS 26's SDK now **declares `pipe2()`** in its headers, so Ruby's `configure` sets `HAVE_PIPE2` and `rb_cloexec_pipe()` compiles a call to `pipe2`. However, **libSystem does not actually provide the symbol at runtime**. The weak-imported `_pipe2` binds to NULL, and the call during timer-thread setup jumps to address 0. Crash report (`~/Library/Logs/DiagnosticReports/miniruby-*.ips`): ``` Exception: EXC_BAD_ACCESS (SIGSEGV), KERN_INVALID_ADDRESS at 0x0000000000000000 Faulting thread frames: 0x0 ← call through NULL function pointer miniruby rb_cloexec_pipe miniruby setup_communication_pipe_internal miniruby rb_thread_create_timer_thread miniruby Init_Thread miniruby rb_call_inits miniruby ruby_setup / ruby_init miniruby main dyld start ``` Confirmation that `pipe2` is declared but not present at runtime: ``` $ cat > /tmp/pipe2test.c <<'EOF' #include <stdio.h> extern int pipe2(int[2], int); int main(void){ printf("%p\n", (void*)pipe2); return 0; } EOF $ clang -o /tmp/pipe2test /tmp/pipe2test.c && /tmp/pipe2test dyld[]: Symbol not found: _pipe2 Expected in: /usr/lib/libSystem.B.dylib ``` **Steps to reproduce** 1. On macOS 26 (Apple Silicon), build Ruby 3.4.x from source (`./configure && make`). 2. `make` segfaults at `builtin_binary.inc` while executing `miniruby`. **Expected** `configure` should not enable `HAVE_PIPE2` when the symbol is declared but unavailable at runtime, or `rb_cloexec_pipe` should guard the call (e.g. `__builtin_available` / weak-symbol NULL check) and fall back to `pipe()` + `FD_CLOEXEC`. **Actual** `HAVE_PIPE2` is enabled based solely on the declaration; the resulting binary calls a NULL symbol and crashes. **Workaround** ``` ac_cv_func_pipe2=no ./configure ... # or, with rbenv: RUBY_CONFIGURE_OPTS="ac_cv_func_pipe2=no" rbenv install 3.4.10 ``` **Suggested fix** Make the `pipe2` detection on Darwin a *link-and-availability* test rather than a declaration check, or wrap the call site with an availability guard so it degrades to the `pipe()` fallback when `&pipe2 == NULL`. (macOS historically lacked `pipe2`; the macOS 26 SDK appears to declare it ahead of libSystem actually providing it.) -- https://bugs.ruby-lang.org/