Ruby 4.0.7 compilation fails on macOS 26.6.2

[mudge]

Description

Attempting to compile Ruby 4.0.7 with ruby-install 0.10.2 on macOS 26.6.2 fails with the following output:

building libruby.a
partial linking /Users/mudge/src/ruby-4.0.7/target/release/libruby.a into /Users/mudge/src/ruby-4.0.7/target/release/libruby.o
linking miniruby
make: *** [builtin_binary.rbbin] Segmentation fault: 11
!!! Compiling ruby 4.0.7 failed!

Steps To Reproduce

Steps to reproduce the bug:

1. $ ruby-install ruby 4.0.7

Expected Behavior

Ruby 4.0.7 should be compiled and installed.

Actual Behavior

building libruby.a
partial linking /Users/mudge/src/ruby-4.0.7/target/release/libruby.a into /Users/mudge/src/ruby-4.0.7/target/release/libruby.o
linking miniruby
make: *** [builtin_binary.rbbin] Segmentation fault: 11
!!! Compiling ruby 4.0.7 failed!

Environment

$ ruby-install --version
ruby-install: 0.10.1
$ uname -a
Darwin Pauls-MacBook-Pro.local 25.6.0 Darwin Kernel Version 25.6.0: Fri Jul 31 19:18:48 PDT 2026; root:xnu-12377.161.14~5/RELEASE_ARM64_T6020 arm64
$ cc --version
Apple clang version 21.0.0 (clang-2100.3.34.2)

Target: arm64-apple-darwin25.6.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin
$ openssl version
OpenSSL 3.6.4 25 Aug 2026 (Library: OpenSSL 3.6.4 25 Aug 2026)

See rbenv/ruby-build#2641 for the same issue and resolution with ruby-build, their workaround appears to be set the following:

export ac_cv_func_dup3=no ac_cv_func_pipe2=no

[mudge]

See also python/cpython#153711 for a similar issue.

[monfresh]

What's missing from this bug report is that this only fails if you have v27 of the Apple command line tools and/or Xcode. This is not specific to macOS 26.6.2. For example, Ruby installation works fine on macOS 26.6.2 with CLT/Xcode 26.6

Technically, this is an issue for Ruby to fix. If it were me, I would wait for Ruby to fix this, and in the meantime, revert back to CLT/Xcode 26.6 on my machine.