BUILD FAILED (macOS 14.6.1 on arm64 using ruby-build 20250610)

[Greenball233]

I'm a freshman to Ruby, but I have to install Ruby v2.6.0 for dependency, and I got failure when using ruby-build

ruby-build: using [email protected] from homebrew
==> Downloading ruby-2.6.0.tar.bz2...
-> curl -q -fL -o ruby-2.6.0.tar.bz2 https://cache.ruby-lang.org/pub/ruby/2.6/ruby-2.6.0.tar.bz2
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 13.9M 100 13.9M 0 0 4442k 0 0:00:03 0:00:03 --:--:-- 4442k
==> Installing ruby-2.6.0...

WARNING: ruby-2.6.0 is past its end of life and is now unsupported.
It no longer receives bug fixes or critical security updates.

ruby-build: using readline from homebrew
ruby-build: using libyaml from homebrew
ruby-build: using gmp from homebrew
-> ./configure "--prefix=$HOME/.rbenv/versions/2.6.0" --with-openssl-dir=/opt/homebrew/opt/[email protected] --enable-shared --with-readline-dir=/opt/homebrew/opt/readline --with-libyaml-dir=/opt/homebrew/opt/libyaml --with-gmp-dir=/opt/homebrew/opt/gmp --with-ext=openssl,psych,+
-> make -j 8

BUILD FAILED (macOS 14.6.1 on arm64 using ruby-build 20250610)

You can inspect the build directory at /var/folders/sp/hnh_2gtj6qj6ws4v5t7c2_w40000gn/T/ruby-build.20250714132719.87062.s1xxbx
See the full build log at /var/folders/sp/hnh_2gtj6qj6ws4v5t7c2_w40000gn/T/ruby-build.20250714132719.87062.log

The full log is here: ruby-build.20250714132719.87062.log

[mislav]

Hi, searching for "error:" in the build log you've shared yields this line:

closure.c:264:14: error: call to undeclared function 'ffi_prep_closure'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]

If I search for that error, I'm finding threads that outline some workarounds for building Ruby 2.6 (a very old, unsupported version of Ruby) on newer, Apple Silicon hardware:

• 2.6.6 on ARM64 #1699 (comment)
• error: implicit declaration of function 'ffi_prep_closure' on M1 macOS Big Sur ffi/ffi#869 (comment)
• Installation issues with Arm Mac (M1 Chip) #1853 (comment)

I'm sorry for the bad user experience you've had with ruby-build and encountering this error, but Ruby 2.6 is so old that neither the Ruby project nor us (ruby-build) will do anything to fix it, and instead the responsibility of configuring your build environment is on your end. You should really look for ways to upgrade your project from Ruby 2.6 to at least Ruby 3.1 or newer.