Fixing libv8 and therubyracer on Mac

fix-libv8-mac.txt

brew tap homebrew/versions
brew install v8-315

gem install libv8 -v '3.16.14.13' -- --with-system-v8
gem install therubyracer -- --with-v8-dir=/usr/local/opt/v8-315

bundle install

macOS Monterey doesn't include Python 2 anymore. Python 2 is required by libv8. To install it (from https://www.alfredapp.com/help/kb/python-2-monterey/), execute the following (preferably in a new shell because it changes $PATH):

export PATH="/opt/homebrew/bin:/usr/local/bin:${PATH}"
eval "$(brew shellenv)"
brew install pyenv
pyenv install 2.7.18
ln -s "${HOME}/.pyenv/versions/2.7.18/bin/python2.7" "${HOMEBREW_PREFIX}/bin/python"

For Ruby 3.0.4 in Monterey (macOS 12.3.1), this worked for me:

brew install v8@3.15
bundle config build.libv8 --with-system-v8
bundle config build.therubyracer --with-v8-dir=$(brew --prefix v8@3.15)
bundle install

Unfortunately, it's not so easy in Ruby. 3.1. That includes psych-4 as a "default" (hard-coded in) gem which can't be removed, and psych-4 is incompatible with libv8 (for now at least). I have not found a solution to this, aside from reverting to ruby 3.0.4.

For those who any of the above fixes didn't work I installed Python 3.9.1 set it to the global python version (setting it to local version didn't work), and ran bundle again and it installed mini_racer correctly.

What tipped me off was the following message in the console output after it failed:

Python 3.12. Use setuptools or check PEP 632 for potential alternatives
  from distutils.spawn import find_executable
Please use python3.9 or python3.8 or python3.7 or python3.6 or python3.5 or python2.7.
Node.js configure: Found Python 3.10.2...

Here are the commands I ran:

pyenv install 3.9.1
pyenv global 3.9.1
bundle