brew/Library/Homebrew/utils/ruby.sh

export HOMEBREW_REQUIRED_RUBY_VERSION=2.6.3

# HOMEBREW_LIBRARY is from the user environment
# shellcheck disable=SC2154
test_ruby() {
  if [[ ! -x $1 ]]
  then
    return 1
  fi

  "$1" --enable-frozen-string-literal --disable=gems,did_you_mean,rubyopt \
    "${HOMEBREW_LIBRARY}/Homebrew/utils/ruby_check_version_script.rb" \
    "${HOMEBREW_REQUIRED_RUBY_VERSION}" 2>/dev/null
}

# HOMEBREW_MACOS is set by brew.sh
# HOMEBREW_PATH is set by global.rb
# shellcheck disable=SC2154
find_ruby() {
  if [[ -n "${HOMEBREW_MACOS}" ]]
  then
    echo "/System/Library/Frameworks/Ruby.framework/Versions/Current/usr/bin/ruby"
  else
    IFS=$'\n' # Do word splitting on new lines only
    for ruby_exec in $(command -v -a ruby 2>/dev/null) $(PATH=${HOMEBREW_PATH} command -v -a ruby 2>/dev/null)
    do
      if test_ruby "${ruby_exec}"; then
        echo "${ruby_exec}"
        break
      fi
    done
    IFS=$' \t\n' # Restore IFS to its default value
  fi
}

# HOMEBREW_FORCE_VENDOR_RUBY is from the user environment
# HOMEBREW_MACOS_SYSTEM_RUBY_NEW_ENOUGH are set by brew.sh
# shellcheck disable=SC2154
need_vendored_ruby() {
  if [[ -n "${HOMEBREW_FORCE_VENDOR_RUBY}" ]]
  then
    return 0
  elif [[ -n "${HOMEBREW_MACOS_SYSTEM_RUBY_NEW_ENOUGH}" ]]
  then
    return 1
  elif [[ -z "${HOMEBREW_MACOS}" ]] && test_ruby "${HOMEBREW_RUBY_PATH}"
  then
    return 1
  else
    return 0
  fi
}

# HOMEBREW_LINUX is set by brew.sh
# shellcheck disable=SC2154
setup-ruby-path() {
  local vendor_dir
  local vendor_ruby_root
  local vendor_ruby_path
  local vendor_ruby_terminfo
  local vendor_ruby_latest_version
  local vendor_ruby_current_version
  # When bumping check if HOMEBREW_MACOS_SYSTEM_RUBY_NEW_ENOUGH (in brew.sh)
  # also needs to be changed.
  local ruby_exec
  local upgrade_fail
  local install_fail

  if [[ -n ${HOMEBREW_MACOS} ]]
  then
    upgrade_fail="Failed to upgrade Homebrew Portable Ruby!"
    install_fail="Failed to install Homebrew Portable Ruby (and your system version is too old)!"
  else
    local advice="
If there's no Homebrew Portable Ruby available for your processor:
- install Ruby ${HOMEBREW_REQUIRED_RUBY_VERSION} with your system package manager (or rbenv/ruby-build)
- make it first in your PATH
- try again
"
    upgrade_fail="Failed to upgrade Homebrew Portable Ruby!${advice}"
    install_fail="Failed to install Homebrew Portable Ruby and cannot find another Ruby ${HOMEBREW_REQUIRED_RUBY_VERSION}!${advice}"
  fi

  vendor_dir="${HOMEBREW_LIBRARY}/Homebrew/vendor"
  vendor_ruby_root="${vendor_dir}/portable-ruby/current"
  vendor_ruby_path="${vendor_ruby_root}/bin/ruby"
  vendor_ruby_terminfo="${vendor_ruby_root}/share/terminfo"
  vendor_ruby_latest_version=$(<"${vendor_dir}/portable-ruby-version")
  vendor_ruby_current_version=$(readlink "${vendor_ruby_root}")

  unset HOMEBREW_RUBY_PATH

  if [[ "${HOMEBREW_COMMAND}" == "vendor-install" ]]
  then
    return 0
  fi

  if [[ -x "${vendor_ruby_path}" ]]
  then
    HOMEBREW_RUBY_PATH="${vendor_ruby_path}"
    TERMINFO_DIRS="${vendor_ruby_terminfo}"
    if [[ ${vendor_ruby_current_version} != "${vendor_ruby_latest_version}" ]]
    then
      brew vendor-install ruby || odie "${upgrade_fail}"
    fi
  else
    HOMEBREW_RUBY_PATH=$(find_ruby)
    if need_vendored_ruby
    then
      brew vendor-install ruby || odie "${install_fail}"
      HOMEBREW_RUBY_PATH="${vendor_ruby_path}"
      TERMINFO_DIRS="${vendor_ruby_terminfo}"
    fi
  fi

  export HOMEBREW_RUBY_PATH
  [[ -n "${HOMEBREW_LINUX}" && -n "${TERMINFO_DIRS}" ]] && export TERMINFO_DIRS
}