Use prepended modules instead of `undef` for OS-specific code #11385

	name: Documentation CI

	on:
	push:
	branches:
	- master
	pull_request:

	permissions:
	contents: read
	pages: read

	env:
	HOMEBREW_DEVELOPER: 1
	HOMEBREW_NO_AUTO_UPDATE: 1
	HOMEBREW_NO_ENV_HINTS: 1
	HOMEBREW_BOOTSNAP: 1
	HOMEBREW_NO_INSTALL_CLEANUP: 1

	jobs:
	docs:
	runs-on: ubuntu-22.04
	steps:
	- name: Set up Homebrew
	id: set-up-homebrew
	uses: Homebrew/actions/setup-homebrew@master
	with:
	core: false
	cask: false
	test-bot: false

	- name: Checkout repository
	uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332 # v4

	- name: Install vale
	run: brew install vale

	- name: Cleanup Homebrew/brew docs
	if: github.repository == 'Homebrew/brew'
	run: \|
	set -xeuo pipefail

	# Avoid failing on broken symlinks.
	rm Library/Homebrew/os/mac/pkgconfig/fuse/fuse.pc
	rm Library/Homebrew/os/mac/pkgconfig/fuse/osxfuse.pc

	# No ignore support (https://github.com/errata-ai/vale/issues/131).
	rm -r Library/Homebrew/vendor

	- name: Run Vale
	run: vale docs/

	- name: Install Ruby
	uses: ruby/setup-ruby@f321cf5a4d1533575411f8752cf25b86478b0442 # v1.193.0
	with:
	bundler-cache: true
	working-directory: docs

	- name: Check Markdown syntax
	working-directory: docs
	run: bundle exec rake lint

	- name: Check code blocks conform to our Ruby style guide
	run: brew style docs

	- name: Generate formulae.brew.sh API samples
	if: github.repository == 'Homebrew/formulae.brew.sh'
	working-directory: docs
	run: ../script/generate-api-samples.rb

	- name: Build the site and check for broken links
	working-directory: docs
	run: bundle exec rake test
	env:
	JEKYLL_GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

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