stylesheet_link_tag :all and :app includes build files

[justinfrench]

I'm using a pretty fresh Rails 8 app generated with rails new foo --css=tailwind. The standard application.html.erb includes the following:

<%= stylesheet_link_tag :app, "data-turbo-track": "reload" %>

The problem is that tailwindcss-rails is adding CSS files to app/assets/builds/tailwind/whatever.css, which are being automatically included.

I found the issue while tinkering with the experimental Engine support in tailwindcss-rails (which produced a file that shouldn't be served directly to customers, it needs to be added with an @import to tailwind/application.css), but I think it applies to anything that adds files to app/assets/builds/.

On one hand, I can understand why it's including all CSS files in assets/, but on the other hand, I don't think build files should be included. They're also treated differently in Rails' standard .gitignore.

The work-around is to avoid using :all or :app so I'm not stuck, but I think this is unexpected behaviour, and I wanted to raise the issue here for awareness and discussion.

[rafaelfranca]

The behavior is by design. See

propshaft/lib/propshaft/helper.rb

Lines 102 to 110 in 9bcad5f

	# Returns a sorted and unique array of logical paths for all stylesheets in the load path.
	def all_stylesheets_paths
	Rails.application.assets.load_path.asset_paths_by_type("css")
	end
	# Returns a sorted and unique array of logical paths for all stylesheets in app/assets/**/*.css.
	def app_stylesheets_paths
	Rails.application.assets.load_path.asset_paths_by_glob("#{Rails.root.join("app/assets")}/**/*.css")
	end

I don't think you can use :all or :app with tailwindcss-rails, or anything that is planing to use @import.