FrozenError can't modify frozen Array (Rails 6.0 with zeitwerk autoloader)

[sho918]

Custom exceptions app not working with zeitwerk autoloader.
Works well with classic autoloader (config.autoloader = :classic).

env

• Ruby 2.6.4
• Rails 6.0.0
• Rambulance 1.0.2

log

Started GET "/rambulance/not_found" for 127.0.0.1 at 2019-09-10 14:00:57 +0900
   (0.7ms)  SELECT sqlite_version(*)
  
FrozenError (can't modify frozen Array):
  
activesupport (6.0.0) lib/active_support/dependencies.rb:514:in `concat'
activesupport (6.0.0) lib/active_support/dependencies.rb:514:in `load_file'
activesupport (6.0.0) lib/active_support/dependencies.rb:407:in `block in require_or_load'
activesupport (6.0.0) lib/active_support/dependencies.rb:40:in `block in load_interlock'
activesupport (6.0.0) lib/active_support/dependencies/interlock.rb:14:in `block in loading'
activesupport (6.0.0) lib/active_support/concurrency/share_lock.rb:151:in `exclusive'
activesupport (6.0.0) lib/active_support/dependencies/interlock.rb:13:in `loading'
activesupport (6.0.0) lib/active_support/dependencies.rb:40:in `load_interlock'
activesupport (6.0.0) lib/active_support/dependencies.rb:390:in `require_or_load'
bootsnap (1.4.5) lib/bootsnap/load_path_cache/core_ext/active_support.rb:48:in `block in require_or_load'
bootsnap (1.4.5) lib/bootsnap/load_path_cache/core_ext/active_support.rb:16:in `allow_bootsnap_retry'
bootsnap (1.4.5) lib/bootsnap/load_path_cache/core_ext/active_support.rb:47:in `require_or_load'
activesupport (6.0.0) lib/active_support/dependencies.rb:545:in `load_missing_constant'
bootsnap (1.4.5) lib/bootsnap/load_path_cache/core_ext/active_support.rb:60:in `block in load_missing_constant'
bootsnap (1.4.5) lib/bootsnap/load_path_cache/core_ext/active_support.rb:16:in `allow_bootsnap_retry'
bootsnap (1.4.5) lib/bootsnap/load_path_cache/core_ext/active_support.rb:59:in `load_missing_constant'
rambulance (1.0.2) lib/rambulance/railtie.rb:10:in `block (2 levels) in <class:Railtie>'
actionpack (6.0.0) lib/action_dispatch/routing/mapper.rb:19:in `block in <class:Constraints>'
actionpack (6.0.0) lib/action_dispatch/routing/mapper.rb:48:in `serve'
actionpack (6.0.0) lib/action_dispatch/journey/router.rb:49:in `block in serve'
actionpack (6.0.0) lib/action_dispatch/journey/router.rb:32:in `each'
actionpack (6.0.0) lib/action_dispatch/journey/router.rb:32:in `serve'
actionpack (6.0.0) lib/action_dispatch/routing/route_set.rb:837:in `call'
rack (2.0.7) lib/rack/tempfile_reaper.rb:15:in `call'
rack (2.0.7) lib/rack/etag.rb:25:in `call'
rack (2.0.7) lib/rack/conditional_get.rb:25:in `call'
rack (2.0.7) lib/rack/head.rb:12:in `call'
actionpack (6.0.0) lib/action_dispatch/http/content_security_policy.rb:18:in `call'
rack (2.0.7) lib/rack/session/abstract/id.rb:232:in `context'
rack (2.0.7) lib/rack/session/abstract/id.rb:226:in `call'
actionpack (6.0.0) lib/action_dispatch/middleware/cookies.rb:648:in `call'
activerecord (6.0.0) lib/active_record/migration.rb:567:in `call'
actionpack (6.0.0) lib/action_dispatch/middleware/callbacks.rb:27:in `block in call'
activesupport (6.0.0) lib/active_support/callbacks.rb:101:in `run_callbacks'
actionpack (6.0.0) lib/action_dispatch/middleware/callbacks.rb:26:in `call'
actionpack (6.0.0) lib/action_dispatch/middleware/executor.rb:14:in `call'
actionpack (6.0.0) lib/action_dispatch/middleware/actionable_exceptions.rb:17:in `call'
actionpack (6.0.0) lib/action_dispatch/middleware/debug_exceptions.rb:32:in `call'
web-console (4.0.1) lib/web_console/middleware.rb:132:in `call_app'
web-console (4.0.1) lib/web_console/middleware.rb:28:in `block in call'
web-console (4.0.1) lib/web_console/middleware.rb:17:in `catch'
web-console (4.0.1) lib/web_console/middleware.rb:17:in `call'
actionpack (6.0.0) lib/action_dispatch/middleware/show_exceptions.rb:33:in `call'
railties (6.0.0) lib/rails/rack/logger.rb:38:in `call_app'
railties (6.0.0) lib/rails/rack/logger.rb:26:in `block in call'
activesupport (6.0.0) lib/active_support/tagged_logging.rb:80:in `block in tagged'
activesupport (6.0.0) lib/active_support/tagged_logging.rb:28:in `tagged'
activesupport (6.0.0) lib/active_support/tagged_logging.rb:80:in `tagged'
railties (6.0.0) lib/rails/rack/logger.rb:26:in `call'
sprockets-rails (3.2.1) lib/sprockets/rails/quiet_assets.rb:13:in `call'
actionpack (6.0.0) lib/action_dispatch/middleware/remote_ip.rb:81:in `call'
actionpack (6.0.0) lib/action_dispatch/middleware/request_id.rb:27:in `call'
rack (2.0.7) lib/rack/method_override.rb:22:in `call'
rack (2.0.7) lib/rack/runtime.rb:22:in `call'
activesupport (6.0.0) lib/active_support/cache/strategy/local_cache_middleware.rb:29:in `call'
actionpack (6.0.0) lib/action_dispatch/middleware/executor.rb:14:in `call'
actionpack (6.0.0) lib/action_dispatch/middleware/static.rb:126:in `call'
rack (2.0.7) lib/rack/sendfile.rb:111:in `call'
actionpack (6.0.0) lib/action_dispatch/middleware/host_authorization.rb:83:in `call'
webpacker (4.0.7) lib/webpacker/dev_server_proxy.rb:29:in `perform_request'
rack-proxy (0.6.5) lib/rack/proxy.rb:57:in `call'
railties (6.0.0) lib/rails/engine.rb:526:in `call'
puma (3.12.1) lib/puma/configuration.rb:227:in `call'
puma (3.12.1) lib/puma/server.rb:660:in `handle_request'
puma (3.12.1) lib/puma/server.rb:474:in `process_client'
puma (3.12.1) lib/puma/server.rb:334:in `block in run'
puma (3.12.1) lib/puma/thread_pool.rb:135:in `block in spawn_thread'

[yuki24]

Hi @sho918, thanks for reporting. I just quickly looked into this issue but it seems like the AcitonDispatch::IntegrationTest has a foundational change and I couldn't run the test at all. So this is going to take a little more time unless someone else pokes around it.

[yuki24]

I couldn't replicate the issue with a fresh Rails app:

$ ruby -v
ruby 2.6.2p47 (2019-03-13 revision 67232) [x86_64-darwin18]
$ rails -v
Rails 6.0.0

$ rails new rambulance-test && cd rambulance-test
$ rails webpacker:install
$ bundle add ranbulance
$ rails g rambulance:install
$ rails s &
$ sleep 5 # wait for Rails to spin up
$ open http://localhost:3000/rambulance/not_found

I'm not sure what's going on there, but you may need to purge bootsnap cache when switching.

[sho918]

Thanks for response.
It works well without Custom Exceptions App (or Zeitwerk).

But an error occurs when combination of Custom Exceptions App and Zeitwerk autoloader.

$ rails new rambulance-test
$ cd rambulance-test
$ bundle add rambulance
$ rails g rambulance:install
$ rails s
$ open http://localhost:3000/rambulance/not_found # Works fine

# Install Custom Exceptions App
$ rails g rambulance:exceptions_app

# with Zeitwerk autoloader
$ rails r "puts Rails.autoloaders.zeitwerk_enabled?"
=> true
$ rails s
$ open http://localhost:3000/rambulance/not_found # FrozenError (can't modify frozen Array)

# without Zeitwerk autoloader (`config.autoloader = :classic`)
$ rails r "puts Rails.autoloaders.zeitwerk_enabled?"
=> false
$ rails s
$ open http://localhost:3000/rambulance/not_found # Works fine

[yuki24]

Confirmed this bug. I'll look into it. Thanks for reporting.

[yuki24]

I was able to replicate this bug in an actual rails app, but not in the test. I pushed the fix, but it would be great if you could confirm the fix on your side too. I will cut a new release once it's confirmed.

[sho918]

Thank you for quick fix.
It working without any problems on my rails app.

[yuki24]

released as part of v1.0.3.