From 54878cd44b6ad3289bf10103bf8a23ae11ab5d20 Mon Sep 17 00:00:00 2001
From: Jean Boussier <jean.boussier@gmail.com>
Date: Fri, 29 Nov 2019 13:30:18 +0100
Subject: [PATCH] Distinguish missing controller exceptions from unrelated
 NameError

Fix: https://github.com/rails/rails/issues/37650

The classic autoloader used to totally unregister any constant that
failed midway. Which mean `"SomeConst".constantize` was idempotent.

However Zeitwerk rely on normal `Kernel#require` behavior, which mean
that if an exception is raised during a class/module definition,
it will be left incompletely defined. For instance:

```ruby
class FooController
  ::DoesNotExist

  def index
  end
end
```

Will leave `FooController` defined, but without its `index` method.

Because of this, when silencing a NameError, it's important
to make sure the missing constant is really the one we were trying
to load.
---
 Gemfile.lock                                      |  4 ++--
 actionpack/lib/action_dispatch.rb                 |  3 +++
 actionpack/lib/action_dispatch/http/parameters.rb |  2 +-
 actionpack/lib/action_dispatch/http/request.rb    | 10 +++++++++-
 activesupport/activesupport.gemspec               |  2 +-
 5 files changed, 16 insertions(+), 5 deletions(-)

diff --git a/Gemfile.lock b/Gemfile.lock
index 9ef915d39fbe6..50898697243d0 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -74,7 +74,7 @@ PATH
       i18n (>= 1.6, < 2)
       minitest (~> 5.1)
       tzinfo (~> 1.1)
-      zeitwerk (~> 2.2)
+      zeitwerk (~> 2.2, >= 2.2.2)
     rails (6.1.0.alpha)
       actioncable (= 6.1.0.alpha)
       actionmailbox (= 6.1.0.alpha)
@@ -529,7 +529,7 @@ GEM
     websocket-extensions (0.1.4)
     xpath (3.2.0)
       nokogiri (~> 1.8)
-    zeitwerk (2.2.0)
+    zeitwerk (2.2.2)
 
 PLATFORMS
   java
diff --git a/actionpack/lib/action_dispatch.rb b/actionpack/lib/action_dispatch.rb
index 8c7f2a8eca8b7..c539fd6f82ec6 100644
--- a/actionpack/lib/action_dispatch.rb
+++ b/actionpack/lib/action_dispatch.rb
@@ -40,6 +40,9 @@ module ActionDispatch
   class IllegalStateError < StandardError
   end
 
+  class MissingController < NameError
+  end
+
   eager_autoload do
     autoload_under "http" do
       autoload :ContentSecurityPolicy
diff --git a/actionpack/lib/action_dispatch/http/parameters.rb b/actionpack/lib/action_dispatch/http/parameters.rb
index 3c16817af3f61..deb499a6a0de3 100644
--- a/actionpack/lib/action_dispatch/http/parameters.rb
+++ b/actionpack/lib/action_dispatch/http/parameters.rb
@@ -98,7 +98,7 @@ def set_binary_encoding(params, controller, action)
 
         def binary_params_for?(controller, action)
           controller_class_for(controller).binary_params_for?(action)
-        rescue NameError
+        rescue MissingController
           false
         end
 
diff --git a/actionpack/lib/action_dispatch/http/request.rb b/actionpack/lib/action_dispatch/http/request.rb
index baa425c2c64ae..a5d477c76b002 100644
--- a/actionpack/lib/action_dispatch/http/request.rb
+++ b/actionpack/lib/action_dispatch/http/request.rb
@@ -86,7 +86,15 @@ def controller_class_for(name)
       if name
         controller_param = name.underscore
         const_name = controller_param.camelize << "Controller"
-        ActiveSupport::Dependencies.constantize(const_name)
+        begin
+          ActiveSupport::Dependencies.constantize(const_name)
+        rescue NameError => error
+          if error.missing_name == const_name || const_name.start_with?("#{error.missing_name}::")
+            raise MissingController.new(error.message, error.name)
+          else
+            raise
+          end
+        end
       else
         PASS_NOT_FOUND
       end
diff --git a/activesupport/activesupport.gemspec b/activesupport/activesupport.gemspec
index e3fbcd972dbbe..ec51fbd4837dd 100644
--- a/activesupport/activesupport.gemspec
+++ b/activesupport/activesupport.gemspec
@@ -37,5 +37,5 @@ Gem::Specification.new do |s|
   s.add_dependency "tzinfo",          "~> 1.1"
   s.add_dependency "minitest",        "~> 5.1"
   s.add_dependency "concurrent-ruby", "~> 1.0", ">= 1.0.2"
-  s.add_dependency "zeitwerk",        "~> 2.2"
+  s.add_dependency "zeitwerk",        "~> 2.2", ">= 2.2.2"
 end