Skip Rack applications and redirects when generating urls

When generating an unnamed url (i.e. using `url_for` with an options
hash) we should skip anything other than standard Rails routes otherwise
it will match the first mounted application or redirect and generate a
url with query parameters rather than raising an error if the options
hash doesn't match any defined routes.

Fixes #8018

2 files changed, 17 insertions, 1 deletions

diff --git a/actionpack/lib/action_dispatch/journey/formatter.rb b/actionpack/lib/action_dispatch/journey/formatter.rb
index e288f026c7..7764763791 100644
--- a/actionpack/lib/action_dispatch/journey/formatter.rb
+++ b/actionpack/lib/action_dispatch/journey/formatter.rb
@@ -18,7 +18,11 @@ module ActionDispatch
 
         match_route(name, constraints) do |route|
           parameterized_parts = extract_parameterized_parts(route, options, recall, parameterize)
-          next if !name && route.requirements.empty? && route.parts.empty?
+
+          # Skip this route unless a name has been provided or it is a
+          # standard Rails route since we can't determine whether an options
+          # hash passed to url_for matches a Rack application or a redirect.
+          next unless name || route.dispatcher?
 
           missing_keys = missing_keys(route, parameterized_parts)
           next unless missing_keys.empty?
diff --git a/actionpack/lib/action_dispatch/journey/route.rb b/actionpack/lib/action_dispatch/journey/route.rb
index 50e1853094..c8eb0f6f2d 100644
--- a/actionpack/lib/action_dispatch/journey/route.rb
+++ b/actionpack/lib/action_dispatch/journey/route.rb
@@ -16,6 +16,14 @@ module ActionDispatch
         @app         = app
         @path        = path
 
+        # Unwrap any constraints so we can see what's inside for route generation.
+        # This allows the formatter to skip over any mounted applications or redirects
+        # that shouldn't be matched when using a url_for without a route name.
+        while app.is_a?(Routing::Mapper::Constraints) do
+          app = app.app
+        end
+        @dispatcher  = app.is_a?(Routing::RouteSet::Dispatcher)
+
         @constraints = constraints
         @defaults    = defaults
         @required_defaults = nil
@@ -93,6 +101,10 @@ module ActionDispatch
         end
       end
 
+      def dispatcher?
+        @dispatcher
+      end
+
       def matches?(request)
         constraints.all? do |method, value|
           next true unless request.respond_to?(method)