Prevent invalid code when using dynamic finders with Ruby's reserved words.

The dynamic finder was creating the method signature with the parameters name,
which may have reserved words and this way creating invalid Ruby code.

Closes: #13261

    Example:

        # Before
        Dog.find_by_alias('dog name')

        # Was creating this method
        def self.find_by_alias(alias, options = {})

        # After
        Dog.find_by_alias('dog name')

        # Will create this method
        def self.find_by_alias(_alias, options = {})

1 files changed, 7 insertions, 2 deletions

diff --git a/activerecord/lib/active_record/dynamic_matchers.rb b/activerecord/lib/active_record/dynamic_matchers.rb
index e650ebcf64..5caab09038 100644
--- a/activerecord/lib/active_record/dynamic_matchers.rb
+++ b/activerecord/lib/active_record/dynamic_matchers.rb
@@ -84,13 +84,18 @@ module ActiveRecord
         "#{finder}(#{attributes_hash})"
       end
 
+      # The parameters in the signature may have reserved Ruby words, in order
+      # to prevent errors, we start each param name with `_`.
+      #
       # Extended in activerecord-deprecated_finders
       def signature
-        attribute_names.join(', ')
+        attribute_names.map { |name| "_#{name}" }.join(', ')
       end
 
+      # Given that the parameters starts with `_`, the finder needs to use the
+      # same parameter name.
       def attributes_hash
-        "{" + attribute_names.map { |name| ":#{name} => #{name}" }.join(',') + "}"
+        "{" + attribute_names.map { |name| ":#{name} => _#{name}" }.join(',') + "}"
       end
 
       def finder