Merge pull request rails#41098 from kamipo/fix_source_type_with_symbol

Fix "NoMethodError: undefined method `-@'" for `source_type` with a symbol

Author: kamipo

activerecord/lib/active_record/reflection.rb

@@ -162,7 +162,7 @@ def build_association(attributes, &block)
       # <tt>composed_of :balance, class_name: 'Money'</tt> returns <tt>'Money'</tt>
       # <tt>has_many :clients</tt> returns <tt>'Client'</tt>
       def class_name
-        @class_name ||= -(options[:class_name]&.to_s || derive_class_name)
+        @class_name ||= -(options[:class_name] || derive_class_name).to_s
       end
 
       # Returns a list of scopes that should be applied for this Reflection

activerecord/test/models/club.rb

@@ -5,7 +5,7 @@ class Club < ActiveRecord::Base
   has_many :memberships, inverse_of: false
   has_many :members, through: :memberships
   has_one :sponsor
-  has_one :sponsored_member, through: :sponsor, source: :sponsorable, source_type: "Member"
+  has_one :sponsored_member, through: :sponsor, source: :sponsorable, source_type: :Member
   belongs_to :category
 
   has_many :favourites, -> { where(memberships: { favourite: true }) }, through: :memberships, source: :member