Raise StrictLoadingViolationError with polymorphic relation violations

Performing strict_loading! on a model with a polymorphic association
currently raises an ArgumentError because it attempts to look up the
klass on the polymorphic association, which is not possible. The error
message for StrictLoadingViolationError on models with polymorphic
relationships should omit the klass for the association.

activerecord/lib/active_record/core.rb

@@ -213,7 +213,7 @@ def self.connection_class_for_self # :nodoc:
       def self.strict_loading_violation!(owner:, reflection:) # :nodoc:
         case ActiveRecord.action_on_strict_loading_violation
         when :raise
-          message = "`#{owner}` is marked for strict_loading. The `#{reflection.klass}` association named `:#{reflection.name}` cannot be lazily loaded."
+          message = reflection.strict_loading_violation_message(owner)
           raise ActiveRecord::StrictLoadingViolationError.new(message)
         when :log
           name = "strict_loading_violation.active_record"

activerecord/lib/active_record/log_subscriber.rb

@@ -22,10 +22,8 @@ def self.reset_runtime
     def strict_loading_violation(event)
       debug do
         owner = event.payload[:owner]
-        association = event.payload[:reflection].klass
-        name = event.payload[:reflection].name
-
-        color("Strict loading violation: #{owner} is marked for strict loading. The #{association} association named :#{name} cannot be lazily loaded.", RED)
+        reflection = event.payload[:reflection]
+        color(reflection.strict_loading_violation_message(owner), RED)
       end
     end
 

activerecord/lib/active_record/reflection.rb

@@ -297,6 +297,12 @@ def strict_loading?
         options[:strict_loading]
       end
 
+      def strict_loading_violation_message(owner)
+        message = +"`#{owner}` is marked for strict_loading."
+        message << " The #{polymorphic? ? "polymorphic association" : "#{klass} association"}"
+        message << " named `:#{name}` cannot be lazily loaded."
+      end
+
       protected
         def actual_source_reflection # FIXME: this is a horrible name
           self

activerecord/test/cases/strict_loading_test.rb

@@ -549,13 +549,60 @@ def test_strict_loading_violation_can_log_instead_of_raise
     developer.strict_loading!
     assert_predicate developer, :strict_loading?
 
-    assert_logged("Strict loading violation: Developer is marked for strict loading. The AuditLog association named :audit_logs cannot be lazily loaded.") do
+    expected_log = <<-MSG.squish
+      `Developer` is marked for strict_loading.
+      The AuditLog association named `:audit_logs` cannot be lazily loaded.
+    MSG
+    assert_logged(expected_log) do
       developer.audit_logs.to_a
     end
   ensure
     ActiveRecord.action_on_strict_loading_violation = old_value
   end
 
+  def test_strict_loading_violation_on_polymorphic_relation
+    pirate = Pirate.create!(catchphrase: "Arrr!")
+    Treasure.create!(looter: pirate)
+
+    treasure = Treasure.last
+    treasure.strict_loading!
+    assert_predicate treasure, :strict_loading?
+
+    error = assert_raises ActiveRecord::StrictLoadingViolationError do
+      treasure.looter
+    end
+
+    expected_error_message = <<-MSG.squish
+      `Treasure` is marked for strict_loading.
+      The polymorphic association named `:looter` cannot be lazily loaded.
+    MSG
+
+    assert_equal(expected_error_message, error.message)
+  end
+
+  def test_strict_loading_violation_logs_on_polymorphic_relation
+    old_value = ActiveRecord.action_on_strict_loading_violation
+    ActiveRecord.action_on_strict_loading_violation = :log
+    assert_equal :log, ActiveRecord.action_on_strict_loading_violation
+
+    pirate = Pirate.create!(catchphrase: "Arrr!")
+    Treasure.create!(looter: pirate)
+
+    treasure = Treasure.last
+    treasure.strict_loading!
+    assert_predicate treasure, :strict_loading?
+
+    expected_log = <<-MSG.squish
+      `Treasure` is marked for strict_loading.
+      The polymorphic association named `:looter` cannot be lazily loaded.
+    MSG
+    assert_logged(expected_log) do
+      treasure.looter
+    end
+  ensure
+    ActiveRecord.action_on_strict_loading_violation = old_value
+  end
+
   private
     def with_strict_loading_by_default(model)
       previous_strict_loading_by_default = model.strict_loading_by_default