FIX: Complete protection for potentially illegal reviewables on post deletion (#37536)

This is a follow-up to fd04f690.

The original commit only protected potentially illegal reviewables from
being auto-approved in one code path (direct post deletion). However,
when deleting a post through a reviewable action with
`notify_users_after_responses_deleted_on_flagged_post` enabled, the code
would still call `#ignore` on any flagged reply posts without checking
`#potentially_illegal?`.

lib/post_destroyer.rb

@@ -238,22 +238,7 @@ class PostDestroyer
       DB.after_commit do
         Topic.reset_highest(@post.topic_id)
 
-        if @opts[:reviewable]
-          notify_deletion(
-            @opts[:reviewable],
-            { notify_responders: @opts[:notify_responders], parent_post: @opts[:parent_post] },
-          )
-          if @post.reviewable_flag &&
-               SiteSetting.notify_users_after_responses_deleted_on_flagged_post
-            ignore(@post.reviewable_flag)
-          end
-        elsif reviewable = @post.reviewable_flag
-          if @opts[:defer_flags]
-            ignore(reviewable)
-          else
-            agree(reviewable) unless reviewable.potentially_illegal?
-          end
-        end
+        handle_reviewable_after_deletion
       end
     end
 
@@ -403,6 +388,34 @@ class PostDestroyer
     reviewable.transition_to(:ignored, @user)
   end
 
+  def handle_reviewable_after_deletion
+    if @opts[:reviewable]
+      handle_explicit_reviewable
+    elsif @post.reviewable_flag
+      handle_post_reviewable_flag
+    end
+  end
+
+  def handle_explicit_reviewable
+    notify_deletion(
+      @opts[:reviewable],
+      { notify_responders: @opts[:notify_responders], parent_post: @opts[:parent_post] },
+    )
+
+    return unless @post.reviewable_flag
+    return unless SiteSetting.notify_users_after_responses_deleted_on_flagged_post
+    return if @post.reviewable_flag.potentially_illegal?
+
+    ignore(@post.reviewable_flag)
+  end
+
+  def handle_post_reviewable_flag
+    return ignore(@post.reviewable_flag) if @opts[:defer_flags]
+    return if @post.reviewable_flag.potentially_illegal?
+
+    agree(@post.reviewable_flag)
+  end
+
   def notify_deletion(reviewable, options = {})
     return if @post.user.blank?
 

spec/lib/post_destroyer_spec.rb

@@ -1097,6 +1097,19 @@ RSpec.describe PostDestroyer do
         }
         expect(Jobs::SendSystemMessage.jobs).to be_empty
       end
+
+      context "when deleting a reply with a reviewable option and notify_users_after_responses_deleted_on_flagged_post enabled" do
+        let(:parent_reviewable) { flag_result.reviewable }
+        let(:reply_reviewable) { second_post.reviewable_flag }
+
+        before { SiteSetting.notify_users_after_responses_deleted_on_flagged_post = true }
+
+        it "does not ignore a potentially illegal flag on the reply" do
+          expect {
+            PostDestroyer.new(moderator, second_post, reviewable: parent_reviewable).destroy
+          }.not_to change { reply_reviewable.reload.pending? }
+        end
+      end
     end
 
     context "when custom flags" do