modqueue: fix the disapproved: metatag showing posts outside the queue.

Fix a bug where filtering the modqueue by the `disapproved:<reason>` tag
would return posts outside the modqueue.

app/logical/concerns/searchable.rb

@@ -9,6 +9,22 @@ module Searchable
     relation.where(all.where_clause.invert.ast)
   end
 
+  # Combine two relations like `ActiveRecord::Relation#and`, but allow structurally incompatible relations.
+  def and_relation(relation)
+    q = all
+    raise "incompatible FROM clauses: #{q.to_sql}; #{relation.to_sql}" if !q.from_clause.empty? && q.from_clause != relation.from_clause
+    raise "incompatible GROUP BY clauses: #{q.to_sql}; #{relation.to_sql}" if !q.group_values.empty? && q.group_values != relation.group_values
+
+    q = q.select(q.select_values + relation.select_values) if !relation.select_values.empty?
+    q = q.from(relation.from_clause.value) if !relation.from_clause.empty?
+    q = q.joins(relation.joins_values + q.joins_values) if relation.joins_values.present?
+    q = q.where(relation.where_clause.ast) if relation.where_clause.present?
+    q = q.group(relation.group_values) if relation.group_values.present?
+    q = q.order(relation.order_values) if relation.order_values.present? && !relation.reordering_value
+    q = q.reorder(relation.order_values) if relation.order_values.present? && relation.reordering_value
+    q
+  end
+
   # Search a table column by an Arel operator.
   #
   # @see https://github.com/rails/rails/blob/master/activerecord/lib/arel/predications.rb

app/models/post.rb

@@ -1391,7 +1391,7 @@ class Post < ApplicationRecord
         post_query = PostQuery.normalize(query, current_user: user, tag_limit: tag_limit, safe_mode: safe_mode)
         post_query.validate_tag_limit!
         posts = post_query.with_implicit_metatags.posts
-        merge(posts)
+        and_relation(posts)
       end
 
       def search(params, current_user)
@@ -1409,7 +1409,7 @@ class Post < ApplicationRecord
         )
 
         if params[:tags].present?
-          q = q.user_tag_match(params[:tags], current_user)
+          q = q.where(id: user_tag_match(params[:tags], current_user).select(:id))
         end
 
         if params[:order].present?

test/functional/modqueue_controller_test.rb

@@ -58,6 +58,16 @@ class ModqueueControllerTest < ActionDispatch::IntegrationTest
         assert_equal([], response.parsed_body.pluck("id"))
       end
 
+      should "filter the disapproved:<reason> metatag correctly" do
+        post1 = create(:post, is_pending: true)
+        post2 = create(:post, is_deleted: true)
+        create(:post_disapproval, post: post2, reason: "poor_quality")
+
+        get_auth modqueue_index_path(search: { tags: "disapproved:poor_quality" }), @admin, as: :json
+        assert_response :success
+        assert_equal([], response.parsed_body.pluck("id"))
+      end
+
       should "include appealed posts in the modqueue" do
         @appeal = create(:post_appeal)
         get_auth modqueue_index_path, @admin

test/unit/post_query_builder_test.rb

@@ -1,8 +1,8 @@
 require 'test_helper'
 
 class PostQueryBuilderTest < ActiveSupport::TestCase
-  def assert_tag_match(posts, query, current_user: CurrentUser.user, tag_limit: nil, **options)
-    assert_equal(posts.map(&:id), Post.user_tag_match(query, current_user, tag_limit: tag_limit, **options).pluck("posts.id"))
+  def assert_tag_match(posts, query, relation: Post.all, current_user: CurrentUser.user, tag_limit: nil, **options)
+    assert_equal(posts.map(&:id), relation.user_tag_match(query, current_user, tag_limit: tag_limit, **options).pluck("posts.id"))
   end
 
   def assert_search_error(query, current_user: CurrentUser.user, **options)
@@ -1481,6 +1481,25 @@ class PostQueryBuilderTest < ActiveSupport::TestCase
       assert_tag_match([post2, post1], "id:#{post1.id} or rating:q")
     end
 
+    should "work on a relation with pre-existing scopes" do
+      post1 = create(:post, rating: "g", is_pending: true, tag_string: ["1girl"])
+      post2 = create(:post, rating: "s", is_flagged: true, tag_string: ["1boy"])
+      create(:post_disapproval, post: post2, reason: "poor_quality")
+
+      assert_tag_match([post1], "1girl", relation: Post.pending)
+      assert_tag_match([post1], "1girl", relation: Post.in_modqueue)
+      assert_tag_match([post1], "1boy", relation: Post.in_modqueue)
+      assert_tag_match([post2, post1], "comments:0", relation: Post.in_modqueue)
+      assert_tag_match([post2, post1], "comments:0 notes:0", relation: Post.in_modqueue)
+
+      assert_tag_match([post2], "-1girl", relation: Post.in_modqueue)
+      assert_tag_match([post2], "disapproved:poor_quality", relation: Post.in_modqueue)
+
+      assert_tag_match([], "rating:g", relation: Post.where(rating: "e"))
+      assert_tag_match([], "id:#{post1.id}", relation: Post.where(id: 0))
+      assert_tag_match([], "order:artcomm", relation: Post.in_modqueue)
+    end
+
     should "not allow conflicting order metatags" do
       assert_search_error("order:score ordfav:a")
       assert_search_error("order:score ordfavgroup:a")