[#3213] Reinstated DISTINCT clause for hashtag "any" filtering with 2+ terms. Added test.

lib/pleroma/web/activity_pub/activity_pub.ex

@@ -846,11 +846,18 @@ defp restrict_hashtag_any(_query, %{tag: _tag, skip_preload: true}) do
   end
 
   defp restrict_hashtag_any(query, %{tag: tags}) when is_list(tags) do
+    query =
       from(
         [_activity, object] in query,
         join: hashtag in assoc(object, :hashtags),
         where: hashtag.name in ^tags
       )
+
+    if length(tags) > 1 do
+      distinct(query, [activity], true)
+    else
+      query
+    end
   end
 
   defp restrict_hashtag_any(query, %{tag: tag}) when is_binary(tag) do

lib/pleroma/web/mastodon_api/controllers/timeline_controller.ex

@@ -134,9 +134,9 @@ defp hashtag_fetching(params, user, local_only) do
     tags =
       [params[:tag], params[:any]]
       |> List.flatten()
-      |> Enum.uniq()
       |> Enum.reject(&is_nil/1)
       |> Enum.map(&String.downcase/1)
+      |> Enum.uniq()
 
     tag_all =
       params

test/pleroma/web/activity_pub/activity_pub_test.exs

@@ -217,6 +217,9 @@ test "it fetches the appropriate tag-restricted posts" do
     {:ok, status_two} = CommonAPI.post(user, %{status: ". #essais"})
     {:ok, status_three} = CommonAPI.post(user, %{status: ". #test #reject"})
 
+    {:ok, status_four} = CommonAPI.post(user, %{status: ". #any1 #any2"})
+    {:ok, status_five} = CommonAPI.post(user, %{status: ". #any2 #any1"})
+
     for hashtag_timeline_strategy <- [true, :prefer_aggregation, false] do
       clear_config([:instance, :improved_hashtag_timeline], hashtag_timeline_strategy)
 
@@ -238,8 +241,17 @@ test "it fetches the appropriate tag-restricted posts" do
           tag_all: ["test", "reject"]
         })
 
-      [fetch_one, fetch_two, fetch_three, fetch_four] =
-        Enum.map([fetch_one, fetch_two, fetch_three, fetch_four], fn statuses ->
+      # This test would fail if JOIN with 2+ terms in "any" clause is done without DISTINCT.
+      # The :limit is important (w/o DISTINCT 2 records are deduped by Ecto to 1 b/c of preload).
+      fetch_five =
+        ActivityPub.fetch_activities([], %{
+          type: "Create",
+          tag: ["any1", "any2"],
+          limit: 2
+        })
+
+      [fetch_one, fetch_two, fetch_three, fetch_four, fetch_five] =
+        Enum.map([fetch_one, fetch_two, fetch_three, fetch_four, fetch_five], fn statuses ->
           Enum.map(statuses, fn s -> Repo.preload(s, object: :hashtags) end)
         end)
 
@@ -247,6 +259,7 @@ test "it fetches the appropriate tag-restricted posts" do
       assert fetch_two == [status_one, status_two, status_three]
       assert fetch_three == [status_one, status_two]
       assert fetch_four == [status_three]
+      assert fetch_five == [status_four, status_five]
     end
   end