Fix bug with or/or-join when shortcircuiting resolve-clause

src/datascript/query.cljc

@@ -133,7 +133,9 @@
       (= attrs-a attrs-b)
       (Relation. attrs-a (into (vec tuples-a) tuples-b))
 
-      (not (same-keys? attrs-a attrs-b))
+      (and (not (same-keys? attrs-a attrs-b))
+           (seq tuples-a)  ; could be empty because
+           (seq tuples-b)) ; a query short-circuited
       (raise "Can’t sum relations with different attrs: " attrs-a " and " attrs-b
              {:error :query/where})
 

test/datascript/test/query_or.cljc

@@ -81,7 +81,23 @@
      (or-join [?e]
        (and [?e  :age ?a]
             [?e2 :age ?a]))]
-    #{1 2 3 4 5 6})
+    #{1 2 3 4 5 6}
+
+    [(or-join [?e ?n]
+       (and [?e :age 30] ; no matches, so this branch short-circuits
+            [?e :name ?n])
+       (and [?e :age 20]
+            [?e :name ?n]))
+     [(ground "Ivan") ?n]]
+    #{2 6}
+
+    [(or
+       (and [?e :age 30] ; no matches, so this branch short-circuits
+            [?e :name ?n])
+       (and [?e :age 20]
+            [?e :name ?n]))
+     [(ground "Ivan") ?n]]
+    #{2 6})
 
   ;; #348
   (is (= #{[1] [3] [4] [5]}
@@ -184,4 +200,4 @@
         (d/q '[:find ?e
                :where (or-join [[?e]]
                         [?e :name "Ivan"])]
-             @test-db))))
+             @test-db))))