feat: dispose iterator when it goes out of scope

leveldbstatic.nim

@@ -446,6 +446,10 @@ proc next*(iter: LevelDbQueryIter): (string, string) =
 proc dispose*(iter: LevelDbQueryIter) =
   iter.dispose(iter[])
 
+proc `=destroy`(iter: var LevelDbQueryIterObj) =
+  if iter.dispose != nil:
+    iter.dispose(iter)
+
 proc closeIter(iter: var LevelDbQueryIterObj, iterPtr: ptr leveldb_iterator_t) =
   iter.finished = true
   leveldb_iter_destroy(iterPtr)

tests/test.nim

@@ -255,6 +255,15 @@ suite "leveldb queryIter":
       iter.next() == empty
       iter.finished
 
+  test "iterator is disposed when it goes out of scope":
+    when defined(gcOrc) or defined(gcArc):
+      block:
+        let iter = db.queryIter()
+        discard iter.next()
+      db.close() # crashes if iterator not disposed
+    else:
+      skip()
+
   test "skip":
     let iter = db.queryIter(skip = 1)
     check: