Fix data type of variable in edit distance evaluator (#19618)

* Fix data type of variable in edit distance evaluator.
test=develop

* Add unitest for edit_distance python API.
test=develop

python/paddle/fluid/evaluator.py

@@ -263,7 +263,7 @@ class EditDistance(Evaluator):
 
         zero = layers.fill_constant(shape=[1], value=0.0, dtype='float32')
         compare_result = layers.equal(distances, zero)
-        compare_result_int = layers.cast(x=compare_result, dtype='int')
+        compare_result_int = layers.cast(x=compare_result, dtype='int64')
         seq_right_count = layers.reduce_sum(compare_result_int)
         instance_error_count = layers.elementwise_sub(
             x=seq_num, y=seq_right_count)

python/paddle/fluid/tests/unittests/test_layers.py

@@ -2345,6 +2345,15 @@ class TestBook(LayerTest):
                 label_length=label_length)
             return (output)
 
+    def test_edit_distance(self):
+        with self.static_graph():
+            predict = layers.data(
+                name='predict', shape=[-1, 1], dtype='int64', lod_level=1)
+            label = layers.data(
+                name='label', shape=[-1, 1], dtype='int64', lod_level=1)
+            evaluator = fluid.evaluator.EditDistance(predict, label)
+            return evaluator.metrics
+
 
 if __name__ == '__main__':
     unittest.main()