add deprecated decorator for old apis expand and expand_as (#26759)

* add deprecated, test=develop

python/paddle/fluid/layers/nn.py

@@ -10205,6 +10205,7 @@ def unstack(x, axis=0, num=None):
     return outs
 
 
+@deprecated(since='2.0.0', update_to="paddle.expand")
 def expand(x, expand_times, name=None):
     """
     :alias_main: paddle.expand
@@ -10312,6 +10313,7 @@ def expand(x, expand_times, name=None):
     return out
 
 
+@deprecated(since='2.0.0', update_to="paddle.expand_as")
 def expand_as(x, target_tensor, name=None):
     """
     :alias_main: paddle.expand_as
@@ -10377,6 +10379,9 @@ def expand_as(x, target_tensor, name=None):
         #(3,20)
 
     """
+    if in_dygraph_mode():
+        return core.ops.expand_as(x, target_tensor)
+
     check_variable_and_dtype(
         x, 'x', ['float32', 'float64', 'int32', 'int64', 'bool'], 'expand_as')
     check_variable_and_dtype(target_tensor, 'target_tensor',

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

@@ -102,8 +102,23 @@ class TestExpandAsOpRank4(OpTest):
         self.check_grad(['X'], 'Out')
 
 
+# Test dygraph API
+class TestExpandAsDygraphAPI(unittest.TestCase):
+    def test_api(self):
+        import paddle
+        paddle.disable_static()
+        np_data_x = np.array([1, 2, 3]).astype('int32')
+        np_data_y = np.array([1, 2, 3, 1, 2, 3]).astype('int32')
+        data_x = paddle.to_tensor(np_data_x)
+        data_y = paddle.to_tensor(np_data_y)
+        out = fluid.layers.expand_as(data_x, data_y)
+        np_out = out.numpy()
+        assert np.array_equal(np_out, np.tile(np_data_x, (2)))
+        paddle.enable_static()
+
+
 # Test python API
-class TestExpandAPI(unittest.TestCase):
+class TestExpandAsAPI(unittest.TestCase):
     def test_api(self):
         input1 = np.random.random([12, 14]).astype("float32")
         input2 = np.random.random([48, 14]).astype("float32")