[Dy2stat]Fix error in tensor_shape_transformer. (#37999)

* fix error when tensor_shape_transformer. Before in stmt like `if len(paddle.shape(x)[0]) > 0`, `paddle` will be used as a variable

* handle other call like `fluid.layers.mean` and `fluid.layers.shape`

* add unit test

python/paddle/fluid/dygraph/dygraph_to_static/tensor_shape_transformer.py

@@ -282,6 +282,10 @@ def _is_var_shape(self, node):
             return False
 
         if isinstance(node, gast.Attribute):
+            # If node is `paddle.shape`, return False
+            if (node.attr == 'shape' and isinstance(node.value, gast.Name) and
+                    node.value.id == 'paddle'):
+                return False
             if node.attr != 'shape':
                 return False
             return True

python/paddle/fluid/tests/unittests/dygraph_to_static/test_tensor_shape.py

@@ -217,6 +217,12 @@ def dyfunc_change_shape_after_assign(x):
     return res
 
 
+def dyfunc_len_paddle_shape():
+    x = paddle.to_tensor([1, 2, 3])
+    if len(paddle.shape(x)) > 0:
+        print(x)
+
+
 # 1. Basic tests without control flow
 class TestTensorShapeBasic(unittest.TestCase):
     def setUp(self):
@@ -582,5 +588,11 @@ def test(self):
         func.concrete_program
 
 
+class TestPaddleShape(unittest.TestCase):
+    def test_paddle_shape(self):
+        func = paddle.jit.to_static(dyfunc_len_paddle_shape)
+        self.assertEqual('paddle.shape(x)' in func.code, True)
+
+
 if __name__ == '__main__':
     unittest.main()