catch the generatorfunction and intercept it. (#35369)

* catch the generatorfunction and intercept it.

* add test generator

* add test case

* refine the testcase

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

@@ -167,6 +167,17 @@ def dyfunc(x):
     if is_builtin(func) or is_unsupported(func):
         return func
 
+    if inspect.isgeneratorfunction(func):
+        # NOTE(xiongkun03): inspect.isfunction() will return True even though func is a generator function. 
+        # If we don't deal generatorfunction here, we will regard it as normal function and get errors in some
+        # occasion.
+        number_of_stars = 30
+        translator_logger.warn(
+            "\n\n" + "*" * number_of_stars +
+            "\nYour function:`{}` doesn't support to transform to static function because it is a generator function, it will be run as-is."
+            .format(func.__name__) + "\n" + "*" * number_of_stars + "\n\n")
+        return func
+
     if inspect.isfunction(func):
         # TODO(liym27): If func is a lambda function, special conversion is needed.
         if func.__name__ == '<lambda>':

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

@@ -0,0 +1,49 @@
+#   Copyright (c) 2021 PaddlePaddle Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from __future__ import print_function
+
+import unittest
+
+import logging
+import numpy as np
+
+import paddle
+import paddle.fluid as fluid
+from paddle.fluid.dygraph import ProgramTranslator
+from paddle.fluid.dygraph.dygraph_to_static.convert_call_func import CONVERSION_OPTIONS
+from test_program_translator import get_source_code
+from paddle.jit import to_static
+
+
+def dyfunc_generator():
+    for i in range(100):
+        yield paddle.to_tensor([i] * 10)
+
+
+def main_func():
+    """ Error will raise, but we only report a warning not intercept
+     """
+    for i in dyfunc_generator():
+        print(i)
+
+
+class TestConvertGenerator(unittest.TestCase):
+    def test_raise_error(self):
+        with self.assertRaises(Exception):
+            to_static(main_func)()
+
+
+if __name__ == '__main__':
+    unittest.main()