Fix bug in ProgramTranslator.get_output, convert all items into VarBase in nested list. (#24267)

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

@@ -27,8 +27,9 @@ from paddle.fluid.dygraph.dygraph_to_static.ast_transformer import convert_to_st
 from paddle.fluid.dygraph.dygraph_to_static.ast_transformer import DygraphToStaticAst
 from paddle.fluid.dygraph.dygraph_to_static.utils import ast_to_source_code
 from paddle.fluid.dygraph.dygraph_to_static.variable_trans_func import data_layer_not_check
-from paddle.fluid.framework import in_dygraph_mode
 from paddle.fluid.data_feeder import check_type
+from paddle.fluid.framework import in_dygraph_mode
+from paddle.fluid.layers.utils import map_structure
 
 __all__ = ['ProgramTranslator', 'convert_function_with_cache']
 
@@ -403,10 +404,11 @@ class ProgramTranslator(object):
         if not program_cache.in_build_process:
             outputs = self._run(*args, **kwargs)
             with guard():
+                outputs = map_structure(to_variable, outputs)
                 if len(outputs) == 1:
-                    outputs = to_variable(outputs[0])
+                    outputs = outputs[0]
                 else:
-                    outputs = tuple(to_variable(x) for x in outputs)
+                    outputs = tuple(outputs)
         return outputs
 
     def get_func(self, dygraph_func):