[GitHub] [incubator-mxnet] Vigilans commented on issue #14116: Failure in generated op.h in version 1.3.1

[GitBox <gi...@apache.org>]

Vigilans commented on issue #14116: Failure in generated op.h in version 1.3.1
URL: https://github.com/apache/incubator-mxnet/issues/14116#issuecomment-498497289
 
 
   Problem found. Here is my procedures to trace the bug:
   
   * Debug [`OpWrapperGenerator.py#L364`](https://github.com/apache/incubator-mxnet/blob/master/cpp-package/scripts/OpWrapperGenerator.py#L364), and view `(name, description, argNames, argTypes, argDescs)` of `multi_sgd_update`.
   * From `argNames` and `argTypes`, we could see that `lrs` and `wds`'s type is `", required"`. 
   * From `name`, `description` and `argDescs`, we could locate the definition of op:
   * Definition of MultiSGDParam: [src/operator/optimizer_op-inl.h#L85](https://github.com/apache/incubator-mxnet/blob/master/src/operator/optimizer_op-inl.h#L85):
   * Generic Param Declaration Method: [3rdparty\...\dmlc\parameter.h#L231](https://github.com/dmlc/dmlc-core/blob/3943914eed66470bd010df581e29e4dca4f7df6f/include/dmlc/parameter.h#L228)
   * `lrs` and `wds`'s type `mxnet::Tuple<float>` falls back to [FieldsEntryBase<DT=mxnet::Tuple<Float>>](https://github.com/dmlc/dmlc-core/blob/3943914eed66470bd010df581e29e4dca4f7df6f/include/dmlc/parameter.h#L551)
   * In `GetFieldInfo`, here is where the evil [**", required"**](https://github.com/dmlc/dmlc-core/blob/3943914eed66470bd010df581e29e4dca4f7df6f/include/dmlc/parameter.h#L593) comes from.
   * We could see that `FieldsEntryBase` uses [`os << type_`](https://github.com/dmlc/dmlc-core/blob/3943914eed66470bd010df581e29e4dca4f7df6f/include/dmlc/parameter.h#L588) to fill the content before ", required".
   * Then we could see that `type_` is inited by [`dmlc::type_name<DT>()`](https://github.com/dmlc/dmlc-core/blob/3943914eed66470bd010df581e29e4dca4f7df6f/include/dmlc/parameter.h#L632).
   * Finally we could see that the type name is specified by custom specialization of [`type_name_helper<T>`](https://github.com/dmlc/dmlc-core/blob/3943914eed66470bd010df581e29e4dca4f7df6f/include/dmlc/type_traits.h#L101).
   
   Then, what happened to our `mxnet::Tuple<float>`?
   Here: https://github.com/apache/incubator-mxnet/blob/master/include/mxnet/tuple.h#L744
   ```cpp
   namespace dmlc {
   /*! \brief description for optional TShape */
   DMLC_DECLARE_TYPE_NAME(optional<mxnet::TShape>, "Shape or None");
   DMLC_DECLARE_TYPE_NAME(optional<mxnet::Tuple<int>>, "Shape or None");
   // avoid low version of MSVC
   #if !defined(_MSC_VER) // <----------- Here !
   template<typename T>
   struct type_name_helper<mxnet::Tuple<T> > {
     static inline std::string value() {
       return "tuple of <" + type_name<T>() + ">";
     }
   };
   #endif
   }  // namespace dmlc
   ```
   So the specialization of `mxnet::tuple<T>` was disabled for Visual Studio at the first place!!!
   
   I removed the `#if` block, recompile, then everything works fine.
   @junrushao1994 

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