[ONNX] automatically detect value types of TensorProto and AttributeProto (#2262)

* [ONNX] detect automatically value types of TensorProto and AttributeProto
Signed-off-by: Artur Wojcik <artur.wojcik@intel.com>

* onnx: style apply
Signed-off-by: Artur Wojcik <artur.wojcik@intel.com>

src/ngraph/frontend/onnx_import/core/attribute.hpp

@@ -29,6 +29,13 @@ namespace ngraph
         class Graph;
         class Model;
 
+        // Detecting automatically the underlying type used to store the information
+        // for data type of values an attribute is holding. A bug was discovered in
+        // protobuf which forced ONNX team to switch from `enum AttributeProto_AttributeType`
+        // to `int32` in order to workaround the bug. This line allows using both versions
+        // of ONNX generated wrappers.
+        using AttributeProto_AttributeType = decltype(onnx::AttributeProto{}.type());
+
         namespace error
         {
             namespace attribute
@@ -37,7 +44,7 @@ namespace ngraph
                 {
                     struct Attribute : ngraph_error
                     {
-                        Attribute(const std::string& msg, onnx::AttributeProto_AttributeType type)
+                        Attribute(const std::string& msg, AttributeProto_AttributeType type)
                             : ngraph_error{msg + ": " +
                                            onnx::AttributeProto_AttributeType_Name(type)}
                         {
@@ -48,7 +55,7 @@ namespace ngraph
 
                 struct InvalidData : detail::Attribute
                 {
-                    explicit InvalidData(onnx::AttributeProto_AttributeType type)
+                    explicit InvalidData(AttributeProto_AttributeType type)
                         : Attribute{"invalid attribute type", type}
                     {
                     }
@@ -56,7 +63,7 @@ namespace ngraph
 
                 struct UnsupportedType : detail::Attribute
                 {
-                    explicit UnsupportedType(onnx::AttributeProto_AttributeType type)
+                    explicit UnsupportedType(AttributeProto_AttributeType type)
                         : Attribute{"unsupported attribute type", type}
                     {
                     }

src/ngraph/frontend/onnx_import/core/tensor.hpp

@@ -17,6 +17,7 @@
 #pragma once
 
 #include <onnx-ml.pb.h>
+#include <utility>
 #include <vector>
 
 #include "ngraph/shape.hpp"
@@ -26,24 +27,33 @@ namespace ngraph
 {
     namespace onnx_import
     {
+        // Detecting automatically the underlying type used to store the information
+        // for data type of values a tensor is holding. A bug was discovered in protobuf
+        // which forced ONNX team to switch from `enum TensorProto_DataType` to `int32`
+        // in order to workaround the bug. This line allows using both versions of ONNX
+        // generated wrappers.
+        using TensorProto_DataType = decltype(onnx::TensorProto{}.data_type());
+
         namespace error
         {
             namespace tensor
             {
                 struct invalid_data_type : ngraph_error
                 {
-                    explicit invalid_data_type(onnx::TensorProto_DataType type)
+                    explicit invalid_data_type(TensorProto_DataType type)
                         : ngraph_error{"invalid data type: " +
-                                       onnx::TensorProto_DataType_Name(type)}
+                                       onnx::TensorProto_DataType_Name(
+                                           static_cast<onnx::TensorProto_DataType>(type))}
                     {
                     }
                 };
 
                 struct unsupported_data_type : ngraph_error
                 {
-                    explicit unsupported_data_type(onnx::TensorProto_DataType type)
+                    explicit unsupported_data_type(TensorProto_DataType type)
                         : ngraph_error{"unsupported data type: " +
-                                       onnx::TensorProto_DataType_Name(type)}
+                                       onnx::TensorProto_DataType_Name(
+                                           static_cast<onnx::TensorProto_DataType>(type))}
                     {
                     }
                 };
@@ -306,7 +316,7 @@ namespace ngraph
                 }
             }
 
-            operator onnx::TensorProto_DataType() const { return m_tensor_proto->data_type(); }
+            operator TensorProto_DataType() const { return m_tensor_proto->data_type(); }
         private:
             const onnx::TensorProto* m_tensor_proto;
             Shape m_shape;

src/ngraph/frontend/onnx_import/core/value_info.hpp

@@ -43,9 +43,10 @@ namespace ngraph
                 };
                 struct unsupported_element_type : ngraph_error
                 {
-                    explicit unsupported_element_type(onnx::TensorProto_DataType type)
+                    explicit unsupported_element_type(TensorProto_DataType type)
                         : ngraph_error{"unsupported value info element type: " +
-                                       onnx::TensorProto_DataType_Name(type)}
+                                       onnx::TensorProto_DataType_Name(
+                                           static_cast<onnx::TensorProto_DataType>(type))}
                     {
                     }
                 };