Fix compilation issues for default constructors (#3928)

src/ngraph/op/fused/clamp.hpp

@@ -53,8 +53,8 @@ namespace ngraph
             double get_min() const { return m_min; }
             double get_max() const { return m_max; }
         private:
-            const double m_min;
-            const double m_max;
+            double m_min;
+            double m_max;
         };
     }
 }

src/ngraph/op/relu.hpp

@@ -56,7 +56,10 @@ namespace ngraph
             NGRAPH_API
             static constexpr NodeTypeInfo type_info{"ReluBackprop", 0};
             const NodeTypeInfo& get_type_info() const override { return type_info; }
-            ReluBackprop() = default;
+            ReluBackprop()
+                : BinaryElementwiseArithmetic(AutoBroadcastSpec::NONE)
+            {
+            }
             /// \brief Constructs a ReluBackprop operation.
             ///
             /// \param arg Node that produces the relu forward input tensor.

src/ngraph/op/util/activation_functions.hpp

@@ -84,6 +84,7 @@ namespace ngraph
                 ActivationFunction(ActivationFunctionType f, float alpha, float beta);
                 ActivationFunction(ActivationFunctionType f, float alpha);
                 ActivationFunction(ActivationFunctionType f);
+                ActivationFunction() = default;
 
                 ///
                 /// \brief  Calls stored activation function with provided node argument.

src/ngraph/op/util/rnn_cell_base.hpp

@@ -56,6 +56,8 @@ namespace ngraph
                             const std::vector<float>& activations_alpha,
                             const std::vector<float>& activations_beta);
 
+                RNNCellBase() = default;
+
                 std::size_t get_hidden_size() const { return m_hidden_size; }
                 float get_clip() const { return m_clip; }
                 const std::vector<std::string>& get_activations() const { return m_activations; }
@@ -117,12 +119,12 @@ namespace ngraph
                 ///
                 std::shared_ptr<Node> clip(const Output<Node>& data) const;
 
-            private:
-                const std::size_t m_hidden_size;
-                const float m_clip;
-                const std::vector<std::string> m_activations;
-                const std::vector<float> m_activations_alpha;
-                const std::vector<float> m_activations_beta;
+            protected:
+                std::size_t m_hidden_size;
+                float m_clip;
+                std::vector<std::string> m_activations;
+                std::vector<float> m_activations_alpha;
+                std::vector<float> m_activations_beta;
             };
         } // namespace util
     }     // namespace op