Make Node's type_info mandatory (#3891)

* Make Node's type_info mandatory

* Add ReplaceSlice to ZeroDimTensorEliminiation pass (#3899)

* Add ReplaceSlice to ZeroDimTensorEliminiation pass

* style

* Force Gelu decompose on CPU (#3902)

src/ngraph/node.hpp

@@ -178,7 +178,7 @@ namespace ngraph
         /// Returns the NodeTypeInfo for the node's class.
         /// During transition to type_info, returns a dummy type_info for Node if the class
         /// has not been updated yet.
-        virtual const NodeTypeInfo& get_type_info() const { return type_info; }
+        virtual const NodeTypeInfo& get_type_info() const = 0;
         virtual const char* get_type_name() const
         {
             auto& info = get_type_info();

test/control_dependencies.cpp

@@ -47,6 +47,8 @@ using namespace std;
 class ControlDependencyOp : public ngraph::op::Op
 {
 public:
+    static constexpr NodeTypeInfo type_info{"ControlDependencyOp", 0};
+    const NodeTypeInfo& get_type_info() const override { return type_info; }
     virtual std::shared_ptr<Node> copy_with_new_args(const NodeVector& new_args) const override
     {
         auto clone = make_shared<ControlDependencyOp>(new_args, std::set<std::shared_ptr<Node>>{});
@@ -77,6 +79,7 @@ public:
         }
     }
 };
+constexpr NodeTypeInfo ControlDependencyOp::type_info;
 
 TEST(control_dependencies, cdep_ops)
 {