polish

test=develop

paddle/fluid/imperative/layer.cc

@@ -27,6 +27,9 @@
 namespace paddle {
 namespace imperative {
 
+const char* PyLayer::kFwdInp = PyLayer::kFwdInp;
+const char* PyLayer::kFwdOut = PyLayer::kFwdOut;
+
 std::map<int, py::object> py_funcs_;
 
 using framework::Variable;

paddle/fluid/imperative/layer.h

@@ -200,8 +200,8 @@ class PyLayer {
  public:
   virtual ~PyLayer() {}
 
-  static constexpr char* kFwdInp = "X";
-  static constexpr char* kFwdOut = "Out";
+  static const char* kFwdInp;
+  static const char* kFwdOut;
 
   static void RegisterFunc(int func_id, const py::object& py_func);