包含的功能隐藏了重载的虚拟功能

Question

I am developing a system using OpenCV. This system has a class with a virtual function which has the same name (train) as a virtual function used by OpenCV. When I compile, I get the following warning:

/opt/local/include/opencv2/ml/ml.hpp:957:18: warning: 'CvForestTree::train' hides overloaded virtual functions [-Woverloaded-virtual]

Most questions related to hiding overloaded virtual functions deal with classes and derived classes, but in this case my (perhaps incorrect) assumption the problem is that a class OpenCV implements has a function with the same name. Note that OpenCV headers must be included for my class definition of the function to work.

Obviously, I'd prefer not to change the name of the function in the class I made and I suspect I am doing something stupid to get this problem.

EDIT: CvForestTree is OpenCV's class, not mine. I'm not sure the exact area of line of code that causes the problem because the warning occurs for any file that includes OpenCV headers. Maybe that means it is an OpenCV bug.

Answer 1

The problem isn't with your code but the code of OpenCV: the CvForestTree class derives from CvTree and both classes have [virtual] train() member functions. Since the CvForestTree doesn't override all three overloads (I don't know if it overrides any but there are two train() overloads in CvForestTree and three in CvTree ), at least one of the CvTree::train() functions is hidden.

The fix to the problem is to have a declaration like

using CvTree::train;

in the definition of CvForestTree . Of course, this isn't your class. That's one of the problems with warnings: The are often emitted for code you don't control.

Answer 2

In fact you have to add this using CvDTree::train; in couple of places in ml.hpp:

class CV_EXPORTS CvBoostTree: public CvDTree
{
public:
  using CvDTree::train;
    CvBoostTree();


class CV_EXPORTS CvForestTree: public CvDTree
{
public:
  using CvDTree::train;
    CvForestTree();

Answer 3

My solution was to add using CvDTree::train; in two lines within include/opencv2/ml/ml.hpp . 1.Within CvForestTree class definition:

class CV_EXPORTS CvForestTree: public CvDTree
{
using CvDTree::train;

2. Within CvBoostTree class definition:

class CV_EXPORTS CvBoostTree: public CvDTree
{
using CvDTree::train;