why is “candidate function(s) not accessible” alth

问题:

I am getting compile error candidate function(s) not accessible when calling certain members, although I declared them as public. I only get the error when some class from vtk is involved (as return type or as argument) and when the class to be called is not in the same VS-project as the calling code. I also tried other vtk types with no luck :(

Here is some test code:

// A.h, in a seperate class library
#include <vtkActor.h>
public ref class A
{
public:
    A(void);

    void test1(vtkActor* actor);
    vtkActor* test2();
    void test3(char* actor);
    char* test4();
};


// B.h, Same as A but in the same project as the calling code 
#include <vtkActor.h>
ref class B
{
public:
    B(void);

    void test1(vtkActor* actor);
    vtkActor* test2();
    void test3(char* actor);
    char* test4();
};

I tried to call the functions from the same project B is in like this:

// calls to class library
A^ testA = gcnew A();    
testA ->test1(vtkActor::New());  // error
testA ->test2();                 // error
testA ->test3("");               // ok
testA ->test4();                 // ok

// calls to this project
B^ testB = gcnew B();
testB ->test1(vtkActor::New());  // ok
testB ->test2();                 // ok
testB ->test3("");               // ok
testB ->test4();                 // ok

In the two lines with //error this is the exact message:

error C3767: 'A::test1': candidate function(s) not accessible

How I can resolve this error? Why does it occur only on vtk-types?

kind regards, richn

回答1:

A short look at C3767 documentation and the community comments shows:

Another error-generating scenario

Another thing that seems to generate this error is using a native type in the signature of a public method, and then trying to call that method from a different assembly.

The solution here is to add a #pragma make_public on the native type, after defining the native type but before defining the managed method that uses it. The docs for #pragma make_public imply you're supposed to get a compiler warning when a non-public native type is exposed by a public managed type, but (at least with the default warning levels) that does not seem to be the case.

Did you check that suggestion?