doxygenfunction fails to document operator() overload

[cmas1]

Hi, I am using breathe 4.18.0 + sphinx 3.0.3 + doxygen 1.8.17 and I am encountering a problem when using the directive doxygenfunction to document the operator() of a class

Here is a dummy example

namespace test{
    
template<typename T>
class MyClass{
public:
    //constructors destructor and other stuff

    /**
     * This is an operator+
     * 
     * \param val input
     * \return something
     */
    T operator+(T val) const noexcept{
        return x+val;
    }

    /**
     * This is an operator()
     * 
     * \param val input
     * \return something
     */
    T operator()(T val) const noexcept{
        return val*x;
    }

private:
        T x;
};

}//namespace test

Now, when I build the documentation from

Test Documentation
==================

Using doxygenclass
~~~~~~~~~~~~~~~~~~
.. doxygenclass:: test::MyClass
    :members:

Using doxygenfunction
~~~~~~~~~~~~~~~~~~~~~
.. doxygenfunction:: test::MyClass::operator+(T val) const noexcept
.. doxygenfunction:: test::MyClass::operator()(T val) const noexcept

I got this result

So the directive doxygenclass manages to document the overload, whereas the directive doxygenfunction fails to find the function. I tried to change the signature of the function in the .rst file, but to no success.

[vermeeren]

When this issue is handled the thread from #524 (comment) should also be handled, which is about create_function_signature() in directives.py.