c++ - Conversion in derived class inaccessible if base class is protected -

update:
this bug in wxwidgets. has been fixed in wxwidgets 3.1.1, if you're using c++11 compatible compiler.

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i'm trying dynamically bind event handler event in wxwidgets. unfortunately if derived class protected doesn't seem work.

minimal example:

// test.h class test : protected wxframe { public:     test();  private:     void sizing(wxsizeevent& event); };  // test.cpp test::test() {     bind(wxevt_sizing, &test::sizing, this); }  void test::sizing(wxsizeevent& event) { } 

that unfortunately doesn't seem work , nets following error on visual studio 2015 update 3:

wxwidgets\include\wx/meta/convertible.h(31): error c2243: 'type cast': conversion 'test *' 'wxevthandler *' exists, inaccessible   wxwidgets\include\wx/event.h(335): note: see reference class template instantiation 'wxconvertibleto<class,wxevthandler>' being compiled                     [               class=test           ]   wxwidgets\include\wx/event.h(3568): note: see reference class template instantiation 'wxeventfunctormethod<eventtag,test,eventarg,eventhandler>' being compiled                     [               eventtag=wxeventtypetag<wxsizeevent>,               eventarg=wxsizeevent,               eventhandler=test           ]   test.cpp(78): note: see reference function template instantiation 'void wxevthandler::bind<wxeventtypetag<wxsizeevent>,test,wxsizeevent,test>(const eventtag &,void (__cdecl test::* )(eventarg &),eventhandler *,int,int,wxobject *)' being compiled                     [               eventtag=wxeventtypetag<wxsizeevent>,               eventarg=wxsizeevent,               eventhandler=test           ] 

changing inheritance public makes work:

class test : public wxframe 

1. why conversion inaccessible when inheritance protected?
2. i not wish expose wxframe world, classes derive test class. how can while still being able dynamically bind event handler?

you work around using following:

bind(wxevt_sizing, std::bind(&test::sizing, this, std::placeholders::_1)); 

minimal sample compiles:

#include <wx/wx.h> #include <functional> using namespace std::placeholders;  class test : protected wxframe { public:     test();  private:     void sizing(wxsizeevent& event); }; test::test() {     bind(wxevt_sizing, std::bind(&test::sizing, this, _1)); }  void test::sizing(wxsizeevent& event) { }  class myapp: public wxapp { public:     virtual bool oninit(); }; class myframe: public wxframe { public:     myframe(const wxstring& title, const wxpoint& pos, const wxsize& size); private: }; wximplement_app(myapp); bool myapp::oninit() {     myframe *frame = new myframe( "", wxpoint(50, 50), wxsize(450, 340) );     frame->show( true );     return true; }  myframe::myframe(const wxstring& title, const wxpoint& pos, const wxsize& size) : wxframe(null, wxid_any, title, pos, size) {     test* test = new test(); }