Question

This compiles fine in GCC 3 and 4. MSVC++ can’t figure out the type of noFunction and throws some hideous errors. Note if you cast noFunction to BFunction, it works just fine in VS2010.

My question: is this a defect in VS2010, or GCC bending the rules?

#include <map>

using namespace std;

typedef bool (*AFunction)(int arg1, int arg2);
typedef bool (*BFunction)(long arg1, bool arg2);

bool noFunction(long, bool) { return true; }

void test(AFunction a)
{

    make_pair(a, noFunction); //fails in VS2010

}

N.B. casting noFunction to BFunction fixes the problem in VS2010.

make_pair(a, (BFunction)noFunction);  //works everywhere

.

.

.

Here is the error for reference:

    1>  makepairtest.cpp
1>c:\program files (x86)\microsoft visual studio 10.0\vc\include\type_traits(197): error C2752: 'std::tr1::_Remove_reference<_Ty>' : more than one partial specialization matches the template argument list
1>          with
1>          [
1>              _Ty=bool (__cdecl &)(long,bool)
1>          ]
1>          c:\program files (x86)\microsoft visual studio 10.0\vc\include\xtr1common(356): could be 'std::tr1::_Remove_reference<_Ty&&>'
1>          c:\program files (x86)\microsoft visual studio 10.0\vc\include\xtr1common(350): or       'std::tr1::_Remove_reference<_Ty&>'
1>          c:\program files (x86)\microsoft visual studio 10.0\vc\include\type_traits(962) : see reference to class template instantiation 'std::tr1::remove_reference<_Ty>' being compiled
1>          with
1>          [
1>              _Ty=bool (__cdecl &)(long,bool)
1>          ]
1>          c:\program files (x86)\microsoft visual studio 10.0\vc\include\utility(26) : see reference to class template instantiation 'std::tr1::decay<_Ty>' being compiled
1>          with
1>          [
1>              _Ty=bool (__cdecl &)(long,bool)
1>          ]
1>          c:\xxx\makepairtest.cpp(14) : see reference to class template instantiation 'std::tr1::_Unrefwrap<_Type>' being compiled
1>          with
1>          [
1>              _Type=bool (__cdecl &)(long,bool)
1>          ]
1>c:\program files (x86)\microsoft visual studio 10.0\vc\include\type_traits(965): error C2528: 'abstract declarator' : pointer to reference is illegal
1>c:\program files (x86)\microsoft visual studio 10.0\vc\include\type_traits(349): error C2528: 'type' : pointer to reference is illegal
1>          c:\program files (x86)\microsoft visual studio 10.0\vc\include\type_traits(967) : see reference to class template instantiation 'std::tr1::add_pointer<_Ty>' being compiled
1>          with
1>          [
1>              _Ty=bool (__cdecl &)(long,bool)
1>          ]
1>c:\program files (x86)\microsoft visual studio 10.0\vc\include\utility(148): error C2535: 'std::_Pair_base<_Ty1,_Ty2>::_Pair_base(const _Ty1 &,const _Ty2)' : member function already defined or declared
1>          with
1>          [
1>              _Ty1=bool (__cdecl *)(int,int),
1>              _Ty2=bool (__cdecl &)(long,bool)
1>          ]
1>          c:\program files (x86)\microsoft visual studio 10.0\vc\include\utility(134) : see declaration of 'std::_Pair_base<_Ty1,_Ty2>::_Pair_base'
1>          with
1>          [
1>              _Ty1=bool (__cdecl *)(int,int),
1>              _Ty2=bool (__cdecl &)(long,bool)
1>          ]
1>          c:\program files (x86)\microsoft visual studio 10.0\vc\include\utility(174) : see reference to class template instantiation 'std::_Pair_base<_Ty1,_Ty2>' being compiled
1>          with
1>          [
1>              _Ty1=bool (__cdecl *)(int,int),
1>              _Ty2=bool (__cdecl &)(long,bool)
1>          ]
1>          c:\xxx\makepairtest.cpp(14) : see reference to class template instantiation 'std::pair<_Ty1,_Ty2>' being compiled
1>          with
1>          [
1>              _Ty1=bool (__cdecl *)(int,int),
1>              _Ty2=bool (__cdecl &)(long,bool)
1>          ]

Answer 1

Taking the address of noFunction works with VC10 and gcc 4.5.2, i.e.:

make_pair(a, &noFunction);

Per the error message you posted, I would guess it has to do with how VC handles binding to rvalues.