Question

MSVC++ doesn’t yet support variadic templates, so its standard library “fakes” these for classes like std::tuple through use of macros. I recently tried compiling one of my projects with the VC11 beta, and got this to show for it:

gtest\gtest.h(9735): error C2977: 'std::tuple' : too many template arguments
c:\program files (x86)\microsoft visual studio 11.0\vc\include\utility(72) : see declaration of 'std::tuple'
gtest\gtest.h(9743): error C2977: 'std::tuple' : too many template arguments
gtest\gtest.h(14568): error C2977: 'std::tuple' : too many template arguments
gtest\gtest.h(14568): error C3203: 'tuple' : unspecialized class template can't be used as a template argument for template parameter 'T', expected a real type
gtest\gtest.h(14568): error C2955: 'std::tuple' : use of class template requires template argument list
gtest\gtest.h(14568): error C2955: 'testing::internal::ParamGeneratorInterface' : use of class template requires template argument list
c:\users\billy\documents\visual studio 2010\projects\instalog\logtests\gtest\gtest.h(10076) : see declaration of 'testing::internal::ParamGeneratorInterface'
gtest\gtest.h(14570): error C2977: 'std::tuple' : too many template arguments
gtest\gtest.h(14581): error C3203: 'tuple' : unspecialized class template can't be used as a template argument for template parameter 'T', expected a real type
gtest\gtest.h(14581): error C2955: 'std::tuple' : use of class template requires template argument list
gtest\gtest.h(14586): error C3203: 'tuple' : unspecialized class template can't be used as a template argument for template parameter 'T', expected a real type
gtest\gtest.h(14586): error C2955: 'std::tuple' : use of class template requires template argument list
gtest\gtest.h(14593): error C3203: 'tuple' : unspecialized class template can't be used as a template argument for template parameter 'T', expected a real type
c:\users\billy\documents\visual studio 2010\projects\instalog\logtests\gtest\gtest.h(14593) : see reference to class template instantiation 'testing::internal::CartesianProductGenerator9<T1,T2,T3,T4,T5,T6,T7,T8,T9>::Iterator' being compiled
gtest\gtest.h(14593): error C2955: 'std::tuple' : use of class template requires template argument list
gtest\gtest.h(14593): error C2955: 'testing::internal::ParamIteratorInterface' : use of class template requires template argument list
c:\users\billy\documents\visual studio 2010\projects\instalog\logtests\gtest\gtest.h(10003) : see declaration of 'testing::internal::ParamIteratorInterface'
gtest\gtest.h(14595): error C3203: 'tuple' : unspecialized class template can't be used as a template argument for template parameter 'T', expected a real type
gtest\gtest.h(14595): error C2955: 'std::tuple' : use of class template requires template argument list
gtest\gtest.h(14628): error C3203: 'tuple' : unspecialized class template can't be used as a template argument for template parameter 'T', expected a real type
gtest\gtest.h(14628): error C2955: 'std::tuple' : use of class template requires template argument list
gtest\gtest.h(14670): error C3203: 'tuple' : unspecialized class template can't be used as a template argument for template parameter 'T', expected a real type
gtest\gtest.h(14670): error C2955: 'std::tuple' : use of class template requires template argument list
gtest\gtest.h(14674): error C3203: 'tuple' : unspecialized class template can't be used as a template argument for template parameter 'T', expected a real type
gtest\gtest.h(14674): error C2955: 'std::tuple' : use of class template requires template argument list
gtest\gtest.h(14755): error C3203: 'tuple' : unspecialized class template can't be used as a template argument for template parameter 'T', expected a real type
gtest\gtest.h(14755): error C2955: 'std::tuple' : use of class template requires template argument list
gtest\gtest.h(14807): error C2977: 'std::tuple' : too many template arguments
gtest\gtest.h(14807): error C3203: 'tuple' : unspecialized class template can't be used as a template argument for template parameter 'T', expected a real type
gtest\gtest.h(14807): error C2955: 'std::tuple' : use of class template requires template argument list
gtest\gtest.h(14807): error C2955: 'testing::internal::ParamGeneratorInterface' : use of class template requires template argument list
gtest\gtest.h(14809): error C2977: 'std::tuple' : too many template arguments
gtest\gtest.h(14821): error C3203: 'tuple' : unspecialized class template can't be used as a template argument for template parameter 'T', expected a real type
gtest\gtest.h(14821): error C2955: 'std::tuple' : use of class template requires template argument list
gtest\gtest.h(14826): error C3203: 'tuple' : unspecialized class template can't be used as a template argument for template parameter 'T', expected a real type
gtest\gtest.h(14826): error C2955: 'std::tuple' : use of class template requires template argument list
gtest\gtest.h(14833): error C3203: 'tuple' : unspecialized class template can't be used as a template argument for template parameter 'T', expected a real type
c:\users\billy\documents\visual studio 2010\projects\instalog\logtests\gtest\gtest.h(14833) : see reference to class template instantiation 'testing::internal::CartesianProductGenerator10<T1,T2,T3,T4,T5,T6,T7,T8,T9,T10>::Iterator' being compiled
gtest\gtest.h(14833): error C2955: 'std::tuple' : use of class template requires template argument list
gtest\gtest.h(14833): error C2955: 'testing::internal::ParamIteratorInterface' : use of class template requires template argument list
gtest\gtest.h(14835): error C3203: 'tuple' : unspecialized class template can't be used as a template argument for template parameter 'T', expected a real type
gtest\gtest.h(14835): error C2955: 'std::tuple' : use of class template requires template argument list
gtest\gtest.h(14871): error C3203: 'tuple' : unspecialized class template can't be used as a template argument for template parameter 'T', expected a real type
gtest\gtest.h(14871): error C2955: 'std::tuple' : use of class template requires template argument list
gtest\gtest.h(14917): error C3203: 'tuple' : unspecialized class template can't be used as a template argument for template parameter 'T', expected a real type
gtest\gtest.h(14917): error C2955: 'std::tuple' : use of class template requires template argument list
gtest\gtest.h(14921): error C3203: 'tuple' : unspecialized class template can't be used as a template argument for template parameter 'T', expected a real type
gtest\gtest.h(14921): error C2955: 'std::tuple' : use of class template requires template argument list
gtest\gtest.h(15007): error C3203: 'tuple' : unspecialized class template can't be used as a template argument for template parameter 'T', expected a real type
gtest\gtest.h(15007): error C2955: 'std::tuple' : use of class template requires template argument list
gtest\gtest.h(15289): error C2977: 'std::tuple' : too many template arguments
gtest\gtest.h(15289): error C3203: 'tuple' : unspecialized class template can't be used as a template argument for template parameter 'T', expected a real type
gtest\gtest.h(15289): error C2955: 'std::tuple' : use of class template requires template argument list
gtest\gtest.h(15333): error C2977: 'std::tuple' : too many template arguments
gtest\gtest.h(15333): error C3203: 'tuple' : unspecialized class template can't be used as a template argument for template parameter 'T', expected a real type
gtest\gtest.h(15333): error C2955: 'std::tuple' : use of class template requires template argument list

I’ve heard there’s a #define that can be set somewhere to change this setting, but I (for the life of me) can’t remember what it is. What is it?

Answer 1

You can define _VARIADIC_MAX to any value between 5 and 10, inclusive.

This, and many other interesting facts about Visual C++ 11, can be found in the MSDN article, “C++11 Features (Modern C++).” This particular macro is discussed in the section entitled “Faux variadics.”