How to force g++ to compile c++11 standard only?

Question

std::vector<bool>::emplace_back is available only since C++14. However, with my g++ 5.4.0 it compiles ok even if I specify -std=c++11 .

When I compile the same code with g++ 4.8.4, it fails. Is there a way how to convince g++ to strictly check the selected standard?

Note: I already use -pedantic -Wextra -Wall .

Example test.cpp :

#include <vector>

int main()
{
    std::vector<bool> v;
    v.emplace_back(true);
    return 0;
}

Compile with g++ -std=c++11 test.cpp -o test . With g++ 5.4.0 compiles ok, g++ 4.8.4 fires:

test.cpp: In function ‘int main()’:
test.cpp:6:7: error: ‘class std::vector<bool>’ has no member named ‘emplace_back’
    v.emplace_back(true);
      ^

Answer 1

This is related to libstdc++ that ships with gcc . In libstdc++ , bits/vector.tcc , you have the std::vector<bool> specialization with

 #if __cplusplus >= 201103L template<typename _Tp, typename _Alloc> template<typename... _Args> // ... more stuff vector<_Tp, _Alloc>::emplace_back(_Args&&... __args) 

The preprocessor branch enables the member function for C++11. In libc++ (the standard library implementation within the Llvm project), it's different:

 #if _LIBCPP_STD_VER > 11 template <class... _Args> #if _LIBCPP_STD_VER > 14 _LIBCPP_INLINE_VISIBILITY reference emplace_back(_Args&&... __args) #else _LIBCPP_INLINE_VISIBILITY void emplace_back(_Args&&... __args) #endif 

so here, emplace_back is only defined with a standard beyond C++11. You cannot do much about it, but I see two options.

1. To achieve strict conformance to C++11, not only compile with g++ , but also with clang++ . clang uses libc++ by default on MacOS, and on Linux you can pass some flag to enforce that (otherwise, it uses libstdc++ ), which does complain about emplace_back with -std=c++11 . Then use the results of compiling with clang to adjust your sources that are otherwise built with gcc .

2. Compile with gcc , but tell the compiler to use libcxx . From here , this also complains:

    g++ -std=c++11 -nostdinc++ -I /path/to/libcxx/include -nodefaultlibs \\ -lc++ -lc++abi -lm -lc -lgcc vecbool-emplace_back.cpp 

I would go with option 1, because it hardens your program in different ways, too, not only standard compliance. Also, option 2 is cumbersome.