#include <future>

int main (){
return 0;
}

Standart c++ header <future> includes  <ppltasks.h> (line 18). <ppltasks.h> in it's turn uses header 
<ppl.h>(line 21), where such definition appears: 

    mutable _Combinable_type &_Combinable; // (line 4151: column 5)

In such definition keyword mutable is applied to a reference type despite the fact that it violates C++11 standart:
"The mutable specifier shall appear only in the declaration of a non-static data member (9.2) whose type is
neither const-qualified nor a reference type."  (C++11 standart: 7.1.1 Storage class specifiers)