Inheriting std::stack causes an error with clang but works with gcc - c++

Question

Irrelevant. See update below.
I've been playing around with std::stack and noticed something strange. Here's the code:
.h file
template<typename Tp> using VecOfRef = std::vector<std::reference_wrapper<Tp>>;
template <typename T>
struct Stack : public std::stack<T,VecOfRef<T>> {};
struct Simple {
std::string txt = "txt";
};
.cpp file
int main () {
Simple smpl;
auto vec = VecOfRef<Simple>{std::ref(smpl)};
auto stdStack = std::stack<Simple,decltype(vec)>(vec); //works fine
auto myStack = Stack<Simple>(vec); //error
//to check if a reference is stored
stdStack.push(smpl);
smpl.txt.append("append");
Simple& r = sStack.top();
cout << r.txt << endl;
return 0;
}
The error message says:
19:
No matching conversion for functional-style cast from
'std::__1::vector,
std::__1::allocator > >' to
'Stack'
UPDATE:
I have been playing around with this and managed to almost get the code to work:
#include <vector>
#include <string>
#include <stack>
#include <iostream>
#include <functional>
template<typename Tp> using VecOfRef = std::vector<std::reference_wrapper<Tp>>;
template <typename T>
class Stack : public std::stack<T,VecOfRef<T>> {
public:
using std::stack<T,VecOfRef<T>>::stack;
using std::stack<T,VecOfRef<T>>::c;
T& top() {
return c.back().get();
}
};
struct Simple {
std::string txt = "txt";
void print() { std::cout << txt << std::endl; }
};
int main() {
Simple smpl;
Simple smpl_2;
Simple smpl_3;
VecOfRef<Simple> vr {smpl,smpl_2,smpl_3};
// auto myStack = Stack<Simple> (vr); // error
auto myStack = Stack<Simple> ({smpl,smpl_2,smpl_3}); // ok
auto stk = std::stack<Simple,std::vector<std::reference_wrapper<Simple>>>(vr); // ok_2
smpl.txt.append("_append");
smpl_2.txt.append("_append_2");
smpl_3.txt.append("_append_3");
myStack.top().print(); // txt_append_3
myStack.pop();
myStack.top().print(); // txt_append_2
myStack.pop();
myStack.top().print(); // txt_append
return 0;
}
It compiles under gcc but does not under clang. The error says:
Error: stack:154:43: No type named 'type' in 'std::__1::enable_if'; 'enable_if' cannot be used to disable this declaration
Line in the stack file:

Answer 1

Maybe the reason is that you missed a constructor
template <typename T>
struct Stack : public std::stack<T,VecOfRef<T>>
{
Stack(VecOfRef<T>){}
};

Answer 2

You didn't add any constructors to your Stack class.
If you want to inherit std:stack's constructors, you must specify that, using:
using std::stack<T,VecOfRef<T>>::stack; in your class.