How to check if two types are the same, ignoring const and reference?

Question

In C++, it is possible to use std::is_same to check if two types are exactly identical. Is there a way to check if two types are identical except, maybe, a const or a & modifier? Here is an example:

#include <type_traits>
#include <iostream>
using namespace std;

int main() {
    cout << boolalpha;
    cout << is_same<char,int>::value << endl;    // false - OK
    cout << is_same<char,char>::value << endl;   // true  - OK
    cout << is_same<char,const char>::value << endl;  // false - should be true
    cout << is_same<char,const char&>::value << endl; // false - should be true
}

Answer 1

Removing cv-qualifiers as well as returning a non reference type will be supported from C++20 onward std::remove_cvref

However as of current standard, you can use Type modifications functions in conjunction

template<class T1, class T2>
void print_is_same() {
  std::cout << std::is_same<T1, T2>() << '\n';
}

int main() {
  std::cout << std::boolalpha;

  print_is_same<char, int>(); //false
  print_is_same<char, char>(); //true

  print_is_same<char, std::remove_const<const char>::type>(); //true
  print_is_same<char, std::remove_const<std::remove_reference<const char &>::type>::type>(); //true
}

Or probably create a type alias such as

template<typename T>
using base_type = typename std::remove_cv<typename std::remove_reference<T>::type>::type;