instantiation of template class 'std::basic_string<unsigned int>' requested. #include <SFML/System.hpp>

I am trying to use the Clock from SFML/System.hpp, but as soon as I include #include <SFML/System.hpp> in my header, and call make in the terminal, I get the error shown below. If I remove that line, there is no more error. This was never the case before today. I have tried multiple cases, but no help.

I have the following headers:

#include <string>
#include <iostream>
#include <fstream>
#include <SFML/System.hpp>
#include "EDistance.hpp"

ERROR:

g++ --std=c++17 -Wall -Werror -pedantic -g -c main.cpp -I/opt/homebrew/Cellar/boost/1.87.0_1/include/ -I/opt/homebrew/Cellar/sfml@2/2.6.2_1/include/
In file included from main.cpp:1:
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/c++/v1/string:821:42: error: implicit instantiation of undefined template 'std::char_traits<unsigned int>'
  821 |   static_assert(is_same<_CharT, typename traits_type::char_type>::value,
      |                                          ^
/opt/homebrew/Cellar/sfml@2/2.6.2_1/include/SFML/System/String.hpp:52:18: note: in instantiation of template class 'std::basic_string<unsigned int>' requested here
   52 |     typedef std::basic_string<Uint32>::iterator       Iterator;      //!< Iterator type
      |                  ^
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/c++/v1/__fwd/string.h:23:29: note: template is declared here
   23 | struct _LIBCPP_TEMPLATE_VIS char_traits;
      |                             ^
1 error generated.
make: *** [main.o] Error 1

Solution

std::basic_string, and in particular std::char_traits, is not intended to be used with integer types, only character types. That's why the compiler is complaining about std::char_traits<unsigned int> being undefined.

SFML's sf::String type is a UTF-32 string, so they should be using char32_t instead of UInt32. char32_t was added in C++11 specifically for supporting UTF-32.

You appear to be using an older version of SFML (2.6.2), where Sf::String uses std::basic_string<UInt32>. In SFML 3.0.0, they changed Sf::String to instead use std::u32string (aka std::basic_string<char32_t>). You should consider upgrading your copy of SFML.