> cat main.cpp
#include <type_traits>
int main() {
static_assert((::std::is_same<char, signed char>::value) == true);
static_assert((::std::is_same<char, unsigned char>::value) == true);
return 0;
}
> g++ -Wall -Wextra main.cpp
main.cpp: In function 'int main()':
main.cpp:4:2: error: static assertion failed
static_assert((::std::is_same<char, signed char>::value) == true);
^~~~~~~~~~~~~
main.cpp:5:2: error: static assertion failed
static_assert((::std::is_same<char, unsigned char>::value) == true);
^~~~~~~~~~~~~