Starting with C++17 std::string_view is available. It supports constexpr comparisson:
#include <string_view>
constexpr bool strings_equal(char const * a, char const * b) {
return std::string_view(a)==b;
}
int main() {
static_assert(strings_equal("abc", "abc" ), "strings are equal");
static_assert(!strings_equal("abc", "abcd"), "strings are not equal");
return 0;
}