prog.cpp: In function ‘int main()’:
prog.cpp:13:29: in constexpr expansion of ‘operator""_int(((const char*)"ABC"), 3ul)’
prog.cpp:7:52: error: expression ‘<throw-expression>’ is not a constant-expression
return (len == 2) ? s[0] | (s[1] << 8) : throw "len must be 2!";
^~~~~~~~~~~~~~~~