Constant USERINFO_ENCODE_SET 

const USERINFO_ENCODE_SET: &AsciiSet;

Characters that must be percent-encoded in userinfo (RFC 3986 section 3.2.1). This includes: gen-delims (:/?#[]@) and sub-delims (!$&’()*+,;=) except those allowed. For userinfo, we encode: : @ / ? # [ ] and space, plus control characters.