func parse(rawURL string, viaRequest bool) (*URL, error) {
	var rest string
	var err error

	if stringContainsCTLByte(rawURL) {
		return nil, errors.New("net/url: invalid control character in URL")
	}

	if rawURL == "" && viaRequest {
		return nil, errors.New("empty url")
	}
	url := new(URL)

	if rawURL == "*" {
		url.Path = "*"
		return url, nil
	}

	// Split off possible leading "http:", "mailto:", etc.
	// Cannot contain escaped characters.
	if url.Scheme, rest, err = getScheme(rawURL); err != nil {
		return nil, err
	}
	url.Scheme = strings.ToLower(url.Scheme)

	if strings.HasSuffix(rest, "?") && strings.Count(rest, "?") == 1 {
		url.ForceQuery = true
		rest = rest[:len(rest)-1]
	} else {
		rest, url.RawQuery, _ = strings.Cut(rest, "?")
	}

	if !strings.HasPrefix(rest, "/") {
		if url.Scheme != "" {
			// We consider rootless paths per RFC 3986 as opaque.
			url.Opaque = rest
			return url, nil
		}
		if viaRequest {
			return nil, errors.New("invalid URI for request")
		}

		// Avoid confusion with malformed schemes, like cache_object:foo/bar.
		// See golang.org/issue/16822.
		//
		// RFC 3986, §3.3:
		// In addition, a URI reference (Section 4.1) may be a relative-path reference,
		// in which case the first path segment cannot contain a colon (":") character.
		if segment, _, _ := strings.Cut(rest, "/"); strings.Contains(segment, ":") {
			// First path segment has colon. Not allowed in relative URL.
			return nil, errors.New("first path segment in URL cannot contain colon")
		}
	}

	if (url.Scheme != "" || !viaRequest && !strings.HasPrefix(rest, "///")) && strings.HasPrefix(rest, "//") {
		var authority string
		authority, rest = rest[2:], ""
		if i := strings.Index(authority, "/"); i >= 0 {
			authority, rest = authority[:i], authority[i:]
		}
		url.User, url.Host, err = parseAuthority(authority)
		if err != nil {
			return nil, err
		}
	} else if url.Scheme != "" && strings.HasPrefix(rest, "/") {
		// OmitHost is set to true when rawURL has an empty host (authority).
		// See golang.org/issue/46059.
		url.OmitHost = true
	}

	// Set Path and, optionally, RawPath.
	// RawPath is a hint of the encoding of Path. We don't want to set it if
	// the default escaping of Path is equivalent, to help make sure that people
	// don't rely on it in general.
	if err := url.setPath(rest); err != nil {
		return nil, err
	}
	return url, nil
}