builtin: change IError msg and code to methods + fix vlib, add a deprecation notice for the old usages (#13041)

vlib/net/errors.v

@@ -21,7 +21,7 @@ pub const (
 )
 
 pub fn socket_error_message(potential_code int, s string) ?int {
-	return socket_error(potential_code) or { return error('$err.msg; $s') }
+	return socket_error(potential_code) or { return error('$err.msg(); $s') }
 }
 
 pub fn socket_error(potential_code int) ?int {

vlib/net/http/header.v

@@ -627,18 +627,25 @@ fn (mut h Header) add_key(key string) {
 
 // Custom error struct for invalid header tokens
 struct HeaderKeyError {
-	msg          string
+	Error
 	code         int
 	header       string
 	invalid_char byte
 }
 
+pub fn (err HeaderKeyError) msg() string {
+	return "Invalid header key: '$err.header'"
+}
+
+pub fn (err HeaderKeyError) code() int {
+	return err.code
+}
+
 // is_valid checks if the header token contains all valid bytes
 fn is_valid(header string) ? {
 	for _, c in header {
 		if int(c) >= 128 || !is_token(c) {
 			return IError(HeaderKeyError{
-				msg: "Invalid header key: '$header'"
 				code: 1
 				header: header
 				invalid_char: c
@@ -647,7 +654,6 @@ fn is_valid(header string) ? {
 	}
 	if header.len == 0 {
 		return IError(HeaderKeyError{
-			msg: "Invalid header key: '$header'"
 			code: 2
 			header: header
 			invalid_char: 0

vlib/net/http/request.v

@@ -261,15 +261,20 @@ pub:
 }
 
 pub struct UnexpectedExtraAttributeError {
-pub:
-	msg  string
-	code int
+	Error
+	attributes []string
+}
+
+pub fn (err UnexpectedExtraAttributeError) msg() string {
+	return 'Encountered unexpected extra attributes: $err.attributes'
 }
 
 pub struct MultiplePathAttributesError {
-pub:
-	msg  string = 'Expected at most one path attribute'
-	code int
+	Error
+}
+
+pub fn (err MultiplePathAttributesError) msg() string {
+	return 'Expected at most one path attribute'
 }
 
 // multipart_form_body converts form and file data into a multipart/form

vlib/net/http/server.v

@@ -48,7 +48,7 @@ pub fn (mut s Server) listen_and_serve() ? {
 			break
 		}
 		mut conn := s.listener.accept() or {
-			if err.msg != 'net: op timed out' {
+			if err.msg() != 'net: op timed out' {
 				eprintln('accept() failed: $err; skipping')
 			}
 			continue

vlib/net/tcp.v

@@ -21,13 +21,13 @@ mut:
 
 pub fn dial_tcp(address string) ?&TcpConn {
 	addrs := resolve_addrs_fuzzy(address, .tcp) or {
-		return error('$err.msg; could not resolve address $address in dial_tcp')
+		return error('$err.msg(); could not resolve address $address in dial_tcp')
 	}
 
 	// Very simple dialer
 	for addr in addrs {
 		mut s := new_tcp_socket(addr.family()) or {
-			return error('$err.msg; could not create new tcp socket in dial_tcp')
+			return error('$err.msg(); could not create new tcp socket in dial_tcp')
 		}
 		s.connect(addr) or {
 			// Connection failed
@@ -215,10 +215,10 @@ mut:
 }
 
 pub fn listen_tcp(family AddrFamily, saddr string) ?&TcpListener {
-	s := new_tcp_socket(family) or { return error('$err.msg; could not create new socket') }
+	s := new_tcp_socket(family) or { return error('$err.msg(); could not create new socket') }
 
 	addrs := resolve_addrs(saddr, family, .tcp) or {
-		return error('$err.msg; could not resolve address $saddr')
+		return error('$err.msg(); could not resolve address $saddr')
 	}
 
 	// TODO(logic to pick here)

vlib/net/urllib/urllib.v

@@ -410,7 +410,7 @@ fn split_by_scheme(rawurl string) ?[]string {
 }
 
 fn get_scheme(rawurl string) ?string {
-	split := split_by_scheme(rawurl) or { return err.msg }
+	split := split_by_scheme(rawurl) or { return err.msg() }
 	return split[0]
 }
 
@@ -593,9 +593,9 @@ fn parse_host(host string) ?string {
 		// We do impose some restrictions on the zone, to avoid stupidity
 		// like newlines.
 		if zone := host[..i].index('%25') {
-			host1 := unescape(host[..zone], .encode_host) or { return err.msg }
-			host2 := unescape(host[zone..i], .encode_zone) or { return err.msg }
-			host3 := unescape(host[i..], .encode_host) or { return err.msg }
+			host1 := unescape(host[..zone], .encode_host) or { return err.msg() }
+			host2 := unescape(host[zone..i], .encode_zone) or { return err.msg() }
+			host3 := unescape(host[i..], .encode_host) or { return err.msg() }
 			return host1 + host2 + host3
 		}
 		if idx := host.last_index(':') {
@@ -606,7 +606,7 @@ fn parse_host(host string) ?string {
 			}
 		}
 	}
-	h := unescape(host, .encode_host) or { return err.msg }
+	h := unescape(host, .encode_host) or { return err.msg() }
 	return h
 	// host = h
 	// return host

vlib/net/websocket/websocket_server.v

@@ -122,7 +122,7 @@ fn (mut s Server) serve_client(mut c Client) ? {
 	}
 	s.setup_callbacks(mut server_client)
 	c.listen() or {
-		s.logger.error(err.msg)
+		s.logger.error(err.msg())
 		return err
 	}
 }