log: add log.use_stdout(), use it to silence the transition note for the most commonly used V tools/examples (#23642)

ci/common/runner.v

@@ -34,6 +34,7 @@ pub fn (t Task) run() {
 
 pub fn run(all_tasks map[string]Task) {
 	unbuffer_stdout()
+	log.use_stdout()
 	if os.args.len < 2 {
 		println('Usage: v run macos_ci.vsh <task_name>')
 		println('Available tasks are: ${all_tasks.keys()}')

cmd/tools/fast/fast.v

@@ -41,6 +41,7 @@ fn lexec(cmd string) string {
 
 fn main() {
 	// ensure all log messages will be visible to the observers, even if the program panics
+	log.use_stdout()
 	log.set_always_flush(true)
 
 	total_sw := time.new_stopwatch()

cmd/tools/gen_vc.v

@@ -97,6 +97,7 @@ struct FlagOptions {
 }
 
 fn main() {
+	log.use_stdout()
 	mut fp := flag.new_flag_parser(os.args.clone())
 	fp.application(app_name)
 	fp.version(app_version)

cmd/tools/vcover/main.v

@@ -148,6 +148,7 @@ fn normalize_path(path string) string {
 }
 
 fn main() {
+	log.use_stdout()
 	mut ctx := Context{}
 	ctx.working_folder = normalize_path(os.real_path(os.getwd()))
 	mut fp := flag.new_flag_parser(os.args#[1..])

cmd/tools/vdownload.v

@@ -23,9 +23,7 @@ mut:
 const vexe = os.real_path(os.getenv_opt('VEXE') or { @VEXE })
 
 fn main() {
-	mut l := log.ThreadSafeLog{}
+	log.use_stdout()
-	l.set_output_stream(os.stdout())
-	log.set_logger(l)
 	mut ctx := Context{}
 	mut fp := flag.new_flag_parser(os.args#[1..])
 	fp.application(os.file_name(os.executable()))

cmd/tools/vretry_test.v

@@ -22,6 +22,7 @@ fn run(cmd string) os.Result {
 }
 
 fn test_retry() {
+	log.use_stdout()
 	log.warn('start...')
 	defer {
 		log.warn('... done')

cmd/tools/vshould-compile-all.v

@@ -4,6 +4,7 @@ import log
 const should_clean = os.args.contains('-c')
 
 fn main() {
+	log.use_stdout()
 	mut files := []string{}
 	args := os.args#[2..].filter(it != '-c')
 	for a in args {

examples/pendulum-simulation/animation.v

@@ -8,6 +8,7 @@ import sim.args as simargs
 
 fn main() {
 	unbuffer_stdout()
+	log.use_stdout()
 	args := simargs.parse_args(extra_workers: 1)! as simargs.ParallelArgs
 	mut app := anim.new_app(args)
 	mut workers := []thread{cap: args.workers}

examples/poll_coindesk_bitcoin_vs_usd_rate.v

@@ -7,6 +7,7 @@ import net.http
 const url = 'https://api.coindesk.com/v1/bpi/currentprice.json'
 
 fn main() {
+	log.use_stdout()
 	mut old_rate := f64(0)
 	for i := u64(1); true; i++ {
 		data := http.get(url) or {

examples/veb/websocket/server.v

@@ -12,6 +12,7 @@ import net.websocket
 const app_port = 8990
 
 fn main() {
+	log.use_stdout()
 	mut app := &App{
 		wss: new_websocker_server()!
 	}
@@ -64,6 +65,7 @@ fn wlog(message string) {
 fn new_websocker_server() !&websocket.Server {
 	mut logger := &log.Log{}
 	logger.set_level(.info)
+	logger.set_output_stream(os.stderr())
 	mut wss := websocket.new_server(.ip, app_port, '', logger: logger)
 	wss.set_ping_interval(100)
 	wss.on_connect(fn [mut logger] (mut server_client websocket.ServerClient) !bool {

vlib/log/README.md

@@ -58,16 +58,17 @@ fn main() {
 After 2025/01/21, the `log` module outputs to `stderr` by default.
 Before that, it used `stdout` by default.
 
-If you want to restore the previous behaviour, you have to explicitly call l.set_output_stream():
+If you want to restore the previous behaviour, you have to explicitly call `log.use_stdout()` :
 ```v
 import os
 import log
 
 fn main() {
 	// log.info('this will be printed to stderr after 2025/01/21 by default')
-	mut l := log.ThreadSafeLog{}
+	log.use_stdout()
-	l.set_output_stream(os.stdout())
-	log.set_logger(l)
 	log.info('this will be printed to stdout')
 }
 ```
+
+If you want to just silence the note about the stdout -> stderr, during the transition period,
+call `l.set_output_stream(os.stderr())` explicitly.

vlib/log/log.v

@@ -324,3 +324,11 @@ pub fn (mut l Log) set_short_tag(enabled bool) {
 pub fn (l Log) get_short_tag() bool {
 	return l.short_tag
 }
+
+// use_stdout will restore the old behaviour of logging to stdout, instead of stderr.
+// It will also silence the deprecation note in the transition period.
+pub fn use_stdout() {
+	mut l := ThreadSafeLog{}
+	l.set_output_stream(os.stdout())
+	set_logger(l)
+}