tools: add v timeout to be able to later use v timeout 5.1 git -C . fetch V_REPO in v doctor and other tools.

cmd/tools/vtimeout.v

@@ -0,0 +1,43 @@
+import os
+import time
+import flag
+
+struct Context {
+mut:
+	show_help     bool
+	cmd_line_opts []string
+	full_cmd      string
+	timeout       f64
+}
+
+fn main() {
+	mut ctx := Context{}
+	args := arguments()
+	mut fp := flag.new_flag_parser(args#[1..])
+	fp.application('v timeout')
+	fp.version('0.0.1')
+	fp.description('Run a command with a time limit. Example: `v timeout 0.3 v run examples/hello_world.v`')
+	fp.arguments_description('timeout_in_seconds CMD [ARGS]')
+	fp.skip_executable()
+	fp.limit_free_args_to_at_least(2)!
+	ctx.show_help = fp.bool('help', `h`, false, 'Show this help screen.')
+	if ctx.show_help {
+		println(fp.usage())
+		exit(0)
+	}
+	ctx.cmd_line_opts = fp.finalize() or {
+		eprintln('> error: ${err}')
+		exit(125) // mimic the exit codes of `timeout` in coreutils
+	}
+	ctx.timeout = ctx.cmd_line_opts[0].f64()
+	ctx.cmd_line_opts = ctx.cmd_line_opts#[1..]
+	ctx.full_cmd = ctx.cmd_line_opts.join(' ')
+	spawn fn (ctx Context) {
+		tperiod := time.Duration(i64(ctx.timeout * time.second))
+		time.sleep(tperiod)
+		// eprintln('> error: timeout of ${tperiod.seconds():5.3f}s reached, before command finished; command was: `${ctx.full_cmd}`')
+		exit(124)
+	}(ctx)
+	ecode := os.system(ctx.full_cmd)
+	exit(ecode)
+}

cmd/v/v.v

@@ -49,6 +49,7 @@ const external_tools = [
 	'test-parser',
 	'test-self',
 	'time',
+	'timeout',
 	'tracev',
 	'up',
 	'vet',