v.pref: prevent `Too many targets.` from triggering when the command is an external one

cmd/tools/check_os_api_parity.v

@@ -95,7 +95,7 @@ fn (app App) gen_api_for_module_in_os(mod_name string, os_name string) string {
 	}
 	mpath := os.join_path('vlib', mod_name.replace('.', '/'))
 	tmpname := '/tmp/${mod_name}_${os_name}.c'
-	prefs, _ := pref.parse_args(['-os', os_name, '-o', tmpname, '-shared', mpath])
+	prefs, _ := pref.parse_args([], ['-os', os_name, '-o', tmpname, '-shared', mpath])
 	mut b := builder.new_builder(prefs)
 	b.compile_c()
 	mut res := []string{}

cmd/v/v.v

@@ -10,7 +10,7 @@ import v.util
 import v.builder
 
 const (
-	simple_cmd                          = [
+	external_tools                      = [
 		'fmt',
 		'up',
 		'vet',
@@ -63,14 +63,14 @@ fn main() {
 			} else {
 				mut args_and_flags := util.join_env_vflags_and_os_args()[1..].clone()
 				args_and_flags << ['run', '-']
-				pref.parse_args(args_and_flags)
+				pref.parse_args(external_tools, args_and_flags)
 			}
 		}
 		util.launch_tool(false, 'vrepl', os.args[1..])
 		return
 	}
 	args_and_flags := util.join_env_vflags_and_os_args()[1..]
-	prefs, command := pref.parse_args(args_and_flags)
+	prefs, command := pref.parse_args(external_tools, args_and_flags)
 	if prefs.is_verbose {
 		// println('args= ')
 		// println(args) // QTODO
@@ -95,7 +95,7 @@ fn main() {
 	}
 	// Start calling the correct functions/external tools
 	// Note for future contributors: Please add new subcommands in the `match` block below.
-	if command in simple_cmd {
+	if command in external_tools {
 		// External tools
 		util.launch_tool(prefs.is_verbose, 'v' + command, os.args[1..])
 		return

vlib/v/pref/pref.v

@@ -145,7 +145,7 @@ pub mut:
 	cache_manager       vcache.CacheManager
 }
 
-pub fn parse_args(args []string) (&Preferences, string) {
+pub fn parse_args(known_external_commands []string, args []string) (&Preferences, string) {
 	mut res := &Preferences{}
 	$if x64 {
 		res.m64 = true // follow V model by default
@@ -417,7 +417,8 @@ pub fn parse_args(args []string) (&Preferences, string) {
 						if command == 'run' {
 							break
 						}
-					} else if is_source_file(command) && is_source_file(arg) {
+					} else if is_source_file(command) && is_source_file(arg)
+						&& command !in known_external_commands {
 						eprintln('Too many targets. Specify just one target: <target.v|target_directory>.')
 						exit(1)
 					}