v test-cleancode: add -fix flag (#9364)

Author: zakuro9715

cmd/tools/vtest-cleancode.v

@@ -74,9 +74,11 @@ const (
 	]
 )
 
-const vexe = os.getenv('VEXE')
-
-const vroot = os.dir(vexe)
+const (
+	vexe   = os.getenv('VEXE')
+	vroot  = os.dir(vexe)
+	is_fix = '-fix' in os.args
+)
 
 fn main() {
 	args_string := os.args[1..].join(' ')
@@ -101,8 +103,8 @@ fn tsession(vargs string, tool_source string, tool_cmd string, tool_args string,
 
 fn v_test_vetting(vargs string) {
 	vet_session := tsession(vargs, 'vvet', 'v vet', 'vet', vet_folders, vet_known_failing_exceptions)
-	verify_session := tsession(vargs, 'vfmt.v', 'v fmt -verify', 'fmt -verify', vfmt_verify_list,
-		verify_known_failing_exceptions)
+	fmt_cmd, fmt_args := if is_fix { 'v fmt -w', 'fmt -w' } else { 'v fmt -verify', 'fmt -verify' }
+	verify_session := tsession(vargs, 'vfmt.v', fmt_cmd, fmt_args, vfmt_verify_list, verify_known_failing_exceptions)
 	//
 	if vet_session.benchmark.nfail > 0 || verify_session.benchmark.nfail > 0 {
 		eprintln('\n')