tools: let v fmt use VTMP too, stabilise v test-cleancode

cmd/tools/vfmt.v

@@ -40,6 +40,7 @@ const (
 		['haiku', '_haiku.v'],
 		['qnx', '_qnx.v'],
 	]
+	vtmp_folder                  = util.get_vtmp_folder()
 )
 
 fn main() {
@@ -174,7 +175,7 @@ fn (foptions &FormatOptions) format_file(file string) {
 	formatted_content := fmt.fmt(file_ast, table, foptions.is_debug)
 	file_name := os.file_name(file)
 	ulid := rand.ulid()
-	vfmt_output_path := os.join_path(os.temp_dir(), 'vfmt_${ulid}_$file_name')
+	vfmt_output_path := os.join_path(vtmp_folder, 'vfmt_${ulid}_$file_name')
 	os.write_file(vfmt_output_path, formatted_content)
 	if foptions.is_verbose {
 		eprintln('fmt.fmt worked and $formatted_content.len bytes were written to $vfmt_output_path .')

cmd/tools/vtest-cleancode.v

@@ -82,11 +82,14 @@ fn main() {
 
 fn tsession(vargs string, tool_source string, tool_cmd string, tool_args string, flist []string, slist []string) testing.TestSession {
 	os.chdir(vroot)
-	util.prepare_tool_when_needed(tool_source)
 	testing.eheader('Run `$tool_cmd` over most .v files')
 	mut test_session := testing.new_test_session('$vargs $tool_args')
 	test_session.files << flist
 	test_session.skip_files << slist
+	util.prepare_tool_when_needed(tool_source)
+	// note that util.prepare_tool_when_needed will put its temporary files
+	// in the VTMP from the test session too, so they will be cleaned up
+	// at the end
 	test_session.test()
 	eprintln(test_session.benchmark.total_message('running `$tool_cmd` over most .v files'))
 	return test_session

vlib/v/builder/compile.v

@@ -9,21 +9,8 @@ import rand
 import v.pref
 import v.util
 
-fn get_vtmp_folder() string {
-	mut vtmp := os.getenv('VTMP')
-	if vtmp.len > 0 {
-		return vtmp
-	}
-	vtmp = os.join_path(os.temp_dir(), 'v')
-	if !os.exists(vtmp) || !os.is_dir(vtmp) {
-		os.mkdir_all(vtmp)
-	}
-	os.setenv('VTMP', vtmp, true)
-	return vtmp
-}
-
 fn (mut b Builder) get_vtmp_filename(base_file_name string, postfix string) string {
-	vtmp := get_vtmp_folder()
+	vtmp := util.get_vtmp_folder()
 	mut uniq := ''
 	if !b.pref.reuse_tmpc {
 		uniq = '.$rand.u64()'

vlib/v/util/util.v

@@ -462,6 +462,19 @@ pub fn recompile_file(vexe string, file string) {
 	}
 }
 
+pub fn get_vtmp_folder() string {
+	mut vtmp := os.getenv('VTMP')
+	if vtmp.len > 0 {
+		return vtmp
+	}
+	vtmp = os.join_path(os.temp_dir(), 'v')
+	if !os.exists(vtmp) || !os.is_dir(vtmp) {
+		os.mkdir_all(vtmp)
+	}
+	os.setenv('VTMP', vtmp, true)
+	return vtmp
+}
+
 pub fn should_bundle_module(mod string) bool {
 	return mod in bundle_modules || (mod.contains('.') && mod.all_before('.') in bundle_modules)
 }