apply minor cleanups suggested by tools

GARBLE_PARENT_WORK hasn't been used for a while.
A couple of other minor simplifications.

bench_test.go

@@ -117,7 +117,7 @@ func BenchmarkBuild(b *testing.B) {
 			// The cached rebuild will reuse all dependencies,
 			// but rebuild the main package itself.
 			if cached {
-				writeSourceFile("rebuild.go", []byte(fmt.Sprintf("package main\nvar v%d int", i)))
+				writeSourceFile("rebuild.go", fmt.Appendf(nil, "package main\nvar v%d int", i))
 			}
 
 			cmd := exec.Command(os.Args[0], args...)

internal/ctrlflow/ssa.go

@@ -11,7 +11,7 @@ import (
 
 // setUnexportedField is used to modify unexported fields of ssa api structures.
 // TODO: find an alternative way to access private fields or raise a feature request upstream
-func setUnexportedField(objRaw interface{}, name string, valRaw interface{}) {
+func setUnexportedField(objRaw any, name string, valRaw any) {
 	obj := reflect.ValueOf(objRaw)
 	for obj.Kind() == reflect.Pointer || obj.Kind() == reflect.Interface {
 		obj = obj.Elem()

main.go

@@ -151,7 +151,6 @@ var (
 	fset = token.NewFileSet()
 
 	sharedTempDir = os.Getenv("GARBLE_SHARED")
-	parentWorkDir = os.Getenv("GARBLE_PARENT_WORK")
 )
 
 const actionGraphFileName = "action-graph.json"
@@ -601,15 +600,11 @@ This command wraps "go %s". Below is its help:
 		return nil, err
 	}
 	os.Setenv("GARBLE_SHARED", sharedTempDir)
-	wd, err := os.Getwd()
-	if err != nil {
-		return nil, err
-	}
-	os.Setenv("GARBLE_PARENT_WORK", wd)
 
 	if flagDebugDir != "" {
-		if !filepath.IsAbs(flagDebugDir) {
-			flagDebugDir = filepath.Join(wd, flagDebugDir)
+		flagDebugDir, err = filepath.Abs(flagDebugDir)
+		if err != nil {
+			return nil, err
 		}
 
 		if err := os.RemoveAll(flagDebugDir); err != nil {

scripts/bench_literals.go

@@ -39,7 +39,7 @@ func generateRunSrc() string {
 	sb.WriteString(`
 var alwaysFalseFlag = false
 
-func noop(i interface{}) {
+func noop(i any) {
 	if alwaysFalseFlag {
 		println(i)
 	}