Feature: default to delete orphaned files, with -keepOrphanedFiles argument flag to disable feature

cmd/templ/generatecmd/main.go

@@ -45,7 +45,8 @@ type Arguments struct {
 	IncludeVersion                  bool
 	IncludeTimestamp                bool
 	// PPROFPort is the port to run the pprof server on.
-	PPROFPort int
+	PPROFPort         int
+	KeepOrphanedFiles bool
 }
 
 var defaultWorkerCount = runtime.NumCPU()
@@ -124,7 +125,6 @@ func runCmd(ctx context.Context, w io.Writer, args Arguments) (err error) {
 	if args.Proxy != "" {
 		p = proxy.New(args.ProxyPort, target)
 	}
-
 	fmt.Fprintln(w, "Processing path:", args.Path)
 	bo := backoff.NewExponentialBackOff()
 	bo.InitialInterval = time.Millisecond * 500
@@ -134,7 +134,7 @@ func runCmd(ctx context.Context, w io.Writer, args Arguments) (err error) {
 	var firstRunComplete bool
 	fileNameToLastModTime := make(map[string]time.Time)
 	for !firstRunComplete || args.Watch {
-		changesFound, errs := processChanges(ctx, w, fileNameToLastModTime, args.Path, args.GenerateSourceMapVisualisations, opts, args.WorkerCount)
+		changesFound, errs := processChanges(ctx, w, fileNameToLastModTime, args.Path, args.GenerateSourceMapVisualisations, opts, args.WorkerCount, args.KeepOrphanedFiles)
 		if len(errs) > 0 {
 			if errors.Is(errs[0], context.Canceled) {
 				return errs[0]
@@ -203,7 +203,7 @@ func shouldSkipDir(dir string) bool {
 	return false
 }
 
-func processChanges(ctx context.Context, stdout io.Writer, fileNameToLastModTime map[string]time.Time, path string, generateSourceMapVisualisations bool, opts []generator.GenerateOpt, maxWorkerCount int) (changesFound int, errs []error) {
+func processChanges(ctx context.Context, stdout io.Writer, fileNameToLastModTime map[string]time.Time, path string, generateSourceMapVisualisations bool, opts []generator.GenerateOpt, maxWorkerCount int, keepOrphanedFiles bool) (changesFound int, errs []error) {
 	sem := make(chan struct{}, maxWorkerCount)
 	var wg sync.WaitGroup
 
@@ -220,6 +220,19 @@ func processChanges(ctx context.Context, stdout io.Writer, fileNameToLastModTime
 		if info.IsDir() {
 			return nil
 		}
+		if !keepOrphanedFiles && strings.HasSuffix(fileName, "_templ.go") {
+			// Make sure the generated file is orphaned
+			// by checking if the corresponding .templ file exists.
+			if _, err := os.Stat(strings.TrimSuffix(fileName, "_templ.go") + ".templ"); err == nil {
+				// The .templ file exists, so we don't delete the generated file.
+				return nil
+			}
+			if err = os.Remove(fileName); err != nil {
+				return fmt.Errorf("failed to remove file: %w", err)
+			}
+			logWarning(stdout, "Deleted orphaned file %q\n", fileName)
+			return nil
+		}
 		if strings.HasSuffix(fileName, ".templ") {
 			lastModTime := fileNameToLastModTime[fileName]
 			fileInfo, err := info.Info()

cmd/templ/main.go

@@ -88,6 +88,8 @@ Args:
     Number of workers to use when generating code. (default runtime.NumCPUs)
   -pprof
     Port to run the pprof server on.
+  -keep-orphaned-files
+    Keeps orphaned generated templ files. (default false)
   -help
     Print help and exit.
 
@@ -120,6 +122,7 @@ func generateCmd(w io.Writer, args []string) (code int) {
 	proxyPortFlag := cmd.Int("proxyport", 7331, "")
 	workerCountFlag := cmd.Int("w", runtime.NumCPU(), "")
 	pprofPortFlag := cmd.Int("pprof", 0, "")
+	keepOrphanedFilesFlag := cmd.Bool("keep-orphaned-files", false, "")
 	helpFlag := cmd.Bool("help", false, "")
 	err := cmd.Parse(args)
 	if err != nil || *helpFlag {
@@ -138,6 +141,7 @@ func generateCmd(w io.Writer, args []string) (code int) {
 		IncludeVersion:                  *includeVersionFlag,
 		IncludeTimestamp:                *includeTimestampFlag,
 		PPROFPort:                       *pprofPortFlag,
+		KeepOrphanedFiles:               *keepOrphanedFilesFlag,
 	})
 	if err != nil {
 		color.New(color.FgRed).Fprint(w, "(✗) ")