fix: use temp directory for watch mode files, fixes 1093 (#1099)

Author: a-h

.version

@@ -1 +1 @@
-0.3.850
+0.3.851

cmd/templ/generatecmd/cmd.go

@@ -17,6 +17,8 @@ import (
 	"sync/atomic"
 	"time"
 
+	templruntime "github.com/a-h/templ/runtime"
+
 	"github.com/a-h/templ"
 	"github.com/a-h/templ/cmd/templ/generatecmd/modcheck"
 	"github.com/a-h/templ/cmd/templ/generatecmd/proxy"
@@ -28,7 +30,7 @@ import (
 	"github.com/fsnotify/fsnotify"
 )
 
-const defaultWatchPattern = `(.+\.go$)|(.+\.templ$)|(.+_templ\.txt$)`
+const defaultWatchPattern = `(.+\.go$)|(.+\.templ$)`
 
 func NewGenerate(log *slog.Logger, args Arguments) (g *Generate, err error) {
 	g = &Generate{
@@ -104,6 +106,7 @@ func (cmd Generate) Run(ctx context.Context) (err error) {
 		cmd.Log.Warn("templ version check: " + err.Error())
 	}
 
+	cmd.Log.Debug("Creating filesystem event handler")
 	fseh := NewFSEventHandler(
 		cmd.Log,
 		cmd.Args.Path,
@@ -189,7 +192,6 @@ func (cmd Generate) Run(ctx context.Context) (err error) {
 			"All post-generation events processed, deleting watch mode text files",
 			slog.Int64("errorCount", errorCount.Load()),
 		)
-
 		fileEvents := make(chan fsnotify.Event)
 		go func() {
 			if err := watcher.WalkFiles(ctx, cmd.Args.Path, cmd.WatchPattern, fileEvents); err != nil {
@@ -200,8 +202,9 @@ func (cmd Generate) Run(ctx context.Context) (err error) {
 			close(fileEvents)
 		}()
 		for event := range fileEvents {
-			if strings.HasSuffix(event.Name, "_templ.txt") {
-				if err = os.Remove(event.Name); err != nil {
+			if strings.HasSuffix(event.Name, "_templ.go") || strings.HasSuffix(event.Name, ".templ") {
+				watchModeFileName := templruntime.GetDevModeTextFileName(event.Name)
+				if err := os.Remove(watchModeFileName); err != nil && !errors.Is(err, os.ErrNotExist) {
 					cmd.Log.Warn("Failed to remove watch mode text file", slog.Any("error", err))
 				}
 			}

cmd/templ/generatecmd/eventhandler.go

@@ -21,6 +21,7 @@ import (
 	"github.com/a-h/templ/cmd/templ/visualize"
 	"github.com/a-h/templ/generator"
 	"github.com/a-h/templ/parser/v2"
+	"github.com/a-h/templ/runtime"
 	"github.com/fsnotify/fsnotify"
 )
 
@@ -118,20 +119,6 @@ func (h *FSEventHandler) HandleEvent(ctx context.Context, event fsnotify.Event)
 		}
 		return GenerateResult{Updated: true, GoUpdated: true, TextUpdated: false}, nil
 	}
-	// Handle _templ.txt files.
-	if !event.Has(fsnotify.Remove) && strings.HasSuffix(event.Name, "_templ.txt") {
-		if h.devMode {
-			// Don't delete the file in dev mode, ignore changes to it, since the .templ file
-			// must have been updated in order to trigger a change in the _templ.txt file.
-			return GenerateResult{Updated: false, GoUpdated: false, TextUpdated: false}, nil
-		}
-		h.Log.Debug("Deleting watch mode file", slog.String("file", event.Name))
-		if err = os.Remove(event.Name); err != nil {
-			h.Log.Warn("Failed to remove watch mode text file", slog.Any("error", err))
-			return GenerateResult{}, nil
-		}
-		return GenerateResult{}, nil
-	}
 
 	// If the file hasn't been updated since the last time we processed it, ignore it.
 	lastModTime, updatedModTime := h.UpsertLastModTime(event.Name)
@@ -274,7 +261,8 @@ func (h *FSEventHandler) generate(ctx context.Context, fileName string) (result
 
 	// Add the txt file if it has changed.
 	if h.devMode {
-		txtFileName := strings.TrimSuffix(fileName, ".templ") + "_templ.txt"
+		txtFileName := runtime.GetDevModeTextFileName(fileName)
+		h.Log.Debug("Writing development mode text file", slog.String("file", fileName), slog.String("output", txtFileName))
 		joined := strings.Join(generatorOutput.Literals, "\n")
 		txtHash := sha256.Sum256([]byte(joined))
 		if h.UpsertHash(txtFileName, txtHash) {

cmd/templ/generatecmd/main_test.go

@@ -11,6 +11,7 @@ import (
 	"time"
 
 	"github.com/a-h/templ/cmd/templ/testproject"
+	"github.com/a-h/templ/runtime"
 	"golang.org/x/sync/errgroup"
 )
 
@@ -69,13 +70,14 @@ func TestGenerate(t *testing.T) {
 		})
 
 		// Check the templates_templ.go file was created, with backoff.
+		devModeTextFileName := runtime.GetDevModeTextFileName(path.Join(dir, "templates_templ.go"))
 		for i := 0; i < 5; i++ {
 			time.Sleep(time.Second * time.Duration(i))
 			_, err = os.Stat(path.Join(dir, "templates_templ.go"))
 			if err != nil {
 				continue
 			}
-			_, err = os.Stat(path.Join(dir, "templates_templ.txt"))
+			_, err = os.Stat(devModeTextFileName)
 			if err != nil {
 				continue
 			}
@@ -91,7 +93,7 @@ func TestGenerate(t *testing.T) {
 		}
 
 		// Check the templates_templ.txt file was removed.
-		_, err = os.Stat(path.Join(dir, "templates_templ.txt"))
+		_, err = os.Stat(path.Join(dir, devModeTextFileName))
 		if err == nil {
 			t.Fatalf("templates_templ.txt was not removed")
 		}
@@ -110,14 +112,14 @@ func TestDefaultWatchPattern(t *testing.T) {
 			matches: false,
 		},
 		{
-			name:    "*_templ.txt matches, Windows",
+			name:    "*_templ.txt is no longer matched, Windows",
 			input:   `C:\Users\adrian\github.com\a-h\templ\cmd\templ\testproject\strings_templ.txt`,
-			matches: true,
+			matches: false,
 		},
 		{
-			name:    "*_templ.txt matches, Unix",
+			name:    "*_templ.txt is no longer matched, Unix",
 			input:   "/Users/adrian/github.com/a-h/templ/cmd/templ/testproject/strings_templ.txt",
-			matches: true,
+			matches: false,
 		},
 		{
 			name:    "*.templ files match, Windows",

cmd/templ/main.go

@@ -208,7 +208,7 @@ func generateCmd(stdout, stderr io.Writer, args []string) (code int) {
 	includeVersionFlag := cmd.Bool("include-version", true, "")
 	includeTimestampFlag := cmd.Bool("include-timestamp", false, "")
 	watchFlag := cmd.Bool("watch", false, "")
-	watchPatternFlag := cmd.String("watch-pattern", "(.+\\.go$)|(.+\\.templ$)|(.+_templ\\.txt$)", "")
+	watchPatternFlag := cmd.String("watch-pattern", "(.+\\.go$)|(.+\\.templ$)", "")
 	openBrowserFlag := cmd.Bool("open-browser", true, "")
 	cmdFlag := cmd.String("cmd", "", "")
 	proxyFlag := cmd.String("proxy", "", "")

runtime/watchmode.go

@@ -1,10 +1,13 @@
 package runtime
 
 import (
+	"crypto/sha256"
+	"encoding/hex"
 	"errors"
 	"fmt"
 	"io"
 	"os"
+	"path/filepath"
 	"runtime"
 	"strconv"
 	"strings"
@@ -14,6 +17,42 @@ import (
 
 var developmentMode = os.Getenv("TEMPL_DEV_MODE") == "true"
 
+func GetDevModeTextFileName(templFileName string) string {
+	if strings.HasSuffix(templFileName, "_templ.go") {
+		templFileName = strings.TrimSuffix(templFileName, "_templ.go") + ".templ"
+	}
+	absFileName, err := filepath.Abs(templFileName)
+	if err != nil {
+		absFileName = templFileName
+	}
+	absFileName, err = filepath.EvalSymlinks(absFileName)
+	if err != nil {
+		absFileName = templFileName
+	}
+	absFileName = normalizePath(absFileName)
+
+	hashedFileName := sha256.Sum256([]byte(absFileName))
+	outputFileName := fmt.Sprintf("templ_%s.txt", hex.EncodeToString(hashedFileName[:]))
+
+	root := os.TempDir()
+	if os.Getenv("TEMPL_DEV_MODE_ROOT") != "" {
+		root = os.Getenv("TEMPL_DEV_MODE_ROOT")
+	}
+
+	return filepath.Join(root, outputFileName)
+}
+
+// normalizePath converts Windows paths to Unix style paths.
+func normalizePath(p string) string {
+	p = strings.ReplaceAll(filepath.Clean(p), `\`, `/`)
+	parts := strings.SplitN(p, ":", 2)
+	if len(parts) == 2 && len(parts[0]) == 1 {
+		drive := strings.ToLower(parts[0])
+		p = "/" + drive + parts[1]
+	}
+	return p
+}
+
 // WriteString writes the string to the writer. If development mode is enabled
 // s is replaced with the string at the index in the _templ.txt file.
 func WriteString(w io.Writer, index int, s string) (err error) {
@@ -22,13 +61,16 @@ func WriteString(w io.Writer, index int, s string) (err error) {
 		if !strings.HasSuffix(path, "_templ.go") {
 			return errors.New("templ: attempt to use WriteString from a non templ file")
 		}
-		txtFilePath := strings.Replace(path, "_templ.go", "_templ.txt", 1)
+		path, err := filepath.EvalSymlinks(path)
+		if err != nil {
+			return fmt.Errorf("templ: failed to eval symlinks for %q: %w", path, err)
+		}
 
+		txtFilePath := GetDevModeTextFileName(path)
 		literals, err := getWatchedStrings(txtFilePath)
 		if err != nil {
-			return fmt.Errorf("templ: failed to cache strings: %w", err)
+			return fmt.Errorf("templ: failed to get watched strings for %q: %w", path, err)
 		}
-
 		if index > len(literals) {
 			return fmt.Errorf("templ: failed to find line %d in %s", index, txtFilePath)
 		}

runtime/watchmode_test.go

@@ -0,0 +1,40 @@
+package runtime
+
+import (
+	"os"
+	"testing"
+)
+
+func TestWatchMode(t *testing.T) {
+	os.Setenv("TEMPL_DEV_MODE_ROOT", "/tmp")
+	defer os.Unsetenv("TEMPL_DEV_MODE_ROOT")
+
+	t.Run("GetDevModeTextFileName respects the TEMPL_DEV_MODE_ROOT environment variable", func(t *testing.T) {
+		expected := "/tmp/templ_14a26e43676c091fa17a7f4eccbbf62a44339e3cc6454b9a82c042227a21757f.txt"
+		actual := GetDevModeTextFileName("test.templ")
+		if actual != expected {
+			t.Errorf("got %q, want %q", actual, expected)
+		}
+	})
+	t.Run("GetDevModeTextFileName replaces _templ.go with .templ", func(t *testing.T) {
+		expected := "/tmp/templ_14a26e43676c091fa17a7f4eccbbf62a44339e3cc6454b9a82c042227a21757f.txt"
+		actual := GetDevModeTextFileName("test_templ.go")
+		if actual != expected {
+			t.Errorf("got %q, want %q", actual, expected)
+		}
+	})
+	t.Run("GetDevModeTextFileName accepts absolute Linux paths", func(t *testing.T) {
+		expected := "/tmp/templ_629591f679da14bbba764530c2965c6c8d3a8931f0ba867104c2ec441691ae22.txt"
+		actual := GetDevModeTextFileName("/home/user/test.templ")
+		if actual != expected {
+			t.Errorf("got %q, want %q", actual, expected)
+		}
+	})
+	t.Run("GetDevModeTextFileName accepts absolute Windows paths, which are normalized to Unix style before hashing", func(t *testing.T) {
+		expected := "/tmp/templ_f0321c47222350b736aaa2d18a2b313be03da4fd4ebd80af5745434d8776376f.txt"
+		actual := GetDevModeTextFileName(`C:\Windows\System32\test.templ`)
+		if actual != expected {
+			t.Errorf("got %q, want %q", actual, expected)
+		}
+	})
+}