fix #3643: delete outputs if a watch build fails

evanw · Feb 2, 2025 · 0c4f4c8 · 0c4f4c8
1 parent e5d4303
commit 0c4f4c8
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -2,6 +2,10 @@
 
 ## Unreleased
 
+* Delete output files when a build fails in watch mode ([#3643](https://github.com/evanw/esbuild/issues/3643))
+
+    It has been requested for esbuild to delete files when a build fails in watch mode. Previously esbuild left the old files in place, which could cause people to not immediately realize that the most recent build failed. With this release, esbuild will now delete all output files if a rebuild fails. Fixing the build error and triggering another rebuild will restore all output files again.
+
 * Fix incorrect package for `@esbuild/netbsd-arm64` ([#4018](https://github.com/evanw/esbuild/issues/4018))
 
     Due to a copy+paste typo, the binary published to `@esbuild/netbsd-arm64` was not actually for `arm64`, and didn't run in that environment. This release should fix running esbuild in that environment (NetBSD on 64-bit ARM). Sorry about the mistake.

diff --git a/pkg/api/api_impl.go b/pkg/api/api_impl.go
@@ -1484,10 +1484,12 @@ func rebuildImpl(args rebuildArgs, oldHashes map[string]string) (rebuildState, m
 	newHashes := oldHashes
 
 	// Stop now if there were errors
+	var results []graph.OutputFile
+	var metafile string
 	if !log.HasErrors() {
 		// Compile the bundle
 		result.MangleCache = cloneMangleCache(log, args.mangleCache)
-		results, metafile := bundle.Compile(log, timer, result.MangleCache, linker.Link)
+		results, metafile = bundle.Compile(log, timer, result.MangleCache, linker.Link)
 
 		// Canceling a build generates a single error at the end of the build
 		if args.options.CancelFlag.DidCancel() {
@@ -1497,92 +1499,94 @@ func rebuildImpl(args rebuildArgs, oldHashes map[string]string) (rebuildState, m
 		// Stop now if there were errors
 		if !log.HasErrors() {
 			result.Metafile = metafile
+		}
+	}
 
-			// Populate the results to return
-			var hashBytes [8]byte
-			result.OutputFiles = make([]OutputFile, len(results))
-			newHashes = make(map[string]string)
-			for i, item := range results {
-				if args.options.WriteToStdout {
-					item.AbsPath = "<stdout>"
-				}
-				hasher := xxhash.New()
-				hasher.Write(item.Contents)
-				binary.LittleEndian.PutUint64(hashBytes[:], hasher.Sum64())
-				hash := base64.RawStdEncoding.EncodeToString(hashBytes[:])
-				result.OutputFiles[i] = OutputFile{
-					Path:     item.AbsPath,
-					Contents: item.Contents,
-					Hash:     hash,
+	// Populate the results to return
+	var hashBytes [8]byte
+	result.OutputFiles = make([]OutputFile, len(results))
+	newHashes = make(map[string]string)
+	for i, item := range results {
+		if args.options.WriteToStdout {
+			item.AbsPath = "<stdout>"
+		}
+		hasher := xxhash.New()
+		hasher.Write(item.Contents)
+		binary.LittleEndian.PutUint64(hashBytes[:], hasher.Sum64())
+		hash := base64.RawStdEncoding.EncodeToString(hashBytes[:])
+		result.OutputFiles[i] = OutputFile{
+			Path:     item.AbsPath,
+			Contents: item.Contents,
+			Hash:     hash,
+		}
+		newHashes[item.AbsPath] = hash
+	}
+
+	// Write output files before "OnEnd" callbacks run so they can expect
+	// output files to exist on the file system. "OnEnd" callbacks can be
+	// used to move output files to a different location after the build.
+	if args.write {
+		timer.Begin("Write output files")
+		if args.options.WriteToStdout {
+			// Special-case writing to stdout
+			if log.HasErrors() {
+				// No output is printed if there were any build errors
+			} else if len(results) != 1 {
+				log.AddError(nil, logger.Range{}, fmt.Sprintf(
+					"Internal error: did not expect to generate %d files when writing to stdout", len(results)))
+			} else {
+				// Print this later on, at the end of the current function
+				toWriteToStdout = results[0].Contents
+			}
+		} else {
+			// Delete old files that are no longer relevant
+			var toDelete []string
+			for absPath := range oldHashes {
+				if _, ok := newHashes[absPath]; !ok {
+					toDelete = append(toDelete, absPath)
 				}
-				newHashes[item.AbsPath] = hash
 			}
 
-			// Write output files before "OnEnd" callbacks run so they can expect
-			// output files to exist on the file system. "OnEnd" callbacks can be
-			// used to move output files to a different location after the build.
-			if args.write {
-				timer.Begin("Write output files")
-				if args.options.WriteToStdout {
-					// Special-case writing to stdout
-					if len(results) != 1 {
+			// Process all file operations in parallel
+			waitGroup := sync.WaitGroup{}
+			waitGroup.Add(len(results) + len(toDelete))
+			for _, result := range results {
+				go func(result graph.OutputFile) {
+					defer waitGroup.Done()
+					fs.BeforeFileOpen()
+					defer fs.AfterFileClose()
+					if oldHash, ok := oldHashes[result.AbsPath]; ok && oldHash == newHashes[result.AbsPath] {
+						if contents, err := ioutil.ReadFile(result.AbsPath); err == nil && bytes.Equal(contents, result.Contents) {
+							// Skip writing out files that haven't changed since last time
+							return
+						}
+					}
+					if err := fs.MkdirAll(realFS, realFS.Dir(result.AbsPath), 0755); err != nil {
 						log.AddError(nil, logger.Range{}, fmt.Sprintf(
-							"Internal error: did not expect to generate %d files when writing to stdout", len(results)))
+							"Failed to create output directory: %s", err.Error()))
 					} else {
-						// Print this later on, at the end of the current function
-						toWriteToStdout = results[0].Contents
-					}
-				} else {
-					// Delete old files that are no longer relevant
-					var toDelete []string
-					for absPath := range oldHashes {
-						if _, ok := newHashes[absPath]; !ok {
-							toDelete = append(toDelete, absPath)
+						var mode os.FileMode = 0666
+						if result.IsExecutable {
+							mode = 0777
+						}
+						if err := ioutil.WriteFile(result.AbsPath, result.Contents, mode); err != nil {
+							log.AddError(nil, logger.Range{}, fmt.Sprintf(
+								"Failed to write to output file: %s", err.Error()))
 						}
 					}
-
-					// Process all file operations in parallel
-					waitGroup := sync.WaitGroup{}
-					waitGroup.Add(len(results) + len(toDelete))
-					for _, result := range results {
-						go func(result graph.OutputFile) {
-							defer waitGroup.Done()
-							fs.BeforeFileOpen()
-							defer fs.AfterFileClose()
-							if oldHash, ok := oldHashes[result.AbsPath]; ok && oldHash == newHashes[result.AbsPath] {
-								if contents, err := ioutil.ReadFile(result.AbsPath); err == nil && bytes.Equal(contents, result.Contents) {
-									// Skip writing out files that haven't changed since last time
-									return
-								}
-							}
-							if err := fs.MkdirAll(realFS, realFS.Dir(result.AbsPath), 0755); err != nil {
-								log.AddError(nil, logger.Range{}, fmt.Sprintf(
-									"Failed to create output directory: %s", err.Error()))
-							} else {
-								var mode os.FileMode = 0666
-								if result.IsExecutable {
-									mode = 0777
-								}
-								if err := ioutil.WriteFile(result.AbsPath, result.Contents, mode); err != nil {
-									log.AddError(nil, logger.Range{}, fmt.Sprintf(
-										"Failed to write to output file: %s", err.Error()))
-								}
-							}
-						}(result)
-					}
-					for _, absPath := range toDelete {
-						go func(absPath string) {
-							defer waitGroup.Done()
-							fs.BeforeFileOpen()
-							defer fs.AfterFileClose()
-							os.Remove(absPath)
-						}(absPath)
-					}
-					waitGroup.Wait()
-				}
-				timer.End("Write output files")
+				}(result)
+			}
+			for _, absPath := range toDelete {
+				go func(absPath string) {
+					defer waitGroup.Done()
+					fs.BeforeFileOpen()
+					defer fs.AfterFileClose()
+					os.Remove(absPath)
+				}(absPath)
 			}
+			waitGroup.Wait()
 		}
+		timer.End("Write output files")
 	}
 
 	// Only return the mangle cache for a successful build

diff --git a/scripts/js-api-tests.js b/scripts/js-api-tests.js
@@ -4010,7 +4010,7 @@ let watchTests = {
         )
         assert.strictEqual(result2.errors.length, 1)
         assert.strictEqual(result2.errors[0].text, 'Expected ";" but found "2"')
-        assert.strictEqual(await readFileAsync(outfile, 'utf8'), 'throw 3;\n')
+        assert.strictEqual(fs.existsSync(outfile), false)
       }
 
       // Fourth rebuild: edit
@@ -4031,8 +4031,7 @@ let watchTests = {
           result => result.errors.length > 0,
         )
         assert.strictEqual(result2.errors.length, 1)
-        assert.strictEqual(await readFileAsync(outfile, 'utf8'), 'throw 4;\n')
-        assert.strictEqual(await readFileAsync(outfile, 'utf8'), 'throw 4;\n')
+        assert.strictEqual(fs.existsSync(outfile), false)
       }
 
       // Sixth rebuild: restore