Adding incremental Frontend Server-compatible DDC builders + supporting infrastructure

build_modules/lib/build_modules.dart

@@ -2,17 +2,23 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+export 'src/ddc_names.dart';
 export 'src/errors.dart' show MissingModulesException, UnsupportedModules;
-export 'src/kernel_builder.dart'
-    show KernelBuilder, multiRootScheme, reportUnusedKernelInputs;
+export 'src/kernel_builder.dart' show KernelBuilder, reportUnusedKernelInputs;
 export 'src/meta_module_builder.dart'
     show MetaModuleBuilder, metaModuleExtension;
 export 'src/meta_module_clean_builder.dart'
     show MetaModuleCleanBuilder, metaModuleCleanExtension;
 export 'src/module_builder.dart' show ModuleBuilder, moduleExtension;
+export 'src/module_library.dart' show ModuleLibrary;
 export 'src/module_library_builder.dart'
     show ModuleLibraryBuilder, moduleLibraryExtension;
 export 'src/modules.dart';
 export 'src/platform.dart' show DartPlatform;
 export 'src/scratch_space.dart' show scratchSpace, scratchSpaceResource;
-export 'src/workers.dart' show dartdevkDriverResource, maxWorkersPerTask;
+export 'src/workers.dart'
+    show
+        dartdevkDriverResource,
+        frontendServerProxyDriverResource,
+        maxWorkersPerTask,
+        persistentFrontendServerResource;

build_modules/lib/src/common.dart

@@ -2,9 +2,17 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+import 'dart:io';
+
 import 'package:build/build.dart';
+import 'package:path/path.dart' as p;
 import 'package:scratch_space/scratch_space.dart';
 
+const multiRootScheme = 'org-dartlang-app';
+const webHotReloadOption = 'web-hot-reload';
+final sdkDir = p.dirname(p.dirname(Platform.resolvedExecutable));
+final packagesFilePath = p.join('.dart_tool', 'package_config.json');
+
 final defaultAnalysisOptionsId = AssetId(
   'build_modules',
   'lib/src/analysis_options.default.yaml',
@@ -16,6 +24,12 @@ String defaultAnalysisOptionsArg(ScratchSpace scratchSpace) =>
 enum ModuleStrategy { fine, coarse }
 
 ModuleStrategy moduleStrategy(BuilderOptions options) {
+  // DDC's Library Bundle module system only supports fine modules since it must
+  // align with the Frontend Server's library management scheme.
+  final usesWebHotReload = options.config[webHotReloadOption] as bool? ?? false;
+  if (usesWebHotReload) {
+    return ModuleStrategy.fine;
+  }
   final config = options.config['strategy'] as String? ?? 'coarse';
   switch (config) {
     case 'coarse':

build_web_compilers/lib/src/ddc_names.dart → build_modules/lib/src/ddc_names.dart

@@ -1,14 +1,25 @@
-// Copyright (c) 2018, the Dart project authors.  Please see the AUTHORS file
+// Copyright (c) 2025, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 import 'package:path/path.dart' as p;
 
+/// Logic in this file must be synchronized with their namesakes in DDC at:
+/// pkg/dev_compiler/lib/src/compiler/js_names.dart
+
+bool isSdkInternalRuntimeUri(Uri importUri) {
+  return importUri.isScheme('dart') && importUri.path == '_runtime';
+}
+
+String libraryUriToJsIdentifier(Uri importUri) {
+  if (importUri.isScheme('dart')) {
+    return isSdkInternalRuntimeUri(importUri) ? 'dart' : importUri.path;
+  }
+  return pathToJSIdentifier(p.withoutExtension(importUri.pathSegments.last));
+}
+
 /// Transforms a path to a valid JS identifier.
 ///
-/// This logic must be synchronized with [pathToJSIdentifier] in DDC at:
-/// pkg/dev_compiler/lib/src/compiler/module_builder.dart
-///
 /// For backwards compatibility, if this pattern is changed,
 /// dev_compiler_bootstrap.dart must be updated to accept both old and new
 /// patterns.
@@ -35,12 +46,11 @@ String toJSIdentifier(String name) {
   for (var i = 0; i < name.length; i++) {
     final ch = name[i];
     final needsEscape = ch == r'$' || _invalidCharInIdentifier.hasMatch(ch);
-    if (needsEscape && buffer == null) {
-      buffer = StringBuffer(name.substring(0, i));
-    }
-    if (buffer != null) {
-      buffer.write(needsEscape ? '\$${ch.codeUnits.join("")}' : ch);
+    if (needsEscape) {
+      buffer ??= StringBuffer(name.substring(0, i));
     }
+
+    buffer?.write(needsEscape ? '\$${ch.codeUnits.join("")}' : ch);
   }
 
   final result = buffer != null ? '$buffer' : name;
@@ -56,7 +66,11 @@ String toJSIdentifier(String name) {
 /// Also handles invalid variable names in strict mode, like "arguments".
 bool invalidVariableName(String keyword, {bool strictMode = true}) {
   switch (keyword) {
-    // http://www.ecma-international.org/ecma-262/6.0/#sec-future-reserved-words
+    // https://262.ecma-international.org/6.0/#sec-reserved-words
+    case 'true':
+    case 'false':
+    case 'null':
+    // https://262.ecma-international.org/6.0/#sec-keywords
     case 'await':
     case 'break':
     case 'case':
@@ -79,7 +93,6 @@ bool invalidVariableName(String keyword, {bool strictMode = true}) {
     case 'import':
     case 'in':
     case 'instanceof':
-    case 'let':
     case 'new':
     case 'return':
     case 'super':
@@ -99,6 +112,7 @@ bool invalidVariableName(String keyword, {bool strictMode = true}) {
     // http://www.ecma-international.org/ecma-262/6.0/#sec-identifiers-static-semantics-early-errors
     case 'implements':
     case 'interface':
+    case 'let':
     case 'package':
     case 'private':
     case 'protected':