Transformation of static blocks breaks existing code

Commencez par le dépôt angular-monaco-repro lié et comparez les builds en utilisant @babel/plugin-transform-class-static-block 7.27.1 et 7.28.3 via le Webpack builder. Suivez l’endroit où le plugin entre dans le build Angular CLI, puis vérifiez que le CodeEditorWidget généré ne lève plus l’erreur de super-constructor signalée avec la version actuelle du plugin.

Command

build

Is this a regression?

• Yes, this behavior used to work in the previous version

The previous version in which this bug was not present was

No response

Description

It appears that when Angular compiles using a recent version of Babel's plugin-transform-class-static-block, with the Webpack builder, the output is transformed in such a way it breaks existing code.

Angular code compiled and bundled with @babel/plugin-transform-class-static-block@7.27.1:

let CodeEditorWidget = class CodeEditorWidget extends _base_common_lifecycle_js__WEBPACK_IMPORTED_MODULE_5__.Disposable {
  static #_ = CodeEditorWidget_1 = this;
  static #_2 = this.dropIntoEditorDecorationOptions = _common_model_textModel_js__WEBPACK_IMPORTED_MODULE_27__.ModelDecorationOptions.register({
    description: 'workbench-dnd-target',
    className: 'dnd-target'
  }); //#endregion
  get isSimpleWidget() {
    return this._configuration.isSimpleWidget;
  }
  get contextMenuId() {
    return this._configuration.contextMenuId;
  }
  constructor(domElement, _options, codeEditorWidgetOptions, instantiationService, codeEditorService, commandService, contextKeyService, themeService, notificationService, accessibilityService, languageConfigurationService, languageFeaturesService) {
    var _this;
    super();
    _this = this;

   // Omitted for brevity
};

Angular code compiled and bundled with @babel/plugin-transform-class-static-block@7.28.3:

let CodeEditorWidget = (class CodeEditorWidget extends _base_common_lifecycle_js__WEBPACK_IMPORTED_MODULE_5__.Disposable {                 
  //#endregion
  get isSimpleWidget() {
    return this._configuration.isSimpleWidget;
  }
  get contextMenuId() {
    return this._configuration.contextMenuId;
  }
  constructor(domElement, _options, codeEditorWidgetOptions, instantiationService, codeEditorService, commandService, contextKeyService, themeService, notificationService, accessibilityService, languageConfigurationService, languageFeaturesService) {
    var _this = this;
    super();

    // Omitted for brevity

  static #_ = _staticBlock = () => (CodeEditorWidget_1 = this, this.dropIntoEditorDecorationOptions = _common_model_textModel_js__WEBPACK_IMPORTED_MODULE_27__.ModelDecorationOptions.register({
    description: 'workbench-dnd-target',
    className: 'dnd-target'
  }), this);
}, _staticBlock());

The workaround, which you will also see explained in the attached reproducer, is to override the version of the Babel's plugin to 7.27.1.

I don't understand why, and under which circumstance, that plugin is injected into the compilation process.

Minimal Reproduction

Steps to reproduce can be found on the reproducer's repository: https://github.com/lppedd/angular-monaco-repro

Exception or Error

ERROR ReferenceError: Must call super constructor in derived class before accessing 'this' or returning from derived constructor
  at new CodeEditorWidget (codeEditorWidget.js:69:252)
  at new StandaloneCodeEditor (standaloneCodeEditor.js:69:9)
  at new StandaloneEditor (standaloneCodeEditor.js:188:9)
  at InstantiationService._createInstance (instantiationService.js:130:24)
  at InstantiationService.createInstance (instantiationService.js:101:27)
  at Object.create (standaloneEditor.js:43:33)
  at App.ngAfterViewInit (app.ts:16:33)
  at callHookInternal (debug_node.mjs:860:14)
  at callHook (debug_node.mjs:887:13)
  at callHooks (debug_node.mjs:841:17)

Your Environment

Angular CLI: 20.3.8
Node: 22.18.0
Package Manager: npm 11.6.2
OS: win32 x64
    

Angular: 20.3.9
... common, compiler, compiler-cli, core, forms
... platform-browser, router

Package                         Version
---------------------------------------
@angular-devkit/architect       0.2003.8
@angular-devkit/build-angular   20.3.8
@angular-devkit/core            20.3.8
@angular-devkit/schematics      20.3.8
@angular/build                  20.3.8
@angular/cli                    20.3.8
@schematics/angular             20.3.8
rxjs                            7.8.2
typescript                      5.9.3
zone.js                         0.15.1

Anything else relevant?

No response