fix(core): add noSideEffects() to ɵɵdefineComponent() (#35769)

dgp1130 · atscott · commit ba3612774f1a · 2020-03-03T08:50:03.000-08:00
This marks the function are "pure" and eligible to be tree shaken by Closure. Without this, initializing `ngDevMode` is considered a side effect which prevents this function from being tree shaken and also any component which calls it. PR Close #35769
diff --git a/packages/core/src/render3/definition.ts b/packages/core/src/render3/definition.ts
@@ -289,56 +289,56 @@ export function ɵɵdefineComponent<T>(componentDefinition: {
    */
   schemas?: SchemaMetadata[] | null;
 }): never {
-  // Initialize ngDevMode. This must be the first statement in ɵɵdefineComponent.
-  // See the `initNgDevMode` docstring for more information.
-  (typeof ngDevMode === 'undefined' || ngDevMode) && initNgDevMode();
-
-  const type = componentDefinition.type;
-  const typePrototype = type.prototype;
-  const declaredInputs: {[key: string]: string} = {} as any;
-  const def: Mutable<ComponentDef<any>, keyof ComponentDef<any>> = {
-    type: type,
-    providersResolver: null,
-    decls: componentDefinition.decls,
-    vars: componentDefinition.vars,
-    factory: null,
-    template: componentDefinition.template || null !,
-    consts: componentDefinition.consts || null,
-    ngContentSelectors: componentDefinition.ngContentSelectors,
-    hostBindings: componentDefinition.hostBindings || null,
-    hostVars: componentDefinition.hostVars || 0,
-    hostAttrs: componentDefinition.hostAttrs || null,
-    contentQueries: componentDefinition.contentQueries || null,
-    declaredInputs: declaredInputs,
-    inputs: null !,   // assigned in noSideEffects
-    outputs: null !,  // assigned in noSideEffects
-    exportAs: componentDefinition.exportAs || null,
-    onChanges: null,
-    onInit: typePrototype.ngOnInit || null,
-    doCheck: typePrototype.ngDoCheck || null,
-    afterContentInit: typePrototype.ngAfterContentInit || null,
-    afterContentChecked: typePrototype.ngAfterContentChecked || null,
-    afterViewInit: typePrototype.ngAfterViewInit || null,
-    afterViewChecked: typePrototype.ngAfterViewChecked || null,
-    onDestroy: typePrototype.ngOnDestroy || null,
-    onPush: componentDefinition.changeDetection === ChangeDetectionStrategy.OnPush,
-    directiveDefs: null !,  // assigned in noSideEffects
-    pipeDefs: null !,       // assigned in noSideEffects
-    selectors: componentDefinition.selectors || EMPTY_ARRAY,
-    viewQuery: componentDefinition.viewQuery || null,
-    features: componentDefinition.features as DirectiveDefFeature[] || null,
-    data: componentDefinition.data || {},
-    // TODO(misko): convert ViewEncapsulation into const enum so that it can be used directly in the
-    // next line. Also `None` should be 0 not 2.
-    encapsulation: componentDefinition.encapsulation || ViewEncapsulation.Emulated,
-    id: 'c',
-    styles: componentDefinition.styles || EMPTY_ARRAY,
-    _: null as never,
-    setInput: null,
-    schemas: componentDefinition.schemas || null,
-    tView: null,
-  };
-  def._ = noSideEffects(() => {
+  return noSideEffects(() => {
+    // Initialize ngDevMode. This must be the first statement in ɵɵdefineComponent.
+    // See the `initNgDevMode` docstring for more information.
+    (typeof ngDevMode === 'undefined' || ngDevMode) && initNgDevMode();
+
+    const type = componentDefinition.type;
+    const typePrototype = type.prototype;
+    const declaredInputs: {[key: string]: string} = {} as any;
+    const def: Mutable<ComponentDef<any>, keyof ComponentDef<any>> = {
+      type: type,
+      providersResolver: null,
+      decls: componentDefinition.decls,
+      vars: componentDefinition.vars,
+      factory: null,
+      template: componentDefinition.template || null !,
+      consts: componentDefinition.consts || null,
+      ngContentSelectors: componentDefinition.ngContentSelectors,
+      hostBindings: componentDefinition.hostBindings || null,
+      hostVars: componentDefinition.hostVars || 0,
+      hostAttrs: componentDefinition.hostAttrs || null,
+      contentQueries: componentDefinition.contentQueries || null,
+      declaredInputs: declaredInputs,
+      inputs: null !,   // assigned in noSideEffects
+      outputs: null !,  // assigned in noSideEffects
+      exportAs: componentDefinition.exportAs || null,
+      onChanges: null,
+      onInit: typePrototype.ngOnInit || null,
+      doCheck: typePrototype.ngDoCheck || null,
+      afterContentInit: typePrototype.ngAfterContentInit || null,
+      afterContentChecked: typePrototype.ngAfterContentChecked || null,
+      afterViewInit: typePrototype.ngAfterViewInit || null,
+      afterViewChecked: typePrototype.ngAfterViewChecked || null,
+      onDestroy: typePrototype.ngOnDestroy || null,
+      onPush: componentDefinition.changeDetection === ChangeDetectionStrategy.OnPush,
+      directiveDefs: null !,  // assigned in noSideEffects
+      pipeDefs: null !,       // assigned in noSideEffects
+      selectors: componentDefinition.selectors || EMPTY_ARRAY,
+      viewQuery: componentDefinition.viewQuery || null,
+      features: componentDefinition.features as DirectiveDefFeature[] || null,
+      data: componentDefinition.data || {},
+      // TODO(misko): convert ViewEncapsulation into const enum so that it can be used directly in
+      // the next line. Also `None` should be 0 not 2.
+      encapsulation: componentDefinition.encapsulation || ViewEncapsulation.Emulated,
+      id: 'c',
+      styles: componentDefinition.styles || EMPTY_ARRAY,
+      _: null as never,
+      setInput: null,
+      schemas: componentDefinition.schemas || null,
+      tView: null,
+    };
     const directiveTypes = componentDefinition.directives !;
     const feature = componentDefinition.features;
     const pipeTypes = componentDefinition.pipes !;
@@ -353,9 +353,9 @@ export function ɵɵdefineComponent<T>(componentDefinition: {
     def.pipeDefs = pipeTypes ?
         () => (typeof pipeTypes === 'function' ? pipeTypes() : pipeTypes).map(extractPipeDef) :
         null;
-  }) as never;
 
-  return def as never;
+    return def as never;
+  });
 }
 
 /**
