feat(compiler): set enableLegacyTemplate to false by default (#18756)

BREAKING CHANGE: the compiler option `enableLegacyTemplate` is now disabled by default as the `<template>` element has been deprecated since v4. Use `<ng-template>` instead. The option `enableLegacyTemplate` and the `<template>` element will both be removed in Angular v6.
PR Close #18756

aio/content/examples/ngcontainer/src/app/app.component.html

@@ -92,22 +92,22 @@ <h4>#3 &lt;ng-container&gt; and &lt;p&gt;</h4>
   </div>
 
   <div>
-    The <code>hero.id</code> in the &lt;template *ngIf&gt; disappears:
+    The <code>hero.id</code> in the &lt;ng-template *ngIf&gt; disappears:
     <p>
-      <template *ngIf="showId">
+      <ng-template *ngIf="showId">
         Id: ({{hero.id}})
-      </template>
+      </ng-template>
       Name: {{hero.name}}
     </p>
   </div>
 
   <div>
-    The <code>hero.id</code> in the &lt;template [ngIf]&gt;
+    The <code>hero.id</code> in the &lt;ng-template [ngIf]&gt;
     is unaffected by the <span>p-span</span> CSS:
     <p>
-      <template [ngIf]="showId">
+      <ng-template [ngIf]="showId">
         Id: ({{hero.id}})
-      </template>
+      </ng-template>
       Name: {{hero.name}}
     </p>
   </div>

aio/content/examples/structural-directives/e2e-spec.ts

@@ -18,9 +18,9 @@ describe('Structural Directives', function () {
     expect(allLis.get(0).getText()).toEqual('Mr. Nice');
   });
 
-  it('ngSwitch have three <happy-hero> instances', function () {
+  it('ngSwitch have two <happy-hero> instances', function () {
     const happyHeroEls = element.all(by.tagName('happy-hero'));
-    expect(happyHeroEls.count()).toEqual(3);
+    expect(happyHeroEls.count()).toEqual(2);
   });
 
   it('should toggle *ngIf="hero" with a button', function () {

aio/content/examples/structural-directives/src/app/app.component.html

@@ -55,11 +55,6 @@ <h4>NgIf with template</h4>
 </ng-template>
 <!-- #enddocregion ngif-template -->
 
-<p>template attribute</p>
-<!-- #docregion ngif-template-attr -->
-<div template="ngIf hero">{{hero.name}}</div>
-<!-- #enddocregion ngif-template-attr -->
-
 <hr>
 
 <h2 id="ng-container">&lt;ng-container&gt;</h2>
@@ -131,14 +126,7 @@ <h2 id="ngFor">NgFor</h2>
 </div>
 
 <!--#enddocregion inside-ngfor -->
-<p class="code">&lt;div template="ngFor let hero of heroes; let i=index; let odd=odd; trackBy: trackById" [class.odd]="odd"&gt;</p>
-<!--#docregion inside-ngfor -->
-<div template="ngFor let hero of heroes; let i=index; let odd=odd; trackBy: trackById" [class.odd]="odd">
-  ({{i}}) {{hero.name}}
-</div>
-
-<!--#enddocregion inside-ngfor -->
-<p class="code">&lt;template ngFor let-hero [ngForOf]="heroes" let-i="index" let-odd="odd" [ngForTrackBy]="trackById"&gt;</p>
+<p class="code">&lt;ng-template ngFor let-hero [ngForOf]="heroes" let-i="index" let-odd="odd" [ngForTrackBy]="trackById"/&gt;</p>
 <!--#docregion inside-ngfor -->
 <ng-template ngFor let-hero [ngForOf]="heroes" let-i="index" let-odd="odd" [ngForTrackBy]="trackById">
   <div [class.odd]="odd">({{i}}) {{hero.name}}</div>
@@ -169,16 +157,6 @@ <h4>NgSwitch</h4>
 </div>
 <!-- #enddocregion built-in, ngswitch -->
 
-<h4>NgSwitch with <i>template</i> attribute</h4>
-<!-- #docregion ngswitch-template-attr -->
-<div [ngSwitch]="hero?.emotion">
-  <happy-hero    template="ngSwitchCase 'happy'"    [hero]="hero"></happy-hero>
-  <sad-hero      template="ngSwitchCase 'sad'"      [hero]="hero"></sad-hero>
-  <confused-hero template="ngSwitchCase 'confused'" [hero]="hero"></confused-hero>
-  <unknown-hero  template="ngSwitchDefault"         [hero]="hero"></unknown-hero>
-</div>
-<!-- #enddocregion ngswitch-template-attr -->
-
 <h4>NgSwitch with &lt;ng-template&gt;</h4>
 <!-- #docregion ngswitch-template -->
 <div [ngSwitch]="hero?.emotion">
@@ -199,7 +177,7 @@ <h4>NgSwitch with &lt;ng-template&gt;</h4>
 
 <hr>
 
-<h2>&lt;template&gt;</h2>
+<h2>&lt;ng-template&gt;</h2>
 <!-- #docregion template-tag -->
 <p>Hip!</p>
 <ng-template>
@@ -238,13 +216,13 @@ <h4>UnlessDirective with template</h4>
 <p *myUnless="condition">Show this sentence unless the condition is true.</p>
 <!-- #enddocregion myUnless-1 -->
 
-<p template="myUnless condition" class="code unless">
-  (A) &lt;p template="myUnless condition" class="code unless"&gt;
+<p *myUnless="condition" class="code unless">
+  (A) &lt;p *myUnless="condition" class="code unless"&gt;
 </p>
 
 <ng-template [myUnless]="condition">
   <p class="code unless">
-    (A) &lt;template [myUnless]="condition"&gt;
+    (A) &lt;ng-template [myUnless]="condition"&gt;
   </p>
 </ng-template>
 

aio/content/examples/structural-directives/src/app/unless.directive.ts

@@ -19,8 +19,7 @@ import { Directive, Input, TemplateRef, ViewContainerRef } from '@angular/core';
  * ### Syntax
  *
  * - `<div *myUnless="condition">...</div>`
- * - `<div template="myUnless condition">...</div>`
- * - `<template [myUnless]="condition"><div>...</div></template>`
+ * - `<ng-template [myUnless]="condition"><div>...</div></ng-template>`
  *
 // #docregion no-docs
  */

aio/content/examples/template-syntax/src/app/app.component.html

@@ -78,11 +78,11 @@ <h3>
 
 <p>Template input variable expression context (let hero)</p>
 <!-- template hides the following; plenty of examples later -->
-<template>
+<ng-template>
   <!-- #docregion context-var -->
   <div *ngFor="let hero of heroes">{{hero.name}}</div>
   <!-- #enddocregion context-var -->
-</template>
+</ng-template>
 
 <p>Template reference variable expression context (#heroInput)</p>
 <div (keyup)="0" class="context">

aio/content/guide/structural-directives.md

@@ -208,17 +208,7 @@ Here is `*ngIf` displaying the hero's name if `hero` exists.
 
 
 The asterisk is "syntactic sugar" for something a bit more complicated.
-Internally, Angular desugars it in two stages.
-First, it translates the `*ngIf="..."` into a template _attribute_, `template="ngIf ..."`,  like this.
-
-
-<code-example path="structural-directives/src/app/app.component.html" linenums="false" title="src/app/app.component.html (ngif-template-attr)" region="ngif-template-attr">
-
-</code-example>
-
-
-
-Then it translates the template _attribute_ into a `<ng-template>` _element_, wrapped around the host element, like this.
+Internally, Angular translates the `*ngIf` _attribute_ into a `<ng-template>` _element_, wrapped around the host element, like this.
 
 
 <code-example path="structural-directives/src/app/app.component.html" linenums="false" title="src/app/app.component.html (ngif-template)" region="ngif-template">
@@ -230,8 +220,7 @@ Then it translates the template _attribute_ into a `<ng-template>` _element_, wr
 * The `*ngIf` directive moved to the `<ng-template>` element where it became a property binding,`[ngIf]`.
 * The rest of the `<div>`, including its class attribute, moved inside the `<ng-template>` element.
 
-None of these forms are actually rendered.
-Only the finished product ends up in the DOM.
+The first form is not actually rendered, only the finished product ends up in the DOM.
 
 
 <figure>
@@ -252,10 +241,9 @@ The [`NgFor`](guide/structural-directives#ngFor) and [`NgSwitch...`](guide/struc
 
 ## Inside _*ngFor_
 
-Angular transforms the `*ngFor` in similar fashion from asterisk (*) syntax through
-template _attribute_ to `<ng-template>` _element_.
+Angular transforms the `*ngFor` in similar fashion from asterisk (*) syntax to `<ng-template>` _element_.
 
-Here's a full-featured application of `NgFor`, written all three ways:
+Here's a full-featured application of `NgFor`, written both ways:
 
 
 <code-example path="structural-directives/src/app/app.component.html" linenums="false" title="src/app/app.component.html (inside-ngfor)" region="inside-ngfor">
@@ -415,16 +403,7 @@ The `<unknown-hero>` is the host element for the `*ngSwitchDefault`.
 
 
 As with other structural directives, the `NgSwitchCase` and `NgSwitchDefault`
-can be desugared into the template _attribute_ form.
-
-
-<code-example path="structural-directives/src/app/app.component.html" linenums="false" title="src/app/app.component.html (ngswitch-template-attr)" region="ngswitch-template-attr">
-
-</code-example>
-
-
-
-That, in turn, can be desugared into the `<ng-template>` element form.
+can be desugared into the `<ng-template>` element form.
 
 
 <code-example path="structural-directives/src/app/app.component.html" linenums="false" title="src/app/app.component.html (ngswitch-template)" region="ngswitch-template">
@@ -438,7 +417,7 @@ That, in turn, can be desugared into the `<ng-template>` element form.
 
 ## Prefer the asterisk (*) syntax.
 
-The asterisk (*) syntax is more clear than the other desugared forms.
+The asterisk (*) syntax is more clear than the desugared form.
 Use [&lt;ng-container&gt;](guide/structural-directives#ng-container) when there's no single element
 to host the directive.
 

packages/common/src/directives/ng_for_of.ts

@@ -79,7 +79,6 @@ export class NgForOfContext<T> {
  * ### Syntax
  *
  * - `<li *ngFor="let item of items; index as i; trackBy: trackByFn">...</li>`
- * - `<li template="ngFor let item of items; index as i; trackBy: trackByFn">...</li>`
  *
  * With `<ng-template>` element:
  *

packages/common/src/directives/ng_if.ts

@@ -75,7 +75,6 @@ import {Directive, EmbeddedViewRef, Input, TemplateRef, ViewContainerRef} from '
  *
  * Simple form:
  * - `<div *ngIf="condition">...</div>`
- * - `<div template="ngIf condition">...</div>`
  * - `<ng-template [ngIf]="condition"><div>...</div></ng-template>`
  *
  * Form with an else block:

packages/compiler-cli/src/codegen.ts

@@ -101,7 +101,7 @@ export class CodeGenerator {
       translations: transContent,
       i18nFormat: cliOptions.i18nFormat || undefined,
       locale: cliOptions.locale || undefined, missingTranslation,
-      enableLegacyTemplate: options.enableLegacyTemplate !== false,
+      enableLegacyTemplate: options.enableLegacyTemplate === true,
       enableSummariesForJit: options.enableSummariesForJit !== false,
       preserveWhitespaces: options.preserveWhitespaces,
     });

packages/compiler-cli/src/transformers/api.ts

@@ -90,7 +90,7 @@ export interface CompilerOptions extends ts.CompilerOptions {
   // Print extra information while running the compiler
   trace?: boolean;
 
-  // Whether to enable support for <template> and the template attribute (true by default)
+  // Whether to enable support for <template> and the template attribute (false by default)
   enableLegacyTemplate?: boolean;
 
   // Whether to enable lowering expressions lambdas and expressions in a reference value

packages/compiler/src/aot/compiler_factory.ts

@@ -65,7 +65,7 @@ export function createAotCompiler(compilerHost: AotCompilerHost, options: AotCom
   const config = new CompilerConfig({
     defaultEncapsulation: ViewEncapsulation.Emulated,
     useJit: false,
-    enableLegacyTemplate: options.enableLegacyTemplate !== false,
+    enableLegacyTemplate: options.enableLegacyTemplate === true,
     missingTranslation: options.missingTranslation,
     preserveWhitespaces: options.preserveWhitespaces,
   });

packages/compiler/src/config.ts

@@ -36,7 +36,7 @@ export class CompilerConfig {
     this.useJit = !!useJit;
     this.jitDevMode = !!jitDevMode;
     this.missingTranslation = missingTranslation || null;
-    this.enableLegacyTemplate = enableLegacyTemplate !== false;
+    this.enableLegacyTemplate = enableLegacyTemplate === true;
     this.preserveWhitespaces = preserveWhitespacesDefault(noUndefined(preserveWhitespaces));
   }
 }

packages/compiler/test/template_parser/template_parser_spec.ts

@@ -121,16 +121,19 @@ export function main() {
       schemas?: SchemaMetadata[], preserveWhitespaces?: boolean) => TemplateAst[];
   let console: ArrayConsole;
 
-  function commonBeforeEach() {
+  function configureCompiler() {
+    console = new ArrayConsole();
     beforeEach(() => {
-      console = new ArrayConsole();
       TestBed.configureCompiler({
         providers: [
           {provide: Console, useValue: console},
+          {provide: CompilerConfig, useValue: new CompilerConfig({enableLegacyTemplate: true})}
         ],
       });
     });
+  }
 
+  function commonBeforeEach() {
     beforeEach(inject([TemplateParser], (parser: TemplateParser) => {
       const someAnimation = new CompileAnimationEntryMetadata('someAnimation', []);
       const someTemplate = compileTemplateMetadata({animations: [someAnimation]});
@@ -286,6 +289,7 @@ export function main() {
       });
     });
 
+    configureCompiler();
     commonBeforeEach();
 
     describe('security context', () => {
@@ -318,6 +322,7 @@ export function main() {
       TestBed.configureCompiler({providers: [TEST_COMPILER_PROVIDERS, MOCK_SCHEMA_REGISTRY]});
     });
 
+    configureCompiler();
     commonBeforeEach();
 
     describe('parse', () => {
@@ -2129,13 +2134,13 @@ The pipe 'test' could not be found ("{{[ERROR ->]a | test}}"): TestComp@0:2`);
 
   });
 
-  describe('Template Parser - opt-out `<template>` support', () => {
+  describe('Template Parser - `<template>` support disabled by default', () => {
     beforeEach(() => {
       TestBed.configureCompiler({
-        providers: [{
-          provide: CompilerConfig,
-          useValue: new CompilerConfig({enableLegacyTemplate: false}),
-        }],
+        providers: [
+          {provide: Console, useValue: console},
+          {provide: CompilerConfig, useValue: new CompilerConfig()}
+        ],
       });
     });
 

packages/core/test/linker/integration_spec.ts

@@ -7,6 +7,7 @@
  */
 
 import {CommonModule} from '@angular/common';
+import {CompilerConfig} from '@angular/compiler';
 import {Compiler, ComponentFactory, ComponentRef, ErrorHandler, EventEmitter, Host, Inject, Injectable, InjectionToken, Injector, NO_ERRORS_SCHEMA, NgModule, NgModuleRef, OnDestroy, SkipSelf, ViewRef} from '@angular/core';
 import {ChangeDetectionStrategy, ChangeDetectorRef, PipeTransform} from '@angular/core/src/change_detection/change_detection';
 import {getDebugContext} from '@angular/core/src/errors';
@@ -37,7 +38,14 @@ export function main() {
 function declareTests({useJit}: {useJit: boolean}) {
   describe('integration tests', function() {
 
-    beforeEach(() => { TestBed.configureCompiler({useJit}); });
+    beforeEach(() => {
+      TestBed.configureCompiler({
+        useJit,
+        providers: [
+          {provide: CompilerConfig, useValue: new CompilerConfig({enableLegacyTemplate: true})}
+        ]
+      });
+    });
 
     describe('react to record changes', function() {
       it('should consume text node changes', () => {

packages/platform-browser-dynamic/src/compiler_factory.ts

@@ -160,7 +160,7 @@ export class JitCompilerFactory implements CompilerFactory {
       useJit: true,
       defaultEncapsulation: ViewEncapsulation.Emulated,
       missingTranslation: MissingTranslationStrategy.Warning,
-      enableLegacyTemplate: true,
+      enableLegacyTemplate: false,
     };
 
     this._defaultOptions = [compilerOptions, ...defaultOptions];

packages/tsc-wrapped/src/options.ts

@@ -76,7 +76,7 @@ interface Options extends ts.CompilerOptions {
   // Print extra information while running the compiler
   trace?: boolean;
 
-  // Whether to enable support for <template> and the template attribute (true by default)
+  // Whether to enable support for <template> and the template attribute (false by default)
   enableLegacyTemplate?: boolean;
 
   // Whether to generate .ngsummary.ts files that allow to use AOTed artifacts