refactor(compiler): add flag to disable block syntax in language service (#52683)

Adds the private `_enableBlockSyntax` flag that can be used by the language service to disable blocks on apps that aren't on Angular v17.

PR Close #52683

packages/compiler-cli/src/ngtsc/annotations/component/src/handler.ts

@@ -83,11 +83,13 @@ export class ComponentDecoratorHandler implements
       private hostDirectivesResolver: HostDirectivesResolver, private includeClassMetadata: boolean,
       private readonly compilationMode: CompilationMode,
       private readonly deferredSymbolTracker: DeferredSymbolTracker,
-      private readonly forbidOrphanRendering: boolean) {
+      private readonly forbidOrphanRendering: boolean,
+      private readonly enableBlockSyntax: boolean) {
     this.extractTemplateOptions = {
       enableI18nLegacyMessageIdFormat: this.enableI18nLegacyMessageIdFormat,
       i18nNormalizeLineEndingsInICUs: this.i18nNormalizeLineEndingsInICUs,
       usePoisonedData: this.usePoisonedData,
+      enableBlockSyntax: this.enableBlockSyntax,
     };
   }
 
@@ -106,6 +108,7 @@ export class ComponentDecoratorHandler implements
     enableI18nLegacyMessageIdFormat: boolean,
     i18nNormalizeLineEndingsInICUs: boolean,
     usePoisonedData: boolean,
+    enableBlockSyntax: boolean,
   };
 
   readonly precedence = HandlerPrecedence.PRIMARY;
@@ -360,6 +363,7 @@ export class ComponentDecoratorHandler implements
             enableI18nLegacyMessageIdFormat: this.enableI18nLegacyMessageIdFormat,
             i18nNormalizeLineEndingsInICUs: this.i18nNormalizeLineEndingsInICUs,
             usePoisonedData: this.usePoisonedData,
+            enableBlockSyntax: this.enableBlockSyntax,
           },
           this.compilationMode);
     }

packages/compiler-cli/src/ngtsc/annotations/component/src/resources.ts

@@ -119,6 +119,7 @@ export interface ExtractTemplateOptions {
   usePoisonedData: boolean;
   enableI18nLegacyMessageIdFormat: boolean;
   i18nNormalizeLineEndingsInICUs: boolean;
+  enableBlockSyntax: boolean;
 }
 
 export function extractTemplate(
@@ -237,6 +238,7 @@ function parseExtractedTemplate(
     enableI18nLegacyMessageIdFormat: options.enableI18nLegacyMessageIdFormat,
     i18nNormalizeLineEndingsInICUs,
     alwaysAttemptHtmlToR3AstConversion: options.usePoisonedData,
+    enableBlockSyntax: options.enableBlockSyntax,
   });
 
   // Unfortunately, the primary parse of the template above may not contain accurate source map
@@ -264,6 +266,7 @@ function parseExtractedTemplate(
     i18nNormalizeLineEndingsInICUs,
     leadingTriviaChars: [],
     alwaysAttemptHtmlToR3AstConversion: options.usePoisonedData,
+    enableBlockSyntax: options.enableBlockSyntax,
   });
 
   return {

packages/compiler-cli/src/ngtsc/annotations/component/test/component_spec.ts

@@ -103,6 +103,7 @@ function setup(
       compilationMode,
       new DeferredSymbolTracker(checker),
       /* forbidOrphanRenderering */ false,
+      /* enableBlockSyntax */ true,
   );
   return {reflectionHost, handler, resourceLoader, metaRegistry};
 }

packages/compiler-cli/src/ngtsc/core/api/src/options.ts

@@ -66,6 +66,14 @@ export interface InternalOptions {
    * @internal
    */
   supportJitMode?: boolean;
+
+  /**
+   * Whether block syntax is enabled in the compiler. Defaults to true.
+   * Used in the language service to disable the new syntax for projects that aren't on v17.
+   *
+   * @internal
+   */
+  _enableBlockSyntax?: boolean;
 }
 
 /**

packages/compiler-cli/src/ngtsc/core/src/compiler.ts

@@ -258,6 +258,7 @@ export class NgCompiler {
   readonly ignoreForDiagnostics: Set<ts.SourceFile>;
   readonly ignoreForEmit: Set<ts.SourceFile>;
   readonly enableTemplateTypeChecker: boolean;
+  private readonly enableBlockSyntax: boolean;
 
   /**
    * `NgCompiler` can be reused for multiple compilations (for resource-only changes), and each
@@ -322,6 +323,7 @@ export class NgCompiler {
   ) {
     this.enableTemplateTypeChecker =
         enableTemplateTypeChecker || (options['_enableTemplateTypeChecker'] ?? false);
+    this.enableBlockSyntax = options['_enableBlockSyntax'] ?? true;
     this.constructionDiagnostics.push(
         ...this.adapter.constructionDiagnostics, ...verifyCompatibleTypeCheckOptions(this.options));
 
@@ -1106,7 +1108,7 @@ export class NgCompiler {
           this.incrementalCompilation.depGraph, injectableRegistry, semanticDepGraphUpdater,
           this.closureCompilerEnabled, this.delegatingPerfRecorder, hostDirectivesResolver,
           supportTestBed, compilationMode, deferredSymbolsTracker,
-          !!this.options.forbidOrphanComponents),
+          !!this.options.forbidOrphanComponents, this.enableBlockSyntax),
 
       // TODO(alxhub): understand why the cast here is necessary (something to do with `null`
       // not being assignable to `unknown` when wrapped in `Readonly`).

packages/compiler-cli/test/ngtsc/ngtsc_spec.ts

@@ -8495,6 +8495,25 @@ function allTests(os: string) {
          expect(codes).toEqual([ngErrorCode(ErrorCode.NGMODULE_BOOTSTRAP_IS_STANDALONE)]);
        });
 
+    it('should be able to turn off control flow using a compiler flag', () => {
+      env.tsconfig({_enableBlockSyntax: false});
+      env.write('/test.ts', `
+        import { Component } from '@angular/core';
+
+        @Component({
+          standalone: true,
+          template: 'My email is foo@bar.com',
+        })
+        export class TestCmp {}
+      `);
+
+      env.driveMain();
+
+      // If blocks are enabled, this test will fail since `@bar.com` is an incomplete block.
+      const jsContents = env.getContents('test.js');
+      expect(jsContents).toContain('text(0, "My email is foo@bar.com")');
+    });
+
     describe('InjectorDef emit optimizations for standalone', () => {
       it('should not filter components out of NgModule.imports', () => {
         env.write('test.ts', `