refactor(ivy): verify template type check options are compatible (#34195)

It is now an error if '"fullTemplateTypeCheck"' is disabled while
`"strictTemplates"` is enabled, as enabling the latter implies that the
former is also enabled.

PR Close #34195

packages/compiler-cli/src/ngtsc/diagnostics/src/code.ts

@@ -39,6 +39,7 @@ export enum ErrorCode {
   SYMBOL_EXPORTED_UNDER_DIFFERENT_NAME = 3002,
 
   CONFIG_FLAT_MODULE_NO_INDEX = 4001,
+  CONFIG_STRICT_TEMPLATES_IMPLIES_FULL_TEMPLATE_TYPECHECK = 4002,
 
   /**
    * Raised when a host expression has a parse error, such as a host listener or host binding

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

@@ -82,6 +82,11 @@ export class NgtscProgram implements api.Program {
       verifySupportedTypeScriptVersion();
     }
 
+    const incompatibleTypeCheckOptionsDiagnostic = verifyCompatibleTypeCheckOptions(options);
+    if (incompatibleTypeCheckOptionsDiagnostic !== null) {
+      this.constructionDiagnostics.push(incompatibleTypeCheckOptionsDiagnostic);
+    }
+
     if (shouldEnablePerfTracing(options)) {
       this.perfTracker = PerfTracker.zeroedToNow();
       this.perfRecorder = this.perfTracker;
@@ -829,6 +834,37 @@ function isAngularCorePackage(program: ts.Program): boolean {
   });
 }
 
+/**
+ * Since "strictTemplates" is a true superset of type checking capabilities compared to
+ * "strictTemplateTypeCheck", it is required that the latter is not explicitly disabled if the
+ * former is enabled.
+ */
+function verifyCompatibleTypeCheckOptions(options: api.CompilerOptions): ts.Diagnostic|null {
+  if (options.fullTemplateTypeCheck === false && options.strictTemplates === true) {
+    return {
+      category: ts.DiagnosticCategory.Error,
+      code: ngErrorCode(ErrorCode.CONFIG_STRICT_TEMPLATES_IMPLIES_FULL_TEMPLATE_TYPECHECK),
+      file: undefined,
+      start: undefined,
+      length: undefined,
+      messageText:
+          `Angular compiler option "strictTemplates" is enabled, however "fullTemplateTypeCheck" is disabled.
+
+Having the "strictTemplates" flag enabled implies that "fullTemplateTypeCheck" is also enabled, so
+the latter can not be explicitly disabled.
+
+One of the following actions is required:
+1. Remove the "fullTemplateTypeCheck" option.
+2. Remove "strictTemplates" or set it to 'false'.
+
+More information about the template type checking compiler options can be found in the documentation:
+https://v9.angular.io/guide/template-typecheck#template-type-checking`,
+    };
+  }
+
+  return null;
+}
+
 export class ReferenceGraphAdapter implements ReferencesRegistry {
   constructor(private graph: ReferenceGraph) {}
 

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

@@ -114,6 +114,8 @@ export interface CompilerOptions extends ts.CompilerOptions {
    * whether embedded views are checked.
    *
    * For maximum type-checking, set this to `true`, and set `strictTemplates` to `true`.
+   *
+   * It is an error for this flag to be `false`, while `strictTemplates` is set to `true`.
    */
   fullTemplateTypeCheck?: boolean;
 

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

@@ -1552,6 +1552,41 @@ export declare class AnimationEvent {
         });
       });
     });
+
+    describe('option compatibility verification', () => {
+      beforeEach(() => env.write('index.ts', `export const a = 1;`));
+
+      it('should error if "fullTemplateTypeCheck" is false when "strictTemplates" is true', () => {
+        env.tsconfig({fullTemplateTypeCheck: false, strictTemplates: true});
+
+        const diags = env.driveDiagnostics();
+        expect(diags.length).toBe(1);
+        expect(diags[0].messageText)
+            .toContain(
+                'Angular compiler option "strictTemplates" is enabled, however "fullTemplateTypeCheck" is disabled.');
+      });
+      it('should not error if "fullTemplateTypeCheck" is false when "strictTemplates" is false',
+         () => {
+           env.tsconfig({fullTemplateTypeCheck: false, strictTemplates: false});
+
+           const diags = env.driveDiagnostics();
+           expect(diags.length).toBe(0);
+         });
+      it('should not error if "fullTemplateTypeCheck" is not set when "strictTemplates" is true',
+         () => {
+           env.tsconfig({strictTemplates: true});
+
+           const diags = env.driveDiagnostics();
+           expect(diags.length).toBe(0);
+         });
+      it('should not error if "fullTemplateTypeCheck" is true set when "strictTemplates" is true',
+         () => {
+           env.tsconfig({strictTemplates: true});
+
+           const diags = env.driveDiagnostics();
+           expect(diags.length).toBe(0);
+         });
+    });
   });
 });