refactor(compiler-cli): introduce infrastructure for running additional checks against TypeScript files (#54993)

Adds the new `SourceFileValidator` that will be used to check for file-level issues that may prevent Angular from working, like invoking the `input()` function outside of an initializer. Currently only one check is planned, but this setup will allow us to easily add more in the future.

PR Close #54993

packages/compiler-cli/src/ngtsc/core/BUILD.bazel

@@ -42,6 +42,7 @@ ts_library(
         "//packages/compiler-cli/src/ngtsc/typecheck/template_semantics",
         "//packages/compiler-cli/src/ngtsc/typecheck/template_semantics/api",
         "//packages/compiler-cli/src/ngtsc/util",
+        "//packages/compiler-cli/src/ngtsc/validation",
         "//packages/compiler-cli/src/ngtsc/xi18n",
         "@npm//@types/semver",
         "@npm//semver",

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

@@ -37,6 +37,7 @@ import {ExtendedTemplateChecker} from '../../typecheck/extended/api';
 import {TemplateSemanticsChecker} from '../../typecheck/template_semantics/api/api';
 import {TemplateSemanticsCheckerImpl} from '../../typecheck/template_semantics/src/template_semantics_checker';
 import {getSourceFileOrNull, isDtsPath, toUnredirectedSourceFile} from '../../util/src/typescript';
+import {SourceFileValidator} from '../../validation';
 import {Xi18nContext} from '../../xi18n';
 import {DiagnosticCategoryLabel, NgCompilerAdapter, NgCompilerOptions} from '../api';
 
@@ -62,6 +63,7 @@ interface LazyCompilationState {
   resourceRegistry: ResourceRegistry;
   extendedTemplateChecker: ExtendedTemplateChecker|null;
   templateSemanticsChecker: TemplateSemanticsChecker|null;
+  sourceFileValidator: SourceFileValidator|null;
 
   /**
    * Only available in local compilation mode when option `generateExtraImportsInLocalMode` is set.
@@ -978,10 +980,17 @@ export class NgCompiler {
   private runAdditionalChecks(sf?: ts.SourceFile): ts.Diagnostic[] {
     const diagnostics: ts.Diagnostic[] = [];
     const compilation = this.ensureAnalyzed();
-    const {extendedTemplateChecker, templateSemanticsChecker} = compilation;
+    const {extendedTemplateChecker, templateSemanticsChecker, sourceFileValidator} = compilation;
     const files = sf ? [sf] : this.inputProgram.getSourceFiles();
 
     for (const sf of files) {
+      if (sourceFileValidator !== null) {
+        const sourceFileDiagnostics = sourceFileValidator.getDiagnosticsForFile(sf);
+        if (sourceFileDiagnostics !== null) {
+          diagnostics.push(...sourceFileDiagnostics);
+        }
+      }
+
       if (templateSemanticsChecker !== null) {
         diagnostics.push(...compilation.traitCompiler.runAdditionalChecks(sf, (clazz, handler) => {
           return handler.templateSemanticsCheck?.(clazz, templateSemanticsChecker) || null;
@@ -1239,6 +1248,10 @@ export class NgCompiler {
         new TemplateSemanticsCheckerImpl(templateTypeChecker) :
         null;
 
+    const sourceFileValidator = this.constructionDiagnostics.length === 0 ?
+        new SourceFileValidator(reflector, importTracker) :
+        null;
+
     return {
       isCore,
       traitCompiler,
@@ -1255,6 +1268,7 @@ export class NgCompiler {
       extendedTemplateChecker,
       localCompilationExtraImportsTracker,
       templateSemanticsChecker,
+      sourceFileValidator,
     };
   }
 }

packages/compiler-cli/src/ngtsc/validation/BUILD.bazel

@@ -0,0 +1,18 @@
+load("//tools:defaults.bzl", "ts_library")
+
+package(default_visibility = ["//visibility:public"])
+
+ts_library(
+    name = "validation",
+    srcs = glob(
+        ["**/*.ts"],
+    ),
+    deps = [
+        "//packages/compiler-cli/src/ngtsc/annotations",
+        "//packages/compiler-cli/src/ngtsc/diagnostics",
+        "//packages/compiler-cli/src/ngtsc/imports",
+        "//packages/compiler-cli/src/ngtsc/reflection",
+        "@npm//@types/node",
+        "@npm//typescript",
+    ],
+)

packages/compiler-cli/src/ngtsc/validation/index.ts

@@ -0,0 +1,9 @@
+/**
+ * @license
+ * Copyright Google LLC All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+
+export {SourceFileValidator} from './src/source_file_validator';

packages/compiler-cli/src/ngtsc/validation/src/rules/api.ts

@@ -0,0 +1,27 @@
+/*!
+ * @license
+ * Copyright Google LLC All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+
+import ts from 'typescript';
+
+/**
+ * Rule that checks a source file a specific issue.
+ */
+export interface SourceFileValidatorRule {
+  /**
+   * Whether the file should be checked. Used to stop the traversal of the file early.
+   * @param sourceFile File to be checked.
+   */
+  shouldCheck(sourceFile: ts.SourceFile): boolean;
+
+  /**
+   * Produces diagnostics for a specific node that may
+   * contain the issue that the rule is enforcing.
+   * @param node Node to be checked.
+   */
+  checkNode(node: ts.Node): ts.Diagnostic[]|null;
+}

packages/compiler-cli/src/ngtsc/validation/src/source_file_validator.ts

@@ -0,0 +1,62 @@
+/*!
+ * @license
+ * Copyright Google LLC All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+
+import ts from 'typescript';
+
+import {ImportedSymbolsTracker} from '../../imports';
+import {ReflectionHost} from '../../reflection';
+
+import {SourceFileValidatorRule} from './rules/api';
+
+/**
+ * Validates that TypeScript files match a specific set of rules set by the Angular compiler.
+ */
+export class SourceFileValidator {
+  private rules: SourceFileValidatorRule[];
+
+  constructor(reflector: ReflectionHost, importedSymbolsTracker: ImportedSymbolsTracker) {
+    this.rules = [];  // TODO: implement the rules.
+  }
+
+  /**
+   * Gets the diagnostics for a specific file, or null if the file is valid.
+   * @param sourceFile File to be checked.
+   */
+  getDiagnosticsForFile(sourceFile: ts.SourceFile): ts.Diagnostic[]|null {
+    if (sourceFile.isDeclarationFile || sourceFile.fileName.endsWith('.ngtypecheck.ts')) {
+      return null;
+    }
+
+    let rulesToRun: SourceFileValidatorRule[]|null = null;
+    for (const rule of this.rules) {
+      if (rule.shouldCheck(sourceFile)) {
+        rulesToRun ??= [];
+        rulesToRun.push(rule);
+      }
+    }
+
+    if (rulesToRun === null) {
+      return null;
+    }
+
+    let fileDiagnostics: ts.Diagnostic[]|null = null;
+    sourceFile.forEachChild(function walk(node) {
+      // Note: non-null assertion is here because of g3.
+      for (const rule of rulesToRun!) {
+        const nodeDiagnostics = rule.checkNode(node);
+        if (nodeDiagnostics !== null) {
+          fileDiagnostics ??= [];
+          fileDiagnostics.push(...nodeDiagnostics);
+        }
+      }
+      node.forEachChild(walk);
+    });
+
+    return fileDiagnostics;
+  }
+}