typescript-eslint · bradzacher · May 10, 2020 · Jul 18, 2019 · Jul 18, 2019 · Jul 18, 2019
diff --git a/packages/eslint-plugin/README.md b/packages/eslint-plugin/README.md
@@ -139,7 +139,7 @@ Pro Tip: For larger codebases you may want to consider splitting our linting int
 | [`@typescript-eslint/no-unsafe-call`](./docs/rules/no-unsafe-call.md)                                                 | Disallows calling an any type value                                                                                     |                    |          | :thought_balloon: |
 | [`@typescript-eslint/no-unsafe-member-access`](./docs/rules/no-unsafe-member-access.md)                               | Disallows member access on any typed variables                                                                          |                    |          | :thought_balloon: |
 | [`@typescript-eslint/no-unsafe-return`](./docs/rules/no-unsafe-return.md)                                             | Disallows returning any from a function                                                                                 |                    |          | :thought_balloon: |
-| [`@typescript-eslint/no-unused-vars-experimental`](./docs/rules/no-unused-vars-experimental.md)                       | Disallow unused variables and arguments                                                                                 |                    |          | :thought_balloon: |
+| [`@typescript-eslint/no-unused-vars-experimental`](./docs/rules/no-unused-vars-experimental.md)                       | Disallow unused variables and arguments                                                                                 |                    |          |                   |
 | [`@typescript-eslint/no-var-requires`](./docs/rules/no-var-requires.md)                                               | Disallows the use of require statements except in import statements                                                     | :heavy_check_mark: |          |                   |
 | [`@typescript-eslint/prefer-as-const`](./docs/rules/prefer-as-const.md)                                               | Prefer usage of `as const` over literal type                                                                            |                    | :wrench: |                   |
 | [`@typescript-eslint/prefer-for-of`](./docs/rules/prefer-for-of.md)                                                   | Prefer a ‘for-of’ loop over a standard ‘for’ loop if the index is only used to access the array being iterated          |                    |          |                   |

diff --git a/packages/eslint-plugin/src/rules/no-unused-vars-experimental.ts b/packages/eslint-plugin/src/rules/no-unused-vars-experimental.ts
@@ -29,7 +29,6 @@ export default util.createRule<Options, MessageIds>({
       description: 'Disallow unused variables and arguments',
       category: 'Best Practices',
       recommended: false,
-      requiresTypeChecking: true,
     },
     schema: [
       {
@@ -68,7 +67,7 @@ export default util.createRule<Options, MessageIds>({
     },
   ],
   create(context, [userOptions]) {
-    const parserServices = util.getParserServices(context);
+    const parserServices = util.getParserServices(context, true);
     const tsProgram = parserServices.program;
     const afterAllDiagnosticsCallbacks: (() => void)[] = [];
 
@@ -191,7 +190,7 @@ export default util.createRule<Options, MessageIds>({
       parent: ts.ParameterDeclaration,
     ): void {
       const name = identifier.getText();
-      // regardless of if the paramter is ignored, track that it had a diagnostic fired on it
+      // regardless of if the parameter is ignored, track that it had a diagnostic fired on it
       unusedParameters.add(identifier);
 
       /*

diff --git a/packages/eslint-plugin/tests/docs.test.ts b/packages/eslint-plugin/tests/docs.test.ts
@@ -70,6 +70,10 @@ describe('Validating rule docs', () => {
 });
 
 describe('Validating rule metadata', () => {
+  function requiresFullTypeInformation(content: string): boolean {
+    return /getParserServices(\(\s*[^,\s)]+)\s*(,\s*false\s*)?\)/.test(content);
+  }
+
   for (const [ruleName, rule] of rulesData) {
     describe(`${ruleName}`, () => {
       it('`name` field in rule must match the filename', () => {
@@ -85,9 +89,10 @@ describe('Validating rule metadata', () => {
         // not perfect but should be good enough
         const ruleFileContents = fs.readFileSync(
           path.resolve(__dirname, `../src/rules/${ruleName}.ts`),
+          'utf-8',
         );
 
-        expect(ruleFileContents.includes('getParserServices')).toEqual(
+        expect(requiresFullTypeInformation(ruleFileContents)).toEqual(
           rule.meta.docs?.requiresTypeChecking ?? false,
         );
       });

diff --git a/packages/eslint-plugin/tests/rules/no-unused-vars-experimental.test.ts b/packages/eslint-plugin/tests/rules/no-unused-vars-experimental.test.ts
@@ -14,8 +14,6 @@ const ruleTester = new RuleTester({
   parserOptions: {
     ecmaVersion: 2018,
     sourceType: 'module',
-    project: './tsconfig.json',
-    tsconfigRootDir: rootDir,
   },
   parser: '@typescript-eslint/parser',
 });

diff --git a/packages/eslint-plugin/tests/util/isUnsafeAssignment.test.ts b/packages/eslint-plugin/tests/util/isUnsafeAssignment.test.ts
@@ -16,8 +16,8 @@ describe('isUnsafeAssignment', () => {
       filePath: path.join(rootDir, 'file.ts'),
       tsconfigRootDir: rootDir,
     });
-    const checker = services.program!.getTypeChecker();
-    const esTreeNodeToTSNodeMap = services.esTreeNodeToTSNodeMap!;
+    const checker = services.program.getTypeChecker();
+    const esTreeNodeToTSNodeMap = services.esTreeNodeToTSNodeMap;
 
     const declaration = ast.body[0] as TSESTree.VariableDeclaration;
     const declarator = declaration.declarations[0];

diff --git a/packages/experimental-utils/src/eslint-utils/getParserServices.ts b/packages/experimental-utils/src/eslint-utils/getParserServices.ts
@@ -4,31 +4,38 @@ import { ParserServices } from '../ts-estree';
 const ERROR_MESSAGE =
   'You have used a rule which requires parserServices to be generated. You must therefore provide a value for the "parserOptions.project" property for @typescript-eslint/parser.';
 
-type RequiredParserServices = {
-  [k in keyof ParserServices]: Exclude<ParserServices[k], undefined>;
-};
-
 /**
  * Try to retrieve typescript parser service from context
  */
 function getParserServices<
   TMessageIds extends string,
-  TOptions extends unknown[]
+  TOptions extends readonly unknown[]
 >(
   context: TSESLint.RuleContext<TMessageIds, TOptions>,
-): RequiredParserServices {
+  allowWithoutFullTypeInformation = false,
+): ParserServices {
+  // backwards compatibility check
+  // old versions of the parser would not return any parserServices unless parserOptions.project was set
   if (
     !context.parserServices ||
     !context.parserServices.program ||
-    !context.parserServices.esTreeNodeToTSNodeMap
+    !context.parserServices.esTreeNodeToTSNodeMap ||
+    !context.parserServices.tsNodeToESTreeNodeMap
   ) {
-    /**
-     * The user needs to have configured "project" in their parserOptions
-     * for @typescript-eslint/parser
-     */
     throw new Error(ERROR_MESSAGE);
   }
-  return context.parserServices as RequiredParserServices;
+
+  const hasFullTypeInformation =
+    context.parserServices.hasFullTypeInformation ??
+    /* backwards compatible */ true;
+
+  // if a rule requires full type information, then hard fail if it doesn't exist
+  // this forces the user to supply parserOptions.project
+  if (!hasFullTypeInformation && !allowWithoutFullTypeInformation) {
+    throw new Error(ERROR_MESSAGE);
+  }
+
+  return context.parserServices;
 }
 
 export { getParserServices };
diff --git a/packages/typescript-estree/src/ast-converter.ts b/packages/typescript-estree/src/ast-converter.ts
@@ -10,7 +10,7 @@ export function astConverter(
   ast: SourceFile,
   extra: Extra,
   shouldPreserveNodeMaps: boolean,
-): { estree: TSESTree.Program; astMaps: ASTMaps | undefined } {
+): { estree: TSESTree.Program; astMaps: ASTMaps } {
   /**
    * The TypeScript compiler produced fundamental parse errors when parsing the
    * source.
@@ -63,7 +63,7 @@ export function astConverter(
     estree.comments = convertComments(ast, extra.code);
   }
 
-  const astMaps = shouldPreserveNodeMaps ? instance.getASTMaps() : undefined;
+  const astMaps = instance.getASTMaps();
 
   return { estree, astMaps };
 }
diff --git a/packages/typescript-estree/src/create-program/createProjectProgram.ts b/packages/typescript-estree/src/create-program/createProjectProgram.ts
@@ -93,7 +93,6 @@ function createProjectProgram(
       errorLines.push(
         'The file must be included in at least one of the projects provided.',
       );
-      hasMatchedAnError = true;
     }
 
     throw new Error(errorLines.join('\n'));

diff --git a/packages/typescript-estree/src/create-program/shared.ts b/packages/typescript-estree/src/create-program/shared.ts
@@ -4,7 +4,7 @@ import { Extra } from '../parser-options';
 
 interface ASTAndProgram {
   ast: ts.SourceFile;
-  program: ts.Program | undefined;
+  program: ts.Program;
 }
 
 /**
@@ -16,6 +16,9 @@ const DEFAULT_COMPILER_OPTIONS: ts.CompilerOptions = {
   checkJs: true,
   noEmit: true,
   // extendedDiagnostics: true,
+  /**
+   * Flags required to make no-unused-vars work
+   */
   noUnusedLocals: true,
   noUnusedParameters: true,
 };

diff --git a/packages/typescript-estree/src/parser-options.ts b/packages/typescript-estree/src/parser-options.ts
@@ -184,9 +184,8 @@ export interface ParserWeakMapESTreeToTSNode<
 }
 
 export interface ParserServices {
-  program: Program | undefined;
-  esTreeNodeToTSNodeMap: ParserWeakMapESTreeToTSNode | undefined;
-  tsNodeToESTreeNodeMap:
-    | ParserWeakMap<TSNode | TSToken, TSESTree.Node>
-    | undefined;
+  program: Program;
+  esTreeNodeToTSNodeMap: ParserWeakMapESTreeToTSNode;
+  tsNodeToESTreeNodeMap: ParserWeakMap<TSNode | TSToken, TSESTree.Node>;
+  hasFullTypeInformation: boolean;
 }
diff --git a/packages/typescript-estree/src/parser.ts b/packages/typescript-estree/src/parser.ts
@@ -12,7 +12,7 @@ import { createSourceFile } from './create-program/createSourceFile';
 import { Extra, TSESTreeOptions, ParserServices } from './parser-options';
 import { getFirstSemanticOrSyntacticError } from './semantic-or-syntactic-errors';
 import { TSESTree } from './ts-estree';
-import { ensureAbsolutePath } from './create-program/shared';
+import { ASTAndProgram, ensureAbsolutePath } from './create-program/shared';
 
 const log = debug('typescript-eslint:typescript-estree:parser');
 
@@ -48,11 +48,6 @@ function enforceString(code: unknown): string {
   return code;
 }
 
-interface ASTAndProgram {
-  ast: ts.SourceFile;
-  program: ts.Program | undefined;
-}
-
 /**
  * @param code The code of the file being linted
  * @param shouldProvideParserServices True if the program should be attempted to be calculated from provided tsconfig files
@@ -63,7 +58,7 @@ function getProgramAndAST(
   code: string,
   shouldProvideParserServices: boolean,
   shouldCreateDefaultProgram: boolean,
-): ASTAndProgram | undefined {
+): ASTAndProgram {
   return (
     (shouldProvideParserServices &&
       createProjectProgram(code, shouldCreateDefaultProgram, extra)) ||
@@ -103,7 +98,7 @@ function resetExtra(): void {
     jsx: false,
     loc: false,
     log: console.log, // eslint-disable-line no-console
-    preserveNodeMaps: undefined,
+    preserveNodeMaps: true,
     projects: [],
     range: false,
     strict: false,
@@ -236,7 +231,7 @@ function applyParserOptionsToExtra(options: TSESTreeOptions): void {
   }
 
   /**
-   * Get the file extension
+   * Get the file path
    */
   if (typeof options.filePath === 'string' && options.filePath !== '<input>') {
     extra.filePath = options.filePath;
@@ -298,14 +293,9 @@ function applyParserOptionsToExtra(options: TSESTreeOptions): void {
   /**
    * Allow the user to enable or disable the preservation of the AST node maps
    * during the conversion process.
-   *
-   * NOTE: For backwards compatibility we also preserve node maps in the case where `project` is set,
-   * and `preserveNodeMaps` is not explicitly set to anything.
    */
-  extra.preserveNodeMaps =
-    typeof options.preserveNodeMaps === 'boolean' && options.preserveNodeMaps;
-  if (options.preserveNodeMaps === undefined && extra.projects.length > 0) {
-    extra.preserveNodeMaps = true;
+  if (typeof options.preserveNodeMaps === 'boolean') {
+    extra.preserveNodeMaps = options.preserveNodeMaps;
   }
 
   extra.createDefaultProgram =
@@ -449,20 +439,13 @@ function parseAndGenerateServices<T extends TSESTreeOptions = TSESTreeOptions>(
     extra.createDefaultProgram,
   )!;
 
-  /**
-   * Determine if two-way maps of converted AST nodes should be preserved
-   * during the conversion process
-   */
-  const shouldPreserveNodeMaps =
-    extra.preserveNodeMaps !== undefined
-      ? extra.preserveNodeMaps
-      : shouldProvideParserServices;
-
   /**
    * Convert the TypeScript AST to an ESTree-compatible one, and optionally preserve
    * mappings between converted and original AST nodes
    */
-  const { estree, astMaps } = astConverter(ast, extra, shouldPreserveNodeMaps);
+  const preserveNodeMaps =
+    typeof extra.preserveNodeMaps === 'boolean' ? extra.preserveNodeMaps : true;
+  const { estree, astMaps } = astConverter(ast, extra, preserveNodeMaps);
 
   /**
    * Even if TypeScript parsed the source code ok, and we had no problems converting the AST,
@@ -481,15 +464,10 @@ function parseAndGenerateServices<T extends TSESTreeOptions = TSESTreeOptions>(
   return {
     ast: estree as AST<T>,
     services: {
-      program: shouldProvideParserServices ? program : undefined,
-      esTreeNodeToTSNodeMap:
-        shouldPreserveNodeMaps && astMaps
-          ? astMaps.esTreeNodeToTSNodeMap
-          : undefined,
-      tsNodeToESTreeNodeMap:
-        shouldPreserveNodeMaps && astMaps
-          ? astMaps.tsNodeToESTreeNodeMap
-          : undefined,
+      hasFullTypeInformation: shouldProvideParserServices,
+      program,
+      esTreeNodeToTSNodeMap: astMaps.esTreeNodeToTSNodeMap,
+      tsNodeToESTreeNodeMap: astMaps.tsNodeToESTreeNodeMap,
     },
   };
 }