8000 feat(eslint-plugin): [consistent-return] add new rule (#8289) · yeonjuan/typescript-eslint@46cef96 · GitHub
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feat(eslint-plugin): [consistent-return] add new rule (typescript-eslint#8289)
* feat(eslint-plugin): [consistent-return] add new rule * apply reviews * fix docs * fix order * docs: remove eslint comment * handle treatUndefinedAsUnspecified option * fix rule in rulemap order * add test case * fix docs * add test case * fix default options * refactor * refactor * fix * handle nested promise * fix lint error
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‎packages/eslint-plugin/docs/rules/consistent-return.md

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---
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description: 'Require `return` statements to either always or never specify values.'
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---
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> 🛑 This file is source code, not the primary documentation location! 🛑
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>
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> See **https://typescript-eslint.io/rules/consistent-return** for documentation.
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This rule extends the base [`eslint/consistent-return`](https://eslint.org/docs/rules/consistent-return) rule.
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This version adds support for functions that return `void` or `Promise<void>`.
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<!--tabs-->
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### ❌ Incorrect
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```ts
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function foo(): undefined {}
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function bar(flag: boolean): undefined {
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if (flag) return foo();
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return;
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}
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async function baz(flag: boolean): Promise<undefined> {
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if (flag) return;
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return foo();
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}
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```
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### ✅ Correct
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```ts
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function foo(): void {}
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function bar(flag: boolean): void {
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if (flag) return foo();
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return;
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}
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async function baz(flag: boolean): Promise<void | number> {
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if (flag) return 42;
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return;
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}
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```

‎packages/eslint-plugin/src/configs/all.ts

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'@typescript-eslint/class-methods-use-this': 'error',
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'@typescript-eslint/consistent-generic-constructors': 'error',
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'@typescript-eslint/consistent-indexed-object-style': 'error',
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'consistent-return': 'off',
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'@typescript-eslint/consistent-return': 'error',
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'@typescript-eslint/consistent-type-assertions': 'error',
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'@typescript-eslint/consistent-type-definitions': 'error',
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'@typescript-eslint/consistent-type-exports': 'error',

‎packages/eslint-plugin/src/configs/disable-type-checked.ts

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parserOptions: { project: false, program: null },
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rules: {
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'@typescript-eslint/await-thenable': 'off',
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'@typescript-eslint/consistent-return': 'off',
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'@typescript-eslint/consistent-type-exports': 'off',
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'@typescript-eslint/dot-notation': 'off',
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'@typescript-eslint/naming-convention': 'off',

‎packages/eslint-plugin/src/rules/consistent-return.ts

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import type { TSESTree } from '@typescript-eslint/utils';
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import * as tsutils from 'ts-api-utils';
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import * as ts from 'typescript';
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import type {
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InferMessageIdsTypeFromRule,
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InferOptionsTypeFromRule,
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} from '../util';
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import { createRule, getParserServices, isTypeFlagSet } from '../util';
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import { getESLintCoreRule } from '../util/getESLintCoreRule';
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const baseRule = getESLintCoreRule('consistent-return');
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type Options = InferOptionsTypeFromRule<typeof baseRule>;
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type MessageIds = InferMessageIdsTypeFromRule<typeof baseRule>;
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type FunctionNode =
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| TSESTree.FunctionDeclaration
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| TSESTree.FunctionExpression
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| TSESTree.ArrowFunctionExpression;
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export default createRule<Options, MessageIds>({
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name: 'consistent-return',
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meta: {
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type: 'suggestion',
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docs: {
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description:
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'Require `return` statements to either always or never specify values',
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extendsBaseRule: true,
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requiresTypeChecking: true,
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},
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hasSuggestions: baseRule.meta.hasSuggestions,
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schema: baseRule.meta.schema,
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messages: baseRule.meta.messages,
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},
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defaultOptions: [{ treatUndefinedAsUnspecified: false }],
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create(context, [options]) {
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const services = getParserServices(context);
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const checker = services.program.getTypeChecker();
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const rules = baseRule.create(context);
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const functions: FunctionNode[] = [];
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const treatUndefinedAsUnspecified =
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options?.treatUndefinedAsUnspecified === true;
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function enterFunction(node: FunctionNode): void {
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functions.push(node);
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}
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function exitFunction(): void {
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functions.pop();
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}
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function getCurrentFunction(): FunctionNode | null {
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return functions[functions.length - 1] ?? null;
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}
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function isPromiseVoid(node: ts.Node, type: ts.Type): boolean {
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if (
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tsutils.isThenableType(checker, node, type) &&
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tsutils.isTypeReference(type)
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) {
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const awaitedType = type.typeArguments?.[0];
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if (awaitedType) {
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if (isTypeFlagSet(awaitedType, ts.TypeFlags.Void)) {
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return true;
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}
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return isPromiseVoid(node, awaitedType);
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}
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}
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return false;
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}
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function isReturnVoidOrThenableVoid(node: FunctionNode): boolean {
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const functionType = services.getTypeAtLocation(node);
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const tsNode = services.esTreeNodeToTSNodeMap.get(node);
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const callSignatures = functionType.getCallSignatures();
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return callSignatures.some(signature => {
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const returnType = signature.getReturnType();
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if (node.async) {
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return isPromiseVoid(tsNode, returnType);
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}
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return isTypeFlagSet(returnType, ts.TypeFlags.Void);
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});
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}
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return {
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...rules,
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FunctionDeclaration: enterFunction,
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'FunctionDeclaration:exit'(node): void {
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exitFunction();
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rules['FunctionDeclaration:exit'](node);
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},
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FunctionExpression: enterFunction,
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'FunctionExpression:exit'(node): void {
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exitFunction();
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rules['FunctionExpression:exit'](node);
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},
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ArrowFunctionExpression: enterFunction,
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'ArrowFunctionExpression:exit'(node): void {
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exitFunction();
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rules['ArrowFunctionExpression:exit'](node);
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},
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ReturnStatement(node): void {
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const functionNode = getCurrentFunction();
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if (
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!node.argument &&
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functionNode &&
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isReturnVoidOrThenableVoid(functionNode)
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) {
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return;
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}
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if (treatUndefinedAsUnspecified && node.argument) {
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const returnValueType = services.getTypeAtLocation(node.argument);
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if (returnValueType.flags === ts.TypeFlags.Undefined) {
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rules.ReturnStatement({
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...node,
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argument: null,
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});
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return;
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}
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}
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rules.ReturnStatement(node);
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},
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};
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},
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});

‎packages/eslint-plugin/src/rules/index.ts

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import commaSpacing from './comma-spacing';
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import consistentGenericConstructors from './consistent-generic-constructors';
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import consistentIndexedObjectStyle from './consistent-indexed-object-style';
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import consistentReturn from './consistent-return';
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import consistentTypeAssertions from './consistent-type-assertions';
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import consistentTypeDefinitions from './consistent-type-definitions';
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import consistentTypeExports from './consistent-type-exports';
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'comma-spacing': commaSpacing,
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'consistent-generic-constructors': consistentGenericConstructors,
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'consistent-indexed-object-style': consistentIndexedObjectStyle,
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'consistent-return': consistentReturn,
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'consistent-type-assertions': consistentTypeAssertions,
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'consistent-type-definitions': consistentTypeDefinitions,
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'consistent-type-exports': consistentTypeExports,

‎packages/eslint-plugin/src/util/getESLintCoreRule.ts

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'block-spacing': typeof import('eslint/lib/rules/block-spacing');
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'brace-style': typeof import('eslint/lib/rules/brace-style');
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'comma-dangle': typeof import('eslint/lib/rules/comma-dangle');
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'consistent-return': typeof import('eslint/lib/rules/consistent-return');
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'dot-notation': typeof import('eslint/lib/rules/dot-notation');
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indent: typeof import('eslint/lib/rules/indent');
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'init-declarations': typeof import('eslint/lib/rules/init-declarations');

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