8000 feat(eslint-plugin): [max-params] don't count `this` parameter · StyleShit/typescript-eslint@2779fe8 · GitHub
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feat(eslint-plugin): [max-params] don't count this parameter
Closes typescript-eslint#7538
1 parent 91a3e0c commit 2779fe8

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‎packages/eslint-plugin/docs/rules/max-params.md

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---
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description: 'Enforce a maximum number of parameters in function definitions'
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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/max-params** for documentation.
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This rule extends the base [`eslint/max-params`](https://eslint.org/docs/rules/max-params) rule.
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This version adds support for TypeScript `this` parameter so it won't be counted as a parameter.

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

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@@ -52,6 +52,8 @@ export = {
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'@typescript-eslint/lines-around-comment': 'error',
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'lines-between-class-members': 'off',
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'@typescript-eslint/lines-between-class-members': 'error',
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'max-params': 'off',
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'@typescript-eslint/max-params': 'error',
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'@typescript-eslint/member-delimiter-style': 'error',
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'@typescript-eslint/member-ordering': 'error',
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'@typescript-eslint/method-signature-style': 'error',

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

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@@ -28,6 +28,7 @@ import keySpacing from './key-spacing';
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import keywordSpacing from './keyword-spacing';
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import linesAroundComment from './lines-around-comment';
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import linesBetweenClassMembers from './lines-between-class-members';
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import maxParams from './max-params';
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import memberDelimiterStyle from './member-delimiter-style';
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import memberOrdering from './member-ordering';
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import methodSignatureStyle from './method-signature-style';
@@ -163,6 +164,7 @@ export default {
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'keyword-spacing': keywordSpacing,
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'lines-around-comment': linesAroundComment,
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'lines-between-class-members': linesBetweenClassMembers,
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'max-params': maxParams,
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'member-delimiter-style': memberDelimiterStyle,
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'member-ordering': memberOrdering,
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'method-signature-style': methodSignatureStyle,

‎packages/eslint-plugin/src/rules/max-params.ts

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import { AST_NODE_TYPES, type TSESTree } from '@typescript-eslint/utils';
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import type { JSONSchema4 } from '@typescript-eslint/utils/json-schema';
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import * as util from '../util';
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import { getESLintCoreRule } from '../util/getESLintCoreRule';
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type FunctionLike =
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| TSESTree.FunctionDeclaration
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| TSESTree.FunctionExpression
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| TSESTree.ArrowFunctionExpression;
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type FunctionRuleListener<T extends FunctionLike> = (node: T) => void;
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const baseRule = getESLintCoreRule('max-params');
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export type Options = util.InferOptionsTypeFromRule<typeof baseRule>;
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export type MessageIds = util.InferMessageIdsTypeFromRule<typeof baseRule>;
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const schema = Object.values(
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util.deepMerge(
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{ ...baseRule.meta.schema },
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{
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0: {
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oneOf: [
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baseRule.meta.schema[0].oneOf[0],
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{
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...baseRule.meta.schema[0].oneOf[1],
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properties: {
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...baseRule.meta.schema[0].oneOf[1].properties,
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countVoidThis: {
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type: 'boolean',
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},
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},
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},
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],
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},
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},
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),
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) as JSONSchema4[];
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export default util.createRule<Options, MessageIds>({
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name: 'max-params',
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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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'Enforce a maximum number of parameters in function definitions',
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extendsBaseRule: true,
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},
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schema,
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messages: baseRule.meta.messages,
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},
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defaultOptions: [{ max: 3, countVoidThis: false }],
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create(context, [{ countVoidThis }]) {
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const baseRules = baseRule.create(context);
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if (countVoidThis === true) {
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return baseRules;
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}
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const removeVoidThisParam = <T extends FunctionLike>(node: T): T => {
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if (node.params.length === 0) {
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return node;
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}
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const params = [...node.params];
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if (
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params[0] &&
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params[0].type === AST_NODE_TYPES.Identifier &&
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params[0].name === 'this' &&
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params[0].typeAnnotation?.typeAnnotation.type ===
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AST_NODE_TYPES.TSVoidKeyword
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) {
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params.shift();
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}
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return {
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...node,
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params,
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};
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};
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const wrapListener = <T extends FunctionLike>(
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listener: FunctionRuleListener<T>,
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): FunctionRuleListener<T> => {
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return (node: T): void => {
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listener(removeVoidThisParam(node));
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};
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};
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return {
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ArrowFunctionExpression: wrapListener(baseRules.ArrowFunctionExpression),
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FunctionDeclaration: wrapListener(baseRules.FunctionDeclaration),
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FunctionExpression: wrapListener(baseRules.FunctionExpression),
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};
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},
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});

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

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'keyword-spacing': typeof import('eslint/lib/rules/keyword-spacing');
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'lines-around-comment': typeof import('eslint/lib/rules/lines-around-comment');
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'lines-between-class-members': typeof import('eslint/lib/rules/lines-between-class-members');
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'max-params': typeof import('eslint/lib/rules/max-params');
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'no-dupe-args': typeof import('eslint/lib/rules/no-dupe-args');
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'no-dupe-class-members': typeof import('eslint/lib/rules/no-dupe-class-members');
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'no-empty-function': typeof import('eslint/lib/rules/no-empty-function');

‎packages/eslint-plugin/tests/rules/max-params.test.ts

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import { RuleTester } from '@typescript-eslint/rule-tester';
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import rule from '../../src/rules/max-params';
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const ruleTester = new RuleTester({
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parser: '@typescript-eslint/parser',
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});
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ruleTester.run('max-params', rule, {
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valid: [
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'function foo() {}',
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'const foo = function () {};',
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'const foo = () => {};',
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'function foo(a) {}',
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`
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class Foo {
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constructor(a) {}
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}
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`,
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`
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class Foo {
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method(this: void, a, b, c) {}
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}
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`,
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`
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class Foo {
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method(this: Foo, a, b) {}
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}
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`,
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{
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code: 'function foo(a, b, c, d) {}',
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options: [{ max: 4 }],
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},
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{
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code: 'function foo(a, b, c, d) {}',
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options: [{ maximum: 4 }],
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},
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{
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code: `
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class Foo {
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method(this: void) {}
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}
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`,
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options: [{ max: 0 }],
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},
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{
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code: `
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class Foo {
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method(this: void, a) {}
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}
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`,
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options: [{ max: 1 }],
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},
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{
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code: `
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class Foo {
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method(this: void, a) {}
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}
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`,
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options: [{ max: 2, countVoidThis: true }],
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},
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],
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invalid: [
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{ code: 'function foo(a, b, c, d) {}', errors: [{ messageId: 'exceed' }] },
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{
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code: 'const foo = function (a, b, c, d) {};',
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errors: [{ messageId: 'exceed' }],
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},
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{
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code: 'const foo = (a, b, c, d) => {};',
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errors: [{ messageId: 'exceed' }],
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},
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{
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code: 'const foo = a => {};',
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options: [{ max: 0 }],
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errors: [{ messageId: 'exceed' }],
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},
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{
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code: `
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class Foo {
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method(this: void, a, b, c, d) {}
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}
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`,
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errors: [{ messageId: 'exceed' }],
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},
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{
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code: `
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class Foo {
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method(this: void, a) {}
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}
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`,
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options: [{ max: 1, countVoidThis: true }],
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errors: [{ messageId: 'exceed' }],
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},
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{
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code: `
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class Foo {
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method(this: Foo, a, b, c) {}
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}
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`,
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errors: [{ messageId: 'exceed' }],
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},
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],
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});

‎packages/eslint-plugin/typings/eslint-rules.d.ts

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@@ -272,6 +272,24 @@ declare module 'eslint/lib/rules/keyword-spacing' {
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export = rule;
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}
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declare module 'eslint/lib/rules/max-params' {
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import type { TSESLint, TSESTree } from '@typescript-eslint/utils';
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const rule: TSESLint.RuleModule<
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'exceed',
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(
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| { max: number; countVoidThis?: boolean }
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| { maximum: number; countVoidThis?: boolean }
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)[],
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{
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FunctionDeclaration(node: TSESTree.FunctionDeclaration): void;
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FunctionExpression(node: TSESTree.FunctionExpression): void;
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ArrowFunctionExpression(node: TSESTree.ArrowFunctionExpression): void;
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}
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>;
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export = rule;
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}
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declare module 'eslint/lib/rules/no-dupe-class-members' {
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import type { TSESLint, TSESTree } from '@typescript-eslint/utils';
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