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Add no-zero-quantifier rule (#200)
* Add `no-zero-quantifier` rule * Fixed code example * Shorter message
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‎README.md‎

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@@ -135,6 +135,7 @@ The rules with the following star :star: are included in the `plugin:regexp/reco
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| [regexp/no-useless-quantifier](https://ota-meshi.github.io/eslint-plugin-regexp/rules/no-useless-quantifier.html) | disallow quantifiers that can be removed | :wrench: |
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| [regexp/no-useless-range](https://ota-meshi.github.io/eslint-plugin-regexp/rules/no-useless-range.html) | disallow unnecessary range of characters by using a hyphen | :wrench: |
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| [regexp/no-useless-two-nums-quantifier](https://ota-meshi.github.io/eslint-plugin-regexp/rules/no-useless-two-nums-quantifier.html) | disallow unnecessary `{n,m}` quantifier | :star::wrench: |
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| [regexp/no-zero-quantifier](https://ota-meshi.github.io/eslint-plugin-regexp/rules/no-zero-quantifier.html) | disallow quantifiers with a maximum of zero | |
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| [regexp/optimal-lookaround-quantifier](https://ota-meshi.github.io/eslint-plugin-regexp/rules/optimal-lookaround-quantifier.html) | disallow the alternatives of lookarounds that end with a non-constant quantifier | |
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| [regexp/order-in-character-class](https://ota-meshi.github.io/eslint-plugin-regexp/rules/order-in-character-class.html) | enforces elements order in character class | :wrench: |
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| [regexp/prefer-character-class](https://ota-meshi.github.io/eslint-plugin-regexp/rules/prefer-character-class.html) | enforce using character class | :wrench: |

‎docs/rules/README.md‎

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@@ -49,6 +49,7 @@ The rules with the following star :star: are included in the `plugin:regexp/reco
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| [regexp/no-useless-quantifier](./no-useless-quantifier.md) | disallow quantifiers that can be removed | :wrench: |
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| [regexp/no-useless-range](./no-useless-range.md) | disallow unnecessary range of characters by using a hyphen | :wrench: |
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| [regexp/no-useless-two-nums-quantifier](./no-useless-two-nums-quantifier.md) | disallow unnecessary `{n,m}` quantifier | :star::wrench: |
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| [regexp/no-zero-quantifier](./no-zero-quantifier.md) | disallow quantifiers with a maximum of zero | |
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| [regexp/optimal-lookaround-quantifier](./optimal-lookaround-quantifier.md) | disallow the alternatives of lookarounds that end with a non-constant quantifier | |
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| [regexp/order-in-character-class](./order-in-character-class.md) | enforces elements order in character class | :wrench: |
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| [regexp/prefer-character-class](./prefer-character-class.md) | enforce using character class | :wrench: |

‎docs/rules/no-zero-quantifier.md‎

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---
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pageClass: "rule-details"
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sidebarDepth: 0
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title: "regexp/no-zero-quantifier"
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description: "disallow quantifiers with a maximum of zero"
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---
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# regexp/no-zero-quantifier
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> disallow quantifiers with a maximum of zero
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- :exclamation: <badge text="This rule has not been released yet." vertical="middle" type="error"> ***This rule has not been released yet.*** </badge>
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## :book: Rule Details
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This rule reports quantifiers with a maximum of zero. These quantifiers trivially do not affect the pattern is any way and can be removed.
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<eslint-code-block>
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```js
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/* eslint regexp/no-zero-quantifier: "error" */
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/* ✓ GOOD */
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var foo = /a?/;
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var foo = /a{0,}/;
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var foo = /a{0,1}/;
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/* ✗ BAD */
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var foo = /a{0}/;
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var foo = /a{0,0}?/;
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var foo = /(a){0}/;
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```
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</eslint-code-block>
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## :wrench: Options
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Nothing.
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## :mag: Implementation
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- [Rule source](https://github.com/ota-meshi/eslint-plugin-regexp/blob/master/lib/rules/no-zero-quantifier.ts)
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- [Test source](https://github.com/ota-meshi/eslint-plugin-regexp/blob/master/tests/lib/rules/no-zero-quantifier.ts)

‎lib/rules/no-zero-quantifier.ts‎

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import type { Rule } from "eslint"
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import { hasSomeDescendant } from "regexp-ast-analysis"
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import type { RegExpVisitor } from "regexpp/visitor"
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import type { RegExpContext } from "../utils"
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import { canUnwrapped, createRule, defineRegexpVisitor } from "../utils"
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export default createRule("no-zero-quantifier", {
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meta: {
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docs: {
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description: "disallow quantifiers with a maximum of zero",
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// TODO Switch to recommended in the major version.
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// recommended: true,
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recommended: false,
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},
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schema: [],
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messages: {
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unexpected:
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"Unexpected zero quantifier. The quantifier and its quantified element can be removed without affecting the pattern.",
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withCapturingGroup:
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"Unexpected zero quantifier. The quantifier and its quantified element do not affecting the pattern. Try to remove the elements but be careful because it contains at least one capturing group.",
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// suggestions
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remove: "Remove this zero quantifier.",
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},
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type: "suggestion", // "problem",
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},
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create(context) {
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/**
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* Create visitor
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*/
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function createVisitor(
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regexpContext: RegExpContext,
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): RegExpVisitor.Handlers {
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const {
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node,
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getRegexpLocation,
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fixReplaceNode,
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patternAst,
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} = regexpContext
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return {
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onQuantifierEnter(qNode) {
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if (qNode.max === 0) {
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const containCapturingGroup = hasSomeDescendant(
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qNode,
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(n) => n.type === "CapturingGroup",
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)
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if (containCapturingGroup) {
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context.report({
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node,
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loc: getRegexpLocation(qNode),
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messageId: "withCapturingGroup",
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})
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} else {
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const suggest: Rule.SuggestionReportDescriptor[] = []
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if (patternAst.raw === qNode.raw) {
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suggest.push({
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messageId: "remove",
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fix: fixReplaceNode(qNode, "(?:)"),
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})
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} else if (canUnwrapped(qNode, "")) {
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suggest.push({
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messageId: "remove",
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fix: fixReplaceNode(qNode, ""),
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})
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}
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context.report({
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node,
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loc: getRegexpLocation(qNode),
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messageId: "unexpected",
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suggest,
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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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return defineRegexpVisitor(context, {
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createVisitor,
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})
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},
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})

‎lib/utils/rules.ts‎

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@@ -37,6 +37,7 @@ import noUselessNonGreedy from "../rules/no-useless-non-greedy"
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import noUselessQuantifier from "../rules/no-useless-quantifier"
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import noUselessRange from "../rules/no-useless-range"
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import noUselessTwoNumsQuantifier from "../rules/no-useless-two-nums-quantifier"
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import noZeroQuantifier from "../rules/no-zero-quantifier"
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import optimalLookaroundQuantifier from "../rules/optimal-lookaround-quantifier"
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import orderInCharacterClass from "../rules/order-in-character-class"
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import preferCharacterClass from "../rules/prefer-character-class"
@@ -96,6 +97,7 @@ export const rules = [
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noUselessQuantifier,
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noUselessRange,
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noUselessTwoNumsQuantifier,
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noZeroQuantifier,
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optimalLookaroundQuantifier,
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orderInCharacterClass,
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preferCharacterClass,

‎tests/lib/rules/no-zero-quantifier.ts‎

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import { RuleTester } from "eslint"
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import rule from "../../../lib/rules/no-zero-quantifier"
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const tester = new RuleTester({
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parserOptions: {
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ecmaVersion: 2020,
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sourceType: "module",
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},
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})
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tester.run("no-zero-quantifier", rule as any, {
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valid: [`/a{0,1}/`, `/a{0,}/`],
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invalid: [
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{
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code: `/a{0}/`,
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errors: [
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{
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messageId: "unexpected",
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column: 2,
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endColumn: 6,
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suggestions: [{ output: `/(?:)/` }],
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},
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],
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},
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{
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code: `/a{0,0}/`,
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errors: [
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{
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messageId: "unexpected",
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column: 2,
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endColumn: 8,
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suggestions: [{ output: `/(?:)/` }],
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},
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],
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},
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{
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code: `/a{0,0}?b/`,
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errors: [
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{
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messageId: "unexpected",
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column: 2,
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endColumn: 9,
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suggestions: [{ output: `/b/` }],
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},
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],
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},
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{
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code: `/(a){0}/`,
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errors: [
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{
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messageId: "withCapturingGroup",
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column: 2,
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endColumn: 8,
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suggestions: [],
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},
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],
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},
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],
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})

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