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5.0.0 - Crash with prefer-const rule where code contains array destructuring assignment with 'ignored values'

See original GitHub issue

This is a minimal reproduction for a bug I’ve found in eslint@5.0.0. As far as I can tell the example code below is valid JavaScript (see

Tell us about your environment

  • ESLint Version: 5.0.0
  • Node Version: 8.11.0
  • npm Version: 5.6.0
  • yarn Version: 1.7.0

What parser (default, Babel-ESLint, etc.) are you using? default

Please show your full configuration:

    "parserOptions": {
        "ecmaVersion": 2018
    "rules": {
      "prefer-const": 1

What did you do? Please include the actual source code causing the issue, as well as the command that you used to run ESLint.

const b = [1, 2];
let a;

[, a] = b;

cd eslint-5-array-destructuring-assignment-bug
yarn eslint .

What did you expect to happen? eslint would lint my project

What actually happened? Please include the actual, raw output from ESLint. eslint did not lint my project and threw a TypeError from one of its built-in rules (prefer-const)

Cannot read property 'name' of null
TypeError: Cannot read property 'name' of null
    at (/node_modules/eslint/lib/rules/prefer-const.js:173:49)
    at (<anonymous>)
    at getIdentifierIfShouldBeConst (/node_modules/eslint/lib/rules/prefer-const.js:173:26)
    at groupByDestructuring (/node_modules/eslint/lib/rules/prefer-const.js:227:28)
    at Program:exit (/node_modules/eslint/lib/rules/prefer-const.js:362:17)
    at listeners.(anonymous function).forEach.listener (/node_modules/eslint/lib/util/safe-emitter.js:45:58)
    at Array.forEach (<anonymous>)
    at Object.emit (/node_modules/eslint/lib/util/safe-emitter.js:45:38)
    at NodeEventGenerator.applySelector (/node_modules/eslint/lib/util/node-event-generator.js:251:26)
    at NodeEventGenerator.applySelectors (/node_modules/eslint/lib/util/node-event-generator.js:280:22)

Issue Analytics

  • State:closed
  • Created 5 years ago
  • Comments:6 (6 by maintainers)

github_iconTop GitHub Comments

platinumazurecommented, Jun 25, 2018

Thanks @mjmasn, that makes sense. Would you like to create a PR (maybe with a new test that would trigger the crash)?

aladdin-addcommented, Jun 26, 2018

should we release a patch 5.0.2, since seems it was introduced in 5.0.0-alpha.4? cc @eslint/eslint-team

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