Fix: prefer-destructuring invalid autofix with computed property access

[mdjermanovic]

Prerequisites checklist

• I have read the contributing guidelines.

What is the purpose of this pull request? (put an "X" next to an item)

[ ] Documentation update
[X] Bug fix (template)
[ ] New rule (template)
[ ] Changes an existing rule (template)
[ ] Add autofixing to a rule
[ ] Add a CLI option
[ ] Add something to the core
[ ] Other, please explain:

Tell us about your environment

• ESLint Version: v7.9.0
• Node Version: v12.18.4
• npm Version: v6.14.6

What parser (default, @babel/eslint-parser, @typescript-eslint/parser, etc.) are you using?

default

Please show your full configuration:

Configuration

module.exports = {
  parserOptions: {
    ecmaVersion: 2015
  }
};

What did you do? Please include the actual source code causing the issue.

Online Demo

/* eslint prefer-destructuring: ["error",
  { "object": true },
  { "enforceForRenamedProperties": true }
] */

var a = b[a];

What did you expect to happen?

1 error, but not with an invalid autofix.

What actually happened? Please include the actual, raw output from ESLint.

1 error and autofix to:

/* eslint prefer-destructuring: ["error",
  { "object": true },
  { "enforceForRenamedProperties": true }
] */

var {a} = b;

This changes the semantics. A correct autofix would be var { [a]: a } = b;

What changes did you make? (Give an overview)

Fixed the prefer-destructuring rule to not auto-fix in this case, since the rule generally doesn't auto-fix renamed properties. This was just mistakenly treated as if it was var a = b.a;.

Is there anything you'd like reviewers to focus on?

[nzakas]

Can you add something about this to the docs too? It seems like this new behavior could be misinterpreted as a bug without an explanation somewhere.

[mdjermanovic]

Added a paragraph explaining what code is fixable by this rule.

This PR doesn't change behavior much, the rule already fixes only simple cases:

/* eslint prefer-destructuring: ["error",
  { "object": true },
  { "enforceForRenamedProperties": true }
] */ 

var foo = object.foo; // auto-fixable

var foo = object.bar; // not auto-fixable

var foo = object[bar]; // not auto-fixable

var foo = object[foo]; // was mistakenly auto-fixable

Demo link

[nzakas]

That works. Thanks.

[btmills]

Adding this also covers the var foo = object['foo']; case, which we don't fix either and for which we already have a test asserting the same.