no-var should not fix variables named 'let'

Tell us about your environment

• ESLint Version: 5.16.0
• Node Version: 10.16.0
• npm Version: 6.9.0

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

default

Please show your full configuration:

Configuration

module.exports = {
  parserOptions: {
    ecmaVersion: 6,
  },
  rules: {
    "no-var": "error",
  }
};

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

// this is valid code in non-strict mode

function foo() {
  var let;
}

function bar() {
  var { let } = {};
}

eslint index.js --fix

What did you expect to happen?

No autofix, because it produces SyntaxError.

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

function foo() {
  let let; // SyntaxError
}

function bar() {
  let { let } = {}; // SyntaxError
}

Off topic: ESLint parser doesn’t treat let { let } = {} as SyntaxError (probably an Acorn bug)

Are you willing to submit a pull request to fix this bug? yes

[mdjermanovic]

Sure, reported in acorn #837 now.

[mysticatea]

I confirmed it in the spec: https://www.ecma-international.org/ecma-262/9.0/#sec-let-and-const-declarations-static-semantics-early-errors