Tell us about your environment

• ESLint Version: 6.0.1 (same with 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:

module.exports = {
  parserOptions: {
    ecmaVersion: 6,
  },
  rules: {
    "curly": ["error", "multi"]
  }
};

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

if (foo) {
  let bar;
}

eslint index.js --fix

What did you expect to happen?

No errors, similar to how multi-or-nest works.

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

if (foo) 
  let bar; // SyntaxError: Lexical declaration cannot appear in a single-statement context

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

Yes.