Wrong behaviour in "for...of" statement

Bug Report

Current Behavior Throws this exception:

TypeError: undefined: Duplicate declaration "i"
  1 | 
  2 | for (let i of 'foo') {
> 3 |   let i = 'a';
    |       ^
  4 |   console.log(i);
  5 | }
  6 | 

Input Code

for (let i of 'foo') {
  let i = 'a';
  console.log(i);
}

Expected behavior/code Should prints 'a' three times instead of throws this exception. This is the behaviour in Node and Safari, for example.

Babel Configuration (CLI command)

const output = require('@babel/core').transform(`
for (let i of 'foo') {
  let i = 'a';
  console.log(i);
}
`, {
  presets: ['@babel/preset-env']
});

Environment

• Babel version(s): lastest
• Node/npm version: Node 9
• OS: macOS High Sierra
• Monorepo: yes
• How you are using Babel: cli

[nicolo-ribaudo]

It’s a bug, similar to https://github.com/babel/babel/issues/8498

[liuxingbaoyu]

Seems to have been fixed, feel free to open an issue if the problem persists.