[Bug]: BABEL_PARSE_ERROR regarding duplicate function definitions

[Roise-yue]

💻

• Would you like to work on a fix?

How are you using Babel?

@babel/cli

Input code

function* countDown(begin) {
while (begin >= 0) {
yield begin--;
}
}
var begin;
function* func1() {
yield 'aha';
yield 'ihi';
yield 'uhu';
}
for (const e of func1())
for (const e of countDown(10)) {
console.log(e);
}
function* countDown(begin) {
while (begin >= 0) {
yield begin--;
}
}
for (const e of countDown(10)) {
console.log(e);

}

Configuration file name

.babelrc

Configuration

{
"presets": ["@babel/preset-env"],
"plugins": []
}

Current and expected behavior

I am using babel to run the code,and here is the error reported:Syntax error,Identifier "CountDown" has already been declared.
To my knowledge, in JavaScript, when a function is declared repeatedly, the function declaration defined later will overwrite the previous function declaration. Therefore, I believe that the code I provided is grammatically compliant, but Babel refuses to translate this code. Is this because Babel believes there is a syntax error in this code? Please explain this issue to me, thank you

Environment

Babel:v7.23.9
node.js : v21.6.1
npm: v10.2.4
Ubuntu: v20.04

Possible solution

No response

Additional context

No response

[babel-bot]

Hey @Roise-yue! We really appreciate you taking the time to report an issue. The collaborators on this project attempt to help as many people as possible, but we're a limited number of volunteers, so it's possible this won't be addressed swiftly.

If you need any help, or just have general Babel or JavaScript questions, we have a vibrant Slack community that typically always has someone willing to help. You can sign-up here for an invite.

[liuxingbaoyu]

Please check if the source code type is set to module, duplicate declarations are not allowed in strict mode.
repl

[Roise-yue]

Please check if the source code type is set to module, duplicate declarations are not allowed in strict mode. repl

Thank you for your answer. After checking, I found that the code is not in strict mode, maybe there are other reasons.

[nicolo-ribaudo]

Can you add "sourceType": "script" to your Babel config to actually force Babel to parse the file as a script and not as a module?