SWC handles closures in loops incorrectly

[lorenzobersano]

Describe the bug

If I run the same code with node in a script file the result is correct (1,2,3...), however in Next i always get (32,32,32...), as if let was a var.

Input code

let cols = []

for (let i = 1; i <= 31; i++) {
  cols.push({
    accessor: () => {
      console.log(i)
    }
  })
}

cols.map(({ accessor }) => accessor())

Config

I'm using next 12.1.0, so no .swcrc

Playground link

No response

Expected behavior

I expect to get printed
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31

Actual behavior

On Next, i get
32
32
32
32
32
32
32
32
32
32
32
32
32
32
32
32
32
32
32
32
32
32
32
32
32
32
32
32
32
32
32

Version

As per next peerDeps: "@swc/core": ">=1.2.50",

Additional context

No response

[Austaras]

Should already be fixed in latest swc

[Brooooooklyn]

vercel/next.js#35395 will fix it

[lorenzobersano]

Great, thanks for your work! 🥇

[swc-bot]

This closed issue has been automatically locked because it had no new activity for a month. If you are running into a similar issue, please create a new issue with the steps to reproduce. Thank you.