Bug 171041 – We incorrectly throw a syntax error when declaring a top level for-loop iteration variable the same as a parameter

• Component: JavaScriptCore
• Status: RESOLVED FIXED

[Rob Stutton]

I wouldn't write code like this (below) myself, but it was emitted by the minifier and so my app doesn't work in Safari, or Safari TP.
The code looks legal to me ...

let e = e => {
    console.log(e);
    for (let e of [1, 2, 3]) // Cannot declare a let variable twice: 'e'.
        console.log(e);
};

[Saam Barati]

(In reply to Rob Stutton from comment #0)
> I wouldn't write code like this (below) myself, but it was emitted by the
> minifier and so my app doesn't work in Safari, or Safari TP.
> The code looks legal to me ...
> 
> let e = e => {
>     console.log(e);
>     for (let e of [1, 2, 3]) // Cannot declare a let variable twice: 'e'.
>         console.log(e);
> };

Yeah this looks like it should not be a syntax error, however, I think this should be:
```
let x = (e) => { let e; }
```

I bet the code that ensures that the above is a syntax error is kicking in when it shouldn't be.

[Radar WebKit Bug Importer]

<rdar://problem/32082516>

[Saam Barati]

Created attachment 310818 [details]
patch

[Build Bot]

Attachment 310818 [details] did not pass style-queue:


ERROR: Source/JavaScriptCore/ChangeLog:13:  Line contains tab character.  [whitespace/tab] [5]
ERROR: Source/JavaScriptCore/ChangeLog:20:  Line contains tab character.  [whitespace/tab] [5]
Total errors found: 2 in 7 files


If any of these errors are false positives, please file a bug against check-webkit-style.

[Saam Barati]

Created attachment 310819 [details]
patch

[Yusuke Suzuki]

Comment on attachment 310819 [details]
patch

r=me

[WebKit Commit Bot]

Comment on attachment 310819 [details]
patch

Clearing flags on attachment: 310819

Committed r217200: <http://trac.webkit.org/changeset/217200>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.

[Piotrek Koszuliński (Reinmar)]

How can this patch be not released yet (in a stable channel)? Since May? It will cause most of apps written in minified ES6 to fail.