Bug 121541 – Update identifier syntax to disallow U+2E2F in preparation for ES6

• Component: JavaScriptCore
• Status: RESOLVED FIXED

[Mathias Bynens]

TC39 discussed http://esdiscuss.org/topic/backwards-compatibility-and-u-2e2f-in-identifier-s and concluded that we should not deviate from Unicode because we don’t want separate lists from Unicode.

That means `\u2E2F` and `ⸯ` need to throw when used as identifier.

For reference, here’s the same bug ticket for SpiderMonkey: https://bugzilla.mozilla.org/show_bug.cgi?id=917436 And for V8: https://code.google.com/p/v8/issues/detail?id=2892

[Radar WebKit Bug Importer]

<rdar://problem/15022545>

[Mathias Bynens]

Some more info & examples of what it means to update to the ES6 grammar for identifiers: https://mathiasbynens.be/notes/javascript-identifiers-es6

[Mathias Bynens]

Tests based on ES6 and Unicode 5.1.0, i.e. the minimum required Unicode version as per the spec: https://mathias.html5.org/tests/javascript/identifiers/

[Claude Pache]

For reference, the relevant section in the spec is:

https://tc39.github.io/ecma262/#prod-IdentifierName

[Alexey Proskuryakov]

Is this still needed for ES6?yus

[Mathias Bynens]

(In reply to comment #5)
> Is this still needed for ES6?

Yes.

[Mathias Bynens]

This seems to have been fixed:

```
$ eshost -sx 'var \u2E2F'
#### Chakra

SyntaxError: Invalid character

#### JavaScriptCore

SyntaxError: Invalid unicode escape in identifier: '\u2E2F'

#### SpiderMonkey

SyntaxError: invalid escape sequence:

#### V8, V8 --harmony

SyntaxError: Invalid or unexpected token

#### XS

SyntaxError: invalid character 10
```

…and…

```
$ eshost -sx 'var ⸯ'
#### Chakra

SyntaxError: Invalid character

#### JavaScriptCore

SyntaxError: Invalid character '\u2e2f'

#### SpiderMonkey

SyntaxError: illegal character:

#### V8, V8 --harmony

SyntaxError: Invalid or unexpected token

#### XS

SyntaxError: invalid character 11823
```