476940 - JavaScript: Regular Expressions with duplicate flags should cause an error

Status: VERIFIED FIXED

(Core :: JavaScript Engine, defect)

Description

[T.Rosenau]

User-Agent:       Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.0.5) Gecko/2008121621 Ubuntu/8.04 (hardy) Firefox/3.0.5
Build Identifier: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.0.5) Gecko/2008121621 Ubuntu/8.04 (hardy) Firefox/3.0.5

According to the ECMA Script specification, duplicate RexExp flags must throw a Syntax Error.

For example, these are NOT supposed to work:

var foo = /bar/ii;
var baz = new RexExp('qux', 'ii');

but they do work in Firefox.

I'm not sure whether this is a good thing. But it certainly is a spec violation.

Reproducible: Always

Steps to Reproduce:
1. Enter 'javascript:alert(/.*/ii.test('foo'));' into the address bar
2. Hit Go
Actual Results:  
An alert window shows that the test succeeded.

Expected Results:  
The script should throw an error (cf. error console).

Here are the corresponding sections from the spec (ECMA-262 Edition 3):

> new RegExp(pattern, flags)
> [...]
> If F [= toString(flags)] contains any character other than "g",
> "i", or "m", or if it contains the same one more than once,
> then throw a SyntaxError exception.


> Regular expression literal:
> [...]
> first, the characters comprising the regular expression's RegularExpressionBody
> and RegularExpressionFlags production expansions are collected uninterpreted
> into two strings Pattern and Flags, respectively. Then the new RegExp
> constructor is called with two arguments Pattern and Flags and the result
> becomes the value of the RegularExpressionLiteral.

Comment 1

[Blake Kaplan (:mrbkap) (inactive)]

Attachment: Easy fix

I didn't see a cleaner way to do this.

Comment 2

[Brendan Eich [:brendan]]

Comment on attachment 360774 [details] [diff] [review]
Easy fix

First hunk cries out for a local macro.

Why do we have JSMSG_BAD_FLAG and JSMSG_BAD_REGEXP_FLAG? Unify on latter since it sites the offending flag char?

/be

Comment 3

[Blake Kaplan (:mrbkap) (inactive)]

Attachment: patch v2

With this patch, I get:

js> /asdf/ii
typein:1: SyntaxError: invalid regular expression flag i:
typein:1: /asdf/ii
typein:1: .......^
js> RegExp("asdf", "ii")
typein:2: SyntaxError: invalid regular expression flag i

Comment 4

[Brendan Eich [:brendan]]

Comment on attachment 360824 [details] [diff] [review]
patch v2

Righteous -- one nit: BAD_FLAG is too generic, how about renaming it BAD_REGEXP_FLAG?

/be

Comment 5

[Blake Kaplan (:mrbkap) (inactive)]

http://hg.mozilla.org/tracemonkey/rev/961cb5e9536b

Comment 6

[Robert Sayre]

http://hg.mozilla.org/mozilla-central/rev/961cb5e9536b

Comment 7

[Bob Clary [:bc] (inactive)]

http://hg.mozilla.org/mozilla-central/rev/5e1364e10ba7

Comment 8

[Robert Sayre]

http://hg.mozilla.org/releases/mozilla-1.9.1/rev/fdfb544ed8f1

Comment 9

[Bob Clary [:bc] (inactive)]

v 1.9.1, 1.9.2 ecma_3/RegExp/15.10.4.1-6.js