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Date: Fri, 25 Mar 2016 13:48:16 -0600
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To: Scott Arciszewski <scott@paragonie.com>
Cc: Andrea Faulds <ajf@ajf.me>, PHP Internals <internals@lists.php.net>
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Subject: Re: [PHP-DEV] Why is 0x7F permitted in PHP identifiers?
From: derokorian@gmail.com (Ryan Pallas)

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On Fri, Mar 25, 2016 at 1:25 PM, Scott Arciszewski <scott@paragonie.com>
wrote:

> On Fri, Mar 25, 2016 at 10:20 AM, Andrea Faulds <ajf@ajf.me> wrote:
>
> > Hi everyone,
> >
> > Identifiers in PHP source code (including variables names with $) confo=
rm
> > to the regex /[_a-zA-Z\x7F-\xFF][_0-9a-zA-Z\x7F-\xFF]*/. Most of this
> regex
> > is pretty standard: it allows alphanumeric ASCII characters and
> > underscores, plus any character with the 8th bit set (presumably to all=
ow
> > any extension of ASCII, such as Latin-1 or UTF-8, to be used).
> >
> > But there's one part of this I find rather curious: why is \x7F include=
d?
> > It's not a high-byte/8-bit character, it's a 7-bit ASCII character, and=
 a
> > control character at that. Unless there's some ASCII extension which
> reuses
> > that value as a printing character, I assume it must have been a mistak=
e
> to
> > include this character. As a control character, it is invisible and
> > difficult to type, and it might do weird things in some terminal
> emulators.
> > I can't see the value in permitting it within an identifier.
> >
> > I've done a little bit of looking around, and I can't find an important
> > ASCII extension which changes what 0x7F does. Given that, I assume it w=
as
> > simply a mistake. But one of you might be able to enlighten me otherwis=
e.
> >
> > I've filed a bug report, and made a patch to fix this in php-src and
> > php-langspec master:
> >
> > https://bugs.php.net/bug.php?id=3D71897
> >
> > Thanks!
> > --
> > Andrea Faulds
> > https://ajf.me/
> >
> > --
> > PHP Internals - PHP Runtime Development Mailing List
> > To unsubscribe, visit: http://www.php.net/unsub.php
> >
> >
> =E2=80=8BInterestingly, extract() skips keys with \x7F: https://3v4l.org/=
ZC9ZA\
>

Also the keys after the \x7F were not present in HHVM, PHP7, however in
5.5-5.6 you get
[9]=3D>string(1) "=7F"
along with they key that came after it. That's very strange indeed!


> Scott Arciszewski
> Chief Development Officer
> Paragon Initiative Enterprises <https://paragonie.com/>=E2=80=8B
>

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