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Date: Tue, 22 Aug 2017 11:48:58 +0300
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To: Nikita Popov <nikita.ppv@gmail.com>
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Subject: Re: [PHP-DEV] Re: [Request][Discussion] Double value as array key
 improvement
From: andrew.nester.dev@gmail.com (Andrew Nester)

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> On Aug 19, 2017, at 4:30 PM, Nikita Popov <nikita.ppv@gmail.com> =
wrote:
>=20
> On Thu, Aug 17, 2017 at 5:03 PM, Andrew Nester =
<andrew.nester.dev@gmail.com <mailto:andrew.nester.dev@gmail.com>> =
wrote:
>=20
>=20
> > 13 =D0=B0=D0=B2=D0=B3. 2017 =D0=B3., =D0=B2 21:39, Andrew Nester =
<andrew.nester.dev@gmail.com <mailto:andrew.nester.dev@gmail.com>> =
=D0=BD=D0=B0=D0=BF=D0=B8=D1=81=D0=B0=D0=BB(=D0=B0):
> >
> >
> >
> >> 11 =D0=B0=D0=B2=D0=B3. 2017 =D0=B3., =D0=B2 15:53, Andrew Nester =
<newaltgroup@bk.ru <mailto:newaltgroup@bk.ru>> =D0=BD=D0=B0=D0=BF=D0=B8=D1=
=81=D0=B0=D0=BB(=D0=B0):
> >>
> >>
> >>> On Aug 11, 2017, at 2:10 PM, Andrew Nester <newaltgroup@bk.ru =
<mailto:newaltgroup@bk.ru>> wrote:
> >>>
> >>> Hello everyone!
> >>>
> >>> I was working on following request =
https://bugs.php.net/bug.php?id=3D75053 =
<https://bugs.php.net/bug.php?id=3D75053> which resulted in following =
pull request https://github.com/php/php-src/pull/2676 =
<https://github.com/php/php-src/pull/2676>
> >>>
> >>> The problem here is following: when we=E2=80=99re using large =
numbers as array index when adding new elements it could overwrite =
already existing value.
> >>> Assume we have 2 indexes 5076964154930102272 and =
999999999999999999999999999999 with different value set for them.
> >>>
> >>> Because 999999999999999999999999999999 is larger than maximum long =
int number for 64-bit systems, it will be converted to double. =
(corresponding code here =
https://github.com/php/php-src/blob/master/Zend/zend_language_scanner.l#L1=
648 =
<https://github.com/php/php-src/blob/master/Zend/zend_language_scanner.l#L=
1648>)
> >>> But when double value is used as array indexes, it is converted to =
long integer. (f.e., code is here =
https://github.com/php/php-src/blob/master/Zend/zend_execute.c#L1573 =
<https://github.com/php/php-src/blob/master/Zend/zend_execute.c#L1573>)
> >>> At this case it causes overflow and we=E2=80=99ve got index equal =
to 5076964154930102272 and as a result - we=E2=80=99re overwriting =
previously set value.
> >>>
> >>> My suggestion is following:
> >>> 1) when double key is less than maximum possible long integer - =
convert it to integer
> >>> 2) if it=E2=80=99s larger - convert it to string.
> >>>
> >>> That=E2=80=99s what implemented in proposed PR.
> >>>
> >>> Another possible option is just to throw warning in this case =
(proposed by Nikita Popov)
> >>>
> >>> I would happy to hear any feedback and suggestions about this =
solution.
> >>> Thanks!
> >>
> >> Here is the alternative solution which emits E_WARNING in case of =
integer array index overflow.
> >> https://github.com/php/php-src/pull/2677 =
<https://github.com/php/php-src/pull/2677>
> >
> > My preferred solution is 2nd one (emitting warning) as it more =
obvious for users, doesn't break previous behaviour.
> >
> > Cheers,
> > Andrew
>=20
> Hello internals!
>=20
> I was working on solution for the problem of double to int conversion =
for array indices and would like to create an RFC for proposed solution =
- emitting warning when integer overflow happens during double to int =
conversion.
>=20
> Does it look like good idea?
>=20
> Thanks!
>=20
> Sounds good to me. Something you might want to consider is to also =
throw a warning if the floating point number is not an exact integer. =
For example allow a silent cast of 42.0 to 42, but throw a warning if =
42.5 is used as an index (or worse, 42.999999999, in which case it =
likely isn't doing what the programmer thinks it's doing).
>=20
> Nikita
>=20


Hey Internals!

I am planning to create RFC for this change but my account =
(andrewnesterdev) doesn=E2=80=99t have enough permissions.
Could please someone grant it that I could start creating it?

Thanks!=

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