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Date: Wed, 11 Nov 2015 14:33:49 +0100
Cc: Philip Hofstetter <phofstetter@sensational.ch>,
 PHP internals <internals@lists.php.net>
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References: <CAGKNXQFJ8g0-XqdyCscGmrgJs=EJN5R_e4yt--aY6xtHEjSYGw@mail.gmail.com> <CAF+90c8D1B41ogH2KSMnwQE34DkR4-hiANkzeTyyfrBiGCEN3w@mail.gmail.com>
To: Nikita Popov <nikita.ppv@gmail.com>
Subject: Re: [PHP-DEV] PHP7 / foreach / references / ugly code / discrepancy to PHP 5.6
From: dz@heroku.com (David Zuelke)

Should this be in the UPGRADING notes?


> On 10.11.2015, at 20:45, Nikita Popov <nikita.ppv@gmail.com> wrote:
>=20
> On Tue, Nov 10, 2015 at 5:48 PM, Philip Hofstetter <
> phofstetter@sensational.ch> wrote:
>=20
>> Hi,
>>=20
>> I'm having a cause of slightly ugly code that runs differently from =
PHP 5.6
>> to PHP 7 and I don't think this difference is documented, nor =
expected. As
>> I'm not sure whether this is an intended change or not, I'm asking =
here
>> firstr before making a bug report.
>>=20
>> The code in question is
>>=20
>> ----
>> $b =3D [1, 2, 3];
>>=20
>> foreach($b ?: [] as &$v){
>>    $v =3D $v*2;
>>    unset($v);
>> }
>>=20
>> var_dump($b);
>> ----
>> in PHP7, this produces
>>=20
>> array(3) {
>>  [0] =3D>
>>  int(1)
>>  [1] =3D>
>>  int(2)
>>  [2] =3D>
>>  int(3)
>> }
>>=20
>> whereas in PHP 5.6 and earlier, this produces
>>=20
>> array(3) {
>>  [0] =3D>
>>  int(2)
>>  [1] =3D>
>>  int(4)
>>  [2] =3D>
>>  int(6)
>> }
>>=20
>> what scares me about this is that in order to get the old behaviour =
in PHP7
>> back, you just have to get rid of the ?: operator:
>>=20
>> foreach($b as &$v){
>>=20
>> is fine
>>=20
>> foreach($b ?: [] as &$v){
>>=20
>> is not.
>>=20
>> I guess this is related to
>>=20
>> =
http://php.net/manual/en/migration70.incompatible.php#migration70.incompat=
ible.foreach.by-value
>> or
>>=20
>> =
http://php.net/manual/en/migration70.incompatible.php#migration70.incompat=
ible.foreach.by-ref
>> ,
>> but I'm not entirely sure whether this is actually intended behaviour =
-
>> it's certainly unexpected to me that applying ?: now always makes a =
copy
>> whereas before it didn't.
>>=20
>=20
> This is a bug in PHP 5, which has been fixed in PHP 7 as a side-effect =
of
> other changes. The new behavior is correct. This issue is tracked at
> https://bugs.php.net/bug.php?id=3D70857.
>=20
> Nikita