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Date: Sat, 9 Dec 2017 07:46:48 +0100
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To: Andreas Hennings <andreas@dqxtech.net>
Cc: Internals <internals@lists.php.net>
Content-Type: multipart/alternative; boundary="001a1144b27a568e28055fe2aa02"
Subject: Re: [PHP-DEV] instanceof survives non-object variables, but crashes
 on non-object constants.
From: kalle@php.net (Kalle Sommer Nielsen)

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Hi

That is fine for code that is broken in the first place. Similarly we added
a warning some years back about array to string conversions.

If your code is like the example, it should be updated and warned about as
you are doing something illogical by first checking the type and or value
of the operand you are passing to instanceof after.

The impact should be minimal as is, so persevering bc for broken usage is a
poor argument imo



On 9 Dec 2017 07.38, "Andreas Hennings" <andreas@dqxtech.net> wrote:

> Adding a warning to something that used to be ok would break existing code.
> I remember a number of cases where I used instanceof on possibly
> non-objects.
>
> if ($x instanceof C) {
>   return $x;
> }
> elseif ($x === NULL) {
>  ...
> }
>
> All such code would then produce warnings.
>
>
> On 9 December 2017 at 07:35, Kalle Sommer Nielsen <kalle@php.net> wrote:
>
>> Hi
>>
>> We should just add a warning to the first example, it seems like an
>> oversight that it was left silent
>>
>> On 9 Dec 2017 07.29 <20%2017%2007%2029>, "Andreas Hennings" <
>> andreas@dqxtech.net> wrote:
>>
>>> The following (https://3v4l.org/A2Tp6) is ok, it simply returns false:
>>>
>>>     $x = 1;
>>>     $x instanceof \stdClass;
>>>
>>>
>>> The following (https://3v4l.org/IdSBu) gives a fatal error:
>>>
>>>     1 instanceof \stdclass;
>>>
>>> t think this behavior is inconsistent, and we should consider changing
>>> it.
>>>
>>> There are two options, but only one is BC.
>>>
>>> - Let 1 instanceof \stdClass return false, instead of crashing. -> seems
>>> BC
>>> - Let $x instanceof \stdClass crash, if $x is not an object. -> BC break.
>>>
>>> So it seems the first would the option we should take.
>>> This is also what hhvm does, according to https://3v4l.org/IdSBu.
>>>
>>
>

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