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Subject: Re: [PHP-DEV][RFC] Deprecate type juggling to and from bool type
 within the function type juggling context
Date: Mon, 30 Jun 2025 16:56:51 +0200
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From: cschneid@cschneid.com (Christian Schneider)

Am 26.06.2025 um 14:04 schrieb Gina P. Banyard <internals@gpb.moe>:
> On Monday, 2 June 2025 at 17:11, Gina P. Banyard <internals@gpb.moe> =
wrote:
>=20
>> Hello internals,
>>=20
>> This is the first RFC out of a set of type system related RFCs I want =
to propose for PHP 8.5.
>> It also used the recently enabled Markdown support on the wiki, so =
there might be a few oddities.
>>=20
>> The RFC proposes to deprecate implicit type coercions to and from the =
bool type for other scalar types.
>> This a "weak" mode change only, as when strict_types are enabled none =
of these coercions can happen.
>>=20
>> Let me know what you think about it.
>>=20
>> RFC: https://wiki.php.net/rfc/deprecate-function-bool-type-juggling
>=20
> I have updated the RFC to version 0.2 that expands on it and addresses =
some of the counterarguments which were said during the discussion.
> RFC: https://wiki.php.net/rfc/deprecate-function-bool-type-juggling
>=20
> If there is no-follow up feedback, I will open the vote for it =
sometime next week.

The RFC talks about "from" AND "to" bool conversion but the examples =
under Backward Incompatible Changes only seem mention "from" bool, is =
that correct?

I tried the implementation in branch bool-juggling-dep-poc on =
https://github.com/Girgias/php-src.git and encountered two things:
- php -r 'strlen(false);' produced a core dump with Zend/zend_API.c:561: =
zend_arg_from_bool_deprecated: Assertion `func->common.fn_flags & (1 << =
14)' failed.
- array_slice($a, 1, preserve_keys:"a") did not produce a warning even =
though I would have thought that is a "to" bool conversion. Am I wrong? =
What should I test instead?

So far the "from" conversion warnings need changes in very few places in =
our setup (we very occasionally use false as out-of-band signalling and =
use the side-effect that strlen() can check both for empty string and =
false at the same time but that can be easily adapted), our lesson from =
the nullable parameter that composer packages are the more interesting =
caveat than our our own but so far nothing popped up.

Summary: I am mostly positive about the "from" part, I don't think I was =
able to test the "to" part and I'm not sure why I triggered an =
assertion.

Regards,
- Chris