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Date: Tue, 01 Jul 2025 12:40:49 +0000
To: Christian Schneider <cschneid@cschneid.com>
Cc: PHP internals <internals@lists.php.net>
Subject: Re: [PHP-DEV][RFC] Deprecate type juggling to and from bool type within the function type juggling context
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From: internals@gpb.moe ("Gina P. Banyard")

On Monday, 30 June 2025 at 16:05, Christian Schneider <cschneid@cschneid.co=
m> wrote:

> Am 26.06.2025 um 14:04 schrieb Gina P. Banyard internals@gpb.moe:
>=20
> > On Monday, 2 June 2025 at 17:11, Gina P. Banyard internals@gpb.moe wrot=
e:
> >=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 th=
ere 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.
>=20
>=20
> The RFC talks about "from" AND "to" bool conversion but the examples unde=
r Backward Incompatible Changes only seem mention "from" bool, is that corr=
ect?

I didn't think adding examples for "to" bool was useful, but I can add some=
.

>=20
> I tried the implementation in branch bool-juggling-dep-poc on https://git=
hub.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.

I forgot to update the optimized strlen opcode, I pushed a fix for this, pl=
ease pull in the latest version of the branch that has been force pushed.

>=20
> - array_slice($a, 1, preserve_keys:"a") did not produce a warning even th=
ough I would have thought that is a "to" bool conversion. Am I wrong? What =
should I test instead?

I haven't had time to look at why this is not triggering as it should. But =
some internal functions do weird stuff sometimes.

> 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 nullabl=
e parameter that composer packages are the more interesting caveat than our=
 our own but so far nothing popped up.
>=20
> 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.
>=20
> Regards,
> - Chris






Best regards,

Gina P. Banyard