Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:121634
Message-ID: <D02BC80D-89A4-4C2D-AF2E-2A96ADB45CA0@craigfrancis.co.uk>
Content-Type: multipart/alternative;
	boundary="Apple-Mail=_5D3BE362-9BB2-4D34-BB25-59876A87ABC5"
Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3774.200.91.1.1\))
Date: Fri, 10 Nov 2023 11:29:46 +0000
In-Reply-To: <049d4758-def2-4a29-9e02-afa61e5b977e@gmail.com>
Cc: internals@lists.php.net
To: Rowan Tommins <rowan.collins@gmail.com>
References: <CAFv4g+EqzB7whakuN-sr6YL2ih9xhHPzCsvTsEgJKMXBh9H9wQ@mail.gmail.com>
 <5144806E-E21F-4AF8-B9A2-0161561A6B9E@craigfrancis.co.uk>
 <049d4758-def2-4a29-9e02-afa61e5b977e@gmail.com>
Subject: Re: [PHP-DEV] Passing null to parameter
From: craig@craigfrancis.co.uk (Craig Francis)

--Apple-Mail=_5D3BE362-9BB2-4D34-BB25-59876A87ABC5
Content-Transfer-Encoding: quoted-printable
Content-Type: text/plain;
	charset=utf-8

First, thanks Rowan (same to you Kamil), I do appreciate your thoughts =
on this...



On 9 Nov 2023, at 20:01, Rowan Tommins <rowan.collins@gmail.com> wrote:
> On 09/11/2023 14:58, Craig Francis wrote:
>> We might as well make the PHP 9 upgrade as hard as possible, just to =
force a little bit of `strict_types=3D1` on everyone.
>=20
>=20
> Just to be clear, strict_types has nothing to do with this;

strict_types=3D1 enables strict type checking, which adds fatal type =
errors instead of coercion (all fine, all good); but for everyone not =
using strict_types=3D1, there is a fatal type error when NULL is passed =
to a function argument, while all other type coercions (e.g. string '5' =
to int) work?



> changing it does not allow you to pass nulls to typed parameters, and =
never did: https://3v4l.org/atT0B

Yep, specifically for user defined function parameters, but NULL =
coercion works with string concatenation, =3D=3D comparisons, =
arithmetics, sprintf, print, echo, array keys?

That said, with the original RFC:

https://wiki.php.net/rfc/scalar_type_hints_v5

> "The only exception to this is the handling of NULL: in order to be =
consistent with our existing type declarations for classes, callables =
and arrays, NULL is not accepted by default"


I never understood why NULL was considered a complex value like a =
class/callable/array, when it's more like a simple =
bool/int/float/string, where NULL can be coerced (and NULL is documented =
as being coercible in all other contexts, like concatenation).

Also...

> =E2=80=9Cit should be possible for existing userland libraries to add =
scalar type declarations without breaking compatibility=E2=80=9D


But that's not the case; if you add types to a legacy projects =
functions, fatal type errors happen instead of accepting NULL and =
coercing it as needed (it's why I never bothered adding types to the =
legacy project I still look after).



> Nor has strict_types=3D0 ever been aligned to the loosest coercion =
rules used in other contexts; for instance, an empty string was never an =
acceptable input for an integer parameter, even in versions where it was =
an acceptable operand for addition: https://3v4l.org/khD32

Fair, but that makes a little bit more sense to me (although I'd assume =
an empty string would be coerced to 0).



> As for your previous example:
>=20
> > redirect('/thank-you/?ref=3D' . urlencode($ref));
>=20
> If $ref isn't set, any of these might be the correct URL: =
"/thank-you/", "/thank-you/?ref=3D", "/thank-you/?ref=3Ddefault", ... =
The language can only guess one of those.

NULL has always been coerced to an empty string with urlencode(), it =
happens in a lot of projects, and everyone seemed to be fine with it?



> A similar example I've come across is in manually escaped SQL (yes, I =
know, use parameters instead...):
>=20
> $sql =3D "Insert Into blah ( whatever ) Values ( '" . =
sql_escape($someVar) . "' )";
>=20
> Nine times out of ten, if the PHP variable is null, you want an SQL =
null, not ''; but if the [imaginary] sql_escape function doesn't reject =
nulls, you may not notice the bug until you've ended up with garbage in =
your DB.


Fortunately I only have to maintain 1 legacy project, and I've only had =
to make 29 edits so far, but every single one involved me adding =
strval(), it's certainly not making the code better, and I know there =
are still more to find, but I'll have to wait for customers to trip =
them.

Craig




--Apple-Mail=_5D3BE362-9BB2-4D34-BB25-59876A87ABC5--