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Date: Tue, 22 Feb 2022 10:15:07 +0100
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To: Rowan Tommins <rowan.collins@gmail.com>, Mark Randall <marandall@php.net>
Cc: PHP Internals List <internals@lists.php.net>
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Subject: Re: [PHP-DEV] [RFC] Undefined Variable Error Promotion
From: nicolas.grekas+php@gmail.com (Nicolas Grekas)

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Le ven. 18 f=C3=A9vr. 2022 =C3=A0 12:24, Rowan Tommins <rowan.collins@gmail=
.com> a
=C3=A9crit :

> On 17/02/2022 23:28, Mark Randall wrote:
> > I present:
> >
> > https://wiki.php.net/rfc/undefined_variable_error_promotion
>
>
> It would be good to have a "Scope" or "Unaffected Functionality" section
> here, because there are a number of closely related things which were
> also raised from Notice to Warning in 8.0:
>
> - undefined array keys
> - undefined object properties
> - array access on a non-array
> - property access on a non-object
>
> I think it is sensible to discuss those separately, but it would be good
> to make that clear.
>
>
> Similarly, it would be good to have more discussion of what "accessing"
> means, as the current examples are quite narrow, only showing direct use
> and the ++ operator. Other functionality potentially affected:
>
> - passing the variable to a function, presumably excluding by-reference
> parameters which don't currently warn
> - all the combined assignment operators -
> https://www.php.net/manual/en/language.operators.assignment.php
> - the array append operator ($a[] =3D 42;) does NOT currently give an
> undefined variable Warning
> - variable variables, e.g. "$b =3D 'a'; echo $$b;"
> - the compact() pseudo-function
>
> There's probably others that I've missed.
>

I 100% agree with that. An "Unaffected Functionality" section would be much
welcome.

I would add to the list: isset($foo) when $foo is first seen.
(To me this should not throw anything, like for uninitialized properties.)

If the RFC is about promoting the current warnings to Error without adding
any other Error at places that currently don't throw any warnings, then it
could be useful to say so. And if the RFC is going to propose to throw
Error at places that are currently warning-less, the list should be
explicit.

I very much call for an implementation to be provided before starting any
vote on the topic btw.
This is typically the kind of topic where getting into the actual code
might help spot edge cases.

Thanks for the RFC btw!

Nicolas

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