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To: Rowan Tommins <rowan.collins@gmail.com>, PHP Internals
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Thread-Topic: [PHP-DEV] Allow null variables to be decremented
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Date: Sat, 15 Feb 2020 18:11:41 +0000
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Subject: Re: [PHP-DEV] Allow null variables to be decremented
From: tysonandre775@hotmail.com (tyson andre)

My opinion is that it'd be more consistent for `--` to work like `-=3D 1` (=
e.g. become `-1`).=0A=
It might break some code, but that code was probably incorrect.=0A=
=0A=
Out of scope of the proposed RFC, but this reminds me of a similar issue:=
=0A=
Currently, the `++` and `--` operators do nothing to arrays or objects,=0A=
not even emitting a notice or changing the value.=0A=
I see that `++` on typed properties/references can already throw a TypeErro=
r for integer overflow,=0A=
so it might make sense to also start throwing a TypeError for `++` on objec=
ts (without numeric operation handlers) and arrays.=0A=
=0A=
I'd thought earlier that emitting a notice instead of throwing a TypeError =
for arrays/objects might negatively limit the optimizations opcache can do=
=0A=
because error handlers can have side effects.=0A=
But it looks like I'd just have to allow inferring that MAY_BE_OBJECT and M=
AY_BE_ARRAY=0A=
could have side effects for the INC/DEC opcodes in `may_have_side_effects()=
` in ext/opcache/Optimizer/dce.c.=0A=
=0A=
(If your RFC ends up emitting warnings/notices, it would need to check for =
MAY_BE_NULL|MAY_BE_UNDEF in dce.c, I think.)=0A=
=0A=
Would there be any interest in emitting a warning or deprecation warning fo=
r objects/arrays starting in php 8.0?=0A=
=0A=
- Tyson=