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Date: Sun, 4 Jun 2023 15:37:30 +0200
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To: Claude Pache <claude.pache@gmail.com>
Cc: PHP internals <internals@lists.php.net>
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 <91F5F43D-5A20-4B14-B2D1-475607021940@gmail.com>
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Subject: Re: [PHP-DEV] RFC [Discussion]: Marking overridden methods
 (#[\Override])
From: tim@bastelstu.be (=?UTF-8?Q?Tim_D=c3=bcsterhus?=)

Hi

On 5/29/23 21:34, Claude Pache wrote:
> One weakness of the proposal, is that there is no notice when a method without #[\Override] annotation accidentally overrides a parent method. This is necessary for the sake of BC, of course. Therefore, (inspired by the --noImplicitOverride flag of TypeScript), I suggest adding a complementary #[\NoImplicitOverride] annotation on the derived class, that makes #[\Override] mandatory on overriding methods. The following example would then trigger a compilation error since Laravel 5.4:
> 

Thank you for that suggestion. As a solution to that problem only a 
per-method attribute came to my mind and that clearly does not scale / 
adds too much visual noise for a very common case.

However I'm not sure if a class-level attribute is the right choice 
either. Contrary to #[\Override] itself, which clearly adds metadata 
(namely the "intent") to a single method, the #[\NoImplicitOverride] is 
more of a config flag for the engine behavior, instead of "metadata". It 
doesn't really belong on the class, the class just happens to be a 
convenient location.

The `declare()` construct however is intended to hold this kind of 
behavior directives. So `declare(no_implicit_override=1)`, similarly to 
`declare(strict_types=1)` appears to be the natural solution here. It's 
not particularly pretty, but would be reasonably consistent with the 
rest of the language. It would be less forward-compatible (unknown 
declares emit a Warning), though. I'm also not sure about the impact on 
the implementation. The support for "no implicit override" would require 
at least another bit-flag for only a smaller incremental improvement 
over #[\Override] itself.

Best regards
Tim Düsterhus