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Date: Wed, 29 Jan 2025 20:50:19 +0100
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Subject: Re: [PHP-DEV] RFC: Marking return values as important (#[\NoDiscard])
To: Rob Landers <rob@bottled.codes>, Volker Dusch <volker@tideways-gmbh.com>,
 php internals <internals@lists.php.net>
References: <a995ac24905030e168e7f6006b996cd5@bastelstu.be>
 <a3d14e31-53eb-4a04-8fb2-01f58809fec1@app.fastmail.com>
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From: tim@bastelstu.be (=?UTF-8?Q?Tim_D=C3=BCsterhus?=)

Hi

On 1/29/25 20:31, Rob Landers wrote:
> This looks promising!
> 
> Why do we need the (void) cast? Wouldn't "@" work and avoid a BC issue?

The `@` operator also suppresses any other warning or notice within the 
call chain. That is likely undesirable because it might hide issues one 
is interested in. See this example (https://3v4l.org/NDtR7):

     <?php
     function inner() {
         var_dump($undefined);
     }

     function outer() {
         inner();
     }

     outer();
     outer();
     @outer();

The `(void)` cast makes the intent of not being interested in the return 
value clear. In C casting to `(void)` is an established pattern of 
"using" a value that the compiler would otherwise consider unused. 
Likewise will the `void` operator suppress the TypeScript-ESLint warning 
of not using returned `Promise`: 
https://typescript-eslint.io/rules/no-floating-promises/#ignorevoid

Best regards
Tim Düsterhus