callable.resultDiscarded

Code example

<?php declare(strict_types = 1);

#[\NoDiscard]
function pureCompute(int $x): int
{
	return $x * 2;
}

$fn = Closure::fromCallable('pureCompute');
$fn(5);

Why is it reported?

The callable is invoked on a separate line and its return value is discarded. The underlying function is marked with #[\NoDiscard] (PHP 8.5+), which indicates its return value must be used. Calling it without using the result means the call has no meaningful effect.

This error is not ignorable.

How to fix it

Use the return value of the callable:

 $fn = Closure::fromCallable('pureCompute');
-$fn(5);
+$result = $fn(5);