parameterByRef.tooWideBool

Code example

<?php declare(strict_types = 1);

function setFlag(bool &$flag): void
{
	$flag = true;
}

Why is it reported?

The function declares a by-reference parameter with type bool, but only ever assigns true to it. The false value is never assigned, making the bool type wider than necessary.

How to fix it

If the parameter is always set to a specific boolean value, narrow the by-ref type using a @param-out PHPDoc tag:

 <?php declare(strict_types = 1);

+/** @param-out true $flag */
 function setFlag(bool &$flag): void
 {
 	$flag = true;
 }

Alternatively, if both true and false should be possible, ensure both values are actually assigned on different code paths:

<?php declare(strict_types = 1);

function setFlag(bool &$flag, bool $condition): void
{
	if ($condition) {
		$flag = true;
	} else {
		$flag = false;
	}
}