pow.leftNonNumeric

Code example

<?php declare(strict_types = 1);

function doFoo(): void
{
	$null = null;
	$result = $null ** 2;
}

Why is it reported?

The exponentiation operator (**) is intended for numeric arithmetic. When a non-numeric value such as null, an object, or a non-numeric string is used on the left side of the ** operator, PHP will attempt implicit type coercion, which is error-prone and usually indicates a bug.

In the example above, null is used as the base of the exponentiation, which PHP silently coerces to 0.

This rule is provided by the phpstan-strict-rules package.

How to fix it

Ensure the left operand is a numeric type (int, float, or numeric string):

 <?php declare(strict_types = 1);

-function doFoo(): void
+function doFoo(int $base): void
 {
-	$null = null;
-	$result = $null ** 2;
+	$result = $base ** 2;
 }

Or handle the possibly-null value explicitly:

 <?php declare(strict_types = 1);

 function doFoo(?int $base): void
 {
-	$result = $base ** 2;
+	$result = ($base ?? 0) ** 2;
 }