postInc.nonNumeric

Code example

<?php declare(strict_types = 1);

$value = false;
$value++; // ERROR: Only numeric types are allowed in post-increment, false given.

Why is it reported?

The post-increment operator ($variable++) is intended for numeric types. Using it on non-numeric values like false, null, objects, or union types containing non-numeric members leads to unexpected behavior. In PHP, incrementing null produces 1, incrementing false produces 1 (in PHP 8.3+, this is deprecated), and incrementing objects or other non-numeric types is either undefined or produces warnings.

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

How to fix it

Use the post-increment operator only on numeric types (int, float, or numeric strings):

 <?php declare(strict_types = 1);

-$value = false;
+$value = 0;
 $value++;

If the variable might be non-numeric, initialize it properly before incrementing:

 <?php declare(strict_types = 1);

-$value = null;
-$value++;
+$value = 0;
+$value++;