Error Identifier: postInc.nonNumeric

Every error reported by PHPStan has an error identifier. Here’s a list of all error identifiers. In PHPStan Pro you can see the error identifier next to each error and filter errors by their identifiers.

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++;

How to ignore this error #

You can use the identifier postInc.nonNumeric to ignore this error using a comment:

// @phpstan-ignore postInc.nonNumeric
codeThatProducesTheError();

You can also use only the identifier key to ignore all errors of the same type in your configuration file in the ignoreErrors parameter:

parameters:
	ignoreErrors:
		-
			identifier: postInc.nonNumeric

Rules that report this error #

PHPStan\Rules\Operators\OperandInArithmeticIncrementOrDecrementRule [1] phpstan/phpstan-strict-rules

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