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Error Identifier: mod.rightNonNumeric

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);

function doFoo(int $a, ?string $b): void
{
	$result = $a % $b;
}

Why is it reported? #

This error is reported by phpstan/phpstan-strict-rules.

The right-hand side operand of a modulo (%) is not a numeric type. PHP’s modulo operator expects both operands to be numeric (int, float, or numeric-string). Using a non-numeric type such as null, array, object, or a non-numeric string on the right side of a modulo operation will produce unexpected results or a TypeError in strict mode. A null right operand is equivalent to zero, which causes a DivisionByZeroError.

How to fix it #

Ensure the right-hand operand is a numeric type by narrowing the type:

 <?php declare(strict_types = 1);
 
-function doFoo(int $a, ?string $b): void
+function doFoo(int $a, int $b): void
 {
 	$result = $a % $b;
 }

Or validate and convert the value before use:

 <?php declare(strict_types = 1);
 
 function doFoo(int $a, ?string $b): void
 {
-	$result = $a % $b;
+	if ($b !== null && is_numeric($b)) {
+		$result = $a % (int) $b;
+	}
 }

How to ignore this error #

You can use the identifier mod.rightNonNumeric to ignore this error using a comment:

// @phpstan-ignore mod.rightNonNumeric
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: mod.rightNonNumeric

Rules that report this error #

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

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