Error Identifier: binaryOp.invalid

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);

$a = 'hello';
$b = new \stdClass();

$result = $a - $b;

Why is it reported? #

A binary operator (such as +, -, *, /, ., etc.) is used with operands whose types are not compatible for that operation. The operation would result in a TypeError at runtime.

In the example above, the - operator is applied between a string and an stdClass object, which is not a valid arithmetic operation.

How to fix it #

Ensure both operands have types compatible with the operator:

 <?php declare(strict_types = 1);
 
-$a = 'hello';
-$b = new \stdClass();
+$a = 10;
+$b = 5;

 $result = $a - $b;

Or use the correct operator for the types involved:

 <?php declare(strict_types = 1);
 
 $a = 'hello';
-$b = new \stdClass();
+$b = ' world';

-$result = $a - $b;
+$result = $a . $b;

How to ignore this error #

You can use the identifier binaryOp.invalid to ignore this error using a comment:

// @phpstan-ignore binaryOp.invalid
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: binaryOp.invalid

Rules that report this error #

PHPStan\Rules\Operators\InvalidBinaryOperationRule [1]

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