Error Identifier: assignOp.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';
$a -= 5;

Why is it reported? #

The compound assignment operator (such as +=, -=, *=, .=, etc.) cannot be applied to the given combination of types. The operation between the left-hand variable and the right-hand value produces a type error.

In the example above, the -= operator is applied between a string and an int, which is not a valid binary operation.

How to fix it #

Ensure the variable and the value are compatible types for the operation:

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

Or use the correct operator for the types involved:

 <?php declare(strict_types = 1);
 
 $a = 'hello';
-$a -= 5;
+$a .= ' world';

How to ignore this error #

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

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

Rules that report this error #

PHPStan\Rules\Operators\InvalidBinaryOperationRule [1]

Edit this page on GitHub

Theme