1.2.949. PHP Native Interfaces and Return Type

Native PHP interface which define a type, expect the derived methods to use the same time. In particular, a mixed return type was added to the jsonSerialize() of the JsonSerialize PHP interface.

In PHP 8.1, the mixed return type is now enforced, and a deprecated notice is displayed.

One solution is to add the good return type, or to use the #[`ReturnTypeWillChange]` attribute. This rule covers the following interfaces :

• ArrayAccess <https://www.php.net/manual/en/class.`arrayaccess.php>`_

• Countable

• Exception

• FilterIterator

• Iterator

• JsonSerializable

• php_user_filter

• SessionHandlerInterface

<?php
    class MyJsonSerialize implements jsonserialize {
        function jsonserialize() : int {}
    }
?>

See also JsonSerializable::jsonSerialize.

1.2.949.1. Related PHP errors

• 0

1.2.949.2. Connex PHP features

• json

1.2.949.2.1. Suggestions

• Add the mixed returntype to all implementation of the jsonSerialize method

• Add the #[ReturnTypeWillChange] attribute to the method

1.2.949.2.2. Specs

Short name	Php/JsonSerializeReturnType
Rulesets	All, Analyze, Changed Behavior, CompatibilityPHP81, Deprecated, LintButWontExec
Exakat since	2.3.0
PHP Version	With PHP 8.0 and more recent
Severity	Minor
Time To Fix	Quick (30 mins)
Precision	Very high
Note	This issue may lint but will not run
Available in	Entreprise Edition, Exakat Cloud