Deprecation Notices & Migration Strategy

TL;DR

Explanation

PHP uses E_DEPRECATED to warn that a function, parameter, or behaviour will be removed in a future version. E_USER_DEPRECATED is the user-land equivalent. In PHP 8.x, many PHP 7.x patterns trigger deprecations (dynamic properties, ${} string interpolation, implicitly nullable parameters). Best practice: set error_reporting(E_ALL) in dev to surface them, use PHPStan/Psalm to catch them statically, and use Rector to auto-fix them. Run php -d error_reporting=32767 in CI to catch all notices. Never suppress deprecations with @.

Common Misconception

Why It Matters

Common Mistakes

• Suppressing deprecations with @ operator or error_reporting(~E_DEPRECATED).
• Not running Rector to auto-fix deprecations before upgrades.
• Upgrading PHP major versions without first eliminating all deprecations on the previous version.

Code Examples

// PHP 8.2: Dynamic properties deprecated
class User {
    // No typed properties defined
}
$u = new User();
$u->name = 'Paul'; // Deprecated: Creation of dynamic property

// Fix: declare the property explicitly
class User {
    public string $name = '';
}

// Or add attribute to acknowledge intentional dynamic properties (PHP 8.2+):
#[\AllowDynamicProperties]
class LegacyUser {}

References

• ↗ https://www.php.net/manual/en/migration83.deprecated.php

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