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PossiblyUnusedProperty

Emitted when --find-dead-code is turned on and Psalm cannot find any uses of a particular public/protected property.

If this property is genuinely part of your public API — used from outside the analysed codebase (for example a library entry point, or a property accessed only by a framework) — annotate the containing class with @api (or @psalm-api) — mark the whole class rather than the individual property, since a public-API property almost always belongs to a public-API class. Otherwise the property is dead code and should be removed: a property reported as unused in a class that is not already marked @api is almost always genuinely unused, so annotating the individual property with @api to silence the report is very rarely the right fix.

See @api for the full guidance; note that @psalm-suppress is not a substitute for @api, as it silences the report without marking the property as used.

<?php

class A {
    /** @var string|null */
    public $foo;

    /** @var int|null */
    public $bar;
}

$a = new A();
echo $a->foo;