Lazy proxy calls set hook twice

[iluuu1994]

Description

An assignment to a backing value in the set hook of an uninitialized lazy proxy triggers triggers lazy init. After initialization, we re-read the property from the underlying object. However, since the objects are not the same, we'll actually trigger the set hook again. This is unexpected in two ways:

• The set hook is called twice, as mentioned.
• We'll pass the result of the first set as an input to the second set, applying any side-effects twice.

The following code:

class C {
    public $prop {
        set {
            echo "set\n";
            $this->prop = $value * 2;
        }
    }
}

$rc = new ReflectionClass(C::class);

$obj = $rc->newLazyProxy(function () {
    echo "init\n";
    return new C;
});

function foo(C $c) {
    $c->prop = 1;
    var_dump($c->prop);
}

foo($obj);

Resulted in this output:

set
init
set
int(4)

But I expected this output instead:

set
init
int(2)

PHP Version

PHP 8.4

Operating System

No response