Description:
------------
When a class has no "property" property and you are trying set it as $class->property = 'value', PHP is trying to use magic __set() method. It is correct behavior. But when you are trying to set it as $class->property['index'] = 'value', PHP ignores the setter, creating the "property" as a property of the class. It is incorrect behavior, because class had no "property" property, so it firstly have to use setter.

Test script:
---------------
<?php
class SetterTester {
    public function __set($name, $value) {
        echo 'Setter is used', PHP_EOL, PHP_EOL;
    }
}

echo "Test normal version", PHP_EOL;
$test = new SetterTester();
$test->property = "Some value";

echo "Test array version", PHP_EOL;
$test = new SetterTester();
$test->property["index"] = "Some value";


Expected result:
----------------
Test normal version
Setter is used

Test array version
Setter is used

Actual result:
--------------
Test normal version
Setter is used

Test array version