Hello internals,
I stumbled upon this behavior, if I write this:
```php
class Foo
{
public ?string $prop = null;
public function __construct(?string $prop = null)
{
$this->prop = $prop;
}
}
class Bar extends Foo
{
public function __construct(
public ?string $bar = null,
) {}
}
// Echoes nothing, but it works as expected.
echo (new Bar())->prop;
```
It works as intended, but if I replace the `Foo` class using:
```php
class Foo
{
public function __construct(
public ?string $prop = null,
) {}
}
```
It won't work anymore and I have the following error:
```
PHP Warning: Uncaught Error: Typed property Foo::$prop must not be
accessed before initialization in php shell code:9
```
If I understand it correctly:
- in the first case, default value is attached to the object property,
so if I omit its constructor, I have the default,
- in the second case, default value is attached to the constructor
parameter, and not to the object property, which means that in case the
parent constructor is not called in the `Bar` class, `$prop` remains
initialized.
It doesn't sound like a bug, but I think that many people would actually
expect otherwise: that the constructor promoted property keep their
default even when constructor is not explicitly called.
Is there any good reason behind this ? Wouldn't it be best to change
this behavior ? Would it be a risk for backward compatibility (my guess
is "not that much, probably not a all even") ?
Regards,
--
Pierre
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