TL;DR; Instead of relying to each implementation of the SeirializerInterface to remove the non-sendable stamps from the envelope, we do it before calling the encode method, to make sure they are not send into the transport(even for a user's custom serializer)

Hello, I came across an issue when having a custom php serializer, I was calling PHP's serialize method on the envelope. But serialization was failing with error Serialization of 'Closure' is not allowed.

The issue was that I was trying to serialize the recently added \Symfony\Component\Messenger\Stamp\AckStamp, this class accepts a closure in the constructor and such a class can not be serialized form PHP's native serialize method. It turns out that this class should not be serialized and we should remove the stamps that implement the interface \Symfony\Component\Messenger\Stamp\NonSendableStampInterface by doing that before serializing the message:

$envelope = $envelope->withoutStampsOfType(NonSendableStampInterface::class);

Both of messenger's serializers \Symfony\Component\Messenger\Transport\Serialization\PhpSerializer and \Symfony\Component\Messenger\Transport\Serialization\Serializer make the above call to withoutStampsOfType before serializing an envelope.

Which got me thinking that it would have been nice if messenger was removing the stamps that implement \Symfony\Component\Messenger\Stamp\NonSendableStampInterface before passing the envelope to be encoded to the given serializer. My solution was to create a SerializerDecorator that removes the stamps and calls the serializer that has been provided to the given transport.

This solution makes the behavior consistent with native messenger's serializers and the custom serializers of the users. If a user calls withoutStampsOfType method on its own implementation there will be no error, so no BC break.

Thank you