Issues with 7.0rc1 IAsyncBasicConsumer's method

[Tornhoof]

Describe the bug

The new IAsyncBasicConsumer interface has a method HandleBasicDeliver and a method parameter ReadOnlyBasicProperties , but with the modifier in. You can't have in, ref in async methods. So as soon as you implement the interface and actually have anything async to do, i.e. you add the async keyword, it won't compile anymore, with CS1988 (https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/compiler-messages/ref-modifiers-errors#reference-variable-restrictions).

rabbitmq-dotnet-client/projects/RabbitMQ.Client/client/api/IAsyncBasicConsumer.cs

Lines 49 to 55 in 2a5aed7

	Task HandleBasicDeliver(string consumerTag,
	ulong deliveryTag,
	bool redelivered,
	string exchange,
	string routingKey,
	in ReadOnlyBasicProperties properties,
	ReadOnlyMemory<byte> body);

in basically makes only sense together with ref struct and specifically ref readonly struct, atleast that's what I understand from all the discussions around https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/proposals/csharp-11.0/low-level-struct-improvements.

I highly recommend simply removing in this prior to the 7.0 release, as modifying it would be a breaking change and at the moment implementations would need to jump through loops to use it with async (async local method etc.).

In IBasicConsumer it's not there:

rabbitmq-dotnet-client/projects/RabbitMQ.Client/client/api/IBasicConsumer.cs

Lines 92 to 98 in 2a5aed7

	Task HandleBasicDeliverAsync(string consumerTag,
	ulong deliveryTag,
	bool redelivered,
	string exchange,
	string routingKey,
	ReadOnlyBasicProperties properties,
	ReadOnlyMemory<byte> body);

Reproduction steps

See for example:
https://sharplab.io/#v2:EYLgxg9gTgpgtADwGwBYA0AXEBDAzgWwB8ABAJgEYBYAKGIAYACY8gVgG4biBmJ0hgYQYBvGgzFMexABxMkDALIBPeTAwALCABMAFAEsAdgwAqMXBgDKGKAFcwGBvkUA1bABtrMAJSjxQ8eJ8xAF9AhlDuBlhsTQh9V0UGMxs7Y1MLK1sMUJFqfxDqIKA===

Expected behavior

Additional context

No response

[michaelklishin]

Thank you for providing all the details from the start!

[lukebakken]

Great, this will be easy to fix. Feel free to open a PR yourself if you'd like!

[Tornhoof]

will do.

[bollhals]

The problem with this is, ReadOnlyBasicProperties is a rather large struct, hence the in modifier was added back when it wasn't async yet to avoid copying the struct.

Now that the library moved to async, in is problematic as you've seen.
So the use of a large struct for these API's might actually be worse than creating a class to hold them.