ampq_client 4.0.3 not compatible with Erlang/OTP 28

[benoitc]

Describe the bug

Can you please ship a new version to hex that allows us to build on Erlang OTP 28? Current version returns:

===> Compiling _build/default/lib/rabbit_common/src/rabbit_cert_info.erl failed
rabbit_cert_info.erl:148:15: undefined macro 'street-address'

rabbit_cert_info.erl:127:18: function format_rdn/1 undefined, did you mean format_complex_rdn/1?

rabbit_cert_info.erl:161:1: Warning: function escape_rdn_value/1 is unused
rabbit_cert_info.erl:164:1: Warning: function escape_rdn_value/2 is unused

Reproduction steps

1. buuild the client on erlang otp 28

Expected behavior

works on Erlang OTP 28, build without issues.

Additional context

No response

[michaelklishin]

@benoitc where do we claim that RabbitMQ 4.0.x, or even 4.1.x, is Erlang 28-compatible?

We don't because they are not. 4.2.0 will be, and maybe a certain 4.1.x version if we decide to backport #14114, a non-trivial set of changes.

[leonardb]

@michaelklishin Not a very polite response. I believe @benoitc was reporting this when building the client, not the server. We ran into the same issue and are blocked even testing our code with OTP-28.

The issue is specific to changes in the OTP-28 public_key app, and looking at your referenced PR, the changes required to fix the issue are isolated to the deps/rabbit_common/src/rabbit_cert_info.erl file, which consist of changing the decode module via a define and replacing the macro '?id-streetAddress' with a hard-coded value of 17 (this seems to have been done in PR#13916, but is not reflected in the latest rabbit_common package on hex.pm).

I've manually patched the file locally and everything seems to build/test fine for our client connections to rmq server

[michaelklishin]

@leonardb I did understand that the question has to do with the AMQP 0-9-1 Erlang client.

Our team does not maintain amqp_client separately from the rest of the codebase, and it's still true that we do not claim that Erlang 28 is supported. It also does not change the fact that there won't be any more publicly available 4.0.x releases because that series is out of community support.

#14114 will ship in RabbitMQ 4.2.0 around October 2025.

If that's not good enough for you, you are welcome to maintain a fork of the client for the time being. All the work related to Erlang 28 compatibility, including a lot of feedback to the Erlang/OTP team during the 28.0 RC stages, was done for you. The source is publicly available under a permissive license.