https://compose-spec.io/ is now the place to define Compose file format and evolution. Changes like #2517 should not happen within this repo anymore without a sibling issue/PR on compose-spec.

http://github.com/compose-spec/compose-go was contributed as a git extraction for the types and loader packages from docker/cli. To avoid code to diverge, docker/cli should adopt compose-go ASAP

last but not least, using compose-go would make docker stack command compliant with the compose specification, and allow to mix docker compose config command with docker stack deploy (which seem to be a common pattern)