PEP 751: one last time

[brettcannon]

@charliermarsh

Hopefully not a large ask: could we use default-groups and accept a list?

I’m fine with that. I also removed the requirement that dependency-groups must have values for default-groups to be allowed.

@charliermarsh

What should tools do if they encounter extras or dependency-groups outside of that context? E.g., what if we see that in a Requires-Dist marker?

I’ve updated the PEP to say it will be just like extra; an error like there’s no variable defined when used outside of lock files.

Both changes are covered by PEP 751: Make `default-group` be `default-groups` by brettcannon · Pull Request #4308 · python/peps · GitHub .