[cmp.categories.pre] Remove unused enumerators

[CaseyCarter]

Fixes #3541.

[jensmaurer]

Looks good to me. @tkoeppe?

[zygoloid]

Do we still need the eq enum at all? Perhaps we could merge it into ord?

[CaseyCarter]

Do we still need the eq enum at all? Perhaps we could merge it into ord?

Yes, this is feasible: eq is only used as a constructor parameter type, and the classes with such a constructor already have a constructor that takes ord.

[tkoeppe]

@jensmaurer: sorry, I missed that ping; I agree that a more aggressive cleanup is a nice idea.

[CaseyCarter]

I've made the requested changes.

[jwakely]

We don't really need the equal enumerator either, it's used in exactly one place and we could just use equivalent there. It might even make it clearer that equivalence is the same as equality for strong_ordering.

[jwakely]

LGTM, though as I said in a comment, I don't see any reason to keep equal.

[CaseyCarter]

We don't really need the equal enumerator either, it's used in exactly one place and we could just use equivalent there. It might even make it clearer that equivalence is the same as equality for strong_ordering.

I'd vaguely prefer to keep the equal vs. equivalent distinction to reflect "substitutability", but it's not a hill I'm willing to die on.

[jwakely]

OK, I don't feel strongly about it either.

[CaseyCarter]

Ping. Could someone please remove the changes-requested label so this is visible again?

[jensmaurer]

Done.