Deprecate WildcardVersion::Major?

[udoprog]

Hey,

I'm currently trying to do a comparison for when a VersionReq is a full wildcard: *.

For all intents and purposes, the following states of VersionReq appears to be equivalent:

• predicates is empty, causing the all check to return true.
• there is one predicate, whose op is Op::Wildcard(WildcardVersion::Major).

Both of these cases appears to match any version. Both of them are fmt::Display:ed in a way so that they show *.

I would like to discuss if we could either have VersionReq::any() return the same as when * is parsed (single WildcardVersion::Major predicate) to make comparisons viable. Or to completely deprecate the use of WilcardVersion::Major since its functionality is equivalent to an empty set of predicates.

[steveklabnik]

This is a good question! I'm not sure.

[udoprog]

For my specific problem, introducing a function like is_wildcard would also work:
https://github.com/udoprog/semver/commit/c27a8c9ebf1b3393f500cab05a5d5bd9c36b437b

[steveklabnik]

I've accepted the underlying PR in semver-parser, so we can do this here too.

[udoprog]

I've rebased #151. When version 0.8.0 of semver-parser is available it is good to go.
I've also closed #159 since you'll be taking this approach.

Thanks!

[dtolnay]

This is fixed in 1.0.0. The * requirement is now uniformly represented with an empty comparator set, and there is no WildcardVersion::Major.