Do not require a DSL version in cask header

[jawshooah]

Following up on #15782. Casks can now be created with no DSL version in the header. For example:

cask 'no-dsl-version' do
  version :latest
  ...
end

Casks with DSL versions in the header are still valid, but the DSL version will be ignored.

[jawshooah]

@caskroom/maintainers Any comments? If not, I'll merge at 10pm UTC.

[vitorgalvao]

Why not make it a symbol as well (cask :no-dsl-version do)?

[jawshooah]

@vitorgalvao We could, though I'm not sure what the benefit would be.

[jawshooah]

Also, symbols can't contain hyphens unless surrounded in quotes. So it would need to be either :no_dsl_version or :'no-dsl-version'.

[vitorgalvao]

Ah, no, ignore it. I was thinking of having it as symbol for consistency with what we had, but just realised I misinterpreted it. On first look it seemed like we needed to be explicit about not having a version, but I see now it stands in to be the name of the cask.

[adidalal]

LGTM.

After this merge, existing Casks could be changed to the new header as time permits. That would also be a (silent) indicator that a maintainer has looked at the Cask and ensured that everything checks out.

That would also be a good time to implement any other breaking changes, so it might be best to avoid a mass update (proactively) until the core stabilizes a bit more/the backlog of current PRs that deal with core functionality are merged or otherwise addressed.

[jawshooah]

That would also be a (silent) indicator that a maintainer has looked at the Cask and ensured that everything checks out.

To be honest, I'm not too jazzed about combing through ~3000 casks to find bugs. A mass update would be as easy as s/cask\s+:v[\d_]+\s+=>/cask/g.

Any PRs that include truly breaking changes should also include fixes for affected casks (in separate commits).

[adidalal]

Yeah, on second thought, maybe not the best idea. I forgot how many Casks we had!

I would say then that this PR doesn't seem to have any regressions and so a merge, followed by a mass scripted update whenever convenient should work out well.