Testing back to Julia 1.0: is there still value in doing so?

[Ickaser]

The CI for Unitful currently tests the following versions of Julia:

• 1.0
• 1.6
• 1.10
• 1 (currently 1.11)
• nightly

To me, testing even as far back as 1.6 seems excessive--from what I have seen of other packages, a more common test setup would be

• lts (currently 1.10)
• 1 (currently 1.11)
• pre (currently 1.12)

To me, it's an interesting curiosity that Unitful still works as far back as 1.0. But at this point, my feeling is that any new features don't need to deliberately support that far back--even 1.6 was released 4 years ago, and the ecosystem has come a long way in that time; users still working with pre-Julia 1.6 probably can't use current versions of a lot of other packages, and old versions of Unitful would still be available to them.

(Specifically, for #795 , the package I want to provide an extension for has compat limited to Julia 1.6 and up.)

Can @sostock or @giordano comment on this? Are there any other maintainers still involved who have strong preferences? (Is there anyone else who might be added as a maintainer?)

[giordano]

In my packages I usually follow a pragmatic approach: I support whatever oldest version of Julia can be maintained without (too) much hassle. For example in Measurements.jl I kept support for Julia v1.0 until not long ago because it wasn't a big deal, but then there were a few PRs which would have had an easier life with Julia v1.10 and we moved to that version as minimum instead.

To me, testing even as far back as 1.6 seems excessive--from what I have seen of other packages, a more common test setup would be

• lts (currently 1.10)

I think it's more sensible to use the "min" alias: you test whatever is the minimum version declared by the project file, ensuring consistency.

[Ickaser]

We already have #772 and #765 adding extensions to the package, which requires 1.9; in the case of #765, to avoid making ForwardDiff an outright dependency of Unitful, the extension just isn't even loaded below 1.9. For #795 the minimum compatible is 1.6.

So... although I think 1.9 would be a sane minimum version going forward, there is a case for allowing down to 1.6. (And of course, any users still below Julia 1.6 can simply keep using old versions of Unitful.)