OCaml 5.4.0: packages for the first alpha

[Octachron]

This PR adds the three usual packages for the first alpha release of OCaml 5.4.0:

• ocaml-compiler.5.4.0~alpha1
• ocaml-base-compiler.5.4.0~alpha1
• ocaml-variants.5.4.0~alpha1+options

and it amends the ocaml metapackage to allow to install the prerelease versions of ocaml-base-compiler.5.4.0~... .

[ivnhk]

Hey @Octachron

Thanks for the contribution.

Here are the errors from the pipeline:

Error in ocaml-variants.5.4.0~alpha1+options: No package source directory provided.
Warning in ocaml-compiler.5.4.0~alpha1: The package has a dune-project file but no explicit dependency on dune was found.
Error in ocaml-base-compiler.5.4.0~alpha1: No package source directory provided.
Error in ocaml.5.4.0: conf packages should always use the 'conf-' name prefix, the 'conf' flag, and the 'depext' field all together, but this package only has the 'conf' flag

I'll try to add some suggestions in order to fix those

[ivnhk]

I also think some of those may be false positives, just like here: #27613

@shonfeder @mseri please, take a look when you have a moment

[ivnhk]

I'm not exactly sure but considering you want to publish ocaml.5.4.0, you probably need to remove the conf flag.

Otherwise, you'd have to rename the package into conf-ocaml and add depexts: [ "ocaml" ]. I don't think that something you're aiming for

[Octachron]

None of those linter hint apply to compiler packages:

• Error in ocaml-variants.5.4.0~alpha1+options: No package source directory provided
• Error in ocaml-base-compiler.5.4.0~alpha1: No package source directory provided.

This is intended, the source is defined by the ocaml-compiler package in order to avoid duplicating the complex build configuration.

• Warning in ocaml-compiler.5.4.0~alpha1: The package has a dune-project file but no explicit dependency on dune was found.

The compiler is not built with dune, and thus has no dependencies on dune.

• Error in ocaml.5.4.0: conf packages should always use the 'conf-' name prefix, the 'conf' flag, and the 'depext' field all together, but this package only has the 'conf' flag

Using this flag is intended too.

[ivnhk]

Right. That's what I was thinking, tbh. And that's exactly parts outlined in #27613

May I ask why compiler packages are different and linter hints do not apply, so I get a better understanding?

[dra27]

It's more that the linter doesn't either have more complex interpretations of the rules or, possibly more for these, exceptions embedded in it for these packages.

[shonfeder]

This looks OK to me! Thanks for the review @ivnhk and for the explanations @dra27 and @Octachron.

LMK when you are happy with this and I will merge it in.

re: the false positives on the linting checks, I've opened ocurrent/opam-repo-ci#434

[avsm]

Looks good, thanks! We'll need to patch ocaml-version as well now to get the CI kicking in for this.