OCaml 5.5 support

[kit-ty-kate]

OCaml 5.5 is due to be frozen soon. A handful of big PRs that will change the parsetree are due to be merged before the first alpha, but i'm opening this ticket to track the effort and update on the various upcoming pre-releases.

[patricoferris]

Hi @kit-ty-kate, thanks for the heads up :)

[patricoferris]

Do you have those PR numbers anywhere?

[kit-ty-kate]

Not directly but they can be inferred by looking at the 5.5 milestones https://github.com/ocaml/ocaml/milestone/51 and https://github.com/ocaml/ocaml/milestone/50 (in particular, see the modular explicit documentation PR is here, but the main PR itself is missing from the milestone, i believe this is a simple oversight)

[kit-ty-kate]

A new milestone was created which lists them: https://github.com/ocaml/ocaml/milestone/53

[kit-ty-kate]

modular explicit was just merged so you should be good to go to start the upgrade. I don't anticipate any other large API changes in 5.5 between now and the first alpha

[patricoferris]

5.5 compiler support was merged and ppxlib.0.38.0 is out the door ocaml/opam-repository#29563 :)