Compiler support timeline proposal (up to 2030)

[kit-ty-kate]

Per previous discussion in Raising the OCaml lower bound to 4.11.0 for opam-repository and Dropping some intermediate OCaml versions from CI, the current oldest release of OCaml available in opam-repository is 4.11.

Looking at ocaml's repology entry (unsupported versions excluded) seems to give me the following timeline of support:

• CentOS 9 will be supported until "sometime in 2027" so we could raise the lower-bound to 4.13 at that point
• Debian 12 will be supported until July 2028 so we could raise the lower-bound again up to 4.14
• From there, it's probably best to keep it at 4.14 for a few years regardless of distros given that some people still want to use OCaml 4 and given the removal of the native 32bit backend
• once the need for 4.14 fades, we should probably be able to look at distros again and raise the lower-bound up to something like 5.2 if i had to guess (though at this point it's too far in the future to make accurate prediction)

What do you all think?

[mseri]

Seems reasonable to me

[raphael-proust]

that seems good

we should have something to that effect in a top-level .md file somewhere