Migrate to ppxlib >= 0.18.0

[giltho]

I'm using flow_parser as a dependency for a JavaScript analysis tool, I'm trying to upgrade ocaml but I need newer versions of ppxs all over. Flow_parser is blocking right now because of ppx_gen_rec.
Not merging this wouldn't be blocking for me, I just thought I'd submit it to help a bit

fixes ocaml-ppx/ppxlib#142

[giltho]

There seem to be an issue when using this with ppx_deriving though..
ppx_deriving has its effect at the same time, it unrolls the [@@deriving show] into val show... and ppx_gen_rec raises
"Psig_value not supported yet".
For now, this can't be used in flow_parser...

[mroch]

thanks! i'm on vacation for thanksgiving next week so it'll take a bit to check it out in detail but I skimmed this on my phone.

this is intended to run before deriving, so that the [@@deriving show] in the sig gets copied to the value, and then both are expanded separately. my understanding of ppxlib is that it replaces extensions top down, so it's interesting that this doesn't just work.

hopefully there's a way to make ppxlib work. if not, maybe just upgrading ocaml-migrate-parsetree resolves the version constraints you're running into?

alternatively, solving #3 so we don't need this at all could be a last resort

[mroch]

#2 fixed this same issue in ocaml-migrate-parsetree, but we don't have the same position option in ppxlib

[giltho]

No worry ! It gives me a bit of time to think about it. Very busy with coursework marking this week end :/
Thanks for your feedback

[giltho]

I must have done something wrong when I tested ppx_gen_rec locally the first time, because I just tested it again and actually there's no conflict with ppx_deriving 🤔
To make sure of that, I've added the corresponding test and a CI that executes it

[giltho]

Hello and Happy new year !

Any update on that side ? Anything I should do differently ?
I'm just checking up on the state of my current PRs, no emergency at all of course.

[kit-ty-kate]

Is there any news about this change by any chance?

[mroch]

we've been testing this out for a while internally on flow and it seems to work with ppx_deriving. i'll merge!

[mroch]

now i have to remember how to do a release 😂

[giltho]

Let me know if I can help in any way in publishing / syncing flow with this version :)
I'm quite excited to be able to throw my fork of flow away and use flow_parser directly at the source

[mroch]

published v2.0.0! thanks again