Unused Rec Flag error / warning when compiling using --dev flag

Hello Everyone,

I am still working on my web application, and im trying to compile using the --dev tag which treats all warnings as errors (i like to use this as a way to clean up unused code). Currently i am receiving a warning 39: unused rec flag error on my data structures and I am unsure as to why. the code for the two relatively simple data structures follows.

type note =
title : string;
body : string;
} [@@deriving sexp, fields, compare, yojson]

type note_list =
notes : note list
} [@@deriving sexp, fields, compare, yojson]

these are the declarations in the .ml file and the exact same declarations (deriving statements and all) are in the .mli file. I have looked around on the internet and found (this github link to the ppx_deriving github pull request log) [https://github.com/ocaml/opam-repository/pull/10136] saying that this “issue” was fixed by silencing the warning. is it just that the --dev flag looks for even silenced warnings? or is there actually a work around or fix for this issue?

Thank you all!

Looks like the fix was done as part of: https://github.com/ocaml-ppx/ppx_deriving_yojson/pull/68
I don’t think the current version released on opam (3.1 at the moment) contains this fix.

I don’t see the warning when I pin the package to the current git repo.