Dune: Update vs create target

Learning
,
1

I’d like for dune to

  1. Create the Menhir parser.messages file it it does not exist and
  2. Update the parser.messages file if it does and my parser.mly has changed.

I defined two rules

(rule
 (targets parser.messages)
 (mode fallback)
 (action
  (with-stdout-to
   %{targets}
   (run menhir --list-errors %{targets}))))

(rule
 (targets parser.messages)
 (deps parser.mly)
 (action
  (with-stdout-to
   %{targets}
   (run menhir --update-errors %{targets}))))

but this doesn’t work since dune requires 1 rule to target 1 file.

Can I have my cake and eat it too?

2

Looks like I misunderstood how Menhir works.

3

Dune support for .messages is being worked on: Add `.messages` support for Menhir by nojb · Pull Request #11753 · ocaml/dune · GitHub. You may find useful information there. And I encourage you to chime in if you have any suggestions.

You may also find useful information in the following post: Dune wish list for 2023 - #60 by zozozo.

Cheers,
Nicolas

2 Likes
4

It’s worth mentioning that the general solution for the Dune question (not specific to Menhir) is that you have to create an intermediary file for each rule, e.g. print --list-errors to parser.messages.list. You only need to promote the final file, parser.messages, to your source tree.

1 Like