Dune langage version and menhir version incompatible

[fblanqui]

07:39 ~/src/dedukti ((HEAD détachée sur 5990bc6c)) make install
File "dune-project", line 3, characters 14-17:
3 | (using menhir 2.0)
                  ^^^
Warning: Version 2.0 of the menhir extension is not supported until version
1.4 of the dune language.
Supported versions of this extension in version 1.2 of the dune language:
- 1.0
File "dune-project", line 3, characters 14-17:
3 | (using menhir 2.0)
                  ^^^
Warning: Version 2.0 of the menhir extension is not supported until version
1.4 of the dune language.
Supported versions of this extension in version 1.2 of the dune language:
- 1.0

07:41 ~/src/dedukti ((HEAD détachée sur 5990bc6c)) l dune-project 
(lang dune 1.2)
(name dedukti)
(using menhir 2.0)

Note that the current dune language version is >= 2.7. So 1.2 is very old.

[francoisthire]

I think it can be updated safely, we just need an MR ;)

[ruplet]

I just also ran into it today. Took me an hour to figure out, changing the contents of the dune file to:

(env
        (dev     (flags (:standard -w -8)))
        (release (flags :standard)))

(ignore warning 8: pattern-match is not exhaustive)

and dune-project to:

(lang dune 1.4)
(name dedukti)
(using menhir 2.0)

(update lang dune to 1.4)

seems to resolve the problem. My versions:

$ opam list
# Packages matching: installed
# Name                # Installed # Synopsis
base-bigarray         base
base-domains          base
base-effects          base
base-nnp              base        Naked pointers prohibited in the OCaml heap
base-threads          base
base-unix             base
dune                  3.17.2      Fast, portable, and opinionated build system
ocaml                 5.3.0       The OCaml compiler (virtual package)
ocaml-base-compiler   5.3.0       Official release of OCaml 5.3.0
ocaml-compiler        5.3.0       Official release of OCaml 5.3.0
ocaml-config          3           OCaml Switch Configuration
ocaml-options-vanilla 1           Ensure that OCaml is compiled with no special options enabled