Use (format-dune-file) instead of dune format-dune-file

[nojb]

Hello,

You are currently calling dune format-dune-file from one of your tests. This command does not honour the Dune lang version used in the project which means that your test will break whenever we change the formatting style in Dune.

In Dune 3.18 we introduced a built-in action (format-dune-file <src> <dst>) precisely for this purpose. This action honours the current Dune lang version and does not require shelling out to an external process.

Note that dune format-dune-file may evolve in ways that may not be backwards compatible in the near future (as the CLI interface does not have any backwards compatibility or versioning guarantees), so we are encouraging users of this command to switch to the action instead.

See ocaml/dune#10892 (comment) for some of the context.

[maiste]

Thanks @nojb!
I was about to do it today but you were clearly faster 😄

One question I have regarding this: shouldn't it add a dependency on dune >= 3.18 to make sure it supports the functionality?

[nojb]

Thanks @nojb! I was about to do it today but you were clearly faster 😄

One question I have regarding this: shouldn't it add a dependency on dune >= 3.18 to make sure it supports the functionality?

Yes, indeed. I pushed a fix (I think ; I am not very familiar with OPAM).

[panglesd]

Thanks @nojb! That looks good.

The benchmark CI failure seems to be related to ocaml/dune#11045.
It does not happen on ocaml-ci, which install deps and then call dune. On the contrary, the benchmark ci seems to pin everything and install them with opam, which calls dune subst and that is what is breaking.

Maybe that would be better to wait for the ocaml/dune#11045 fix to be released before raising dune lang if that is what triggers the bug?

[maiste]

The new fix was merged. It should be available in 3.20.