Bug#1111165: ben: Building template fails: Error: Unbound module "Ben_frontends"

[Stéphane Glondu <glondu@debian.org>]

Hello,

Le 15/08/2025 à 12:15, Sebastiaan Couwenberg a écrit :
> Using dune [...]

Good idea.

> [...] seems to work after adding the new template to templates/dune:
>
>   dune build templates/debiangis.cmxs
>
> This does require installing libppx-yojson-conv-ocaml-dev which was not 
> pulled in via the libben-ocaml-dev dependencies.

This way, you might rebuild the whole ben, hence you may need all its 
build-dependencies including this one.

> Copying the .cmxs file to /usr/lib/ben/templates no longer works.

Even after setting BEN_TEMPLATES_DIR? Its default value is $(ocamlc 
-where)/ben/templates, as you've figured out.

> This did work:
>
>   su -c "mkdir /usr/lib/x86_64-linux-gnu/ocaml/5.3.0/ben/templates/ 
> debiangis"
>   su -c "cp -v _build/default/templates/debiangis.* /usr/lib/x86_64- 
> linux-gnu/ocaml/5.3.0/ben/templates/debiangis/"
>
> What is the recommended way to build & install a custom template?

There is no "recommended" way, the way you did seems fine.

If you do not want to fiddle with ben sources:

https://salsa.debian.org/debian/ben/-/tree/master/examples/custom-template


Cheers,

--
Stéphane