OCAML_DUNE_PRETEND_VERSION

[SnarkBoojum]

I'm the Debian packager for elpi and coq-elpi, both using dune, and I have been having some issues with their latest versions.

The elpi tarball on github relies on dune using it's .git to determine the version (%%VERSION_NUM%% substitutions and building a coherent META file) ; unfortunately, it is a .git-less tarball, so it doesn't quite work as expected.

For packagers (I guess other distributions will also find it hard), it would be nice to have an environment variable to bypass the current mechanism to find the version, and I propose OCAML_DUNE_PRETEND_VERSION ; the usage being:

• if it's defined, take that as a basis for version and version_num everywhere ;
• if it isn't, fall back to the current git/hg tricks.

Such a mechanism isn't unheard of: python's setuptools-scm system provides a SETUPTOOLS_SCM_PRETEND_VERSION which does exactly that ; and if you look at the debian/rules files here, you'll see how useful it is.

Thanks

[rgrinberg]

It's fine to have this, but why do you want a runtime configuration option. Wouldn't it be better to have a build time option? E.g. ocaml configure.ml --set-version FOO?

[SnarkBoojum]

I don't get your point : it is a runtime configuration for dune, but it's used at build time for the software currently built -- which is the one we want to pretend the version of.