Bug#971439: Build procedure is incorrect and produces invalid files

[Emilio Jesús Gallego Arias <e+debbugs@x80.org>]

Package: lablgtk3
Version: 3.1.1-1

Dear OCaml maintainers,

as far as I could see this is a general bug on quite a few Debian OCaml
packages; in particular submitting for lablgtk3 but this bug should be
assigned to more packages.

It seems that the build procedure for lablgtk3 is incorrect, see for
example https://github.com/coq/coq/issues/13079 , where the package
contains and invalid META file; moreover as `-p` was not used the wrong
compiler settings were used to build the binaries [for example regarding
optimization]

OCaml packages that use dune as a build system _must_ be built:

- always with `dune build -p $pkg1,$pkg2` for the desired list of packages

and either:

- using the officially released .tbz archive that for example
  dune-release produces, which will contain the right metadata for
  version numbers, etc...

- or if using a git checkout, `dune subst` _must_ be run before the
  build so the metadata is update prior build.

Let us know if we can be of any help.

Kind regards,
Emilio