Generating documentation of private libraries with dune

I initialized my project using the recommended command

$ dune init proj project_name

from Quickstart — Dune documentation, and I want to generate its documentation. I used

$ dune build @doc @doc-private

as indicated in Generating Documentation — Dune documentation. It says that the generated documentation should be in _build/default/_doc/_html/<library> but it doesn’t say what <library> is. I would assume it is the library name from the dune file, but it is not: instead of the expected _build/default/_doc/_html/lib, my doc is in _build/default/_doc/_html/lib@5a6fo525np6/Lib (actually, it’s another seemingly random string of digits and lowercase letters).

As a consequence, some hyperlinks are broken in the generated html pages: they point to files which suppose a _html/Lib pattern instead of the _html/lib@5a6fo525np6/Lib one.

My dune files are

$ cat lib/dune
 (name lib))
$ cat bin/dune
 (public_name project_name)
 (name main)
 (libraries lib))

Am I following the instructions wrong or is there a problem in the documentation or in the doc generation for private libraries?


Remark: in the above code “dune build @doc @doc-private”, both targets are actually needed, contrary to what Aliases — Dune documentation says.