Running "dune build @install" in a workspace sub-project puts files in an unexpected directory

[rlepigre]

Expected Behavior

When I work in a dune workspace containing several dune projects, I expect all produced files (barring promoted ones) to end up in <workspace_root>/_build.

Actual Behavior

This does not seem to be the case when using dune build @install from a project subdirectory: files end up in a _build placed under project's root (instead of the workspace root).

Reproduction

See #7336 install-workspace.tar.gz.

[emillon]

Thanks. The title mentions dune install but the body dune build @install. This is about the latter, right?

[rlepigre]

Thanks. The title mentions dune install but the body dune build @install. This is about the latter, right?

Indeed, sorry, I fixed the title.

[Alizter]

@rlepigre as explained in #7336 this is the intended behaviour since -p will set the root to the current directory. As I explained in the PR, the original cram test was incorrect due to the setting of INSIDE_DUNE. I also mention why unsetting that in fact gives the desired behaviour. All I can add to this is "don't use -p unless you are in the project root or your name is opam".

@emillon maybe it is worth adding some documentation about this difference (the fact that -p is setting the root). However I can only find documentation about -p in the help page rather than in the manual.

[rlepigre]

OK, I see. This behaviour sounds a bit weird to me, but I understand this cannot be changed at this point. Thanks!

[emillon]

maybe it is worth adding some documentation about this difference (the fact that -p is setting the root). However I can only find documentation about -p in the help page rather than in the manual.

I recently added that part to explain how the opam integration works:

https://dune.readthedocs.io/en/latest/explanation/opam-integration.html#what-p-means