Dune install doesn't respect --display=quiet [and maybe other args]

[ejgallego]

Dear dune devs,

doing man dune install shows many command line options which seem to have no effect, a example of such an option is --display.

I wonder whether this is due to the change that had dune install foo not calling dune build -p foo before.

Note that after having a quick look to dune install, indeed there could be a problem if dune install does indeed build things, as a typical workflow for distros is dune build -p foo && sudo dune install foo, so it is usually a desired invariant that no build happens in the install command as it is running with S.U. permissions.

[bobot]

People can work on two things:

• making --display work with dune install
• allow commands to select common flags it wants (e.g things not related to building: cache, ...)

[maroneze]

For now, we are forced to do dune install 2>/dev/null in our build system (with all its negatives consequences, such as missing all error messages) to avoid having hundreds of messages in the CI logs.

[Alizter]

FTR I opened #6648 so we might be able to observe useless arguments in the dune commands.