Add development tools recommendation in opam file (variable) and cli

[rjbou]

At the moment it's not finished, it needs a proper look at the modification (it's just seddish adds)
fix #4959
@rjbou edit:
All clear! Renamed to with-tools : available in cli opam install pkg --with-tools and in opam files as a variable depends: "foo" {with-tools}. Have the same behaviour than with-test and with-doc.

[kit-ty-kate]

Looks good! Thanks!! ❤️

[rjbou]

No, it's not yet good, i set it in a commit, but not in the PR message itself, it's definitively a wip, i just made a sed ftm.

[AltGr]

How does this interact with the previous behaviour ? E.g. are dev deps still turned on automatically when the package doesn't have a fixed checksum ? If so do we have a --without-dev to counter it ? The manpage should be clearer about this.

[rjbou]

It doesn't replace dev, and ye i agree the doc need to be quite clear about this new option/variable. with-dev is meant for development environment, and do not interact at all with dev/--dev variables/option. see referenced issue for more complete view of the needs.

[dra27]

From discussions last December, we proposed --with-tools

[rjbou]

Updated!

[dbuenzli]

I guess I'm a bit late to the party but I think --with-tools is a pretty confusing name. Packages do install tools or not (I have many packages that optionally install command line tools if cmdliner is installed). I can already see people trying to install them using this command line switch. Maybe --with-dev-tools ?

(Personally I'm not entirely convinced by the actual need for the initial request, I'm not sure what's wrong with tagging these dependencies with dev, it looks like micro management of dependencies)

[dbuenzli]

In fact I think for-dev would be a much better and less confusing name.