[bug#38408] [PATCH] WIP patches for the rust importer

[Ivan Petkov]

Hi Martin!

On Dec 1, 2019, at 7:17 PM, Martin Becze <address@hidden> wrote:

oh to be more clear. Even with "#:skip-build? #t" on all the rust libs,
things fail if I omit one optional dependency from somewhere. I'm just
testing on hello-cli but hello-cli inculdes clap which has alot of
optional deps. In ./guix/build-systems/cargo.scm on line 186 it says 

"Cargo requires all transitive crate dependencies' sources to be
available
in its index, even if they are optional (this is so it can generate
deterministic Cargo.lock files regardless of the target platform or
enabled
features). Thus we need all transitive crate dependencies for any cargo
dev-dependencies, but this is only needed when building/testing a crate
directly
(i.e. we will never need transitive dev-dependencies for any dependency
crates)."

I haven't really dug into the cargo build-system yet but my guess is
that the problem lies there. Allllsooo i totally could have missed
something simple.. idk

Yes, this is the primary limitation of packaging rust crates into guix

without manually needing to edit the Cargo.toml definition.

My opinion is that the easiest (to maintain) method for incorporating

rust packages into guix is to bite the bullet and perform a (source)

import of all transitive dependencies that a package might need.

Manually keeping up with tweaking the Cargo.toml file for every single

potential package, across every single published version will make

you go mad :)

Then the challenge would be how to automate the incremental importing

from crates.io (for example, some crates require a specific x.y.z version of

a dependency, some are willing to work with x.y.*, some have ranges, etc.)

and making sure that all packaged crates point to the appropriate dependencies

as they get updated in guix.

—Ivan