Subject: Re: [PATCH] WIP patches for the rust importer

From: Martin Becze <[email-masked]>
Date: Mon, 02 Dec 2019 15:10:06 -0800

On 2019-12-02 04:01, Ivan Petkov wrote:
> Hi Martin!
> 
>> On Dec 1, 2019, at 7:17 PM, Martin Becze <[email-masked]> 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 [1] (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
> 
> Links:
> ------
> [1] http://crates.io

Hi Ivan,

> 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.

When you say source import of the transitive dependencies, do you mean
that all the rust libs should just be source only or do you mean the top
level package should have to declare all the transitive dependencies? If
former I agree but if it is the latter then I would consider rust
packaging to be broken.

> Then the challenge would be how to automate the incremental importing
> from crates.io [1] (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.)

Yes that is what this patch (https://issues.guix.gnu.org/issue/38408)
does. It uses semantic versioning to select the correct package form
crate.io or if available from the alread packaged rust packages.

-Martin