Re: rust-build-system: Unvendor *-sys libraries in phase?

[John Soo]

Hi Efraim,


> IMO the correct way to do it would be in the crate source that we
> download. We regularly add snippets to remove vendored code, this should
> be no different.

Totally agree. It seems like a challenge to me to do the other required work 
since all the building happens only when building the top level package. I will 
totally defer to you here, since you have the knowledge and experience. 

> The only real difference is that right now the
> cargo-build-system is "too smart" and checks the #:cargo-inputs to make
> sure they actually are crates before untarring them and putting them in
> the guix-vendor dor. Currently the 'patch-and-rezip phase always uses xz
> for compression, and crates always use gzip, so we cannot use patches or
> snippets on crates.

Can that be fixed in any way? I actually have no idea. 

> Then the only thing left is to set certain environment variables, some
> of which can probably be moved to the cargo-build-system if they don't
> require an actual path.

Ahh right. I hadn’t realized that restriction. Though couldn’t end variables 
with paths be thunked or g-expressions or be done through propagated paths?  
I’m not sure, just thinking aloud.

Thanks for your maintenance, as always.

John