Re: Cargo build system: Lock file cannot be updated

[David Craven <david@craven.ch>]

> I can assume it’s attempting to modify the current crate's Cargo.lock,
> but obviously is unable to do so. Is this some sort of bug on the build
> system, or is there any parameter which the script is missing?

Ansi term is a rust library. Because of that it does not have a
Cargo.lock file. This means that cargo needs to perform it's
dependency resolution algorithm to determine which dependencies are
needed and which versions. This doesn't work because cargo requires
network connectivity to download the crates.io registry. To prevent
this we pass the --frozen flag to cargo build. This is a bit annoying
in this particular case because there are no dependencies. What you
are experiencing is a known deficiency in the cargo-build-system [0],
the relevant excerpt copied below for reference.

* Cargo build system should not do anything if there isn't a
Cargo.lock file except copy the source to out.

Contributions are welcome!

[0] http://lists.gnu.org/archive/html/guix-devel/2016-12/msg00454.html