building for Embedded RISC-V does not work

[wuyoli]

I'm trying to make a flake for Embedded Development on CH32V307 microcontrollers. I did get Cargo build working successfully, but nix build doesn't work. When trying to do so it fails with the following error:

> Running phase: buildPhase
       > error: no matching package named `compiler_builtins` found
       > location searched: directory source `/build/cargo-vendor-dir` (which is replacing registry `crates-io`)
       > required by package `std v0.0.0 (/nix/store/a9flgvs64klvknn49qrsw3xlqsznyc2g-rust-default-1.85.0-nightly-2025-01-01/lib/rustlib/src/rust/library/std)`
       >     ... which satisfies path dependency `std` (locked to 0.0.0) of package `sysroot v0.0.0 (/nix/store/a9flgvs64klvknn49qrsw3xlqsznyc2g-rust-default-1.85.0-nightly-2025-01-01/lib/rustlib/src/rust/library/sysroot)`

[wuyoli]

Am I doing something wrong or is this out of scope?

[oxalica]

Am I doing something wrong or is this out of scope?

Please provide the nix file you use, the command your run and the Rust project you are building, in order to find out what the issue is.

[wuyoli]

the following repo contains the code + flake:
https://tildegit.org/purelyserious/ch32v307-blink-rust

[wuyoli]

do you have any ideas how to build this with nix?

[tsheinen]

I just ran into a similar problem -- the issue is unrelated to rust-overlay. It's a problem with the combination of vendoring and -Zbuild-std because std requires out-of-tree crates. Naersk will take an extra Cargo.lock as an argument since #328 and that's probably the easiest route forward? Alternatively if you add all the std deps to your dependency graph somewhere (dev-dependencies works) then the regular nixpkgs vendor will work.

naersk.buildPackage {
  src = ./.;
  additionalCargoLock = "${rust-toolchain}/lib/rustlib/src/rust/library/Cargo.lock";
};