How to use cross-rs with nix flakes?

[spreston8]

I have a flake.nix file and when I am in my shell, cross-rs is unable to determine my os.
When I run this command inside my nix-shell ,cross build --profile dev --target aarch64-unknown-linux-gnu -p <my_package>, I see the following output:

Error:
   0: could not determine os in target triplet
   1: unsupported os in target, abi: "1.77.2", system: "default"

Location:
   src/docker/image.rs:342

Also another piece of information (from inside my nix-shell):

rustc --version --verbose
rustc 1.77.2 (25ef9e3d8 2024-04-09)
binary: rustc
commit-hash: 25ef9e3d85d934b27d9dada2f9dd52b1dc63bb04
commit-date: 2024-04-09
host: aarch64-apple-darwin
release: 1.77.2
LLVM version: 17.0.6

This works fine outside of my nix-shell. My question is it possible to pass in os or some flag to tell cross which platform I am on (arm64, M2) inside my nix shell?

[Emilgardis]

You need to check the output of rustc for x86_64, cross wont use the darwin binary.

I have no clue how nix does rustup, but I feel like they've messed something up.

rustup toolchain list -v will show you where the x86_64 toolchain lives, and from there run <path>/bin/rustc -Vv

[otavio]

Is CROSS_CUSTOM_TOOLCHAIN set to 1?

[spreston8]

I just tried running with CROSS_CUSTOM_TOOLCHAIN set to 1 and got this:

CROSS_CUSTOM_TOOLCHAIN=1 cross build --profile dev --target aarch64-unknown-linux-gnu -p rspace_plus_plus_rhotypes
[cross] warning: toolchain `nwp6ljhv90fi976w5im9g6x70k27l4m4-rust-default-1.77.2` may not run on image `ghcr.io/cross-rs/aarch64-unknown-linux-gnu:main`
[+] Building 0.2s (6/6) FINISHED                                                                                                                                                             docker:desktop-linux
 => [internal] load build definition from Dockerfile.aarch64-unknown-linux-gnu-custom                                                                                                                        0.0s
 => => transferring dockerfile: 247B                                                                                                                                                                         0.0s
 => [internal] load metadata for ghcr.io/cross-rs/aarch64-unknown-linux-gnu:main                                                                                                                             0.2s
 => [internal] load .dockerignore                                                                                                                                                                            0.0s
 => => transferring context: 2B                                                                                                                                                                              0.0s
 => [1/2] FROM ghcr.io/cross-rs/aarch64-unknown-linux-gnu:main@sha256:8437f255d81442c810a4e00aa983e00dc9338f0bd0e613217d6bba9fcf6ca7e5                                                                       0.0s
 => => resolve ghcr.io/cross-rs/aarch64-unknown-linux-gnu:main@sha256:8437f255d81442c810a4e00aa983e00dc9338f0bd0e613217d6bba9fcf6ca7e5                                                                       0.0s
 => CACHED [2/2] RUN eval "apt-get update && apt-get install -y protobuf-compiler"                                                                                                                           0.0s
 => exporting to image                                                                                                                                                                                       0.0s
 => => exporting layers                                                                                                                                                                                      0.0s
 => => writing image sha256:441c7f1ba6243111a0a688a07c851de52052fb6aa14a2bce8060d5f0c5b556f1                                                                                                                 0.0s
 => => naming to localhost/cross-rs/cross-custom-rspace:aarch64-unknown-linux-gnu-49d24-pre-build                                                                                                            0.0s

View build details: docker-desktop://dashboard/build/desktop-linux/desktop-linux/l46ce9mc1ddjh9uz0fzimwiiu
sh: 1: cargo: Exec format error
Error:
   0: `rustup component list --toolchain nwp6ljhv90fi976w5im9g6x70k27l4m4-rust-default-1.77.2` failed with exit status: 1

Location:
   src/errors.rs:147

Stderr:
   error: error: invalid value 'nwp6ljhv90fi976w5im9g6x70k27l4m4-rust-default-1.77.2' for '--toolchain <toolchain>': invalid toolchain name: 'nwp6ljhv90fi976w5im9g6x70k27l4m4-rust-default-1.77.2'

   For more information, try '--help'.
   : invalid toolchain name: 'nwp6ljhv90fi976w5im9g6x70k27l4m4-rust-default-1.77.2'

I am on a Mac M2 machine and trying to cross compile to aarch64-unknown-linux-gnu, under a nix environment. That nix environment config file is found here: https://github.com/F1R3FLY-io/f1r3fly/blob/rspace%2B%2B/flake.nix.

I can try to install rustup here in a little bit under nix...

[Emilgardis]

The problem here is that we run docker under/for x86_64-unknown-linux-gnu, so you'll need a rustc for that enironment. I'm not sure if we actually support this, I recognize this as a similar issue to when you want to use cargo-bisect-rustc with a non-x86_64 host. I think this needs to be fixed in the project and it's not possible to workaround (without rustup). I'll make a issue/feature request describing the issue.

[spreston8]

Ok. I was able to resolve my issue by adding rustup to my nix flake file and I guess that's all that was needed. Thank you, now closing.