cargo-zigbuild possible?

[nduchaux]

Hello,

Is it possible to combine cargo-nextest and cargo-zigbuild ?

I am compiling my project on a linux host (x86_64-unknown-linux-gnu). To compile for my other targets (aarch64-unknown-linux-gnu and x86_64-pc-windows-gnu), I am using cargo-zigbuild. Everything is working smoothly. To run my tests on the different targets, I have configured the runner in the .cargo/config.toml file:

[target.aarch64-unknown-linux-gnu]
runner = "qemu-aarch64 -L /usr/aarch64-linux-gnu"

[target.x86_64-pc-windows-gnu]
runner = "wine"

cargo-zigbuild test --target aarch64-unknown-linux-gnu is working perfectly but if I could use cargo-nextest if would be paradise.

[sunshowers]

Thanks for the issue. Nextest will pick up the target runner correctly, but it's possible that zigbuild needs to gain a nextest command.

[nduchaux]

So in your opinion, it would make more sense to add a nextest command to zigbuild:
cargo-zigbuild nextest run --target aarch64-unknown-linux-gnu
compared to a zigbuild command (or parameter) to nextest
cargo-nextest run --target aarch64-unknown-linux-gnu --zigbuild ?

[sunshowers]

Correct, yes. That is how tools like llvm-cov integrate into nextest as well.

[nduchaux]

FYI I created a thread in the zigbuild github to discuss this possibility rust-cross/cargo-zigbuild#427

[aw1cks]

I needed this for nextest archive with cargo-zigbuild, and a small CARGO wrapper works as a workaround.

cargo-nextest invokes Cargo through the CARGO environment variable. I point CARGO at a wrapper which:

• delegates non-test Cargo invocations to the real Cargo binary unchanged;
• intercepts the cargo test invocation that nextest uses while constructing the archive;
• rewrites the canonical Rust target, for example x86_64-unknown-linux-gnu, to Zig’s compatibility target such as x86_64-unknown-linux-gnu.2.17;
• invokes cargo-zigbuild with CARGO reset to the real Cargo binary, avoiding recursion.

The resulting command is effectively:

CARGO=/path/to/cargo-driver \
REAL_CARGO="$(command -v cargo)" \
CARGO_ZIGBUILD="$(command -v cargo-zigbuild)" \
RUST_RUNTIME_ZIG_TARGET=x86_64-unknown-linux-gnu.2.17 \
cargo-nextest nextest archive --target x86_64-unknown-linux-gnu ...

This lets the nextest-facing command retain the canonical target while the actual compilation goes through Zig with its ABI-compatible target. The wrapper validates that exactly one canonical --target was provided, so it does not silently rewrite unexpected invocations.
It is only a workaround, but it has been sufficient for producing a nextest archive to run against older Linux runtime environments.

#!/bin/bash
set -euo pipefail

: "${REAL_CARGO:?REAL_CARGO is required}"
: "${CARGO_ZIGBUILD:?CARGO_ZIGBUILD is required}"
: "${RUST_RUNTIME_ZIG_TARGET:?RUST_RUNTIME_ZIG_TARGET is required}"

args=("$@")

if [[ "${args[0]:-}" != test ]]; then
    exec env -u CARGO "$REAL_CARGO" "${args[@]}"
fi

for index in "${!args[@]}"; do
    case "${args[index]}" in
        --target)
            next_index=$((index + 1))
            [[ "${args[next_index]}" == x86_64-unknown-linux-gnu ]] ||
                { echo "expected canonical Linux target" >&2; exit 1; }
            args[next_index]="$RUST_RUNTIME_ZIG_TARGET"
            ;;
        --target=x86_64-unknown-linux-gnu)
            args[index]="--target=$RUST_RUNTIME_ZIG_TARGET"
            ;;
    esac
done