Description
Checklist
- I've looked through the issues and pull requests for similar reports
Describe your issue
This cargo PR introduced build.build-dir option that can be used to store intermediate artifacts not in <project>/target, but in any other location. I use this option to store artifacts at a XDG cache directory, at /home/yuki/.cache/cargo.
However, cross does not mount this directory inside its container, and it's inaccessible in docker. This leads to strange behavior:
$ cross test --target x86_64-unknown-linux-gnu
error: failed to create directory `/home/yuki/.cache`
Caused by:
Permission denied (os error 13)Adding verbosity reveals the issue: the CARGO_HOME is proxied correctly, but build-dir is never even mentioned.
$ cross test --target x86_64-unknown-linux-gnu -v
+ cargo metadata --format-version 1 --filter-platform x86_64-unknown-linux-gnu
+ rustc --print sysroot
+ /usr/bin/docker
+ /usr/bin/docker version -f '{{ .Server.Os }},,,{{ .Server.Arch }}'
+ /usr/bin/docker info -f {{.SecurityOptions}}
+ rustup toolchain list
+ rustup target list --toolchain nightly-x86_64-unknown-linux-gnu
+ rustup component list --toolchain nightly-x86_64-unknown-linux-gnu
+ /usr/bin/docker run --userns host -e LITHIUM_BACKEND -e LITHIUM_THREAD_LOCAL -e 'XARGO_HOME=/home/yuki/.xargo' -e 'CARGO_HOME=/home/yuki/.local/share/cargo' -e 'CROSS_RUST_SYSROOT=/home/yuki/.local/share/rustup/toolchains/nightly-x86_64-unknown-linux-gnu' -e 'CARGO_TARGET_DIR=/target' -e 'CROSS_RUNNER=' -e TERM -e 'USER=yuki' -e 'CROSS_RUSTC_MAJOR_VERSION=1' -e 'CROSS_RUSTC_MINOR_VERSION=89' -e 'CROSS_RUSTC_PATCH_VERSION=0' --name cross-nightly-x86_64-unknown-linux-gnu-43377-5d707b07e-x86_64-unknown-linux-gnu-12d30-1748974214080 --rm --user 1000:1000 -v /home/yuki/.xargo:/home/yuki/.xargo:z -v /home/yuki/.local/share/cargo:/home/yuki/.local/share/cargo:z -v /home/yuki/.local/share/cargo/bin -v /home/yuki/kek/Mirror/lithium:/home/yuki/kek/Mirror/lithium:z -v /home/yuki/.local/share/rustup/toolchains/nightly-x86_64-unknown-linux-gnu:/home/yuki/.local/share/rustup/toolchains/nightly-x86_64-unknown-linux-gnu:z,ro -v /home/yuki/kek/Mirror/lithium/target:/target:z -w /home/yuki/kek/Mirror/lithium -t ghcr.io/cross-rs/x86_64-unknown-linux-gnu:main sh -c 'PATH="$PATH":"/home/yuki/.local/share/rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin" cargo test --target x86_64-unknown-linux-gnu -v'
error: failed to create directory `/home/yuki/.cache`
Caused by:
Permission denied (os error 13)
+ rustup component list --toolchain nightly-x86_64-unknown-linux-gnuThese examples use host target as it's the simplest target I could imagine, but even without explicitly selecting target this issue persists.
What target(s) are you cross-compiling for?
No response
Which operating system is the host (e.g computer cross is on) running?
- macOS
- Windows
- Linux / BSD
- other OS (specify in description)
What architecture is the host?
- x86_64 / AMD64
- arm32
- arm64 (including Mac M1)
What container engine is cross using?
- docker
- podman
- other container engine (specify in description)
cross version
cross 0.2.5 (51f46f2 2025-05-24)
Example
Relevant configuration is:
$ printenv CARGO_HOME
/home/yuki/.local/share/cargo
$ printenv RUSTUP_HOME
/home/yuki/.local/share/rustup
$ cat $CARGO_HOME/config.toml
cargo-features = ["build-dir"]
[unstable]
build-dir = true
[build]
build-dir = "/home/yuki/.cache/cargo/"Commenting out the last line reverts the build-dir behavior and makes cargo store all intermediate artifarts inside target/, which makes this issue disappear.
Additional information / notes
Additional links on build.build-dir:
- Implemented
build.build-dirconfig option rust-lang/cargo#15104 - Redefine
CARGO_TARGET_DIRto be only an artifacts directory rust-lang/cargo#14125 - https://doc.rust-lang.org/nightly/cargo/reference/unstable.html#build-dir
The source code at 51f46f2 (2025-06-03T18:15Z tip of main branch) does not reference neither config.toml nor build-dir.