cargo-metadata invoked by maturin resolves dependencies differently from cargo fetch with --target specified #2561
Description
Bug Description
With --target argument supplied, cargo-metadata invoked by maturin during building may resolve dependencies differently from cargo-fetch, failing a --frozen build with unresolvable crates that are actually unnecessary on the target.
Your maturin version (maturin --version)
1.8.3
Your Python version (python -V)
3.13.3
Your pip version (pip -V)
25.0.1
What bindings you're using
pyo3
Does cargo build work?
- Yes, it works
If on windows, have you checked that you aren't accidentally using unix path (those with the forward slash /)?
- Yes
Steps to Reproduce
Taking rpds-py as example,
export CARGO_HOME=$PWD/cargocache # ensure a clean environment
cargo fetch --locked --target x86_64-unknown-linux-musl
maturin build --frozen --target x86_64-unknown-linux-musl
cargo build --frozen --target x86_64-unknown-linux-musl
Maturin fails to build, with error message like
$ maturin build --frozen --target x86_64-unknown-linux-musl
error: failed to download `cc v1.0.90`
Caused by:
attempting to make an HTTP request, but --frozen was specified
💥 maturin failed
Caused by: Cargo metadata failed. Does your crate compile with `cargo build`?
Caused by: `cargo metadata` exited with an error:
but cargo builds the crate smoothly,
$ cargo build --target x86_64-unknown-linux-musl --frozen
Compiling target-lexicon v0.13.2
Compiling python3-dll-a v0.2.12
Compiling once_cell v1.19.0
Compiling proc-macro2 v1.0.86
Compiling unicode-ident v1.0.12
Compiling autocfg v1.3.0
Compiling libc v0.2.155
Compiling heck v0.5.0
Compiling memoffset v0.9.1
...
Without specifying --target x86_64-unknown-linux-musl when invoking cargo fetch, both cargo and maturin successfully build the crate. The problematic dependency, cc, is only necessary on windows and shouldn't be pulled in with --target specified.
[target.'cfg(windows)'.dependencies]
cc = "1.0.73"