C-Rust bindings: build works but test fails

1

Hi everyone,

some months ago I decided to create some bindings for a C library that was not available in Rust. I first obtained a static library, and then linked to that in my build.rs file.

Since I would like to keep the original library updated with the latest changes, I decided to add the original project as a git dependency, and then build the library from Rust. My build.rs file now looks like this:

// use make to build the library
Command::new("make")
    .arg("-C")
    .arg("abPOA")
    .output()
    .expect("failed to invoke make");

// include the obtained library(-L ./lib -labpoa)
println!("cargo:rustc-link-search=abPOA/lib");
println!("cargo:rustc-link-lib=abpoa");

// bindgen stuff

This seems to work fine when running cargo build, however cargo test returns this error:

= note: /usr/bin/ld: cannot find -labpoa
collect2: error: ld returned 1 exit status

Does anybody know how to fix this?

2

The problem is likely the relative path. Cargo has a different working directory when testing since integration tests are compiled as separate crates. Try to emit a link annotation containing an absolute path. You will probably want to use CARGO_MANIFEST_PATH or something similar as a reliable reference point.

2 Likes
3

Thanks for the reply, I changed my build.rs file to this:

    let abpoa_dir = format!("{}/{}",env!("CARGO_MANIFEST_DIR"), "abPOA");
    let abpoa_lib = format!("{}/{}",abpoa_dir, "lib");

    // use make to build the library
    Command::new("make")
        .arg("-C")
        .arg(abpoa_dir)
        .output()
        .expect("failed to invoke make");

    // include abpoa (-L ./lib -labpoa)
    println!("cargo:rustc-link-search={}", abpoa_lib);
    println!("cargo:rustc-link-lib=abpoa");

However I'm getting the same error. It still works fine when building, but fails whenever I try to run some tests (or use this library as a dependency in another project).

4

You might try installing (via make install) to prefix OUT_DIR. Or use the cmake crate since libapboa also provides a CMakeLists file.

3 Likes
5

I used the cmake crate and now everything works correctly, thank you very much @MoAlyousef!
Thanks to @H2CO3 as well!

6

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