Make distcheck, VPATH and Autotools vars in build.rs

help
1

Hi all,

I'm trying to access certain vars make distcheck generates, or where my build.rs is currently being called from. I'm trying to access my config.h file from my C project to check some things:

Everything works in my CI apart from this VPATH stage, as I'm obviously using hardcoded paths in my build.rs. I've just tried this:

    eprintln!("Where are we? {:?}", env::var("CARGO_MANIFEST_DIR").unwrap());

but get:

  --- stderr
  Where are we? "/home/ghenry/src/sentrypeer/sentrypeer-4.0.0/sentrypeer_rust"
  thread 'main' panicked at build.rs:35:58:
  called `Result::unwrap()` on an `Err` value: Os { code: 2, kind: NotFound, message: "No such file or directory" }
  note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
make[2]: *** [Makefile:2850: /home/ghenry/src/sentrypeer/sentrypeer-4.0.0/_build/sub/sentrypeer_rust/target/release/libsentrypeer_rust.a]

where is not the VPATH dir.

I'm porting/extending my C project to Rust, using Rust as a lib and my Rust lib re-uses some code from my C project by calling it as a lib.

Any ideas how I can find my C source code? Maybe me parsing my autoconf generated config.h file by hand isn't the best way and that's my problem. cbindgen does then go on to complain if I hardcode a path, as it then can't resolve other includes.

Thanks for reading,
Gavin.

2

Upon inspecting the environment we have we can see CARGO_TARGET_DIR contains
/home/ghenry/src/sentrypeer/sentrypeer-4.0.0/_build/sub/sentrypeer_rust/target

so let's go for that:


    let target_dir = PathBuf::from(env::var("CARGO_TARGET_DIR").unwrap());
    let opendht =
       std::fs::read_to_string(target_dir.join("../../")
      .join("config.h")).unwrap();

which works! But now we get:

--- stderr
  ./../src/conf.h:21:10: fatal error: '../config.h' file not found
  thread 'main' panicked at build.rs:60:10:
  Unable to generate bindings: ClangDiagnostic("./../src/conf.h:21:10:
    fatal error: '../config.h' file not found\n")

Sigh.

3

Ah, I can set and env var I want on my CLI here so can do SRC_DIR=$(srcdir) CARGO_TARGET_DIR=... and pick that up in my build.rs

4

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