Code is recompiled each time

[vertrex]

Hi,

I use CXX in one of my crate and an other depends of it. Each time I run cargo build or cargo run, my c++ code is recompiled even if there is no change in any file. I tried to use println!("cargo:rerun-if-changed/") but I didn't change anything, must I print for each of the file (I have lot of c++ and header file in sub dir) ?

Tahnk you

[adetaylor]

Maybe you could use something like WalkDir to output the cargo:rerun-if-changed string for each C++/header file?

I think this is all largely beyond the control of the cxx crate, since we just use cc for our Cargo C++ build.

[dtolnay]

@vertrex can you provide a minimal repro of this? Ideally the best would be a repo I can check out and run cargo build && cargo build and observe it build two times.

[vertrex]

It worked after adding :

    let paths = fs::read_dir("./").unwrap();
    for path in paths { println!("cargo:rerun-if-change={}", path.unwrap().path().display()) }

Thank you

[dtolnay]

Closing as very likely a consequence of this misbehavior/bug in Cargo: rust-lang/cargo#6003.