gdal crate failing to compile

[spadarian]

Crate name

map-engine

Build failure link

https://docs.rs/crate/map-engine/0.1.0/builds/491073

Additional details

Happy new year to everyone and thanks for your amazing work.

I just published my first crate (map-engine) and I'm having problems generating the docs due to a dependency that fails to compile.

The dependency is gdal which has an external dependency (GDAL). I checked if it was possible to make a PR to crates-build-env but the problem is that Ubuntu 18.04 has a very old version of GDAL.

Is there any recommended way of dealing with this?

• I can generate my docs locally, is there any way to upload those?
• The gdal crate has a custom build.rs that seems to deal with this. Does the build system use that or should I write my own build.rs?

Thanks!

[spadarian]

The error comes from this conditional compilation in gdal:

#[cfg(docsrs)]
pub fn gdal_version_info(_key: &str) -> String {
    "GDAL 3.2.0, released 2222/02/22".to_string()
}

#[cfg(not(docsrs))]
pub fn gdal_version_info(key: &str) -> String {
    let c_key = std::ffi::CString::new(key.as_bytes()).unwrap();

    unsafe {
        let res_ptr = gdal_sys::GDALVersionInfo(c_key.as_ptr());
        let c_res = std::ffi::CStr::from_ptr(res_ptr);
        c_res.to_string_lossy().into_owned()
    }
}

They do provide a flag in their Cargo.toml:

[package.metadata.docs.rs]
rustc-args = ["--cfg", "docsrs"]

But the building system seems to ignore it (you can see "--config" "build.rustflags=[\"--cfg\", \"docsrs\"]" in the build log).

[syphar]

@Nemo157 could you have a look here?

[Nemo157]

I think this is caused by #1580 which is afaik still blocked on rust-lang/cargo#10206; the --cfg docsrs is not passed to the build-script-build. After opening that issue I meant to see if I could fix cargo so we could fix this, but haven't had time to.

[syphar]

@Nemo157 was this solved with the resolved cargo issue?

[Nemo157]

I think it should have been, I've queued a rebuild and we'll see what happens.

[Nemo157]

Rebuild succeeded 🎉