Building the basic example fails about tch-rs

[LaurentMazare]

Glad that it worked, I've actually already switched the github code to use cc by default (this actually was the case a couple days ago) and have the possibility to use cmake via some environment variable.

[ehsanmok]

I'm working on improving the build.rs. I'll send it today.

[LaurentMazare]

Hi,
Thanks for the feedback, yes CI would certainly be a good thing to add.
Re your compilation error, I haven't encountered it despite trying the pre-built cpu version 1.0.0 and 1.0.1 (as per build-version).
Is it on linux or on another platform ? I only tried linux on my side.

[ehsanmok]

Yes, it was on Ubuntu 14.04 with cmake 3.2 and Rust nightly 1.34

[LaurentMazare]

Interesting, googling a bit the closest I found to your error is this issue. Not sure whether it's related but if it's the case updating to cmake 3.5.1 may fix the issue.

Alternatively you can try using the cc crate rather than cmake to compile. This can be done by replacing build.rs with the following. If this works for you we can either switching to cc or having an environment variable to decide between cc and cmake.

use std::env;
use std::path::PathBuf;
extern crate cc;

fn main() {
    let libtorch = env::var("LIBTORCH").expect("LIBTORCH not defined");
    let libtorch = PathBuf::from(libtorch);
    let libtorch_lib = libtorch.join("lib").into_os_string().into_string().unwrap();
    println!("cargo:rustc-link-search=native={}", libtorch_lib);
    println!("cargo:rustc-link-lib=c10");
    println!("cargo:rustc-link-lib=caffe2");
    println!("cargo:rustc-link-lib=torch");
    cc::Build::new()
        .cpp(true)
        .include(libtorch.join("include"))
        .include(libtorch.join("include/torch/csrc/api/include"))
        .flag(&format!("-Wl,-rpath={}", libtorch_lib))
        .flag("-std=c++11")
        .flag("-D_GLIBCXX_USE_CXX11_ABI=0")
        .file("libtch/torch_api.cpp")
        .warnings(false)
        .compile("libtorch");
}

You will also have to add the following line to Cargo.toml build-dependencies section:

cc = "1.0"

[ehsanmok]

cc worked! also upgraded my cmake to the latest v3.14 and it worked as well.

I think, cc is more self-contained and can have it as fallback.

[LaurentMazare]

Cool!
Note that I changed it quite a bit lately: there is now a separate torch-sys crate (in the same repo). When the LIBTORCH variable is not set the build script will automatically download the binary version of libtorch - this is similar to what the tensorflow crate does for tf. The nice thing is that if you're happy with running the cpu version of libtorch, there is no setup needed anymore.

[LaurentMazare]

Closing this now, thanks for your help on this and feel free to re-open if there are further issues!