rust-src

A build-dependency to download a tarball of the Rust source code associated with the current version of rustc. Makes it easier to compile many of Rust's different crates and add them as dependencies to a project where the target triple is not natively supported by rustc.

Add as a build-dependency in Cargo.toml

build = "build.rs"

[build-dependencies.rust_src]
git = "https://github.com/sondrele/rust-src.git"

And download the rust source code in the build script, here build.rs

extern crate rust_src;

fn main() {
    rust_src::fetch();
}