Crate c_compat 

c-compat

This crate’s aim is to bring a one-stop solution to the problem of compiling/linking C libraries (and therefore *-sys crates) by using the least amount of friction possible.

Practical Setup

In your *-sys crate’s build script, which will be using bindgen and cc, you can access the includes folder that c-compat exposes via the DEP_C_COMPAT_METADATA environmental variable.

let c_compat_includes = std::env::var("DEP_C_COMPAT_METADATA").expect("DEP_C_COMPAT_METADATA not set");
let c_compat_includes = c_compat_includes.strip_prefix("include=").unwrap();

You can then make sure that bindgen discards any system includes (which vary across versions, might not be available, or simply risk to not be architecture independent) and use the c-compat includes as a substitute:

    let bindings = bindgen::Builder::default()
        .clang_arg(&format!("-I{c_compat_includes}"))
        .clang_arg("-nostdinc")
        .clang_arg("-nobuiltininc")
        ...

For cc just make sure the headers are available and we also are not using any standard included headers:

    let mut cc_build = cc::Build::new();
    cc_build
        .include(&c_compat_includes)
        .flag("-nostdinc")
        ...

Then in your *-sys crate you can import the symbols so that they are visible by the linker

// Make sure we automatically make the necessary symbols available
use c_compat as _;

and that’s it! As long as all the c-compat includes cover the needs of your *-sys crate, you should be in a position where you are leveraging the power of clang to cross-compile a C library with Rust without needing any extra sysroots, compilers, etc…

Modules

math

math.h Rust implementations

stdlib

stdlib.h Rust implementations