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Showing content from https://github.com/ahlinc/cc-rs below:

ahlinc/cc-rs: Rust library for build scripts to compile C/C++ code into a Rust library

A library to compile C/C++/assembly into a Rust library/application.

Documentation

A simple library meant to be used as a build dependency with Cargo packages in order to build a set of C/C++ files into a static archive. This crate calls out to the most relevant compiler for a platform, for example using cl on MSVC.

First, you'll want to both add a build script for your crate (build.rs) and also add this crate to your Cargo.toml via:

[build-dependencies]
cc = "1.0"

Next up, you'll want to write a build script like so:

// build.rs

fn main() {
    cc::Build::new()
        .file("foo.c")
        .file("bar.c")
        .compile("foo");
}

And that's it! Running cargo build should take care of the rest and your Rust application will now have the C files foo.c and bar.c compiled into a file named libfoo.a. If the C files contain

void foo_function(void) { ... }

and

int32_t bar_function(int32_t x) { ... }

you can call them from Rust by declaring them in your Rust code like so:

extern "C" {
    fn foo_function();
    fn bar_function(x: i32) -> i32;
}

pub fn call() {
    unsafe {
        foo_function();
        bar_function(42);
    }
}

fn main() {
    // ...
}

See the Rustonomicon for more details.

External configuration via environment variables

To control the programs and flags used for building, the builder can set a number of different environment variables.

Furthermore, projects using this crate may specify custom environment variables to be inspected, for example via the Build::try_flags_from_environment function. Consult the project’s own documentation or its use of the cc crate for any additional variables it may use.

Each of these variables can also be supplied with certain prefixes and suffixes, in the following prioritized order:

  1. <var>_<target> - for example, CC_x86_64-unknown-linux-gnu
  2. <var>_<target_with_underscores> - for example, CC_x86_64_unknown_linux_gnu
  3. <build-kind>_<var> - for example, HOST_CC or TARGET_CFLAGS
  4. <var> - a plain CC, AR as above.

If none of these variables exist, cc-rs uses built-in defaults.

In addition to the above optional environment variables, cc-rs has some functions with hard requirements on some variables supplied by cargo's build-script driver that it has the TARGET, OUT_DIR, OPT_LEVEL, and HOST variables.

Currently cc-rs supports parallel compilation (think make -jN) but this feature is turned off by default. To enable cc-rs to compile C/C++ in parallel, you can change your dependency to:

[build-dependencies]
cc = { version = "1.0", features = ["parallel"] }

By default cc-rs will limit parallelism to $NUM_JOBS, or if not present it will limit it to the number of cpus on the machine. If you are using cargo, use -jN option of build, test and run commands as $NUM_JOBS is supplied by cargo.

Compile-time Requirements

To work properly this crate needs access to a C compiler when the build script is being run. This crate does not ship a C compiler with it. The compiler required varies per platform, but there are three broad categories:

cc-rs supports C++ libraries compilation by using the cpp method on Build:

fn main() {
    cc::Build::new()
        .cpp(true) // Switch to C++ library compilation.
        .file("foo.cpp")
        .compile("foo");
}

For C++ libraries, the CXX and CXXFLAGS environment variables are used instead of CC and CFLAGS.

The C++ standard library may be linked to the crate target. By default it's libc++ for macOS, FreeBSD, and OpenBSD, libc++_shared for Android, nothing for MSVC, and libstdc++ for anything else. It can be changed in one of two ways:

  1. by using the cpp_link_stdlib method on Build: 
    fn main() {
    cc::Build::new()
        .cpp(true)
        .file("foo.cpp")
        .cpp_link_stdlib("stdc++") // use libstdc++
        .compile("foo");
}
  2. by setting the CXXSTDLIB environment variable.

In particular, for Android you may want to use c++_static if you have at most one shared library.

Remember that C++ does name mangling so extern "C" might be required to enable Rust linker to find your functions.

cc-rs also supports compiling CUDA C++ libraries by using the cuda method on Build:

fn main() {
    cc::Build::new()
        // Switch to CUDA C++ library compilation using NVCC.
        .cuda(true)
        .cudart("static")
        // Generate code for Maxwell (GTX 970, 980, 980 Ti, Titan X).
        .flag("-gencode").flag("arch=compute_52,code=sm_52")
        // Generate code for Maxwell (Jetson TX1).
        .flag("-gencode").flag("arch=compute_53,code=sm_53")
        // Generate code for Pascal (GTX 1070, 1080, 1080 Ti, Titan Xp).
        .flag("-gencode").flag("arch=compute_61,code=sm_61")
        // Generate code for Pascal (Tesla P100).
        .flag("-gencode").flag("arch=compute_60,code=sm_60")
        // Generate code for Pascal (Jetson TX2).
        .flag("-gencode").flag("arch=compute_62,code=sm_62")
        // Generate code in parallel
        .flag("-t0")
        .file("bar.cu")
        .compile("bar");
}

This project is licensed under either of

at your option.

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in cc-rs by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.

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