# cc-rs A library to compile C/C++/assembly into a Rust library/application. [Documentation](https://docs.rs/cc) 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. > **Note**: this crate was recently renamed from the `gcc` crate, so if you're > looking for the `gcc` crate you're in the right spot! ## Using cc-rs 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: ```toml [build-dependencies] cc = "1.0" ``` Next up, you'll want to write a build script like so: ```rust,no_run // 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. You can call the functions in Rust by declaring functions in your Rust code like so: ```rust,no_run extern { fn foo_function(); fn bar_function(); } pub fn call() { unsafe { foo_function(); bar_function(); } } fn main() { // ... } ``` ## External configuration via environment variables To control the programs and flags used for building, the builder can set a number of different environment variables. * `CFLAGS` - a series of space separated flags passed to compilers. Note that individual flags cannot currently contain spaces, so doing something like: "-L=foo\ bar" is not possible. * `CC` - the actual C compiler used. Note that this is used as an exact executable name, so (for example) no extra flags can be passed inside this variable, and the builder must ensure that there aren't any trailing spaces. This compiler must understand the `-c` flag. For certain `TARGET`s, it also is assumed to know about other flags (most common is `-fPIC`). * `AR` - the `ar` (archiver) executable to use to build the static library. * `CRATE_CC_NO_DEFAULTS` - the default compiler flags may cause conflicts in some cross compiling scenarios. Setting this variable will disable the generation of default compiler flags. Each of these variables can also be supplied with certain prefixes and suffixes, in the following prioritized order: 1. `_` - for example, `CC_x86_64-unknown-linux-gnu` 2. `_` - for example, `CC_x86_64_unknown_linux_gnu` 3. `_` - for example, `HOST_CC` or `TARGET_CFLAGS` 4. `` - 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][cargo] that it has the `TARGET`, `OUT_DIR`, `OPT_LEVEL`, and `HOST` variables. [cargo]: http://doc.crates.io/build-script.html#inputs-to-the-build-script ## Optional features ### Parallel 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: ```toml [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: * Unix platforms require `cc` to be the C compiler. This can be found by installing cc/clang on Linux distributions and Xcode on OSX, for example. * Windows platforms targeting MSVC (e.g. your target triple ends in `-msvc`) require `cl.exe` to be available and in `PATH`. This is typically found in standard Visual Studio installations and the `PATH` can be set up by running the appropriate developer tools shell. * Windows platforms targeting MinGW (e.g. your target triple ends in `-gnu`) require `cc` to be available in `PATH`. We recommend the [MinGW-w64](http://mingw-w64.org) distribution, which is using the [Win-builds](http://win-builds.org) installation system. You may also acquire it via [MSYS2](http://msys2.github.io), as explained [here][msys2-help]. Make sure to install the appropriate architecture corresponding to your installation of rustc. GCC from older [MinGW](http://www.mingw.org) project is compatible only with 32-bit rust compiler. [msys2-help]: http://github.com/rust-lang/rust#building-on-windows ## C++ support `cc-rs` supports C++ libraries compilation by using the `cpp` method on `Build`: ```rust,no_run fn main() { cc::Build::new() .cpp(true) // Switch to C++ library compilation. .file("foo.cpp") .compile("libfoo.a"); } ``` When using C++ library compilation switch, the `CXX` and `CXXFLAGS` env variables are used instead of `CC` and `CFLAGS` and the C++ standard library is linked to the crate target. Remember that C++ does name mangling so `extern "C"` might be required to enable rust linker to find your functions. ## CUDA C++ support `cc-rs` also supports compiling CUDA C++ libraries by using the `cuda` method on `Build` (currently for GNU/Clang toolchains only): ```rust,no_run fn main() { cc::Build::new() // Switch to CUDA C++ library compilation using NVCC. .cuda(true) // 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") .file("bar.cu") .compile("libbar.a"); } ``` ## License This project is licensed under either of * Apache License, Version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0) * MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT) at your option. ### Contribution 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.