Unlock the Power of Cross-Compilation in Rust
Cross-compilation is a game-changer in multiple scenarios, and Rust makes it easier than ever to tap into its benefits. In this article, we’ll explore why you might want to cross-compile, how to set up a Rust project for cross-compilation, and the ins and outs of platform-specific code.
Understanding Cross-Compilation and Its Rust Benefits
Cross-compilation means compiling a program on one platform for use on another. This capability is particularly useful when you need to ship a product on multiple platforms. Instead of maintaining separate machines for each platform, you can build all versions from a single machine. Cross-compilation is also essential in cloud-based build scenarios and allows Rust to run tests across multiple target platforms on the same host platform.
Setting Up an Example Rust Cross-Compilation Project
To get started, we’ll use the Cross crate, which provides built-in support for cross-compiling. First, let’s create a simple project that shows which platform it’s running on. We’ll use the current_platform crate to determine the platform our code is running on, as well as the platform it was compiled on.
How Rust Represents Platforms
To cross-compile, you need to know the “target triple” for the platform you’re building for. Rust uses the same format as LLVM: <arch><sub>-<vendor>-<sys>-<env>. For example, x86_64-unknown-linux-gnu represents a 64-bit Linux machine. You can find the target triple for a platform by running rustc -vV on the platform or looking it up on the Rust Platform Support page.
Cross-Compiling Our Rust Project from Linux to Windows
Now that we know the target triple for Windows is x86_64-pc-windows-msvc, let’s cross-compile our project! We’ll install the Cross crate and use it to compile our project for Windows. Once we’ve set up our container engine, we can run the following command to cross-compile and run our executable:
cross run --target x86_64-pc-windows-msvc
How to Write Platform-Specific Code
Rust makes it easy to write code that only runs on one platform using the cfg attribute. We can apply this attribute to functions, enum variants, struct fields, and match expression arms. Let’s modify our program to add a message that only gets printed on Windows:
<h1>[cfg(target_os = "windows")]</h1>
fn windows_only() {
println!("This is a Windows-specific message!");
}
fn main() {
#[cfg(target<em>os = "windows")]
windows</em>only();
}
Running this on Linux won’t print the Windows-specific message, but running it on Windows will.
Conclusion
Cross-compilation is a powerful capability that can simplify your development workflow and expand your product’s reach. With Rust and the Cross crate, you can easily cross-compile, run, and test your library or application on multiple platforms. While there may be some performance limitations, the benefits of cross-compilation far outweigh the costs.