Bonus question for smarter people than I:

Rust uses the LLVM as its back end for compilation -- so does that make this question irrelevant? Is the real question "Can the LLVM backend target ARM?"

The "arms pattern" is the pattern (plain english word) that belongs to the arm (each case for the match statement is called an arm, as is common for branching statements). It is not a pattern as in the "design patterns" buzzword.

The thing that should match to select a specific arm is called a pattern (rather than, say, a value) as it is not limited to static values, but can, thanks to the expressivenes of the rust type system, describe parts of the value while selecting other parts for use in the pattern.

Here's an example where the thing to match is a tuple:

match (price_in_cents / 100, price_in_cents % 100) {
   (d, 0) => format!("{d} dollar"),
   (0, c) => format!("{c} cents"),
   (d, c) => format!("{d}:{c}"),
}

Note that order is important here, if I would have put the last arm first it would match any value (and the compiler would warn that the other arms are unreachable).

Note that _ in the example from @nneonneo s example is not a magic symbol to match anything, it is a declaration of a variable to put any value in. The only thing special is that the name _ implies that you are not going to use it. You can say x with the same result, except that the compiler will warn about you declaring a variable x and then not using it.

For MacOS better use: musleabihf, for Windows you can use gnueabihf as bellow:

Mac

$ brew install arm-linux-gnueabihf-binutils
$ rustup target add armv7-unknown-linux-musleabihf

In .cargo/config

[build]
target = "armv7-unknown-linux-musleabihf"
[target.armv7-unknown-linux-c]
linker = "arm-linux-gnueabihf-ld"

With simple src/main.rs

fn main() {
    println!("Hello, Raspberry!");
}

Then things are fine:

Hasans-Air:rpi hasan$ cargo build
   Compiling rpi v0.1.0 (/Users/hasan/PycharmProjects/rpi)
    Finished dev [unoptimized + debuginfo] target(s) in 0.41s
Hasans-Air:rpi hasan$ scp target/armv7-unknown-linux-musleabihf/debug/rpi [email protected]:
[email protected]'s password: 
rpi                                                                                         100% 2702KB   2.6MB/s   00:01    
Hasans-Air:rpi hasan$ ssh [email protected] 'chmod +x ~/rpi && ~/rpi'
[email protected]'s password: 
Hello, Raspberry!

Win 10 Get the linker from here, and run:

rustup target add armv7-unknown-linux-gnueabihf

Creating file .cargo/config with content:

[build]
target = "armv7-unknown-linux-gnueabihf"

[target.armv7-unknown-linux-gnueabihf]
linker = "arm-linux-gnueabihf-gcc"

And with simple src/main.rs:

fn main() {
    println!("Hello, Raspberry! from Win 10");
}

I was able to get things done