Add support for our temporary target

crates/compiler/src/compile.rs

@@ -49,3 +49,6 @@
 //! translation—the benefits of not having to manually perform this additional
 //! work far outweighs that downside. If we _do_ need any additional control, we
 //! can always modify this process at a later date.
+
+#[cfg(test)]
+mod test {}

crates/rust-test-input/src/lib.rs

@@ -1,14 +1,6 @@
+#![no_std]
+
+/// Adds two numbers together.
 pub fn add(left: u64, right: u64) -> u64 {
     left + right
 }
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    #[test]
-    fn it_works() {
-        let result = add(2, 2);
-        assert_eq!(result, 4);
-    }
-}

docs/Getting LLVM IR Output.md

@@ -8,9 +8,9 @@ this project.
 ## Rust
 
 `rustc` will emit LLVM IR when passed the `--emit=llvm-ir` flag, and LLVM bytecode when passed the
-`--emit=llvm-bc`. This will output `.ll` files into the `target` directory corresponding to your
-compiled file. For more information, see the
-[`rustc` developer guide](https://rustc-dev-guide.rust-lang.org/backend/debugging.html).
+`--emit=llvm-bc`. This will output `.ll` (or `.bc`) files into the `target` directory corresponding
+to your compiled file (usually in `build-type/deps/crate-name-hash.ll`). For more information, see
+the [`rustc` developer guide](https://rustc-dev-guide.rust-lang.org/backend/debugging.html).
 
 - This can be passed to the correct compiler when using cargo by calling
   `cargo rustc -- --emit=llvm-ir`.

flake.nix

@@ -18,15 +18,22 @@
     flake-utils.lib.eachDefaultSystem (system:
       let
         # We grab our expected rust version from the Cargo.toml.
-        rustVersion = (builtins.fromTOML (builtins.readFile ./Cargo.toml)).workspace.package.rust-version;
+        rustVersion = (lib.importTOML ./Cargo.toml).workspace.package.rust-version;
 
         # Then we set up our libraries for building this thing.
         pkgs = nixpkgs.legacyPackages.${system};
         inherit (pkgs) lib;
         fenixLib = fenix.packages.${system};
+        toolchainHash = "sha256-VZZnlyP69+Y3crrLHQyJirqlHrTtGTsyiSnZB8jEvVo=";
         fenixStable = fenixLib.fromToolchainName {
             name = rustVersion;
-            sha256 = "sha256-VZZnlyP69+Y3crrLHQyJirqlHrTtGTsyiSnZB8jEvVo=";
+            sha256 = toolchainHash;
+        };
+
+        # A target of the same version for our temporary "source" ABI
+        fenixAarch64 = fenixLib.targets.aarch64-unknown-none-softfloat.toolchainOf {
+          channel = rustVersion;
+          sha256 = toolchainHash;
         };
 
         # As we want nightly Rustfmt, we have to build a custom toolchain.
@@ -40,6 +47,7 @@
             "rust-std"
             "rustc"
           ])
+          fenixAarch64.rust-std
         ];
 
         # The crane library configures the Rust toolchain, along with the components we expect it