mcu: simplify buildStm32Firmware

* binaryName and extraCargoBuildArgs are no longer variadic.
* `cargo build` simply always uses binaryName (defaults to the package name) as `--bin` argument.

mcu/default.nix

@@ -8,21 +8,11 @@ let
   rustPlatform = pkgs.recurseIntoAttrs (pkgs.callPackage ./rustPlatform.nix {
     inherit rustManifest;
   });
-  buildStm32Firmware = { name, src, cargoDepsName ? name, patchPhase ? "", extraNativeBuildInputs ? [], checkPhase ? "", doCheck ? true, ... } @ args:
+  buildStm32Firmware = { name, src, cargoDepsName ? name, patchPhase ? "", extraNativeBuildInputs ? [], checkPhase ? "", doCheck ? true, binaryName ? name, extraCargoBuildArgs ? "" }:
     let
       cargoSha256Drv = pkgs.runCommand "${name}-cargosha256" { } ''
         cp "${src}/cargosha256.nix" $out
         '';
-      # If binaryName is specified,
-      # then pass it as an argument for `cargo build`; otherwise, do not add such argument.
-      extraCargoBuildArgs = (
-        (if (args ? extraCargoBuildArgs) then (args.extraCargoBuildArgs + " ") else "") +
-        (if (args ? binaryName) then ("--bin " + binaryName) else "")
-      );
-      # If binaryName is specified,
-      # then use it as the filename of the ELF generated from `cargo build`;
-      # otherwise, use the `name` arg (i.e. the Rust package name) as the ELF filename.
-      binaryName = if (args ? binaryName) then args.binaryName else name;
     in
       rustPlatform.buildRustPackage rec {
         inherit name cargoDepsName;
@@ -35,10 +25,12 @@ let
         nativeBuildInputs = [ pkgs.llvm ] ++ extraNativeBuildInputs;
         buildPhase = ''
           export CARGO_HOME=$(mktemp -d cargo-home.XXX)
-          cargo build --release ${extraCargoBuildArgs}
+          cargo build --release --bin ${binaryName} ${extraCargoBuildArgs}
         '';
 
         inherit checkPhase doCheck;
+        # binaryName defaults to the `name` arg (i.e. the Rust package name);
+        # it is used as the Cargo binary filename
         installPhase = ''
           mkdir -p $out $out/nix-support
           cp target/thumbv7em-none-eabihf/release/${binaryName} $out/${name}.elf
@@ -53,10 +45,10 @@ let
 in
   pkgs.lib.attrsets.mapAttrs'
     (name: value: pkgs.lib.attrsets.nameValuePair ("stabilizer-" + name)
-    (buildStm32Firmware {
+    (buildStm32Firmware ({
       name = "stabilizer-" + name;
       # If binaryName is not specified, use the attribute name as binaryName by default.
-      binaryName = if (value ? binaryName) then value.binaryName else name;
+      binaryName = name;
       cargoDepsName = "stabilizer";
       src = <stabilizerSrc>;
       patchPhase = ''
@@ -67,7 +59,7 @@ in
                     "Ipv4Address::new(192, 168, 1, 1)"
       '';
       doCheck = false;
-    })) {
+    } // value))) {
       dual-iir = {};
       dual-iir-pounder_v1_1 = {
         binaryName = "dual-iir";