Cargo.toml: enable uucore logind integration, add systemd compile flag

Cargo.toml

@@ -28,12 +28,16 @@ toml = "0.9.10"
 tracing = "0.1.44"
 tracing-subscriber = { version = "0.3.22", features = ["env-filter"] }
 # onc-rpc = "0.3.2"
-sd-notify = "0.4.5"
+sd-notify = { version = "0.4.5", optional = true }
 serde_json = "1.0.148"
 uucore = { version = "0.5.0", features = ["utmpx"] }
 zlink = { version = "0.2.0", features = ["introspection"] }
 clap_complete = "4.5.65"
 
+[features]
+default = ["systemd"]
+systemd = ["sd-notify", "uucore/feat_systemd_logind"]
+
 [lib]
 name = "roowho2_lib"
 path = "src/lib.rs"

flake.nix

@@ -53,10 +53,17 @@
       nativeBuildInputs = with pkgs; [
         toolchain
         cargo-edit
-      ];
+      ] ++ (lib.optionals stdenv.buildPlatform.isLinux [
+        systemdLibs
+      ]);
 
-      env.RUST_SRC_PATH = "${toolchain}/lib/rustlib/src/rust/library";
-      env.RUSTFLAGS = "-Zhigher-ranked-assumptions";
+      env = {
+        RUST_SRC_PATH = "${toolchain}/lib/rustlib/src/rust/library";
+        RUSTFLAGS = "-Zhigher-ranked-assumptions";
+        CARGO_CFG_FEATURE = lib.concatStringsSep "," (lib.optionals pkgs.stdenv.buildPlatform.isLinux [
+          "systemd"
+        ]);
+      };
     });
 
     overlays = {

nix/package.nix

@@ -5,6 +5,7 @@
 , buildPackages
 , installShellFiles
 , versionCheckHook
+, systemdLibs
 
 , cargoToml
 , cargoLock
@@ -21,6 +22,14 @@ rustPlatform.buildRustPackage {
 
   RUSTFLAGS = "-Zhigher-ranked-assumptions";
 
+  buildFeatures = lib.optionals stdenv.hostPlatform.isLinux [
+    "systemd"
+  ];
+
+  buildInputs = lib.optionals stdenv.hostPlatform.isLinux [
+    systemdLibs
+  ];
+
   nativeBuildInputs = [ installShellFiles ];
   postInstall = let
     emulator = stdenv.hostPlatform.emulator buildPackages;