nix: improve RUSTFLAGS + add overlay

Cargo.toml

@@ -47,9 +47,3 @@ pedantic = "warn"
 perf = "warn"
 style = "warn"
 suspicious = "deny"
-
-[profile.release]
-codegen-units = 1
-opt-level = "s"
-panic = "abort"
-strip = "symbols"

nix/deployment/static.nix

@@ -28,7 +28,7 @@
     buildWith = rustPlatform:
       self'.packages.refraction.override {
         inherit rustPlatform;
-        lto = true;
+        optimizeSize = true;
       };
   in {
     packages =

nix/derivation.nix

@@ -4,7 +4,8 @@
   rustPlatform,
   darwin,
   self,
-  lto ? false,
+  lto ? true,
+  optimizeSize ? false,
 }:
 rustPlatform.buildRustPackage {
   pname = "refraction";
@@ -35,11 +36,22 @@ rustPlatform.buildRustPackage {
     SystemConfiguration
   ]);
 
-  env = {
-    CARGO_BUILD_RUSTFLAGS = lib.concatStringsSep " " (
-      lib.optionals lto ["-C" "lto=thin" "-C" "embed-bitcode=yes" "-Zdylib-lto"]
+  env = let
+    toRustFlags = lib.mapAttrs' (
+      name:
+        lib.nameValuePair
+        "CARGO_PROFILE_RELEASE_${lib.toUpper (builtins.replaceStrings ["-"] ["_"] name)}"
     );
-  };
+  in
+    lib.optionalAttrs lto (toRustFlags {
+      lto = "thin";
+    })
+    // lib.optionalAttrs optimizeSize (toRustFlags {
+      codegen-units = "1";
+      opt-level = "s";
+      panic = "abort";
+      strip = "symbols";
+    });
 
   meta = with lib; {
     mainProgram = "refraction";

nix/packages.nix

@@ -6,8 +6,11 @@
   }: {
     packages = {
       refraction = pkgs.callPackage ./derivation.nix {inherit self;};
-
       default = self'.packages.refraction;
     };
   };
+
+  flake.overlays.default = _: prev: {
+    refraction = prev.callPackage ./derivation.nix {inherit self;};
+  };
 }