Set explicit srcs in hand-written bild build

I'm not sure when `lib.fileset` was introduced, but it allows me to easily
create a source that can be unpacked by the `unpackPhase` which also maintains
the directory structure. This means I can pass a subset of the whole repo to the
builder, and changing an unrelated file (outside of that subset) won't cause a
rebuild of bild, which wasn't the case before.

1 files changed, 12 insertions, 1 deletions

diff --git a/Biz/Bild.nix b/Biz/Bild.nix
index c24cecd..7d23d6a 100644
--- a/Biz/Bild.nix
+++ b/Biz/Bild.nix
@@ -107,7 +107,18 @@ let
     # hand-written builder we need
     bild = self.stdenv.mkDerivation {
       name = "bild";
-      src = ../.;
+      srcs = self.lib.fileset.toSource {
+        root = ../.;
+        fileset = self.lib.fileset.unions [
+          ../Alpha.hs
+          ../Biz/Bild.hs
+          ../Biz/Bild/Meta.hs
+          ../Biz/Cli.hs
+          ../Biz/Log.hs
+          ../Biz/Namespace.hs
+          ../Biz/Test.hs
+        ];
+      };
       nativeBuildInputs = [ self.haskell.ghcPackageSetBild ];
       buildInputs = [ self.makeWrapper ];
       propagatedBuildInputs = with self.pkgs; [