overlay.nix: refactor using pipe, add buildFromSdist

Author: sorki

overlay.nix

@@ -1,14 +1,32 @@
-pkgs: hlib: helf: huper: {
+pkgs: hlib: helf: huper:
+let
+  lib = pkgs.lib;
+in
+{
   hnix-store-core =
-    helf.callCabal2nix "hnix-store-core" ./hnix-store-core {};
+    lib.pipe
+      (helf.callCabal2nix "hnix-store-core" ./hnix-store-core {})
+      [
+        hlib.compose.buildFromSdist
+      ];
   hnix-store-remote =
-    if pkgs.stdenv.isDarwin
-    then helf.callCabal2nix "hnix-store-remote" ./hnix-store-remote { }
-    else
-      ( helf.callCabal2nixWithOptions "hnix-store-remote" ./hnix-store-remote "-fio-testsuite" { }
-      ).overrideAttrs (attrs: {
+    lib.pipe
+      # enable -fio-testsuite for Linux systems as
+      # it requires linux-namespaces
+      # NOTE: we cannot use hlib.compose.enableCabalFlag
+      # as the testsuite deps won't get picked up
+      # after cabal2nix step
+      (
+      if pkgs.stdenv.isDarwin
+      then helf.callCabal2nix "hnix-store-remote" ./hnix-store-remote {}
+      else helf.callCabal2nixWithOptions "hnix-store-remote" ./hnix-store-remote "-fio-testsuite" {}
+      )
+      [
+        hlib.compose.buildFromSdist
+        (pkg: pkg.overrideAttrs (attrs: {
           buildInputs = attrs.buildInputs ++ [
             pkgs.nix
           ];
-      });
+        }))
+      ];
 }