WIP - Try two different ways of mkMerging component configs

1. Set a default value for the components.all option.
2. Add another module to merge component options for each package.

Author: rvl

modules/all-component.nix

@@ -0,0 +1,24 @@
+{ lib, config, pkgs, ... }:
+
+with lib;
+
+############################################################################
+# this is an attempt to use mkMerge for combining package options
+############################################################################
+let
+  haskellLib = let hl = import ../lib { inherit lib; haskellLib = hl; }; in hl;
+
+  subComponents = packageConfig: sub: attrValues (packageConfig.components.${sub} or {});
+
+  allComponent = packageConfig: {
+    components.all = mkMerge ([ packageConfig.components.library ] ++
+        concatMap (subComponents packageConfig) haskellLib.subComponentTypes);
+  };
+
+in {
+  # Does not work -- infinite recursion
+  # packages = mapAttrs (name: packageConfig: allComponent packageConfig) config.packages;
+
+  # A single package works
+  # packages.cabal-simple = allComponent (config.packages.cabal-simple);
+}

modules/package.nix

@@ -175,18 +175,20 @@ in {
         type = attrsOf (componentType {});
         default = {};
       };
+      # Try merging component options by setting the default to mkMerge [...].
+      # This does not work.
       all = let
-        subComponentsDepends = sub: concatLists
-            (mapAttrsToList (_: c: c.depends or []) config.components.${sub} or {});
-        default = {
-          depends = config.components.library.depends ++
-            concatMap subComponentsDepends haskellLib.subComponentTypes;
-        };
+        subComponents = sub: attrValues (config.components.${sub} or {});
+        default = mkMerge ([ config.components.library ] ++
+          concatMap subComponents haskellLib.subComponentTypes);
       in mkOption {
-        type = componentType default;
+        type = componentType {};
         inherit default;
-        defaultText = "The merged dependencies of all other components";
+        defaultText = "The merged options of all other components";
       };
+      # all = mkOption {
+      #   type = componentType {};
+      # };
     };
 
     name = mkOption {

package-set.nix

@@ -71,6 +71,8 @@ in pkgs.lib.evalModules {
     # Supplies metadata
     ./modules/cabal.nix
 
+    ./modules/all-component.nix
+
     # Converts config.packages into config.hsPkgs
     # Replace this with compat-driver.nix to use nixpkgs haskell build infra
     ./modules/component-driver.nix

test/with-packages/default.nix

@@ -39,17 +39,33 @@ let
     buildInputs = (oldAttrs.buildInputs or []) ++ [ pkgs.cabal-install ];
   });
 
+
+  package = packages.test-with-packages;
+  inherit (package.components) library;
+
+  pkgId = p: "${p.identifier.name}-${p.identifier.version}";
+  showDepends = component: concatMapStringsSep " " pkgId component.depends;
+
 in
   stdenv.mkDerivation {
     name = "with-packages-test";
+    libraryDepends = showDepends pkgSet.config.packages.test-with-packages.components.library;
+    allDepends = showDepends pkgSet.config.packages.test-with-packages.components.all;
 
-    buildCommand = let
-      package = packages.test-with-packages;
-      inherit (package.components) library;
-    in ''
+    buildCommand = ''
       ########################################################################
       # test with-packages
 
+      printf "checking merging of the 'all' component depends ... " >& 2
+      if [ -n "$libraryDepends" -a "$libraryDepends" = "$allDepends" ]; then
+        echo "PASS" >& 2
+      else
+        echo "FAIL" >& 2
+        echo "libraryDepends = $libraryDepends"
+        echo "allDepends = $allDepends"
+        exit 1
+      fi
+
       printf "checking that the 'all' component works... " >& 2
       echo ${package.components.all} >& 2
 
@@ -62,7 +78,7 @@ in
 
       printf "checking that components.library.env has the dependencies... " >& 2
       ${library.env}/bin/runghc ${./Point.hs}
-      # echo >& 2
+      echo >& 2
 
       touch $out
     '';