split moduleClosure in two parts:

* unifyModuleSyntax: handle all kind of module syntax to convert them into
  a module which has the following form:

  {
    imports = [ <paths> ];
    options = <attribute set of options declarations>;
    config = <attribute set (with properties) of option definitions>;
  }

  This function assume that there is at most one imported attribute set which
  correspond to option declarations.

* moduleClosure: handle a list of module's paths which are converted with
  the previous function to do the closure of the imports with the function
  lazyGenericClosure (which does the same as builtins.genericClosure except
  that it doesn't evaluate the content of modules).  The "key" and "paths"
  attributes are left to be used as debug information in futur
  implementation(s).

svn path=/nixpkgs/trunk/; revision=17108

pkgs/lib/modules.nix

@@ -32,16 +32,10 @@ rec {
     else
       f;
 
-  moduleClosure = initModules: args:
+  # Convert module to a set which has imports / options and config
+  # attributes.
+  unifyModuleSyntax = m:
     let
-      moduleImport = m:
-        (applyIfFunction (importIfPath m) args) // {
-          # used by generic closure to avoid duplicated imports.
-          key = m;
-        };
-
-      removeKeys = list: map (m: removeAttrs m ["key"]) list;
-
       getImports = m:
         if m ? config || m ? options then
           attrByPath ["imports"] [] m
@@ -51,13 +45,39 @@ rec {
       getImportedPaths = m: filter isPath (getImports m);
       getImportedSets = m: filter (x: !isPath x) (getImports m);
 
-      inlineImportedSets = list:
-        lib.concatMap (m:[m] ++ map moduleImport (getImportedSets m)) list;
+      getConfig = m:
+        removeAttrs (delayProperties m) ["require"];
     in
-      removeKeys (inlineImportedSets (lazyGenericClosure {
+      if m ? config || m ? options then
+        m
+      else
+        {
+          imports = getImportedPaths m;
+          config = getConfig m;
+        } // (
+          if getImportedSets m != [] then
+            assert tail (getImportedSets m) == [];
+            { options = head (getImportedSets m); }
+          else
+            {}
+        );
+
+  moduleClosure = initModules: args:
+    let
+      moduleImport = m: lib.addErrorContext "Import module ${m}." (
+        (unifyModuleSyntax (applyIfFunction (import m) args)) // {
+          # used by generic closure to avoid duplicated imports.
+          key = m;
+          paths = [ m ];
+        }
+      );
+
+      getImports = m: attrByPath ["imports"] [] m;
+    in
+      lazyGenericClosure {
         startSet = map moduleImport initModules;
-        operator = m: map moduleImport (getImportedPaths m);
-      }));
+        operator = m: map moduleImport (getImports m);
+      };
 
   selectDeclsAndDefs = modules:
     lib.concatMap (m: