krebs pkgs: detect old overrides

krebs/5pkgs/default.nix

@@ -1,7 +1,20 @@
 { config, lib, pkgs, ... }@args:
 with config.krebs.lib;
 {
-  nixpkgs.config.packageOverrides = pkgs: {
+  nixpkgs.config.packageOverrides = pkgs: let
+
+    # This callPackage will try to detect obsolete overrides.
+    callPackage = path: args: let
+      override = pkgs.callPackage path args;
+      upstream = optionalAttrs (override ? "name")
+        (pkgs.${(parseDrvName override.name).name} or {});
+    in if upstream ? "name" &&
+          override ? "name" &&
+          compareVersions upstream.name override.name != -1
+      then trace "Upstream `${upstream.name}' gets overridden by `${override.name}'." override
+      else override;
+
+  in {
     haskellPackages = pkgs.haskellPackages.override {
       overrides = self: super:
         mapAttrs (name: path: self.callPackage path {})
@@ -16,18 +29,18 @@ with config.krebs.lib;
             (builtins.readDir ./haskell-overrides));
     };
 
-    push = pkgs.callPackage ./push {
+    push = callPackage ./push {
       inherit (subdirs) get;
     };
 
-    ReaktorPlugins = pkgs.callPackage ./Reaktor/plugins.nix {};
+    ReaktorPlugins = callPackage ./Reaktor/plugins.nix {};
 
     test = {
-      infest-cac-centos7 = pkgs.callPackage ./test/infest-cac-centos7 {};
+      infest-cac-centos7 = callPackage ./test/infest-cac-centos7 {};
     };
   }
   // import ./builders.nix args
-  // mapAttrs (_: flip pkgs.callPackage {})
+  // mapAttrs (_: flip callPackage {})
               (filterAttrs (_: dir.has-default-nix)
                            (subdirsOf ./.));
 }