add Outpaths module for checking how many derivations change

src/Outpaths.hs

@@ -0,0 +1,80 @@
+{-# LANGUAGE ExtendedDefaultRules #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE QuasiQuotes #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE LambdaCase #-}
+{-# OPTIONS_GHC -fno-warn-type-defaults #-}
+
+module Outpaths
+where
+
+import           Data.Semigroup ((<>))
+import           Data.Text (Text)
+import qualified Data.Text as T
+import           NeatInterpolation (text)
+import           Shelly
+import           Utils
+default (Text)
+
+outPathsExpr = [text|
+
+(let
+  lib = import ./lib;
+  hydraJobs = import ./pkgs/top-level/release.nix
+    # Compromise: accuracy vs. resources needed for evaluation.
+    {
+      supportedSystems = [
+        "aarch64-linux"
+        "i686-linux"
+        "x86_64-linux"
+        "x86_64-darwin"
+      ];
+
+      nixpkgsArgs = {
+        config = {
+          allowBroken = true;
+          allowUnfree = true;
+          allowInsecurePredicate = x: true;
+          checkMeta = true;
+
+          handleEvalIssue = reason: errormsg:
+            if reason == "unknown-meta"
+              then abort errormsg
+              else true;
+
+          inHydra = true;
+        };
+      };
+    };
+  recurseIntoAttrs = attrs: attrs // { recurseForDerivations = true; };
+
+  # hydraJobs leaves recurseForDerivations as empty attrmaps;
+  # that would break nix-env and we also need to recurse everywhere.
+  tweak = lib.mapAttrs
+    (name: val:
+      if name == "recurseForDerivations" then true
+      else if lib.isAttrs val && val.type or null != "derivation"
+              then recurseIntoAttrs (tweak val)
+      else val
+    );
+
+  # Some of these contain explicit references to platform(s) we want to avoid;
+  # some even (transitively) depend on ~/.nixpkgs/config.nix (!)
+  blacklist = [
+    "tarball" "metrics" "manual"
+    "darwin-tested" "unstable" "stdenvBootstrapTools"
+    "moduleSystem" "lib-tests" # these just confuse the output
+  ];
+
+in
+  tweak (builtins.removeAttrs hydraJobs blacklist))
+|]
+
+--downloadOutPath :: Sh ()
+
+outPath :: Sh Text
+outPath = sub $ do
+  Utils.setupNixpkgs
+  cmd "curl" "-o" "outpaths.nix" "https://raw.githubusercontent.com/NixOS/ofborg/released/ofborg/src/outpaths.nix"
+  setenv "GC_INITIAL_HEAP_SIZE" "4g"
+  cmd "nix-env" "-f" "./outpaths.nix" "-qaP" "--no-name" "--out-path" "--arg" "checkMeta" "true"