3 files changed, 35 insertions, 0 deletions

diff --git a/custom/redo-wrapper.nix b/custom/redo-wrapper.nix
new file mode 100644
index 00000000..20e1675a
--- /dev/null
+++ b/custom/redo-wrapper.nix
@@ -0,0 +1,16 @@
+{ stdenv, makeWrapper, haskellPackages }:
+
+let
+  redo = haskellPackages.callPackage ./redo.nix {};
+in stdenv.mkDerivation {
+  name = "redo-wrapper";
+
+  nativeBuildInputs = [ makeWrapper ];
+
+  buildCommand = ''
+    mkdir -p $out/bin
+    ln -s $out/bin/redo $out/bin/redo-ifchange
+    makeWrapper ${redo}/bin/redo $out/bin/redo \
+      --set REDO_PATH "$out/bin"
+  '';
+}
diff --git a/custom/redo.nix b/custom/redo.nix
index 9d679e55..b5255f98 100644
--- a/custom/redo.nix
+++ b/custom/redo.nix
@@ -9,6 +9,7 @@ cabal.mkDerivation (self: {
   isLibrary = false;
   isExecutable = true;
   buildDepends = [ filepath pureMD5 ];
+  patches = [ ./redo.patch ];
   meta = {
     homepage = "https://github.com/jekor/redo";
     description = "software build system, make replacement, implementation of djb's redo";
diff --git a/custom/redo.patch b/custom/redo.patch
new file mode 100644
index 00000000..cd3a678e
--- /dev/null
+++ b/custom/redo.patch
@@ -0,0 +1,18 @@
+diff --git a/redo.hs b/redo.hs
+index f0e816a..01c6a2e 100644
+--- a/redo.hs
++++ b/redo.hs
+@@ -48,7 +48,12 @@ redo target dir = do
+          createDirectoryIfMissing True metaDepsDir
+          writeMD5 target path
+          oldEnv <- getEnvironment
+-         let newEnv = toList $ adjust (++ ":.") "PATH" $ insert "REDO_TARGET" target $ fromList oldEnv
++         redoPath <- lookupEnv "REDO_PATH"
++         let
++           redoPath' = case redoPath of
++             Just p -> p
++             _ -> "."
++           newEnv = toList $ adjust (++ (':' : redoPath')) "PATH" $ insert "REDO_TARGET" target $ fromList oldEnv
+          (_, _, _, ph) <- createProcess $ (shell $ cmd path) {env = Just newEnv}
+          exit <- waitForProcess ph
+          case exit of