From 662bc073b2579e29caad1d40aaed7b0b91f91888 Mon Sep 17 00:00:00 2001
From: Kosyrev Serge <serge.kosyrev@iohk.io>
Date: Mon, 12 Mar 2018 02:23:23 +0300
Subject: [PATCH] ghc841:  cabal2nix fixed upstream

---
 .../configuration-ghc-8.4.x.nix               | 25 +++++++++++++------
 1 file changed, 18 insertions(+), 7 deletions(-)

diff --git a/pkgs/development/haskell-modules/configuration-ghc-8.4.x.nix b/pkgs/development/haskell-modules/configuration-ghc-8.4.x.nix
index 1582dfe8612..d4c884a5f61 100644
--- a/pkgs/development/haskell-modules/configuration-ghc-8.4.x.nix
+++ b/pkgs/development/haskell-modules/configuration-ghc-8.4.x.nix
@@ -194,6 +194,24 @@ self: super: {
     };
   });
 
+  ## Upstreamed, awaiting a Hackage release
+  cabal2nix = (overrideCabal super.cabal2nix (drv: {
+    ##     Ambiguous occurrence ‘<>’
+    ##     It could refer to either ‘Prelude.<>’,
+    ##                              imported from ‘Prelude’ at src/Distribution/Nixpkgs/Haskell/Derivation.hs:6:8-46
+    src = pkgs.fetchFromGitHub {
+      owner  = "nixos";
+      repo   = "cabal2nix";
+      rev    = "32974fcc3d9b485bd35167d9ae90941a5b3d06df";
+      sha256 = "1racp49z5922rvrc62clslzdkxh4axj2i0k83w5y6w5chl83abyd";
+    };
+  })).override {
+    ##     • No instance for (Semigroup (List a))
+    ##         arising from the 'deriving' clause of a data type declaration
+    ##       Possible fix:
+    hpack = self.hpack;
+  };
+
   haskell-gi = overrideCabal super.haskell-gi (drv: {
     ## Setup: Encountered missing dependencies:
     ## haskell-gi-base ==0.20.*
@@ -558,13 +576,6 @@ self: super: {
     ];
   });
 
-  cabal2nix = super.cabal2nix.override {
-    ##     • No instance for (Semigroup (List a))
-    ##         arising from the 'deriving' clause of a data type declaration
-    ##       Possible fix:
-    hpack = self.hpack;
-  };
-
   deepseq-generics = overrideCabal super.deepseq-generics (drv: {
     ## Setup: Encountered missing dependencies:
     ## base >=4.5 && <4.11