From fe5183105afb1a6c46aa5dcf3b6e292b5ffb3e7c Mon Sep 17 00:00:00 2001
From: Kosyrev Serge <serge.kosyrev@iohk.io>
Date: Tue, 27 Feb 2018 03:19:52 +0300
Subject: [PATCH] ghc84 | cabal2nix:  ghc84 needs its own very fixed hpack

---
 .../haskell-modules/configuration-ghc-8.4.x.nix            | 7 +++++++
 1 file changed, 7 insertions(+)

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 6161abdc993..0bf9cda5516 100644
--- a/pkgs/development/haskell-modules/configuration-ghc-8.4.x.nix
+++ b/pkgs/development/haskell-modules/configuration-ghc-8.4.x.nix
@@ -575,6 +575,13 @@ self: super: {
     jailbreak       = true;
   });
 
+  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;
+  };
+
   cabal-doctest = overrideCabal super.cabal-doctest (drv: {
     ## Setup: Encountered missing dependencies:
     ## Cabal >=1.10 && <2.1, base >=4.3 && <4.11