From 97c9a698d1fa8015d23ba341edfb6783d686395f Mon Sep 17 00:00:00 2001
From: sternenseemann <sternenseemann@systemli.org>
Date: Sun, 20 Feb 2022 13:31:42 +0100
Subject: [PATCH] carp: work around new GHC warning breaking the build

---
 pkgs/development/compilers/carp/default.nix | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/pkgs/development/compilers/carp/default.nix b/pkgs/development/compilers/carp/default.nix
index 3f188e23317c..6941e5f71b18 100644
--- a/pkgs/development/compilers/carp/default.nix
+++ b/pkgs/development/compilers/carp/default.nix
@@ -11,6 +11,12 @@ haskellPackages.mkDerivation rec {
     sha256 = "sha256-o7NLd7jC1BvcoVzbD18LvHg/SqOnfn9yELUrpg2uZtY=";
   };
 
+  # -Werror breaks build with GHC >= 9.0
+  # https://github.com/carp-lang/Carp/issues/1386
+  postPatch = ''
+    substituteInPlace CarpHask.cabal --replace "-Werror" ""
+  '';
+
   buildTools = [ makeWrapper ];
 
   executableHaskellDepends = with haskellPackages; [