From 0767374c40a7179322f14ca40822b96d248fa686 Mon Sep 17 00:00:00 2001
From: sternenseemann <0rpkxez4ksa01gb3typccl0i@systemli.org>
Date: Sat, 3 Apr 2021 23:24:29 +0200
Subject: [PATCH] haskellPackages.ghc-bignum: unbreak

* Enable exactly one backend (Native seems like the safest choice, but
  GMP also seems sane, interested to hear opinions on this!)
* Apply patch which fixes a type mismatch issue between Natural.hs and
  Natural.hs-boot.
---
 .../haskell-modules/configuration-common.nix  | 19 +++++++++++++++++++
 .../configuration-hackage2nix.yaml            |  1 -
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/pkgs/development/haskell-modules/configuration-common.nix b/pkgs/development/haskell-modules/configuration-common.nix
index 8f337dd868ef..0f20e73703fd 100644
--- a/pkgs/development/haskell-modules/configuration-common.nix
+++ b/pkgs/development/haskell-modules/configuration-common.nix
@@ -1777,4 +1777,23 @@ self: super: {
   # May be possible to remove at the next release (1.11.0)
   taskell = doJailbreak super.taskell;
 
+  # ghc-bignum is not buildable if none of the three backends
+  # is explicitly enabled. We enable Native for now as it doesn't
+  # depend on anything else as oppossed to GMP and FFI.
+  # Apply patch which fixes a compilation failure we encountered.
+  # Can be removed if the following issue is resolved / the patch
+  # is merged and released:
+  # * https://gitlab.haskell.org/ghc/ghc/-/issues/19638
+  # * https://gitlab.haskell.org/ghc/ghc/-/merge_requests/5454
+  ghc-bignum = overrideCabal super.ghc-bignum (old: {
+    configureFlags = (old.configureFlags or []) ++ [ "-f" "Native" ];
+    patches = (old.patches or []) ++ [
+      (pkgs.fetchpatch {
+        url = "https://gitlab.haskell.org/ghc/ghc/-/commit/08d1588bf38d83140a86817a7a615db486357d4f.patch";
+        sha256 = "1qx4r031y72px291vz38bng9sb23r8zb35s03v5hhawlmgzfzcb5";
+        stripLen = 2;
+      })
+    ];
+  });
+
 } // import ./configuration-tensorflow.nix {inherit pkgs haskellLib;} self super
diff --git a/pkgs/development/haskell-modules/configuration-hackage2nix.yaml b/pkgs/development/haskell-modules/configuration-hackage2nix.yaml
index 07f3ba4dfa27..9149f6ad0e97 100644
--- a/pkgs/development/haskell-modules/configuration-hackage2nix.yaml
+++ b/pkgs/development/haskell-modules/configuration-hackage2nix.yaml
@@ -5653,7 +5653,6 @@ broken-packages:
   - GGg
   - ggtsTC
   - gh-labeler
-  - ghc-bignum
   - ghc-clippy-plugin
   - ghc-core-smallstep
   - ghc-datasize