From 241f01ea4c645c6220e6e04bd145f4f33b02d1d5 Mon Sep 17 00:00:00 2001
From: Alexandre Esteves <alexandre.fmp.esteves@gmail.com>
Date: Wed, 24 Jul 2019 22:42:12 +0100
Subject: [PATCH 1/2] Workaround for ghcjs hardcoding to linux

---
 default.nix                  |  1 +
 haskell-overlays/default.nix |  5 +++--
 haskell-overlays/ghcjs.nix   | 16 ++++++++++++++--
 3 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/default.nix b/default.nix
index ccb5a6e02..a13103e3b 100644
--- a/default.nix
+++ b/default.nix
@@ -43,6 +43,7 @@ let iosSupport = system == "x86_64-darwin";
           inherit (self) lib;
           haskellLib = self.haskell.lib;
           inherit
+            system
             useFastWeak useReflexOptimizer enableLibraryProfiling enableTraceReflexEvents
             useTextJSString enableExposeAllUnfoldings
             haskellOverlays;
diff --git a/haskell-overlays/default.nix b/haskell-overlays/default.nix
index ca4a29d1f..ffff922ea 100644
--- a/haskell-overlays/default.nix
+++ b/haskell-overlays/default.nix
@@ -1,4 +1,5 @@
-{ lib
+{ system
+, lib
 , haskellLib
 , nixpkgs
 , useFastWeak, useReflexOptimizer, enableLibraryProfiling, enableTraceReflexEvents
@@ -112,7 +113,7 @@ rec {
 
   # Just for GHCJS
   ghcjs = import ./ghcjs.nix {
-    inherit lib haskellLib nixpkgs fetchgit fetchFromGitHub useReflexOptimizer;
+    inherit system lib haskellLib nixpkgs fetchgit fetchFromGitHub useReflexOptimizer;
   };
   ghcjs-fast-weak = import ./ghcjs-fast-weak {
    inherit lib;
diff --git a/haskell-overlays/ghcjs.nix b/haskell-overlays/ghcjs.nix
index ffe2c9303..74e2d8de9 100644
--- a/haskell-overlays/ghcjs.nix
+++ b/haskell-overlays/ghcjs.nix
@@ -1,8 +1,18 @@
-{ lib, haskellLib, nixpkgs, fetchgit, fetchFromGitHub, useReflexOptimizer }:
+{ system, lib, haskellLib, nixpkgs, fetchgit, fetchFromGitHub, useReflexOptimizer }:
 
 with haskellLib;
 
-self: super: {
+self: super:
+
+let dontHardcodeLinux = package: cabalFile:
+  if ! self.ghc.isGhcjs then package
+  else nixpkgs.haskell.lib.overrideCabal package (drv: {
+    postPatch = (drv.postPatch or "") + nixpkgs.lib.optionalString (system == "x86_64-darwin") ''
+      substituteInPlace ${cabalFile}.cabal --replace 'if os(linux)' 'if os(linux) && !impl(ghcjs)'
+      substituteInPlace ${cabalFile}.cabal --replace 'if os(osx)' 'if os(linux) && impl(ghcjs)'
+    '';
+  });
+in {
   _dep = super._dep or {} // {
     ghcjsBaseSrc = fetchgit {
       url = "https://github.com/ghcjs/ghcjs-base.git";
@@ -82,4 +92,6 @@ self: super: {
       sha256 = "1sy51nz096sv91nxqk6yk7b92b5a40axv9183xakvki2nc09yhqg";
     };
   }));
+
+  foundation = dontHardcodeLinux super.foundation "foundation";
 }

From 2a07b9af75bf926177fd9f25fc109cabc8653ab0 Mon Sep 17 00:00:00 2001
From: Alexandre Esteves <alexandre.fmp.esteves@gmail.com>
Date: Wed, 24 Jul 2019 23:02:04 +0100
Subject: [PATCH 2/2] Explain workaround in comment

---
 haskell-overlays/ghcjs.nix | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/haskell-overlays/ghcjs.nix b/haskell-overlays/ghcjs.nix
index 74e2d8de9..3bdec99a9 100644
--- a/haskell-overlays/ghcjs.nix
+++ b/haskell-overlays/ghcjs.nix
@@ -4,6 +4,8 @@ with haskellLib;
 
 self: super:
 
+# Workaround for https://github.com/ghcjs/ghcjs/issues/674
+# 'os (osx)' will always evaluate to 'false'
 let dontHardcodeLinux = package: cabalFile:
   if ! self.ghc.isGhcjs then package
   else nixpkgs.haskell.lib.overrideCabal package (drv: {