clightning: add darwin support

- Patch usage of gsed to sed
- Add darwin natives

pkgs/applications/blockchains/clightning/default.nix

@@ -1,5 +1,6 @@
 { lib
 , stdenv
+, darwin
 , fetchurl
 , autoconf
 , automake
@@ -27,16 +28,25 @@ stdenv.mkDerivation rec {
     sha256 = "3c9dcb686217b2efe0e988e90b95777c4591e3335e259e01a94af87e0bf01809";
   };
 
-  nativeBuildInputs = [ autogen autoconf automake gettext libtool pkg-config py3 unzip which ];
+  # when building on darwin we need dawin.cctools to provide the correct libtool
+  # as libwally-core detects the host as darwin and tries to add the -static
+  # option to libtool, also we have to add the modified gsed package.
+  nativeBuildInputs = [ autogen autoconf automake gettext pkg-config py3 unzip which ] 
+    ++ lib.optionals stdenv.isDarwin [ darwin.cctools ] ++ [ libtool ];
 
   buildInputs = [ gmp libsodium sqlite zlib ];
 
-  postPatch = ''
+  # this causes some python trouble on a darwin host so we skip this step.
+  # also we have to tell libwally-core to use sed instead of gsed.
+  postPatch = if !stdenv.isDarwin then ''
     patchShebangs \
       tools/generate-wire.py \
       tools/update-mocks.sh \
       tools/mockup.sh \
       devtools/sql-rewrite.py
+  '' else ''
+    substituteInPlace external/libwally-core/tools/autogen.sh --replace gsed sed && \
+    substituteInPlace external/libwally-core/configure.ac --replace gsed sed
   '';
 
   configureFlags = [ "--disable-developer" "--disable-valgrind" ];
@@ -56,6 +66,6 @@ stdenv.mkDerivation rec {
     homepage = "https://github.com/ElementsProject/lightning";
     maintainers = with maintainers; [ jb55 prusnak ];
     license = licenses.mit;
-    platforms = platforms.linux;
+    platforms = platforms.linux ++ [ "x86_64-darwin" ];
   };
 }