Merge pull request #44902 from danieldk/grpcio-darwin

python/grpcio: fix darwin build

pkgs/development/python-modules/grpcio/default.nix

@@ -1,6 +1,7 @@
-{ stdenv, buildPythonPackage, fetchPypi, lib
-, six, protobuf, enum34, futures, isPy27, isPy34 }:
+{ stdenv, buildPythonPackage, fetchPypi, lib, darwin
+, six, protobuf, enum34, futures, isPy27, isPy34, pkgconfig }:
 
+with stdenv.lib;
 buildPythonPackage rec {
   pname = "grpcio";
   version = "1.13.0";
@@ -10,10 +11,14 @@ buildPythonPackage rec {
     sha256 = "6324581e215157f0fbe335dff2e21a65b4406db98ac7cca05f1e23b4f510b426";
   };
 
+  nativeBuildInputs = [ pkgconfig ] ++ optional stdenv.isDarwin darwin.cctools;
+
   propagatedBuildInputs = [ six protobuf ]
                         ++ lib.optionals (isPy27 || isPy34) [ enum34 ]
                         ++ lib.optionals (isPy27) [ futures ];
 
+  preBuild = optionalString stdenv.isDarwin "unset AR";
+
   meta = with stdenv.lib; {
     description = "HTTP/2-based RPC framework";
     license = lib.licenses.asl20;