core/pkgs/by-name/gr/grpc/packages.nix

{ ... }:
res: pkgs: super:

with pkgs; {
  grpc = darwin.apple_sdk_11_0.callPackage ../development/libraries/grpc {
    stdenv = if stdenv.isDarwin && stdenv.isx86_64 then
      overrideSDK darwin.apple_sdk_11_0.stdenv { darwinMinVersion = "10.13"; }
    else
      stdenv;
  };
}