feat(3p/grpc): Build gRPC using LLVM10 & libcxx

third_party/default.nix

@@ -65,7 +65,6 @@ let
       go
       google-cloud-sdk
       graphviz
-      grpc
       gzip
       haskell
       iana-etc
@@ -163,7 +162,7 @@ in exposed.lib.fix(self: exposed // {
 
   # Packages to be overridden
   originals = {
-    inherit (nixpkgs) notmuch;
+    inherit (nixpkgs) grpc notmuch;
     inherit (stableNixpkgs) git;
     ffmpeg = nixpkgs.ffmpeg-full;
   };

third_party/grpc/default.nix

@@ -0,0 +1,14 @@
+{ pkgs, ... }:
+
+(pkgs.originals.grpc.override {
+  protobuf = pkgs.protobuf;
+  stdenv = pkgs.llvmPackages.libcxxStdenv;
+}).overrideAttrs(orig: {
+  buildInputs = orig.buildInputs ++ [
+    pkgs.abseil_cpp
+  ];
+
+  cmakeFlags = orig.cmakeFlags ++ [
+    "-DgRPC_ABSL_PROVIDER=package"
+  ];
+})