protobuf + nix setup

.gitignore

+result
+.vscode

default.nix

+{ pkgs ? import (fetchTarball {
+    url = "https://github.com/NixOS/nixpkgs/archive/22.05.tar.gz";
+    sha256 = "0d643wp3l77hv2pmg2fi7vyxn4rwy0iyr8djcw1h5x72315ck9ik";
+  }) {}
+}:
+
+let self = rec {
+  pythonPackages = pkgs.python3Packages;
+  simgrid = pkgs.simgrid;
+  protocol-cpp = pkgs.stdenv.mkDerivation {
+    pname = "protocol-cpp";
+    version = "local";
+    src = pkgs.lib.sourceByRegex ./protocol [
+      "hello\.proto"
+      "meson\.build"
+    ];
+    propagatedBuildInputs = with pkgs; [
+      protobuf
+    ];
+    buildInputs = with pkgs; [
+      meson
+      pkg-config
+      ninja
+    ];
+  };
+
+};
+in
+  self

protocol/hello.proto

+syntax = "proto2";
+
+package hello;
+
+message Hello {
+  optional string name = 1;
+}
+
+message Bye {
+}

protocol/meson.build

+project('protocol-cpp', 'cpp', version: '0.1.0', default_options: ['cpp_std=c++17'])
+
+protoc = find_program('protoc', required: true)
+protobuf_dep = dependency('protobuf', required: true)
+
+gen = generator(protoc, \
+  output    : ['@BASENAME@.pb.cc', '@BASENAME@.pb.h'],
+  arguments : ['--proto_path=@CURRENT_SOURCE_DIR@', '--cpp_out=@BUILD_DIR@', '@INPUT@'])
+
+proto_generated_cpp = custom_target('protobuf-generated-sources',
+    input: ['hello.proto'],
+    output: ['hello.pb.h', 'hello.pb.cc'],
+    command: [protoc, '--proto_path=@CURRENT_SOURCE_DIR@', '--cpp_out=@OUTDIR@', '@INPUT@'],
+    install: true,
+    install_dir: [get_option('includedir'), false],
+)
+
+lib = shared_library('protocol', proto_generated_cpp, dependencies: protobuf_dep, install: true)
+
+pkg = import('pkgconfig')
+pkg.generate(lib)