[c++ grpc] Add gRPC to CMake-based build

* Integrates building gRPC via its CMakeList
* Includes a dummy project to test that gRPC++ builds and can be linked
  correctly.

.gitmodules

@@ -1,6 +1,6 @@
 [submodule "thirdparty/grpc"]
 	path = thirdparty/grpc
-	url = https://github.com/grpc/grpc.git
+	url = https://github.com/chwarr/grpc.git
 
 [submodule "thirdparty/rapidjson"]
 	path = thirdparty/rapidjson

CMakeLists.txt

@@ -1,12 +1,16 @@
 cmake_minimum_required (VERSION 3.1)
-project (bond)
 
+project (bond)
 cmake_policy (SET CMP0022 NEW)
 
 set (CMAKE_MODULE_PATH
     ${CMAKE_CURRENT_SOURCE_DIR}/cmake
     ${CMAKE_CURRENT_SOURCE_DIR}/thirdparty/cmake-modules)
 
+# We need to include third-party CMake modules before we configure our own
+# settings so that we don't apply our settings to third-party code.
+include (ThirdParty)
+
 enable_testing()
 
 set (BOND_IDL ${CMAKE_CURRENT_SOURCE_DIR}/idl)
@@ -35,6 +39,7 @@ add_subfolder (doc "doc")
 add_python_subdirectory (python)
 add_subdirectory (examples)
 
+
 install (DIRECTORY
     cpp/inc/bond
     cpp/generated/bond

cmake/ThirdParty.cmake

@@ -0,0 +1,7 @@
+set (BOND_ENABLE_GRPC
+    "FALSE"
+    CACHE BOOL "If TRUE, then Bond C++ gRPC support will be built, using the grpc submodule. The grpc pre-requesites will need to have been installed.")
+
+if (BOND_ENABLE_GRPC)
+    add_subdirectory(thirdparty/grpc)
+endif()

examples/cpp/CMakeLists.txt

@@ -5,3 +5,10 @@ endif()
 if (NOT BOND_CORE_ONLY)
     add_subfolder (comm "examples/comm")
 endif()
+
+if (BOND_ENABLE_GRPC)
+    # This is a dummy project to make sure that gRPC++ builds and can be
+    # linked correctly. This will be removed later, when we have a
+    # Bond-over-gRPC++ test.
+    add_subfolder (grpc-dummy "examples/grpc-dummy")
+endif()

examples/cpp/grpc-dummy/CMakeLists.txt

@@ -0,0 +1,14 @@
+# This is a dummy project to make sure that gRPC++ builds and can be linked
+# correctly. This will be removed later, when we have a Bond-over-gRPC++
+# test.
+
+add_bond_test (grpc-dummy g.bond g.cpp)
+
+cxx_target_compile_definitions (MSVC grpc-dummy PRIVATE -D_WIN32_WINNT=0x0600)
+
+target_link_libraries(grpc-dummy PRIVATE grpc++)
+target_include_directories(grpc-dummy
+  # TODO: It feels like the grpc++ target should have this as part of its
+  # interface... Perhaps a patch for upstream?
+  PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/../../../thirdparty/grpc/include
+)

examples/cpp/grpc-dummy/g.bond

@@ -0,0 +1,11 @@
+namespace g;
+
+struct Box
+{
+    0: string sf;
+}
+
+service Greeter
+{
+    Box SayHello(Box);
+}

examples/cpp/grpc-dummy/g.cpp

@@ -0,0 +1,25 @@
+#include "g_types.h"
+
+#pragma warning (push)
+#pragma warning (disable: 4100)
+
+#include <grpc++/grpc++.h>
+
+#pragma warning (pop)
+
+#include <stdio.h>
+
+using namespace g;
+
+int main()
+{
+    Box b;
+    b.sf = "world";
+
+    printf("Hello, %s\n", b.sf.c_str());
+
+    grpc::ServerBuilder sb;
+    sb.AddListeningPort("127.0.0.1:12345", nullptr);
+
+    return 0;
+}

thirdparty/grpc

@@ -1 +1 @@
-Subproject commit e48dd23092a58c76a1cb486846fbeea38f60af3e
+Subproject commit 2306937f5011b886457569871cfad18fc5805927