Convert grpc and protobuf CMake builds to add_subdirectory (#1537)

* Build zlib with grpc's add_subdirectory

* Build grpc and its children with add_subdirectory.

* Build c-ares with grpc's add_subdirectory

* Convert protobuf to a download-only ExternalProject

* Temporarily break protobuf within grpc

This works because libgrpc has no actual dependency on protobuf

* Update boringssl to master@{2018-07-10}

3 files changed, 44 insertions, 8 deletions

diff --git a/Firestore/CMakeLists.txt b/Firestore/CMakeLists.txt
index cbcd49d..039cb06 100644
--- a/Firestore/CMakeLists.txt
+++ b/Firestore/CMakeLists.txt
@@ -42,9 +42,8 @@ if(APPLE)
   find_package(FirebaseCore REQUIRED)
   find_package(GoogleUtilities REQUIRED)
 endif()
-find_package(GRPC REQUIRED)
 find_package(LevelDB REQUIRED)
-find_package(Protobuf REQUIRED)
+find_package(ZLIB)
 
 
 # Googletest
@@ -64,6 +63,48 @@ add_subdirectory(
 )
 
 
+# gRPC
+if(ZLIB_FOUND)
+  set(gRPC_ZLIB_PROVIDER package CACHE STRING "Use external ZLIB")
+endif()
+
+set(gRPC_BUILD_TESTS OFF CACHE BOOL "Disable gRPC tests")
+add_subdirectory(
+  ${FIREBASE_BINARY_DIR}/src/grpc
+  ${FIREBASE_BINARY_DIR}/src/grpc-build
+  EXCLUDE_FROM_ALL
+)
+
+# Fix up targets included by gRPC's build
+add_alias(OpenSSL::Crypto crypto)
+target_include_directories(
+  crypto
+  INTERFACE
+    $<BUILD_INTERFACE:${FIREBASE_BINARY_DIR}/src/grpc/third_party/boringssl/include>
+)
+
+add_alias(OpenSSL::SSL ssl)
+target_include_directories(
+  ssl
+  INTERFACE
+    $<BUILD_INTERFACE:${FIREBASE_BINARY_DIR}/src/grpc/third_party/boringssl/include>
+)
+
+add_alias(protobuf::libprotobuf libprotobuf)
+target_compile_options(
+  libprotobuf
+  PUBLIC -Wno-unused-parameter
+)
+
+if(NOT ZLIB_FOUND)
+  target_include_directories(
+    zlibstatic
+    INTERFACE
+      $<BUILD_INTERFACE:${FIREBASE_BINARY_DIR}/src/grpc/third_party/zlib>
+  )
+endif()
+
+
 # nanopb
 set(nanopb_BUILD_GENERATOR ON CACHE BOOL "Enable the nanopb generator")
 set(nanopb_PROTOC_PATH ${NANOPB_PROTOC_BIN} CACHE STRING "Protoc location")
diff --git a/Firestore/Protos/CMakeLists.txt b/Firestore/Protos/CMakeLists.txt
index 214c15f..c2132ae 100644
--- a/Firestore/Protos/CMakeLists.txt
+++ b/Firestore/Protos/CMakeLists.txt
@@ -97,8 +97,3 @@ target_include_directories(
   firebase_firestore_protos_libprotobuf PUBLIC
   ${FIREBASE_SOURCE_DIR}/Firestore/Protos/cpp
 )
-
-set_target_properties(
-  firebase_firestore_protos_libprotobuf
-  PROPERTIES COMPILE_FLAGS "-Wno-unused-parameter"
-)
diff --git a/Firestore/core/src/firebase/firestore/remote/CMakeLists.txt b/Firestore/core/src/firebase/firestore/remote/CMakeLists.txt
index af62ab1..5de4648 100644
--- a/Firestore/core/src/firebase/firestore/remote/CMakeLists.txt
+++ b/Firestore/core/src/firebase/firestore/remote/CMakeLists.txt
@@ -29,5 +29,5 @@ cc_library(
     firebase_firestore_nanopb
     firebase_firestore_protos_nanopb
     firebase_firestore_util
-    grpc::grpc
+    grpc
 )