Convert googletest and nanopb CMake builds to add_subdirectory (#1522)

* Add a download-only boringssl ExternalProject

Match boringssl version to grpc submodule version

Note: not yet in use

* Split grpc into separate download and build tasks

This allows other external targets to download into the gRPC source tree
before grpc is actually built.

* Convert grpc to an http download

* Build googletest with add_subdirectory

Also:
  * Revert library-name modifications in the abseil-cpp build
  * Move abseil-cpp add_subdirectory build into place

* Build nanopb with add_subdirectory

* Force nanopb first to work around ODR violations

This is a temporary work-around for b/111328563.

6 files changed, 53 insertions, 21 deletions

diff --git a/Firestore/CMakeLists.txt b/Firestore/CMakeLists.txt
index eb9744b..cbcd49d 100644
--- a/Firestore/CMakeLists.txt
+++ b/Firestore/CMakeLists.txt
@@ -42,16 +42,49 @@ if(APPLE)
   find_package(FirebaseCore REQUIRED)
   find_package(GoogleUtilities REQUIRED)
 endif()
-find_package(GMock REQUIRED)
 find_package(GRPC REQUIRED)
-find_package(GTest REQUIRED)
 find_package(LevelDB REQUIRED)
-find_package(Nanopb REQUIRED)
 find_package(Protobuf REQUIRED)
 
-enable_testing()
-add_subdirectory(third_party/abseil-cpp)
 
+# Googletest
+add_subdirectory(
+  ${FIREBASE_BINARY_DIR}/src/googletest
+  ${FIREBASE_BINARY_DIR}/src/googletest-build
+  EXCLUDE_FROM_ALL
+)
+add_alias(GTest::GTest gtest)
+add_alias(GTest::Main gtest_main)
+add_alias(GMock::GMock gmock)
+
+
+# Abseil-cpp
+add_subdirectory(
+  third_party/abseil-cpp
+)
+
+
+# nanopb
+set(nanopb_BUILD_GENERATOR ON CACHE BOOL "Enable the nanopb generator")
+set(nanopb_PROTOC_PATH ${NANOPB_PROTOC_BIN} CACHE STRING "Protoc location")
+add_subdirectory(
+  ${FIREBASE_BINARY_DIR}/src/nanopb
+  ${FIREBASE_BINARY_DIR}/src/nanopb-build
+  EXCLUDE_FROM_ALL
+)
+
+target_compile_definitions(
+  protobuf-nanopb
+  PUBLIC -DPB_FIELD_16BIT
+)
+
+target_include_directories(
+  protobuf-nanopb
+  INTERFACE $<BUILD_INTERFACE:${FIREBASE_BINARY_DIR}/src/nanopb>
+)
+
+
+enable_testing()
 include(CompilerSetup)
 
 # Superbuild installed results
diff --git a/Firestore/Protos/CMakeLists.txt b/Firestore/Protos/CMakeLists.txt
index fdf45e7..214c15f 100644
--- a/Firestore/Protos/CMakeLists.txt
+++ b/Firestore/Protos/CMakeLists.txt
@@ -53,13 +53,6 @@ cc_library(
     protobuf-nanopb
 )
 
-target_compile_definitions(
-  firebase_firestore_protos_nanopb
-  PUBLIC -DPB_FIELD_16BIT
-)
-
-# TODO(rsgowman): this may be worth moving into cc_library, possibly via an
-# INCLUDE_DIRS or similar.
 target_include_directories(
   firebase_firestore_protos_nanopb
   PUBLIC ${FIREBASE_SOURCE_DIR}/Firestore/Protos/nanopb
diff --git a/Firestore/core/src/firebase/firestore/local/CMakeLists.txt b/Firestore/core/src/firebase/firestore/local/CMakeLists.txt
index 5a47187..f1c65c4 100644
--- a/Firestore/core/src/firebase/firestore/local/CMakeLists.txt
+++ b/Firestore/core/src/firebase/firestore/local/CMakeLists.txt
@@ -22,6 +22,9 @@ cc_library(
     local_serializer.h
     local_serializer.cc
   DEPENDS
+    # TODO(b/111328563) Force nanopb first to work around ODR violations
+    protobuf-nanopb
+
     LevelDB::LevelDB
     absl_strings
     firebase_firestore_model
@@ -29,5 +32,4 @@ cc_library(
     firebase_firestore_protos_nanopb
     firebase_firestore_remote
     firebase_firestore_util
-    protobuf-nanopb
 )
diff --git a/Firestore/core/src/firebase/firestore/nanopb/CMakeLists.txt b/Firestore/core/src/firebase/firestore/nanopb/CMakeLists.txt
index fd34c2e..0471b1c 100644
--- a/Firestore/core/src/firebase/firestore/nanopb/CMakeLists.txt
+++ b/Firestore/core/src/firebase/firestore/nanopb/CMakeLists.txt
@@ -21,7 +21,9 @@ cc_library(
     writer.h
     writer.cc
   DEPENDS
+    # TODO(b/111328563) Force nanopb first to work around ODR violations
+    protobuf-nanopb
+
     firebase_firestore_util
     firebase_firestore_protos_nanopb
-    protobuf-nanopb
 )
diff --git a/Firestore/core/src/firebase/firestore/remote/CMakeLists.txt b/Firestore/core/src/firebase/firestore/remote/CMakeLists.txt
index a2bdbe2..af62ab1 100644
--- a/Firestore/core/src/firebase/firestore/remote/CMakeLists.txt
+++ b/Firestore/core/src/firebase/firestore/remote/CMakeLists.txt
@@ -22,10 +22,12 @@ cc_library(
     serializer.h
     serializer.cc
   DEPENDS
+    # TODO(b/111328563) Force nanopb first to work around ODR violations
+    protobuf-nanopb
+
     firebase_firestore_model
     firebase_firestore_nanopb
     firebase_firestore_protos_nanopb
     firebase_firestore_util
     grpc::grpc
-    protobuf-nanopb
 )
diff --git a/Firestore/third_party/abseil-cpp/CMakeLists.txt b/Firestore/third_party/abseil-cpp/CMakeLists.txt
index 4b939fa..7318cd3 100644
--- a/Firestore/third_party/abseil-cpp/CMakeLists.txt
+++ b/Firestore/third_party/abseil-cpp/CMakeLists.txt
@@ -76,14 +76,14 @@ endif()
 
 ## check targets
 if(BUILD_TESTING)
-  check_target(GTest::GTest)
-  check_target(GTest::Main)
-  check_target(GMock::GMock)
+  check_target(gtest)
+  check_target(gtest_main)
+  check_target(gmock)
 
   list(APPEND ABSL_TEST_COMMON_LIBRARIES
-    GTest::GTest
-    GTest::Main
-    GMock::GMock
+    gtest_main
+    gtest
+    gmock
     ${CMAKE_THREAD_LIBS_INIT}
   )
 endif()