Use protobuf_generate_cpp

cmake/external/protobuf.cmake

@@ -13,6 +13,10 @@
 # limitations under the License.
 
 INCLUDE(ExternalProject)
+# Always invoke `FIND_PACKAGE(Protobuf)` for importing function protobuf_generate_cpp
+FIND_PACKAGE(Protobuf QUIET)
+SET(PROTOBUF_FOUND "OFF")
+
 
 # Print and set the protobuf library information,
 # finish this cmake process and exit from this file.
@@ -44,6 +48,9 @@ macro(PROMPT_PROTOBUF_LIB)
 
     ADD_EXECUTABLE(protoc IMPORTED GLOBAL)
     SET_PROPERTY(TARGET protoc PROPERTY IMPORTED_LOCATION ${PROTOBUF_PROTOC_EXECUTABLE})
+    # FIND_Protobuf.cmake uses `Protobuf_PROTOC_EXECUTABLE`.
+    # make `protobuf_generate_cpp` happy.
+    SET(Protobuf_PROTOC_EXECUTABLE ${PROTOBUF_PROTOC_EXECUTABLE})
 
     FOREACH(dep ${protobuf_DEPS})
         ADD_DEPENDENCIES(protobuf ${dep})

cmake/generic.cmake

@@ -338,22 +338,7 @@ function(pb_cc_library TARGET_NAME)
   cmake_parse_arguments(pb_cc_library "${options}" "${oneValueArgs}" "${multiValueArgs}" ${ARGN})
   set(proto_srcs)
   set(proto_hdrs)
-  foreach(FIL ${pb_cc_library_SRCS})
-    get_filename_component(ABS_FIL ${FIL} ABSOLUTE)
-    get_filename_component(FIL_WE ${FIL} NAME_WE)
-    list(APPEND proto_srcs "${CMAKE_CURRENT_BINARY_DIR}/${FIL_WE}.pb.cc")
-    list(APPEND proto_hdrs "${CMAKE_CURRENT_BINARY_DIR}/${FIL_WE}.pb.h")
-
-    add_custom_command(
-            OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/${FIL_WE}.pb.cc"
-            "${CMAKE_CURRENT_BINARY_DIR}/${FIL_WE}.pb.h"
-            COMMAND  ${PROTOBUF_PROTOC_EXECUTABLE}
-            ARGS "--cpp_out=${DLL_EXPORT_DECL}${CMAKE_CURRENT_BINARY_DIR}" "-I" ${CMAKE_CURRENT_SOURCE_DIR} ${ABS_FIL}
-            DEPENDS ${ABS_FIL} protoc
-            COMMENT "Running C++ protocol buffer compiler on ${FIL}"
-            VERBATIM )
-  endforeach()
-  set_source_files_properties(${proto_srcs} ${proto_hdrs} PROPERTIES GENERATED TRUE)
+  protobuf_generate_cpp(proto_srcs proto_hdrs ${pb_cc_library_SRCS})
   include_directories(${CMAKE_CURRENT_BINARY_DIR})
   cc_library(${TARGET_NAME} SRCS ${proto_srcs})
 endfunction()