Merge pull request #3675 from hesmar/hesmar/cmakeAddDllExport

protobuf_generate: add EXPORT_MACRO option

cmake/protobuf-config.cmake.in

@@ -11,7 +11,7 @@ function(protobuf_generate)
   include(CMakeParseArguments)
 
   set(_options APPEND_PATH)
-  set(_singleargs LANGUAGE OUT_VAR)
+  set(_singleargs LANGUAGE OUT_VAR EXPORT_MACRO)
   if(COMMAND target_sources)
     list(APPEND _singleargs TARGET)
   endif()
@@ -34,6 +34,10 @@ function(protobuf_generate)
   endif()
   string(TOLOWER ${protobuf_generate_LANGUAGE} protobuf_generate_LANGUAGE)
 
+  if(protobuf_generate_EXPORT_MACRO AND protobuf_generate_LANGUAGE STREQUAL cpp)
+    set(_dll_export_decl "dllexport_decl=${protobuf_generate_EXPORT_MACRO}:")
+  endif()
+
   if(NOT protobuf_GENERATE_EXTENSIONS)
     if(protobuf_generate_LANGUAGE STREQUAL cpp)
       set(protobuf_GENERATE_EXTENSIONS .pb.h .pb.cc)
@@ -95,7 +99,7 @@ function(protobuf_generate)
     add_custom_command(
       OUTPUT ${_generated_srcs}
       COMMAND  protobuf::protoc
-      ARGS --${protobuf_generate_LANGUAGE}_out  ${CMAKE_CURRENT_BINARY_DIR} ${_protobuf_include_path} ${_abs_file}
+      ARGS --${protobuf_generate_LANGUAGE}_out ${_dll_export_decl}${CMAKE_CURRENT_BINARY_DIR} ${_protobuf_include_path} ${_abs_file}
       DEPENDS ${ABS_FIL} protobuf::protoc
       COMMENT "Running ${protobuf_generate_LANGUAGE} protocol buffer compiler on ${_proto}"
       VERBATIM )

cmake/protobuf-module.cmake.in

@@ -2,7 +2,10 @@
 # Functions
 
 function(PROTOBUF_GENERATE_CPP SRCS HDRS)
-  if(NOT ARGN)
+  cmake_parse_arguments(protobuf_generate_cpp "" "EXPORT_MACRO" "" ${ARGN})
+
+  set(_proto_files "${protobuf_generate_cpp_UNPARSED_ARGUMENTS}")
+  if(NOT _proto_files)
     message(SEND_ERROR "Error: PROTOBUF_GENERATE_CPP() called without any proto files")
     return()
   endif()
@@ -16,7 +19,7 @@ function(PROTOBUF_GENERATE_CPP SRCS HDRS)
   endif()
 
   set(_outvar)
-  protobuf_generate(${append_arg} LANGUAGE cpp OUT_VAR _outvar ${_import_arg} PROTOS ${ARGN})
+  protobuf_generate(${append_arg} LANGUAGE cpp EXPORT_MACRO ${protobuf_generate_cpp_EXPORT_MACRO} OUT_VAR _outvar ${_import_arg} PROTOS ${_proto_files})
 
   set(${SRCS})
   set(${HDRS})