Support setting (or unsetting) dllexport macros

cmake/gz_msgs_generate.cmake

@@ -8,6 +8,7 @@
 #   FACTORY_GEN_SCRIPT  - Location of the factory generator script
 #   PROTO_PATH          - Base directory of the proto files
 #   DEPENDENCY_DESCRIPTIONS - .gz_desc files for each dependency
+#   DLLEXPORT_DECL      - Visibilty macro to apply to messages
 #   OUTPUT_DIRECTORY    - CMake binary directoy to place generated artifacts
 #   OUTPUT_SOURCES      - Variable to contain list of generated source files
 #   OUTPUT_HEADERS      - Variable to contain list of generated header files
@@ -21,6 +22,7 @@ function(gz_msgs_generate_messages_impl)
     # Inputs
     PROTO_PACKAGE MSGS_GEN_SCRIPT GZ_PROTOC_PLUGIN FACTORY_GEN_SCRIPT PROTO_PATH
     DEPENDENCY_DESCRIPTIONS
+    DLLEXPORT_DECL
     OUTPUT_DIRECTORY
     # Outputs
     OUTPUT_SOURCES
@@ -57,6 +59,8 @@ function(gz_msgs_generate_messages_impl)
 
       # Cpp Specific arguments
       GENERATE_CPP
+      DLLEXPORT_DECL
+        ${generate_messages_DLLEXPORT_DECL}
       OUTPUT_CPP_HH_VAR
         ${generate_messages_OUTPUT_HEADERS}
       OUTPUT_DETAIL_CPP_HH_VAR

cmake/gz_msgs_protoc.cmake

@@ -8,6 +8,7 @@
 #   PROTO_PACKAGE       - Protobuf package the file belongs to (e.g. "gz.msgs")
 #   PROTOC_EXEC         - Path to protoc
 #   GZ_PROTOC_PLUGIN    - Path to the gazebo-specific protobuf compiler executable
+#   DLLEXPORT_DECL      - DLL visibility macro (eg GZ_MSGS_VISIBLE)
 #   INPUT_PROTO         - Path to the input .proto file
 #   OUTPUT_CPP_DIR      - Path where C++ files are saved
 #   OUTPUT_PYTON_DIR    - Path where Python files are saved
@@ -25,6 +26,7 @@ function(gz_msgs_protoc)
     PROTO_PACKAGE
     PROTOC_EXEC
     GZ_PROTOC_PLUGIN
+    DLLEXPORT_DECL
     INPUT_PROTO
     OUTPUT_CPP_DIR
     OUTPUT_CPP_HH_VAR
@@ -96,6 +98,12 @@ function(gz_msgs_protoc)
     )
   endif()
 
+  if(gz_msgs_protoc_DLLEXPORT_DECL)
+    list(APPEND GENERATE_ARGS
+      --dllexport-decl "${gz_msgs_protoc_DLLEXPORT_DECL}"
+    )
+  endif()
+
   if(${gz_msgs_protoc_GENERATE_CPP})
     list(APPEND GENERATE_ARGS
       --generate-cpp

core/CMakeLists.txt

@@ -35,6 +35,8 @@ gz_msgs_generate_messages_impl(
     $<TARGET_FILE:${PROJECT_NAME}_protoc_plugin>
   INPUT_PROTOS
     ${proto_files}
+  DLLEXPORT_DECL
+    "GZ_MSGS_VISIBLE"
   PROTO_PACKAGE
     "gz.msgs"
   PROTO_PATH

tools/gz_msgs_generate.py

@@ -57,6 +57,9 @@ def main(argv=sys.argv[1:]):
         '--dependency-proto-descs',
         nargs='*',
         help='The location of proto descriptor files these messages depend on')
+    parser.add_argument(
+        '--dllexport-decl',
+        help='The DLL visibility macro to use, if not set, no macro will be used')
     args = parser.parse_args(argv)
 
     # First generate the base cpp files
@@ -71,7 +74,11 @@ def main(argv=sys.argv[1:]):
 
     if args.generate_cpp:
         cmd += [f'--plugin=protoc-gen-gzmsgs={args.gz_generator_bin}']
-        cmd += [f'--cpp_out=dllexport_decl=GZ_MSGS_VISIBLE:{args.output_cpp_path}']
+        if args.dllexport_decl:
+            cmd += [f'--cpp_out=dllexport_decl={args.dllexport_decl}:{args.output_cpp_path}']
+        else:
+            cmd += [f'--cpp_out={args.output_cpp_path}']
+
         cmd += [f'--gzmsgs_out={args.output_cpp_path}']
     if args.generate_python:
         cmd += [f'--python_out={args.output_python_path}']