Restore message generation pipeline and generate message libraries

.gitignore

@@ -6,3 +6,6 @@ build_*
 .DS_Store
 *.swp
 *.orig
+
+# Python generated files 
+__pycache__

CMakeLists.txt

@@ -17,13 +17,14 @@ find_package(gz-cmake3 REQUIRED)
 set(CMAKE_CXX_STANDARD 17)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 
-gz_configure_project(VERSION_SUFFIX)
+gz_configure_project(VERSION_SUFFIX
+  CONFIG_EXTRAS "gz-msgs-extras.cmake.in")
 
-if (UNIX AND NOT APPLE)
-  set (EXTRA_TEST_LIB_DEPS stdc++fs)
-else()
-  set (EXTRA_TEST_LIB_DEPS)
-endif()
+# Install cmake support files
+install(
+  DIRECTORY cmake/
+  DESTINATION "${PROJECT_CMAKE_EXTRAS_INSTALL_DIR}"
+)
 
 #============================================================================
 # Set project-specific options
@@ -80,11 +81,18 @@ gz_find_package(GzProtobuf
                  COMPONENTS all
                  PRETTY Protobuf)
 
+#--------------------------------------
+# Find gz-utils
+gz_find_package(gz-utils2 REQUIRED)
+set(GZ_UTILS_VER ${gz-utils2_VERSION_MAJOR})
+
 #--------------------------------------
 # Find gz-math
 gz_find_package(gz-math7 REQUIRED)
 set(GZ_MATH_VER ${gz-math7_VERSION_MAJOR})
 
+find_package(Python3 REQUIRED COMPONENTS Interpreter)
+
 #--------------------------------------
 # Find if command is available. This is used to enable tests.
 # Note that CLI files are installed regardless of whether the dependency is
@@ -96,6 +104,12 @@ set(GZ_TOOLS_VER 1)
 # Find Tinyxml2
 gz_find_package(TINYXML2 REQUIRED PRIVATE PRETTY tinyxml2)
 
+#--------------------------------------
+# Find DL if doing relocatable installation
+if (GZ_ENABLE_RELOCATABLE_INSTALL)
+  gz_find_package(DL REQUIRED)
+endif()
+
 #--------------------------------------
 # Find Python
 find_package(Python3 REQUIRED COMPONENTS Interpreter)
@@ -129,10 +143,6 @@ add_subdirectory(tools)
 #============================================================================
 # Install proto files
 #============================================================================
-# TODO: Consider tweaking gz_configure_build() to call add_subdirectory(proto)
-# whenever a proto subdirectory exists. This could be used alongside
-# gz_msgs_protoc to get uniform support for proto messages across all Gazebo
-# projects.
 add_subdirectory(proto)
 
 # Generate python

Migration.md

@@ -5,6 +5,14 @@ Deprecated code produces compile-time warnings. These warning serve as
 notification to users that their code should be upgraded. The next major
 release will remove the deprecated code.
 
+## Gazebo Msgs 9.X to 10.X
+
+### Modifications 
+
+1. Th message generation pipeline is now accessible in downstream packages .
+  * For more information, consult the `using_gz_msgs` example.
+  * Note that there will no longer be Ruby generated messages, this support will be restored as-needed. 
+
 ## Gazebo Msgs 8.X to 9.X
 
 1. **SuppressWarnings.hh** is deprecated and isn't part of `msgs.hh` anymore.

cmake/gz_msgs_factory.cmake

@@ -0,0 +1,71 @@
+##################################################
+# A function that generates factory methods for generated gz-msgs
+# The output of this is are a header and source file that can be used as part of your library
+# for the gz::msgs::Factory
+# Options:
+# One value arguments:
+#   FACTORY_GEN_SCRIPT  - Location of the factory generator script
+#   PROTO_PACKAGE       - Protobuf package the file belongs to (e.g. "gz.msgs")
+#   PROTOC_EXEC         - Path to protoc
+#   OUTPUT_CPP_DIR      - Path where C++ files are saved
+#   OUTPUT_CPP_HH_VAR   - A CMake variable name containing a list that the C++ headers should be appended to
+#   OUTPUT_CPP_CC_VAR   - A Cmake variable name containing a list that the C++ sources should be appended to
+# Multi value arguments
+#   INPUT_PROTOS        - List of input proto files
+#   PROTO_PATH          - Base directory of the proto files
+function(gz_msgs_factory)
+  set(options "")
+  set(oneValueArgs
+    FACTORY_GEN_SCRIPT
+    PROTO_PACKAGE
+    OUTPUT_CPP_DIR
+    OUTPUT_CPP_HH_VAR
+    OUTPUT_CPP_CC_VAR)
+  set(multiValueArgs INPUT_PROTOS PROTO_PATH)
+
+  cmake_parse_arguments(gz_msgs_factory "${options}" "${oneValueArgs}" "${multiValueArgs}" ${ARGN})
+
+  _gz_msgs_proto_pkg_to_path(${gz_msgs_factory_PROTO_PACKAGE} proto_package_dir)
+
+  set(output_header "${gz_msgs_factory_OUTPUT_CPP_DIR}/${proto_package_dir}/MessageTypes.hh")
+  set(output_source "${gz_msgs_factory_OUTPUT_CPP_DIR}/${proto_package_dir}/register.cc")
+
+  list(APPEND ${gz_msgs_factory_OUTPUT_CPP_HH_VAR} ${output_header})
+  list(APPEND ${gz_msgs_factory_OUTPUT_CPP_CC_VAR} ${output_source})
+
+  list(APPEND output_files ${output_header})
+  list(APPEND output_files ${output_source})
+
+  set(${gz_msgs_factory_OUTPUT_CPP_HH_VAR} ${${gz_msgs_factory_OUTPUT_CPP_HH_VAR}} PARENT_SCOPE)
+  set(${gz_msgs_factory_OUTPUT_CPP_CC_VAR} ${${gz_msgs_factory_OUTPUT_CPP_CC_VAR}} PARENT_SCOPE)
+
+  set(depends_index)
+  # Full path to an index file, which contains all defined message types for that proto file
+  foreach(proto_file ${gz_msgs_factory_INPUT_PROTOS})
+    # Get a unique path (gz.msgs.foo -> gz_msgs_foo) for naming the index
+    _gz_msgs_proto_to_unique(${proto_file} ${gz_msgs_factory_PROTO_PACKAGE} UNIQUE_NAME)
+    set(input_index "${gz_msgs_factory_OUTPUT_CPP_DIR}/${UNIQUE_NAME}.pb_index")
+    list(APPEND depends_index ${input_index})
+  endforeach()
+
+  set(GENERATE_ARGS
+    --output-cpp-path "${gz_msgs_factory_OUTPUT_CPP_DIR}"
+    --proto-package "${gz_msgs_factory_PROTO_PACKAGE}"
+    --proto-path "${gz_msgs_factory_PROTO_PATH}"
+    --protos "${gz_msgs_factory_INPUT_PROTOS}"
+    )
+
+  add_custom_command(
+    OUTPUT ${output_files}
+    COMMAND Python3::Interpreter
+    ARGS ${gz_msgs_factory_FACTORY_GEN_SCRIPT} ${GENERATE_ARGS}
+    DEPENDS
+      ${depends_index}
+    # While the script is executed in the source directory, it does not write
+    # to the source tree.  All outputs are stored in the build directory.
+    WORKING_DIRECTORY ${PROJECT_SOURCE_DIR}
+    COMMENT "Running factory generator"
+    VERBATIM
+  )
+
+endfunction()