Restore message generation pipeline and generate message libraries (#368

)

This it the final rework of the message generation pipeline for Harmonic.

After trying multiple approaches, we decided to keep the messages in one location and generate the library as part of gz-msgs to derisk the long term supported Harmonic release.

This PR adds the new message generation pipeline, but uses it internally to keep the API similar to previous releases.
---------

Signed-off-by: Michael Carroll <mjcarroll@intrinsic.ai>

.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()