Fix multiple dependency descriptor generation

[caguero]

🦟 Bug fix

Our current code has an issue that only external consumers generating custom messages (with more than one dependency) will trigger it.

The core issue is in this loop:

foreach(dep ${generate_messages_DEPENDENCY_DESCRIPTIONS})
    list(APPEND ARGS --descriptor_set_in="${msgs_desc_file}")
  endforeach()

It should be:

foreach(dep ${generate_messages_DEPENDENCY_DESCRIPTIONS})
    list(APPEND ARGS --descriptor_set_in="${dep}")
  endforeach()

The fix has been combined with the ability to pass more than one message dependency and use colon or semicolon delimiters depending on the system.

For testing I modified the example to trigger the issue without this fix. You should be able to run the updated generating_custom_messages example.

Summary

Checklist

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• Added tests
• Updated documentation (as needed)
• Updated migration guide (as needed)
• Consider updating Python bindings (if the library has them)
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• Updated Bazel files (if adding new files). Created an issue otherwise.
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[azeey]

I got the following error when trying to build the example

${_IMPORT_PREFIX}/share/gz/protos/msgs.gz_desc: No such file or directory
Failed to execute protoc compiler: Command '['/opt/homebrew/bin/protoc-34.0.0', '--proto_path=/Users/addisuzt/ws/rotary/src/gz-msgs/examples/generating_custom_msgs/proto2', '--descriptor_set_in=${_IMPORT_PREFIX}/share/gz/protos/msgs.gz_desc', '--plugin=protoc-gen-gzmsgs=/Users/addisuzt/ws/rotary/install//bin/gz-msgs_protoc_plugin', '--cpp_out=/Users/addisuzt/ws/rotary/src/gz-msgs/examples/generating_custom_msgs/build/generating_custom_messages-msgs2_genmsg', '--gzmsgs_out=/Users/addisuzt/ws/rotary/src/gz-msgs/examples/generating_custom_msgs/build/generating_custom_messages-msgs2_genmsg', '--python_out=/Users/addisuzt/ws/rotary/src/gz-msgs/examples/generating_custom_msgs/build/generating_custom_messages-msgs2_genmsg/python/', '/Users/addisuzt/ws/rotary/src/gz-msgs/examples/generating_custom_msgs/proto2/gz/custom_msgs2/qux.proto']' returned non-zero exit status 1.
make[2]: *** [generating_custom_messages-msgs2_genmsg/gz/custom_msgs2/qux.pb.h] Error 255
make[1]: *** [CMakeFiles/generating_custom_messages-msgs2.dir/all] Error 2
make: *** [all] Error 2

Also, would it be possible to turn the example into a test? As it stands, I don't know which test fails without the change in this PR.

[caguero]

I got the following error when trying to build the example

${_IMPORT_PREFIX}/share/gz/protos/msgs.gz_desc: No such file or directory
Failed to execute protoc compiler: Command '['/opt/homebrew/bin/protoc-34.0.0', '--proto_path=/Users/addisuzt/ws/rotary/src/gz-msgs/examples/generating_custom_msgs/proto2', '--descriptor_set_in=${_IMPORT_PREFIX}/share/gz/protos/msgs.gz_desc', '--plugin=protoc-gen-gzmsgs=/Users/addisuzt/ws/rotary/install//bin/gz-msgs_protoc_plugin', '--cpp_out=/Users/addisuzt/ws/rotary/src/gz-msgs/examples/generating_custom_msgs/build/generating_custom_messages-msgs2_genmsg', '--gzmsgs_out=/Users/addisuzt/ws/rotary/src/gz-msgs/examples/generating_custom_msgs/build/generating_custom_messages-msgs2_genmsg', '--python_out=/Users/addisuzt/ws/rotary/src/gz-msgs/examples/generating_custom_msgs/build/generating_custom_messages-msgs2_genmsg/python/', '/Users/addisuzt/ws/rotary/src/gz-msgs/examples/generating_custom_msgs/proto2/gz/custom_msgs2/qux.proto']' returned non-zero exit status 1.
make[2]: *** [generating_custom_messages-msgs2_genmsg/gz/custom_msgs2/qux.pb.h] Error 255
make[1]: *** [CMakeFiles/generating_custom_messages-msgs2.dir/all] Error 2
make: *** [all] Error 2

I cannot reproduce this issue. Do you have any other gz-msg version installed in the system by any chance? Because the error looks like the type of error you'd get without this patch.

[azeey]

Well, I can't seem to reproduce it myself either. It's possible that I had another version of gz-msgs built in the same colcon workspace.