Build sources jar for rcljava

[gonzodepedro]

Adds a cmake file and instructions to CMakeList.txt to build a sources jar for rcljava

Signed-off-by: Gonzalo de Pedro gonzalo@depedro.com.ar

[jacobperron]

Thanks for adding this!

I've given it a first pass and left some initial feedback. Was there some references used when adding this? It might be good to attribute any references used.

[gonzodepedro]

Thanks for adding this!

I've given it a first pass and left some initial feedback. Was there some references used when adding this? It might be good to attribute any references used.

This is highly inspired in the add_jar function found in UseJava cmake module. It is also intended to be used together with it, as there are some functions defined in that module used here.

[jacobperron]

After looking at this a bit more, I'm confused why add_jar doesn't supply an option to just bundle the source files, or resource-only jars (ie. no compilation). Perhaps it's not a common use-case?

It seems rather simple to do from the command-line, e.g.

jar -cf mysource.jar src/*.java

@gonzodepedro Do you think we could make this cmake implementation simpler (to make maintenance easier)? It seems like there's a lot of special cases being handled that we don't care about. Really, all we want is a way to bundle resources files without doing any compiling.

Roughly, I imagine the minimum function looking something like this:

function(add_source_jar TARGET_NAME)
 
  # argument parsing goes here ...

  # Run 'jar passing source files directly (we don't really care what kinds of files they are)
  add_custom_command(
    OUTPUT ${_add_source_jar_OUTPUT}
    COMMAND ${Java_JAR_EXECUTABLE} -cf ${_add_source_jar_OUTPUT} ${_add_source_jar_SOURCES}
    WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
  )
  add_custom_target(${TARGET_NAME} ALL DEPENDS ${_add_source_jar_OUTPUT})

  # Set install property (for 'install_jar()').
  set_property(        
    TARGET ${_target_name}
    PROPERTY
      INSTALL_FILES ${_source_jar_file}
  )

  # Maybe also set JAR_FILE property?
  # I don't think that JNI_SYMLINK or CLASSDIR makes sense for resource-only jars
endfunction()

What do you think?

[jacobperron]

Thanks for refactoring and moving to rcljava_common. Looks more straight-forward now 😅

A couple more minor comments, otherwise LGTM

[jacobperron]

nit: we can remove this line

[gonzodepedro]

Removed

[jacobperron]

We should probably handle the case where OUTPUT_NAME is not given. Maybe it can default to the "${_TARGET_NAME}.jar"?

[gonzodepedro]

Done