build.py `--dev` flag does not do the same as codal.json `"dev": true`

[microbit-carlos]

Looking at build.py, the dev flag is described as "enable developer mode (does not use target-locked.json)":

microbit-v2-samples/build.py

Line 46 in 1a3d477

parser.add_option('-d', '--dev', dest='dev', action="store_true", help='enable developer mode (does not use target-locked.json)', default=False)

There is also another way to "enable developer mode" by setting the "target.dev": true key in codal.json. This mode is processed in the CMake files and it read target-locked.json instead of target.json from codal-microbit-v2:

microbit-v2-samples/CMakeLists.txt

Lines 67 to 73 in 1a3d477

	if("${codal.target.dev}" STRGREATER "")
	file(READ "./${LIB_DEST}/${codal.target.name}/target.json" device_json)
	message("${BoldMagenta}Using target.json (dev version) ${ColourReset}")
	else()
	file(READ "./${LIB_DEST}/${codal.target.name}/target-locked.json" device_json)
	message("${BoldMagenta}Using target-locked.json${ColourReset}")
	endif()

The build.py --dev flag it's only used:

• When the --update flag is used to update (git pull) the libraries:
  • build.py#L61
  • In this case a build.py does not invoke any CMake files, so it never uses target-locked.json or target.json
  • So in this case, the build.py description of the --dev flag does not quite apply
• When the "target" command argument is used (e.g. python build.py codal-microbit --dev)
  • build.py#L116
  • In this case it completely overwrites the codal.json to include this flag, and incidentally loses all other configured options from the file
  • Also, this needs an existing target to be specified in utils/targets.json, which right now does not contain an entry for codal-microbit-v2
  • So this is either an obsolete option, or something that needs to be updated for micro:bit V2

With the normal python build.py invocation with the --dev flag does not do anything at all, which is also a bit confusing.