This directory is used to host binaries installed during pip wheel build time.

1. Update [project.scripts] section of pyproject.toml file. Add the new binary name and it's corresponding module name similar to:

flatc = "executorch.data.bin:flatc"

For example, flatc is built during wheel packaging, we first build flatc through CMake and copy the file to <executorch root>/data/bin/flatc and ask setuptools to generate a commandline wrapper for flatc, then route it to <executorch root>/data/bin/flatc.

This way after installing executorch, a user will be able to call flatc directly in commandline and it points to <executorch root>/data/bin/flatc

2. Update setup.py to include the logic of building the new binary and copying the binary to this directory.

BuiltFile(
    src_dir="%CMAKE_CACHE_DIR%/third-party/flatbuffers/%BUILD_TYPE%/",
    src_name="flatc",
    dst="executorch/data/bin/",
    is_executable=True,
),

This means find flatc in CMAKE_CACHE_DIR and copy it to <executorch root>/data/bin. Notice that this works for both pip wheel packaging as well as editable mode install.

The reason is without data/bin/ present in source file, we can't tell setuptools to generate a module executorch.data.bin in editable mode, partially because we don't have a good top level module executorch and have to enumerate all the second level modules, including executorch.data.bin.