From the PR:

Synthetic targets are overridable. If you declare a target with the same address (and target type) as a synthetic target in a BUILD file it replaces the synthetic target, unless the

_extend_synthetic

target field value is true in which case only the field values provided in the BUILD file are overridden.

Theoretically, could we not have

python_sources

generate synthetic targets (does it now?). The user then has:

python_sources(sources=["**/*.py", ...])

in the root. Then in

projectA/subdirX/BUILD

they define:

python_source(
    name="IDK whatever it needs to be",
    source="myfile.py"
    dependencies=["./myresource.json"]
    _extend_synthetic=True
)

As a way to augment the generated

python_source

with the new dependency (in this case ADDING the dep to the list defined way above)

Thats the kind of world I wanna live in (minus the awkward

name

and

_extend_synthetic

). Perhaps

_extend_synthetic

becomes a new target type per target type: e.g.

extend_python_source

,

extend_shell_source

, ...