When using the gazelle starlark API, new files do not update existing rules

[avx-rchung]

I am trying to use a gazelle rule with the starlark extension API to dynamically update rules to generate a type library

The standard gazelle:proto_plugin already supports using builtin:pyi to generate python type stubs from protobuf, but there isn't a good way out of the box to create a library out of these pyi files for consumption. The bazel-mypy-integration project has a mypy_stubs rule that is good for this purpose (https://github.com/bazel-contrib/bazel-mypy-integration/blob/main/rules.bzl) so we just need to glue these together.

I attempted to do it using these gazelle declarations:

# gazelle:proto_plugin python implementation builtin:python
# gazelle:proto_rule proto_python_library implementation stackb:rules_proto:proto_py_library
# gazelle:proto_rule proto_python_stub_library implementation example/starlark_proto/lib/rules.star%proto_python_stubs_library
# gazelle:proto_rule proto_python_stub_library visibility //visibility:public
# gazelle:proto_language python plugin python
# gazelle:proto_language python rule proto_python_library
# gazelle:proto_language python rule proto_python_stub_library

and a rules.star like this:

"""rules_proto based language rules."""
# Ref: https://github.com/stackb/rules_proto/blob/master/pkg/protoc/starlark_rule.go
def _make_proto_python_rule(rule_cfg, protoc_cfg):
    return gazelle.Rule(
        kind = "mypy_stubs",
        name = protoc_cfg.proto_library.base_name + "_pyi_library",
        attrs = {
           "srcs": [x.replace(".proto", "_pb2.pyi") for x in protoc_cfg.proto_library.srcs],
           "visibility": rule_cfg.visibility,
        },
     )

def _provide_python(rctx, pctx):
    return struct(
        name = "proto_python_stubs_library",
        rule = lambda: _make_proto_python_rule(rctx, pctx),
        experimental_resolve_attr = "deps",
    )

protoc.Rule(
    name = "proto_python_stubs_library",
    load_info = lambda: gazelle.LoadInfo(name = "//example/starlark_proto/lib:rules.bzl", symbols = ["mypy_stubs"]),
    kind_info = lambda: gazelle.KindInfo(mergeable_attrs = {"srcs": True}, resolve_attrs = {"deps": True}),
    provide_rule = _provide_python,

This works on the first run, but when a new proto is added, I noticed that while the "native" rules are updated, the starlark based one is not.

Full example here: https://github.com/avx-rchung/rules_proto/tree/starlark-example in the example/starlark_proto directory

Initial run to check everything is generated as expected:

$ bazel run :gazelle -- example/starlark_proto

check output in example/starlark_proto/proto/BUILD.bazel -- looks good.

Add a new protobuf:

$ sed -e 's/Bar/Baz/' example/starlark_proto/proto/b.proto  > example/starlark_proto/proto/c.proto
$ bazel run :gazelle -- example/starlark_proto

Note that c_pb2.* gets added to proto_library, proto_compile, proto_py_library but not mypy_stubs

If I delete the mypy_stub run and re-run gazelle and the rule is regenerated properly (including c_pb2)