Add package_info rule and a new gatherer to manage it.

- Add rules/package_info.bzl
- Refactor get_transitive_licenses to get_transitive_metadata.
  - Take a list of providers to gather.
  - Some hackery for Bazel 5.x support. This can be fixed if starlark
    visibility gets backported to Bazel 5.
- Add gather_metadata.bzl.  This is so we can freely experiment on
  techniques for multi provider support in OSS land, without impacting
  existing users in Google. We can merge them some day in the future.
- Create a dummy sbom writer.

There is also experimental code to show a different design choice
for new types of Metadata. I want to preserve both for a while
to have a broader design discussion over the next month.

1 files changed, 2 insertions, 2 deletions

diff --git a/rules/gather_licenses_info.bzl b/rules/gather_licenses_info.bzl
index a5f1a41..b676972 100644
--- a/rules/gather_licenses_info.bzl
+++ b/rules/gather_licenses_info.bzl
@@ -16,7 +16,7 @@
 load(
     "@rules_license//rules:licenses_core.bzl",
     "TraceInfo",
-    "gather_licenses_info_common",
+    "gather_metadata_info_common",
     "should_traverse",
 )
 load(
@@ -41,7 +41,7 @@ def _strip_null_repo(label):
     return s
 
 def _gather_licenses_info_impl(target, ctx):
-    return gather_licenses_info_common(target, ctx, TransitiveLicensesInfo, NAMESPACES, should_traverse)
+    return gather_metadata_info_common(target, ctx, TransitiveLicensesInfo, NAMESPACES, [], should_traverse)
 
 gather_licenses_info = aspect(
     doc = """Collects LicenseInfo providers into a single TransitiveLicensesInfo provider.""",