fix error about headers_abi3 not being defined identified by real usages

Author: rickeylev

python/private/BUILD.bazel

@@ -31,6 +31,7 @@ filegroup(
     name = "distribution",
     srcs = glob(["**"]) + [
         "//python/private/api:distribution",
+        "//python/private/cc:distribution",
         "//python/private/pypi:distribution",
         "//python/private/whl_filegroup:distribution",
         "//tools/build_defs/python/private:distribution",

python/private/cc/BUILD.bazel

@@ -0,0 +1,20 @@
+load("@rules_cc//cc:cc_library.bzl", "cc_library")
+load("//python/private:visibility.bzl", "NOT_ACTUALLY_PUBLIC")
+
+package(
+    default_visibility = ["//:__subpackages__"],
+)
+
+licenses(["notice"])
+
+filegroup(
+    name = "distribution",
+    srcs = glob(["**"]),
+)
+
+# An empty cc target for use when a cc target is needed to satisfy
+# Bazel, but its contents don't matter.
+cc_library(
+    name = "empty",
+    visibility = NOT_ACTUALLY_PUBLIC,
+)

python/private/py_cc_toolchain_rule.bzl

@@ -83,6 +83,7 @@ The {obj}`features.headers_abi3` attribute can be used to detect if this
 attribute is available or not.
 :::
 """,
+            default = "//python/private/cc:empty",
             providers = [CcInfo],
         ),
         "libs": attr.label(

python/private/visibility.bzl

@@ -0,0 +1,7 @@
+"""Shared code for use with visibility specs."""
+
+# Use when a target isn't actually public, but needs public
+# visibility to keep Bazel happy.
+# Such cases are typically for defaults of rule attributes or macro args that
+# get used outside of rules_python itself.
+NOT_ACTUALLY_PUBLIC = ["//visibility:public"]