Add descriptor.proto to the list of bundled proto files.

To support building after apple/swift-protobuf#727.

RELNOTES: None
PiperOrigin-RevId: 263117318

swift/internal/swift_protoc_gen_aspect.bzl

@@ -27,14 +27,18 @@ load(
 load(":providers.bzl", "SwiftInfo", "SwiftProtoInfo", "SwiftToolchainInfo")
 load(":utils.bzl", "compact", "create_cc_info", "get_providers", "workspace_relative_path")
 
-# The paths of well known type protos that should not be generated by the aspect
-# because they are already included in the SwiftProtobuf runtime. The plugin
-# provides the mapping from these protos to the SwiftProtobuf module for us.
+# The paths of proto files bundled with the runtime. This is mainly the well
+# known type protos, but also includes descriptor.proto to make generation of
+# files that include options easier. These files should not be generated by
+# the aspect because they are already included in the SwiftProtobuf runtime.
+# The plugin provides the mapping from these protos to the SwiftProtobuf
+# module for us.
 # TODO(b/63389580): Once we migrate to proto_lang_toolchain, this information
 # can go in the blacklisted_protos list instead.
-_WELL_KNOWN_TYPE_PATHS = [
+_RUNTIME_BUNDLED_PROTO_FILES = [
     "google/protobuf/any.proto",
     "google/protobuf/api.proto",
+    "google/protobuf/descriptor.proto",
     "google/protobuf/duration.proto",
     "google/protobuf/empty.proto",
     "google/protobuf/field_mask.proto",
@@ -76,7 +80,7 @@ def _filter_out_well_known_types(srcs):
     return [
         f
         for f in srcs
-        if workspace_relative_path(f) not in _WELL_KNOWN_TYPE_PATHS
+        if workspace_relative_path(f) not in _RUNTIME_BUNDLED_PROTO_FILES
     ]
 
 def _register_pbswift_generate_action(