Add a feature that enables -index-include-locals for Swift compiles.

PiperOrigin-RevId: 574234005

swift/internal/feature_names.bzl

@@ -68,6 +68,12 @@ SWIFT_FEATURE_INDEX_SYSTEM_MODULES = "swift.index_system_modules"
 # store among its outputs.
 SWIFT_FEATURE_INDEX_WHILE_BUILDING = "swift.index_while_building"
 
+# If enabled, indexstore data will contain local definitions and references.
+#
+# NOTE: This is only applicable if `SWIFT_FEATURE_INDEX_WHILE_BUILDING` is also
+# enabled.
+SWIFT_FEATURE_INDEX_INCLUDE_LOCALS = "swift.index_include_locals"
+
 # If enabled, indexing will be completely modular - PCMs and Swift Modules will only
 # be indexed when they are compiled. While indexing a module/PCM, none of its dependencies
 # will be indexed.

swift/toolchains/config/compile_config.bzl

@@ -39,6 +39,7 @@ load(
     "SWIFT_FEATURE_FASTBUILD",
     "SWIFT_FEATURE_FILE_PREFIX_MAP",
     "SWIFT_FEATURE_FULL_DEBUG_INFO",
+    "SWIFT_FEATURE_INDEX_INCLUDE_LOCALS",
     "SWIFT_FEATURE_INDEX_SYSTEM_MODULES",
     "SWIFT_FEATURE_INDEX_WHILE_BUILDING",
     "SWIFT_FEATURE_INTERNALIZE_AT_LINK",
@@ -744,6 +745,14 @@ def compile_action_configs(
             configurators = [_index_while_building_configurator],
             features = [SWIFT_FEATURE_INDEX_WHILE_BUILDING],
         ),
+        ActionConfigInfo(
+            actions = [SWIFT_ACTION_COMPILE],
+            configurators = [add_arg("-index-include-locals")],
+            features = [
+                SWIFT_FEATURE_INDEX_WHILE_BUILDING,
+                SWIFT_FEATURE_INDEX_INCLUDE_LOCALS,
+            ],
+        ),
         ActionConfigInfo(
             actions = [SWIFT_ACTION_COMPILE],
             configurators = [add_arg("-index-ignore-system-modules")],