Update extract symbol graphs rule to include swiftdoc (#1286)

This updates the symbol graph extract configurator to additionally
include the `.swiftdoc` files created by the the Swift module
compilation. This is required to produce documentation comments in the
`.symbolgraphs` when using the symbol graph extract rule.

swift/internal/symbol_graph_extracting.bzl

@@ -80,16 +80,20 @@ def extract_symbol_graph(
     # conditionally.
     transitive_modules = merged_swift_info.transitive_modules.to_list()
 
+    direct_swiftdocs = []
     transitive_swiftmodules = []
     for module in transitive_modules:
         swift_module = module.swift
         if swift_module:
             transitive_swiftmodules.append(swift_module.swiftmodule)
+            if module.name == module_name and swift_module.swiftdoc:
+                direct_swiftdocs.append(swift_module.swiftdoc)
 
     prerequisites = struct(
         bin_dir = feature_configuration._bin_dir,
         cc_compilation_context = merged_compilation_context,
         developer_dirs = swift_toolchain.developer_dirs,
+        direct_swiftdocs = direct_swiftdocs,
         emit_extension_block_symbols = emit_extension_block_symbols,
         genfiles_dir = feature_configuration._genfiles_dir,
         include_dev_srch_paths = include_dev_srch_paths,

swift/toolchains/config/compile_config.bzl

@@ -43,6 +43,7 @@ load(
     "SWIFT_FEATURE_DISABLE_SYSTEM_INDEX",
     "SWIFT_FEATURE_EMIT_BC",
     "SWIFT_FEATURE_EMIT_PRIVATE_SWIFTINTERFACE",
+    "SWIFT_FEATURE_EMIT_SWIFTDOC",
     "SWIFT_FEATURE_EMIT_SWIFTINTERFACE",
     "SWIFT_FEATURE_ENABLE_BATCH_MODE",
     "SWIFT_FEATURE_ENABLE_LIBRARY_EVOLUTION",
@@ -815,9 +816,15 @@ def compile_action_configs(
 
         # swift-symbolgraph-extract doesn't yet support explicit Swift module
         # maps.
+        ActionConfigInfo(
+            actions = [SWIFT_ACTION_SYMBOL_GRAPH_EXTRACT],
+            configurators = [_dependencies_swiftmodules_and_swiftdocs_configurator],
+            features = [SWIFT_FEATURE_EMIT_SWIFTDOC],
+        ),
         ActionConfigInfo(
             actions = [SWIFT_ACTION_SYMBOL_GRAPH_EXTRACT],
             configurators = [_dependencies_swiftmodules_configurator],
+            not_features = [SWIFT_FEATURE_EMIT_SWIFTDOC],
         ),
     ])
 
@@ -1671,6 +1678,20 @@ def _swift_module_search_path_map_fn(module):
     else:
         return None
 
+def _dependencies_swiftmodules_and_swiftdocs_configurator(prerequisites, args):
+    """Adds `.swiftmodule` and `.swiftdoc` files from the transitive modules to search paths and action inputs."""
+    args.add_all(
+        prerequisites.transitive_modules,
+        format_each = "-I%s",
+        map_each = _swift_module_search_path_map_fn,
+        uniquify = True,
+    )
+
+    return ConfigResultInfo(
+        inputs = prerequisites.transitive_swiftmodules +
+                 prerequisites.direct_swiftdocs,
+    )
+
 def _dependencies_swiftmodules_configurator(prerequisites, args):
     """Adds `.swiftmodule` files from deps to search paths and action inputs."""
     args.add_all(