From a96abe6f29022eda111d53009ceae70a4275029a Mon Sep 17 00:00:00 2001
From: Fabian Meumertzheim <fabian@meumertzhe.im>
Date: Thu, 11 Jul 2024 19:21:47 +0000
Subject: [PATCH] Update unix_cc_toolchain_config.bzl

---
 tools/cpp/unix_cc_toolchain_config.bzl | 32 ++++++++++++++++++++++----
 1 file changed, 28 insertions(+), 4 deletions(-)

diff --git a/tools/cpp/unix_cc_toolchain_config.bzl b/tools/cpp/unix_cc_toolchain_config.bzl
index 5a0cd710575076..d87917d9043714 100644
--- a/tools/cpp/unix_cc_toolchain_config.bzl
+++ b/tools/cpp/unix_cc_toolchain_config.bzl
@@ -102,6 +102,33 @@ def parse_headers_support(parse_headers_tool_path):
     if not parse_headers_tool_path:
         return [], []
     action_configs = [
+        action_config(
+            action_name = ACTION_NAMES.c_header_parsing,
+            tools = [
+                tool(path = parse_headers_tool_path),
+            ],
+            flag_sets = [
+                flag_set(
+                    flag_groups = [
+                        flag_group(
+                            flags = [
+                                "-xc-header",
+                                "-fsyntax-only",
+                            ],
+                        ),
+                    ],
+                ),
+            ],
+            implies = [
+                # Copied from the legacy feature definition in CppActionConfigs.java.
+                "legacy_compile_flags",
+                "user_compile_flags",
+                "sysroot",
+                "unfiltered_compile_flags",
+                "compiler_input_flags",
+                "compiler_output_flags",
+            ],
+        ),
         action_config(
             action_name = ACTION_NAMES.cpp_header_parsing,
             tools = [
@@ -112,10 +139,6 @@ def parse_headers_support(parse_headers_tool_path):
                     flag_groups = [
                         flag_group(
                             flags = [
-                                # Note: This treats all headers as C++ headers, which may lead to
-                                # parsing failures for C headers that are not valid C++.
-                                # For such headers, use features = ["-parse_headers"] to selectively
-                                # disable parsing.
                                 "-xc++-header",
                                 "-fsyntax-only",
                             ],
@@ -145,6 +168,7 @@ all_compile_actions = [
     ACTION_NAMES.linkstamp_compile,
     ACTION_NAMES.assemble,
     ACTION_NAMES.preprocess_assemble,
+    ACTION_NAMES.c_header_parsing,
     ACTION_NAMES.cpp_header_parsing,
     ACTION_NAMES.cpp_module_compile,
     ACTION_NAMES.cpp_module_codegen,