Add support for parse_headers (#524)

Fixes #522

Author: fmeum

tests/scripts/bazel.sh

@@ -50,6 +50,7 @@ common_test_args=(
   "--keep_going"
   "--test_output=errors"
   "--features=layering_check"
+  "--process_headers_in_dependencies"
 )
 
 # Do not run autoconf to configure local CC toolchains.

toolchain/cc_toolchain_config.bzl

@@ -348,6 +348,7 @@ def cc_toolchain_config(
     # https://cs.opensource.google/bazel/bazel/+/master:src/main/starlark/builtins_bzl/common/cc/cc_toolchain_provider_helper.bzl;l=75;drc=f0150efd1cca473640269caaf92b5a23c288089d
     # https://cs.opensource.google/bazel/bazel/+/master:src/main/java/com/google/devtools/build/lib/rules/cpp/CcModule.java;l=1257;drc=6743d76f9ecde726d592e88d8914b9db007b1c43
     # https://cs.opensource.google/bazel/bazel/+/refs/tags/7.0.0:tools/cpp/unix_cc_toolchain_config.bzl;l=192,201;drc=044a14cca2747aeff258fc71eaeb153c08cb34d5
+    # https://github.com/bazelbuild/rules_cc/blob/fe41fc4ea219c9d3680ee536bba6681f3baf838e/cc/private/toolchain/unix_cc_toolchain_config.bzl#L1887
     # NOTE: Ensure these are listed in toolchain_tools in toolchain/internal/common.bzl.
     tool_paths = {
         "ar": tools_path_prefix + ("llvm-ar" if not use_libtool else "libtool"),
@@ -362,6 +363,7 @@ def cc_toolchain_config(
         "objcopy": tools_path_prefix + "llvm-objcopy",
         "objdump": tools_path_prefix + "llvm-objdump",
         "strip": tools_path_prefix + "llvm-strip",
+        "parse_headers": wrapper_bin_prefix + "cc_wrapper.sh",
     }
 
     # Start-end group linker support:

toolchain/cc_wrapper.sh.tpl

@@ -82,6 +82,18 @@ if [[ ! -f ${toolchain_path_prefix}bin/clang ]]; then
   exit 5
 fi
 
+OUTPUT=
+
+function parse_option() {
+  local -r opt="$1"
+  if [[ "${OUTPUT}" = "1" ]]; then
+    OUTPUT=${opt}
+  elif [[ "${opt}" = "-o" ]]; then
+    # output is coming
+    OUTPUT=1
+  fi
+}
+
 function sanitize_option() {
   local -r opt=$1
   if [[ ${opt} == */cc_wrapper.sh ]]; then
@@ -106,6 +118,7 @@ for ((i = 0; i <= $#; i++)); do
         set -e
         sanitize_option "${opt}"
       )"
+      parse_option "${opt}"
       echo "${opt}" >>"${tmpfile}"
     done <"${!i:1}"
     cmd+=("@${tmpfile}")
@@ -114,9 +127,15 @@ for ((i = 0; i <= $#; i++)); do
       set -e
       sanitize_option "${!i}"
     )"
+    parse_option "${opt}"
     cmd+=("${opt}")
   fi
 done
 
 # Call the C++ compiler.
 "${cmd[@]}"
+
+# Generate an empty file if header processing succeeded.
+if [[ "${OUTPUT}" == *.h.processed ]]; then
+  echo -n >"${OUTPUT}"
+fi

toolchain/internal/configure.bzl

@@ -531,6 +531,7 @@ cc_toolchain(
     strip_files = "strip-files-{suffix}",
     toolchain_config = "local-{suffix}",
     module_map = "module-{suffix}",
+    supports_header_parsing = True,
 )
 """
 

toolchain/osx_cc_wrapper.sh.tpl

@@ -183,6 +183,11 @@ fi
 # Call the C++ compiler.
 "${cmd[@]}"
 
+# Generate an empty file if header processing succeeded.
+if [[ "${OUTPUT}" == *.h.processed ]]; then
+  echo -n >"${OUTPUT}"
+fi
+
 function get_library_path() {
   for libdir in ${LIB_DIRS}; do
     if [[ -f "${libdir}/lib$1".so ]]; then