From: uazo <uazo@users.noreply.github.com>
Date: Thu, 20 Oct 2022 09:34:48 +0000
Subject: Add kill switch for unsupported clangd flags

Allows build with clangd by suppressing unsupported parameters

Original License: GPL-2.0-or-later - https://spdx.org/licenses/GPL-2.0-or-later.html
License: GPL-3.0-only - https://spdx.org/licenses/GPL-3.0-only.html
---
 build/config/compiler/BUILD.gn | 17 ++++++++++++++---
 build_overrides/build.gni      |  5 +++++
 2 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/build/config/compiler/BUILD.gn b/build/config/compiler/BUILD.gn
--- a/build/config/compiler/BUILD.gn
+++ b/build/config/compiler/BUILD.gn
@@ -681,7 +681,7 @@ config("compiler") {
     # TODO(crbug.com/376278218): This causes segfault on Linux ARM builds.
     # It also causes segfault on Linux s390x:
     # https://github.com/llvm/llvm-project/issues/149511
-    if (is_linux && use_lld && current_cpu != "arm" && current_cpu != "s390x") {
+    if (is_linux && !skip_clangd_unsupported_options && use_lld && current_cpu != "arm" && current_cpu != "s390x") {
       cflags += [ "-Wa,--crel,--allow-experimental-crel" ]
     }
   }
@@ -1886,7 +1886,7 @@ config("clang_revision") {
 # e.g. by setting in the the project's .gn file.
 config("clang_warning_suppression") {
   # Some build configs use older versions of clang that don't support WSMs
-  if (use_clang_warning_suppression_file) {
+  if (use_clang_warning_suppression_file && !skip_clangd_unsupported_options) {
     from_build_root =
         rebase_path(clang_warning_suppression_file, root_build_dir)
     inputs = [ clang_warning_suppression_file ]
@@ -2283,7 +2283,9 @@ config("default_warnings") {
       # TODO(crbug.com/432275627): Fix and re-enable.
       "-Wno-uninitialized-const-pointer",
     ]
-
+    if (skip_clangd_unsupported_options) {
+      cflags -= [ "-Wno-uninitialized-const-pointer" ]
+    }
     cflags_cc += [
       # TODO(crbug.com/328490295): Fix and re-enable for C flags.
       "-Wenum-compare-conditional",
@@ -2337,6 +2339,15 @@ config("default_warnings") {
       ldflags += [ "-Wno-version-check" ]
     }
 
+    if (skip_clangd_unsupported_options) {
+      cflags -= [
+        "-Wno-thread-safety-reference-return",
+        "-Wno-nontrivial-memcall",
+      ]
+      cflags_cc -= [
+      ]
+    }
+
     # Disable the GNU line marker warning when building a target with Icecc,
     # ccache, or both. This warning appears frequently when compiling
     # files that use GNU-style line markers with Clang and Icecc. It can
diff --git a/build_overrides/build.gni b/build_overrides/build.gni
--- a/build_overrides/build.gni
+++ b/build_overrides/build.gni
@@ -54,6 +54,11 @@ declare_args() {
   gtest_enable_absl_printers = true
 }
 
+declare_args() {
+  # Allows clangd builds by suppressing unsupported parameters
+  skip_clangd_unsupported_options = false
+}
+
 # Features used by //base/trace_event.
 declare_args() {
   # Use Perfetto's trace processor for converting protobuf-encoded traces to
--