Add kill switch for unsupported clangd flags: updated patch for clangd v21

build/patches/Add-kill-switch-for-unsupported-clangd-flags.patch

@@ -7,13 +7,31 @@ 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 | 11 ++++++++++-
+ build/config/compiler/BUILD.gn | 14 +++++++++++---
  build_overrides/build.gni      |  3 +++
- 2 files changed, 13 insertions(+), 1 deletion(-)
+ 2 files changed, 14 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
+@@ -634,7 +634,7 @@ config("compiler") {
+ 
+     # TODO(crbug.com/413427035): Remove once
+     # https://github.com/llvm/llvm-project/pull/136867/ is landed.
+-    if (!is_win && !llvm_android_mainline &&
++    if (!is_win && !llvm_android_mainline && !skip_clangd_unsupported_options &&
+         default_toolchain != "//build/toolchain/cros:target") {
+       cflags += [ "-fextend-variable-liveness=none" ]
+     }
+@@ -1728,7 +1728,7 @@ config("clang_revision") {
+ config("clang_warning_suppression") {
+   # Some build configs use older versions of clang that don't support WSMs
+   if (!is_nacl && default_toolchain != "//build/toolchain/cros:target" &&
+-      !llvm_android_mainline && is_clang &&
++      !llvm_android_mainline && is_clang && !skip_clangd_unsupported_options &&
+       clang_warning_suppression_file != "") {
+     from_build_root =
+         rebase_path(clang_warning_suppression_file, root_build_dir)
 @@ -2065,7 +2065,6 @@ config("default_warnings") {
          # TODO(crbug.com/376641662): Fix and re-enable.
          "-Wno-nontrivial-memcall",
@@ -22,23 +40,22 @@ diff --git a/build/config/compiler/BUILD.gn b/build/config/compiler/BUILD.gn
        cflags_cc += [
          # TODO(crbug.com/328490295): Fix and re-enable for C flags.
          "-Wenum-compare-conditional",
-@@ -2091,6 +2090,16 @@ config("default_warnings") {
-       # other issues if the versions are incompatible.
-       cflags += [ "-Wno-version-check" ]
-       ldflags += [ "-Wno-version-check" ]
-+      if (skip_clangd_unsupported_options) {
-+        cflags -= [
-+          "-Wno-thread-safety-reference-return",
-+          "-Wno-nontrivial-memcall",
-+        ]
-+        cflags_cc -= [
-+          "-Wno-c++11-narrowing-const-reference",
-+          "-Wno-missing-template-arg-list-after-template-kw",
-+        ]
-+      }
+@@ -2104,6 +2103,15 @@ config("default_warnings") {
+       ]
      }
  
-     # Some builders, such as Cronet, use a different version of Clang than
++    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