-- Allow building pdfium on FreeBSD by treating FreeBSD as a Linux-like
-- target for toolchain selection and default library configuration.
-- Also disable the UBSan array-bounds/return hardening configs, which are not
-- supported by the Clang used for this FreeBSD port and alter test semantics.
--- build/config/BUILDCONFIG.gn.orig	2026-09-24 10:29:01 UTC
+++ build/config/BUILDCONFIG.gn
@@ -222,7 +222,7 @@ if (host_toolchain == "") {
   # TODO(dpranke): Add some sort of assert here that verifies that
   # no toolchain omitted host_toolchain from its toolchain_args().
 
-  if (host_os == "linux") {
+  if (host_os == "linux" || host_os == "freebsd") {
     if (target_os != "linux") {
       host_toolchain = "//build/toolchain/linux:clang_$host_cpu"
     } else if (is_clang) {
@@ -262,7 +262,7 @@ if (target_os == "android") {
   # Targeting android on Mac is best-effort and not guaranteed to work.
   assert(host_os == "linux", "Android builds are only supported on Linux.")
   _default_toolchain = "//build/toolchain/android:android_clang_$target_cpu"
-} else if (target_os == "chromeos" || target_os == "linux") {
+} else if (target_os == "chromeos" || target_os == "linux" || target_os == "freebsd") {
   # See comments in build/toolchain/cros/BUILD.gn about board compiles.
   if (is_clang) {
     _default_toolchain = "//build/toolchain/linux:clang_$target_cpu"
@@ -335,7 +335,7 @@ is_ios = current_os == "ios"
 is_chromeos = current_os == "chromeos"
 is_fuchsia = current_os == "fuchsia"
 is_ios = current_os == "ios"
-is_linux = current_os == "linux"
+is_linux = current_os == "linux" || current_os == "freebsd"
 is_mac = current_os == "mac"
 is_wasm = current_os == "emscripten"
 is_watchos = current_os == "watchos"
@@ -381,8 +381,6 @@ default_compiler_configs = [
   "//build/config/compiler:no_rtti",
   "//build/config/compiler:no_unresolved_symbols",
   "//build/config/compiler:runtime_library",
-  "//build/config/compiler:sanitize_c_array_bounds",
-  "//build/config/compiler:sanitize_return",
   "//build/config/compiler:thin_archive",
   "//build/config/compiler:thinlto_optimize_default",
   "//build/config/compiler:tot_warnings",
@@ -391,6 +389,13 @@ default_compiler_configs = [
   "//build/config:feature_flags",
 ]
 
+if (current_os != "freebsd") {
+  default_compiler_configs += [
+    "//build/config/compiler:sanitize_c_array_bounds",
+    "//build/config/compiler:sanitize_return",
+  ]
+}
+
 if (is_win) {
   default_compiler_configs += [
     "//build/config/win:default_cfg_compiler",
@@ -625,10 +630,6 @@ foreach(_target_type,
         not_needed([ "strict_deps" ])
       }
 
-      if (!defined(generate_modulemap)) {
-        generate_modulemap = default_modulemap_mode
-      }
-
       if (use_libcxx_modules) {
         # Add a dependency needed for Clang modules builds.
         deps += [ "//buildtools/third_party/libc++:all_modules" ]
@@ -759,10 +760,6 @@ foreach(_target_type,
         }
       } else {
         not_needed([ "strict_deps" ])
-      }
-
-      if (!defined(generate_modulemap)) {
-        generate_modulemap = default_modulemap_mode
       }
 
       if (use_libcxx_modules) {