--- chromium-78.0.3904.21/build/config/compiler/BUILD.gn.build-gentoo	2019-09-19 20:50:21.000000000 +0200
+++ chromium-78.0.3904.21/build/config/compiler/BUILD.gn	2019-09-21 21:08:53.313381239 +0200
@@ -250,8 +250,6 @@ config("compiler") {
 
   configs += [
     # See the definitions below.
-    ":clang_revision",
-    ":compiler_cpu_abi",
     ":compiler_codegen",
     ":compiler_deterministic",
   ]
@@ -1436,9 +1434,6 @@ config("default_warnings") {
       # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63872
       cflags += [ "-Wno-unused-local-typedefs" ]
 
-      # Don't warn about "maybe" uninitialized. Clang doesn't include this
-      # in -Wall but gcc does, and it gives false positives.
-      cflags += [ "-Wno-maybe-uninitialized" ]
       cflags += [ "-Wno-deprecated-declarations" ]
 
       # -Wcomment gives too many false positives in the case a
@@ -1492,37 +1487,6 @@ config("default_warnings") {
         # Currently goma can not handle case sensitiveness for windows well.
         cflags += [ "-Wno-nonportable-include-path" ]
       }
-
-      if (current_toolchain == host_toolchain || !use_xcode_clang) {
-        # Flags NaCl (Clang 3.7) and Xcode 9.2 (Clang clang-900.0.39.2) do not
-        # recognize.
-        cflags += [
-          # Ignore warnings about MSVC optimization pragmas.
-          # TODO(thakis): Only for no_chromium_code? http://crbug.com/912662
-          "-Wno-ignored-pragma-optimize",
-
-          # TODO(https://crbug.com/989932): Evaluate and possibly enable.
-          "-Wno-implicit-int-float-conversion",
-
-          # TODO(https://crbug.com/995200): Clean up and enable.
-          "-Wno-xor-used-as-pow",
-
-          # TODO(https://crbug.com/999871): Decide if we want to clean up the
-          # codebase or just disable this.  Doesn't seem super useful, but
-          # also fires in only 4 files.
-          "-Wno-c99-designator",
-
-          # This is a side effect of -Wc99-designator; easier to clean up.
-          "-Wno-reorder-init-list",
-
-          # TODO(https://crbug.com/999886): Clean up, enable.
-          "-Wno-final-dtor-non-final-class",
-        ]
-        cflags_c += [
-          # TODO(https://crbug.com/995993): Clean up and enable.
-          "-Wno-implicit-fallthrough",
-        ]
-      }
     }
   }
 }
@@ -1562,15 +1526,6 @@ config("chromium_code") {
       "__STDC_FORMAT_MACROS",
     ]
 
-    if (!is_debug && !using_sanitizer && current_cpu != "s390x" &&
-        current_cpu != "s390" && current_cpu != "ppc64" &&
-        current_cpu != "mips" && current_cpu != "mips64") {
-      # Non-chromium code is not guaranteed to compile cleanly with
-      # _FORTIFY_SOURCE. Also, fortified build may fail when optimizations are
-      # disabled, so only do that for Release build.
-      defines += [ "_FORTIFY_SOURCE=2" ]
-    }
-
     if (is_mac) {
       cflags_objc = [ "-Wobjc-missing-property-synthesis" ]
       cflags_objcc = [ "-Wobjc-missing-property-synthesis" ]
@@ -1971,7 +1926,8 @@ config("default_stack_frames") {
 }
 
 # Default "optimization on" config.
-config("optimize") {
+config("optimize") { }
+config("xoptimize") {
   if (is_win) {
     # TODO(thakis): Remove is_clang here, https://crbug.com/598772
     if (is_official_build && full_wpo_on_official && !is_clang) {
@@ -1997,7 +1953,8 @@ config("optimize") {
 }
 
 # Same config as 'optimize' but without the WPO flag.
-config("optimize_no_wpo") {
+config("optimize_no_wpo") { }
+config("xoptimize_no_wpo") {
   if (is_win) {
     # Favor size over speed, /O1 must be before the common flags. The GYP
     # build also specifies /Os and /GF but these are implied by /O1.
@@ -2020,7 +1977,8 @@ config("optimize_no_wpo") {
 }
 
 # Turn off optimizations.
-config("no_optimize") {
+config("no_optimize") { }
+config("xno_optimize") {
   if (is_win) {
     cflags = [
       "/Od",  # Disable optimization.
@@ -2048,7 +2006,8 @@ config("no_optimize") {
 # Turns up the optimization level. On Windows, this implies whole program
 # optimization and link-time code generation which is very expensive and should
 # be used sparingly.
-config("optimize_max") {
+config("optimize_max") { }
+config("xoptimize_max") {
   if (is_nacl && is_nacl_irt) {
     # The NaCl IRT is a special case and always wants its own config.
     # Various components do:
@@ -2087,7 +2046,8 @@ config("optimize_max") {
 #
 # TODO(crbug.com/621335) - rework how all of these configs are related
 # so that we don't need this disclaimer.
-config("optimize_speed") {
+config("optimize_speed") { }
+config("xoptimize_speed") {
   if (is_nacl && is_nacl_irt) {
     # The NaCl IRT is a special case and always wants its own config.
     # Various components do:
@@ -2117,7 +2077,8 @@ config("optimize_speed") {
   }
 }
 
-config("optimize_fuzzing") {
+config("optimize_fuzzing") { }
+config("xoptimize_fuzzing") {
   cflags = [ "-O1" ] + common_optimize_on_cflags
   ldflags = common_optimize_on_ldflags
   visibility = [ ":default_optimization" ]
@@ -2219,7 +2180,8 @@ config("win_pdbaltpath") {
 }
 
 # Full symbols.
-config("symbols") {
+config("symbols") { }
+config("xsymbols") {
   if (is_win) {
     if (use_goma || is_clang) {
       # Note that with VC++ this requires is_win_fastlink, enforced elsewhere.
@@ -2329,7 +2291,8 @@ config("symbols") {
 # Minimal symbols.
 # This config guarantees to hold symbol for stack trace which are shown to user
 # when crash happens in unittests running on buildbot.
-config("minimal_symbols") {
+config("minimal_symbols") { }
+config("xminimal_symbols") {
   if (is_win) {
     # Functions, files, and line tables only.
     cflags = []
@@ -2384,7 +2347,8 @@ config("minimal_symbols") {
 }
 
 # No symbols.
-config("no_symbols") {
+config("no_symbols") { }
+config("xno_symbols") {
   if (!is_win) {
     cflags = [ "-g0" ]
     asmflags = cflags