clang: Enable -Wfor-loop-analysis.

build/config/compiler/BUILD.gn

 # Copyright (c) 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/android/config.gni")
 import("//build/config/chrome_build.gni")
 import("//build/config/compiler/compiler.gni")
 import("//build/config/nacl/config.gni")
 import("//build/toolchain/ccache.gni")
 
@@ skipping 812 matching lines @@
   if (!is_win || is_clang) {
     cflags += [
       # Disables.
       "-Wno-missing-field-initializers",  # "struct foo f = {0};"
       "-Wno-unused-parameter",  # Unused function parameters.
     ]
   }
 
   if (is_clang) {
     cflags += [
+      # TODO(thakis): Add -Wfor-loop-analysis to -Wall in clang, remove this:
+      "-Wfor-loop-analysis",
+
+      # TODO(thakis): Consider -Wloop-analysis (turns on
+      # -Wrange-loop-analysis too).
+
       # This warns on using ints as initializers for floats in
       # initializer lists (e.g. |int a = f(); CGSize s = { a, a };|),
       # which happens in several places in chrome code. Not sure if
       # this is worth fixing.
       "-Wno-c++11-narrowing",
 
       # Warns on switches on enums that cover all enum values but
       # also contain a default: branch. Chrome is full of that.
       "-Wno-covered-switch-default",
 
@@ skipping 454 matching lines @@
   if (symbol_level == 0) {
     configs = [ ":no_symbols" ]
   } else if (symbol_level == 1) {
     configs = [ ":minimal_symbols" ]
   } else if (symbol_level == 2) {
     configs = [ ":symbols" ]
   } else {
     assert(false)
   }
 }