src/third_party/chromium/src/build/config/compiler/BUILD.gn - incubator-pagespeed-debian - Git at Google

 # 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")
 if (cpu_arch == "arm") {
   import("//build/config/arm.gni")
 }

 # compiler ---------------------------------------------------------------------
 #
 # Base compiler configuration.
 #
 # See also "runtime_library" below for related stuff and a discusison about
 # where stuff should go. Put warning related stuff in the "warnings" config.

 config("compiler") {
   cflags = []
   cflags_c = []
   cflags_cc = []
   ldflags = []
   defines = []
   include_dirs = []

   include_dirs += [ "//", root_gen_dir ]

   # In general, Windows is totally different, but all the other builds share
   # some common GCC configuration. This section sets up Windows and the common
   # GCC flags, and then we handle the other non-Windows platforms specifically
   # below.
   if (is_win) {
     # Windows compiler flags setup.
     # -----------------------------
     cflags += [
       "/Gy",  # Enable function-level linking.
       "/GS",  # Enable buffer security checking.
       "/EHsc",  # Assume C functions can't throw exceptions and don't catch
                 # structured exceptions (only C++ ones).
     ]
   } else {
     # Common GCC compiler flags setup.
     # --------------------------------
     cflags += [
       "-fno-strict-aliasing",  # See http://crbug.com/32204
       "-fvisibility=hidden",
     ]
     cflags_cc += [
       "-fno-exceptions",
       "-fno-threadsafe-statics",
       "-fvisibility-inlines-hidden",
     ]

     # Stack protection.
     if (is_mac) {
       cflags += [ "-fstack-protector-all" ]
     } else if (is_linux) {
       cflags += [ "-fstack-protector", "--param=ssp-buffer-size=4" ]
     }
   }

   # Mac-specific compiler flags setup.
   # ----------------------------------
   if (is_mac || is_ios) {
     # These flags are shared between the C compiler and linker.
     common_mac_flags = []

     # CPU architecture.
     if (cpu_arch == "x64") {
       common_mac_flags += [ "-arch x86_64" ]
     } else if (cpu_arch == "x86") {
       common_mac_flags += [ "-arch i386" ]
     }

     cflags += common_mac_flags

     # Without this, the constructors and destructors of a C++ object inside
     # an Objective C struct won't be called, which is very bad.
     cflags_objcc = [ "-fobjc-call-cxx-cdtors", ]

     cflags_c += [ "-std=c99" ]
     cflags_cc += [ "-std=gnu++11" ]

     ldflags += common_mac_flags
   } else if (is_posix) {
     # Non-Mac Posix compiler flags setup.
     # -----------------------------------

     # CPU architecture. We may or may not be doing a cross compile now, so for
     # simplicity we always explicitly set the architecture.
     if (cpu_arch == "x64") {
       cflags += [ "-m64" ]
       ldflags += [ "-m64" ]
     } else if (cpu_arch == "x86") {
       cflags += [ "-m32" ]
       ldflags += [ "-m32" ]
     } else if (cpu_arch == "arm") {
       # Don't set the compiler flags for the WebView build. These will come
       # from the Android build system.
       if (!is_android_webview_build) {
         cflags += [
           "-march=$arm_arch",
           "-mfpu=$arm_fpu",
           "-mfloat-abi=$arm_float_abi",
         ]
         if (arm_tune != "") {
           cflags += [ "-mtune=$arm_tune" ]
         }
         if (arm_use_thumb) {
           cflags += [ "-mthumb" ]
           if (is_android && !is_clang) {  # Clang doesn't support this option.
             cflags += [ "-mthumb-interwork" ]
           }
         }
       }
     }

     defines += [ "_FILE_OFFSET_BITS=64" ]

     # Omit unwind support in official builds to save space. We can use breakpad
     # for these builds.
     if (is_chrome_branded && is_official_build) {
       cflags += [
         "-fno-unwind-tables",
         "-fno-asynchronous-unwind-tables",
       ]
     } else {
       cflags += [ "-funwind-tables" ]
     }
   }

   # Linux-specific compiler flags setup.
   # ------------------------------------
   if (is_linux) {
     cflags += [
       "-fPIC",
       "-pipe",  # Use pipes for communicating between sub-processes. Faster.
     ]
     if (!is_android) {
       cflags += [ "-pthread" ]
     }

     if (cpu_arch == "x64") {
       # Use gold for linking on 64-bit Linux only (on 32-bit it runs out of
       # address space, and it doesn't support cross-compiling).
       gold_path = rebase_path("//third_party/gold", root_build_dir)
       ldflags += [
         "-B$gold_path",

         # There seems to be a conflict of --icf and -pie in gold which can
         # generate crashy binaries. As a security measure, -pie takes
         # precendence for now.
         # TODO(brettw) common.gypi has this only for target toolset.
         #"-Wl,--icf=safe",
         "-Wl,--icf=none",

         # Experimentation found that using four linking threads
         # saved ~20% of link time.
         # https://groups.google.com/a/chromium.org/group/chromium-dev/browse_thread/thread/281527606915bb36
         # Only apply this to the target linker, since the host
         # linker might not be gold, but isn't used much anyway.
         # TODO(raymes): Disable threading because gold is frequently
         # crashing on the bots: crbug.com/161942.
         #"-Wl,--threads",
         #"-Wl,--thread-count=4",
       ]
     }

     ldflags += [
       "-fPIC",
       "-pthread",
       "-Wl,-z,noexecstack",
       "-Wl,-z,now",
       "-Wl,-z,relro",
     ]
   }

   # Clang-specific compiler flags setup.
   # ------------------------------------
   if (is_clang) {
     cflags += [
       "-fcolor-diagnostics",
     ]
     cflags_cc += [
       "-std=gnu++11",
     ]
   }

   # Android-specific flags setup.
   # -----------------------------
   if (is_android) {
     cflags += [
       "-ffunction-sections",
       "-funwind-tables",
       "-fno-short-enums",
     ]
     if (!is_clang) {
       # Clang doesn't support this one.
       cflags += [ "-finline-limit=64" ]
     }
     if (is_android_webview_build) {
       # Android predefines this as 1; undefine it here so Chromium can redefine
       # it later to be 2 for chromium code and unset for third party code. This
       # works because cflags are added before defines.
       # TODO(brettw) the above comment seems incorrect. We specify defines
       # before cflags on our compiler command lines.
       cflags += [ "-U_FORTIFY_SOURCE" ]
     }

     if (is_asan) {
       # Android build relies on -Wl,--gc-sections removing unreachable code.
       # ASan instrumentation for globals inhibits this and results in a library
       # with unresolvable relocations.
       # TODO(eugenis): find a way to reenable this.
       cflags += [ "-mllvm -asan-globals=0" ]
     }

     defines += [ "ANDROID" ]
     if (!is_android_webview_build) {
       # The NDK has these things, but doesn't define the constants
       # to say that it does. Define them here instead.
       defines += [ "HAVE_SYS_UIO_H" ]
     }

     ldflags += [
       "-Wl,--no-undefined",
       # Don't export symbols from statically linked libraries.
       "-Wl,--exclude-libs=ALL",
     ]
     if (cpu_arch == "arm") {
       ldflags += [
         # Enable identical code folding to reduce size.
         "-Wl,--icf=safe",
       ]
     }

     if (is_clang) {
       if (cpu_arch == "arm") {
         cflags += [
           "-target arm-linux-androideabi",
           "-mllvm -arm-enable-ehabi",
         ]
         ldflags += [ "-target arm-linux-androideabi" ]
       } else if (cpu_arch == "x86") {
         cflags += [ "-target x86-linux-androideabi" ]
         ldflags += [ "-target x86-linux-androideabi" ]
       }
     }
   }
 }

 # runtime_library -------------------------------------------------------------
 #
 # Sets the runtime library and associated options.
 #
 # How do you determine what should go in here vs. "compiler" above? Consider if
 # a target might choose to use a different runtime library (ignore for a moment
 # if this is possible or reasonable on your system). If such a target would want
 # to change or remove your option, put it in the runtime_library config. If a
 # target wants the option regardless, put it in the compiler config.

 config("runtime_library") {
   cflags = []
   defines = []
   ldflags = []
   lib_dirs = []
   libs = []

   if (is_component_build) {
     # Component mode: dynamic CRT.
     defines += [ "COMPONENT_BUILD" ]
     if (is_win) {
       # Since the library is shared, it requires exceptions or will give errors
       # about things not matching, so keep exceptions on.
       if (is_debug) {
         cflags += [ "/MDd" ]
       } else {
         cflags += [ "/MD" ]
       }
     }
   } else {
     # Static CRT.
     if (is_win) {
       # We don't use exceptions, and when we link statically we can just get
       # rid of them entirely.
       defines += [ "_HAS_EXCEPTIONS=0" ]
       if (is_debug) {
         cflags += [ "/MTd" ]
       } else {
         cflags += [ "/MT" ]
       }
     }
   }

   if (is_win) {
     defines += [
       "__STD_C",
       "__STDC_CONSTANT_MACROS",
       "__STDC_FORMAT_MACROS",
       "_CRT_RAND_S",
       "_CRT_SECURE_NO_DEPRECATE",
       "_SCL_SECURE_NO_DEPRECATE",
       "_UNICODE",
       "UNICODE",
     ]
   }

   # Stlport setup. Android uses a different (smaller) version of the STL.
   if (is_android) {
     if (is_clang) {
       # Work around incompatibilities between bionic and clang headers.
       defines += [
         "__compiler_offsetof=__builtin_offsetof",
         "nan=__builtin_nan",
       ]
     }

     defines += [
       "USE_STLPORT=1",
       "_STLP_USE_PTR_SPECIALIZATIONS=1",
       "__GNU_SOURCE=1",  # Necessary for clone().
     ]

     ldflags += [
       "-nostdlib",
     ]


     # NOTE: The stlport header include paths below are specified in cflags
     # rather than include_dirs because they need to come after include_dirs.
     # Think of them like system headers, but don't use '-isystem' because the
     # arm-linux-androideabi-4.4.3 toolchain (circa Gingerbread) will exhibit
     # strange errors. The include ordering here is important; change with
     # caution.
     if (use_system_stlport) {
       cflags += [
         # For libstdc++/include, which is used by stlport.
         "-I$android_src/bionic",
         "-I$android_src/external/stlport/stlport",
       ]
       libs += [
         "stlport",
       ]
     } else {
       android_stlport_root = "$android_ndk_root/sources/cxx-stl/stlport"

       cflags += [ "-I$android_stlport_root/stlport" ]
       lib_dirs += [ "$android_stlport_root/libs/$android_app_abi" ]

       if (component_mode == "shared_library") {
         libs += [ "stlport_shared" ]
       } else {
         libs += [ "stlport_static" ]
       }
     }
   }
 }

 # chromium_code ---------------------------------------------------------------
 #
 # Toggles between higher and lower warnings for code that is (or isn't)
 # part of Chromium.

 config("chromium_code") {
   if (is_win) {
     cflags = [
       "/W4",  # Warning level 4.
       "/WX",  # Treat warnings as errors.
     ]
   } else {
     cflags = [
       "-Wall",
       "-Werror",

       # GCC turns on -Wsign-compare for C++ under -Wall, but clang doesn't,
       # so we specify it explicitly.
       # TODO(fischman): remove this if http://llvm.org/PR10448 obsoletes it.
       # http://code.google.com/p/chromium/issues/detail?id=90453
       "-Wsign-compare",
     ]

     # In Chromium code, we define __STDC_foo_MACROS in order to get the
     # C99 macros on Mac and Linux.
     defines = [
       "__STDC_CONSTANT_MACROS",
       "__STDC_FORMAT_MACROS",
     ]

     # TODO(brettw) this should also be enabled on Linux but some files
     # currently fail.
     if (is_mac) {
       cflags += [ "-Wextra" ]
     }
   }
 }
 config("no_chromium_code") {
   cflags = []
   cflags_cc = []
   defines = []

   if (is_win) {
     cflags += [
       "/W3",  # Warning level 3.
       "/wd4800",  # Disable warning when forcing value to bool.
     ]
     defines += [
       "_CRT_NONSTDC_NO_WARNINGS",
       "_CRT_NONSTDC_NO_DEPRECATE",
     ]
   }

   if (is_linux) {
     # Don't warn about ignoring the return value from e.g. close(). This is
     # off by default in some gccs but on by default in others. BSD systems do
     # not support this option, since they are usually using gcc 4.2.1, which
     # does not have this flag yet.
     cflags += [ "-Wno-unused-result" ]
   }

   if (is_linux || is_android) {
     cflags += [
       # Don't warn about printf format problems. This is off by default in gcc
       # but on in Ubuntu's gcc(!).
       "-Wno-format",
     ]
     cflags_cc += [
       # Don't warn about hash_map in third-party code.
       "-Wno-deprecated",
     ]
   }

   if (is_android_webview_build) {
     # There is a class of warning which:
     #  1) Android always enables and also treats as errors
     #  2) Chromium ignores in third party code
     # So we re-enable those warnings when building Android.
     cflags += [
       "-Wno-address",
       "-Wno-format-security",
       "-Wno-return-type",
       "-Wno-sequence-point",
     ]
     cflags_cc += [ "-Wno-non-virtual-dtor" ]
   }
 }

 # rtti ------------------------------------------------------------------------
 #
 # Allows turning Run-Time Type Identification on or off.

 config("rtti") {
   if (is_win) {
     cflags_cc = [ "/GR" ]
   }
 }
 config("no_rtti") {
   if (is_win) {
     cflags_cc = [ "/GR-" ]
   } else {
     cflags_cc = [ "-fno-rtti" ]
   }
 }

 # Warnings ---------------------------------------------------------------------
 #
 # This is where we disable various warnings that we've decided aren't
 # worthwhile, and enable special warnings.

 config("default_warnings") {
   if (is_win) {
     # Please keep ordered and add names if you add more.
     cflags = [
       "/wd4018",  # Comparing signed and unsigned values.
       "/wd4100",  # Unreferenced formal function parameter.
       "/wd4121",  # Alignment of a member was sensitive to packing.
       "/wd4125",  # Decimal digit terminates octal escape sequence.
       "/wd4127",  # Conditional expression is constant.
       "/wd4130",  # Logical operation on address of string constant.
       "/wd4189",  # A variable was declared and initialized but never used.
       "/wd4201",  # Nonstandard extension used: nameless struct/union.
       "/wd4238",  # Nonstandard extension used: class rvalue used as lvalue.
       "/wd4244",  # Conversion: possible loss of data.
       "/wd4245",  # Conversion: signed/unsigned mismatch,
       "/wd4251",  # Class needs to have dll-interface.
       "/wd4310",  # Cast truncates constant value.
       "/wd4351",  # Elements of array will be default initialized.
       "/wd4355",  # 'this' used in base member initializer list.
       "/wd4396",  # Inline friend template thing.
       "/wd4428",  # Universal character name encountered in source.
       "/wd4481",  # Nonstandard extension: override specifier.
       "/wd4503",  # Decorated name length exceeded, name was truncated.
       "/wd4505",  # Unreferenced local function has been removed.
       "/wd4510",  # Default constructor could not be generated.
       "/wd4512",  # Assignment operator could not be generated.
       "/wd4530",  # Exception handler used, but unwind semantics not enabled.
       "/wd4610",  # Class can never be instantiated, constructor required.
       "/wd4611",  # C++ object destruction and 'catch'.
       "/wd4701",  # Potentially uninitialized local variable name used.
       "/wd4702",  # Unreachable code.
       "/wd4706",  # Assignment within conditional expression.
       "/wd4819",  # Character not in the current code page.
     ]
   } else {
     # Common GCC warning setup.
     cflags = [
       # Enables.
       "-Wendif-labels",  # Weird old-style text after an #endif.

       # Disables.
       "-Wno-missing-field-initializers",  # "struct foo f = {0};"
       "-Wno-unused-parameter",  # Unused function parameters.
     ]

     if (is_mac) {
       cflags += [
         "-Wnewline-eof",
       ]
     }

     # TODO(brettw) Ones below here should be clang-only when we have a flag
     # for it.
     if (is_clang) {
       cflags += [
         "-Wheader-hygiene",

         # 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",

         # Don't die on dtoa code that uses a char as an array index.
         # This is required solely for base/third_party/dmg_fp/dtoa.cc.
         # TODO(brettw) move this to that project then!
         "-Wno-char-subscripts",

         # 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",

         # Clang considers the `register` keyword as deprecated, but e.g.
         # code generated by flex (used in angle) contains that keyword.
         # http://crbug.com/255186
         "-Wno-deprecated-register",

         # Clang spots more unused functions.
         "-Wno-unused-function",

         # Warns when a const char[] is converted to bool.
         "-Wstring-conversion",
       ]
     }

     if (is_android) {
       # Disable any additional warnings enabled by the Android build system but
       # which chromium does not build cleanly with (when treating warning as
       # errors).
       cflags += [
         "-Wno-extra",
         "-Wno-ignored-qualifiers",
         "-Wno-type-limits",
       ]
       cflags_cc = [
         # Disabling c++0x-compat should be handled in WebKit, but
         # this currently doesn't work because gcc_version is not set
         # correctly when building with the Android build system.
         # TODO(torne): Fix this in WebKit.
         "-Wno-error=c++0x-compat",
         # Other things unrelated to -Wextra:
         "-Wno-non-virtual-dtor",
         "-Wno-sign-promo",
       ]
     }
   }
 }

 # This will generate warnings when using Clang if code generates exit-time
 # destructors, which will slow down closing the program.
 # TODO(thakis): Make this a blacklist instead, http://crbug.com/101600
 config("wexit_time_destructors") {
   if (is_clang) {
     cflags = [ "-Wexit-time-destructors" ]
   }
 }

 # Optimization -----------------------------------------------------------------
 #
 # Note that BUILDCONFIG.gn sets up a variable "default_optimization_config"
 # which it will assign to the config it implicitly applies to every target. If
 # you want to override the optimization level for your target, remove this
 # config (which will expand differently for debug or release builds), and then
 # add back the one you want to override it with:
 #
 #   configs -= default_optimization_config
 #   configs += [ "//build/config/compiler/optimize_max" ]

 # Default "optimization on" config. On Windows, this favors size over speed.
 #
 # IF YOU CHANGE THIS also consider whether optimize_max should be updated.
 config("optimize") {
   if (is_win) {
     cflags = [
       "/O2",
       "/Ob2",  # Both explicit and auto inlining.
       "/Oy-",  # Disable omitting frame pointers, must be after /O2.
       "/Os",   # Favor size over speed.
     ]
   } else {
     if (is_ios) {
       cflags = [ "-Os" ]
     } else {
       cflags = [ "-O2" ]
     }
   }
 }

 # Turn off optimizations.
 config("no_optimize") {
   if (is_win) {
     cflags = [
       "/Od",  # Disable optimization.
       "/Ob0",  # Disable all inlining (on by default).
       "/RTC1",  # Runtime checks for stack frame and uninitialized variables.
     ]
   } else {
     cflags = [ "-O0" ]
   }
 }

 # On Windows, turns up the optimization level. This implies whole program
 # optimization and link-time code generation which is very expensive and should
 # be used sparingly. For non-Windows, this is the same as "optimize".
 config("optimize_max") {
   if (is_win) {
     cflags = [
       "/O2",
       "/Ob2",  # Both explicit and auto inlining.
       "/Oy-",  # Disable omitting frame pointers, must be after /O2.
       "/Ot",   # Favor speed over size.
       "/GL",   # Whole program optimization.
     ]
   } else {
     if (is_ios) {
       cflags = [ "-Os" ]
     } else {
       cflags = [ "-O2" ]
     }
   }
 }

 # Symbols ----------------------------------------------------------------------

 # TODO(brettw) Since this sets ldflags on Windows which is inherited across
 # static library boundaries, if you want to remove the default symbol config
 # and set a different one on a target, you also have to do it for all static
 # libraries that go into that target, which is messed up. Either we need a
 # more flexible system for defining linker flags, or we need to separate this
 # out into a "symbols_linker" config that is only applied to DLLs and EXEs.
 config("symbols") {
   if (is_win) {
     cflags = [ "/Zi" ]  # Produce PDB file, no edit and continue.
     ldflags = [ "/DEBUG" ]
   } else {
     cflags = [ "-g2" ]
   }
 }

 config("minimal_symbols") {
   if (is_win) {
     # Linker symbols for backtraces only.
     ldflags = [ "/DEBUG" ]
   } else {
     cflags = [ "-g1" ]
   }
 }

 config("no_symbols") {
   if (!is_win) {
     cflags = [ "-g0" ]
   }
 }
	# 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")
	if (cpu_arch == "arm") {
	import("//build/config/arm.gni")
	}

	# compiler ---------------------------------------------------------------------
	#
	# Base compiler configuration.
	#
	# See also "runtime_library" below for related stuff and a discusison about
	# where stuff should go. Put warning related stuff in the "warnings" config.

	config("compiler") {
	cflags = []
	cflags_c = []
	cflags_cc = []
	ldflags = []
	defines = []
	include_dirs = []

	include_dirs += [ "//", root_gen_dir ]

	# In general, Windows is totally different, but all the other builds share
	# some common GCC configuration. This section sets up Windows and the common
	# GCC flags, and then we handle the other non-Windows platforms specifically
	# below.
	if (is_win) {
	# Windows compiler flags setup.
	# -----------------------------
	cflags += [
	"/Gy", # Enable function-level linking.
	"/GS", # Enable buffer security checking.
	"/EHsc", # Assume C functions can't throw exceptions and don't catch
	# structured exceptions (only C++ ones).
	]
	} else {
	# Common GCC compiler flags setup.
	# --------------------------------
	cflags += [
	"-fno-strict-aliasing", # See http://crbug.com/32204
	"-fvisibility=hidden",
	]
	cflags_cc += [
	"-fno-exceptions",
	"-fno-threadsafe-statics",
	"-fvisibility-inlines-hidden",
	]

	# Stack protection.
	if (is_mac) {
	cflags += [ "-fstack-protector-all" ]
	} else if (is_linux) {
	cflags += [ "-fstack-protector", "--param=ssp-buffer-size=4" ]
	}
	}

	# Mac-specific compiler flags setup.
	# ----------------------------------
	if (is_mac \|\| is_ios) {
	# These flags are shared between the C compiler and linker.
	common_mac_flags = []

	# CPU architecture.
	if (cpu_arch == "x64") {
	common_mac_flags += [ "-arch x86_64" ]
	} else if (cpu_arch == "x86") {
	common_mac_flags += [ "-arch i386" ]
	}

	cflags += common_mac_flags

	# Without this, the constructors and destructors of a C++ object inside
	# an Objective C struct won't be called, which is very bad.
	cflags_objcc = [ "-fobjc-call-cxx-cdtors", ]

	cflags_c += [ "-std=c99" ]
	cflags_cc += [ "-std=gnu++11" ]

	ldflags += common_mac_flags
	} else if (is_posix) {
	# Non-Mac Posix compiler flags setup.
	# -----------------------------------

	# CPU architecture. We may or may not be doing a cross compile now, so for
	# simplicity we always explicitly set the architecture.
	if (cpu_arch == "x64") {
	cflags += [ "-m64" ]
	ldflags += [ "-m64" ]
	} else if (cpu_arch == "x86") {
	cflags += [ "-m32" ]
	ldflags += [ "-m32" ]
	} else if (cpu_arch == "arm") {
	# Don't set the compiler flags for the WebView build. These will come
	# from the Android build system.
	if (!is_android_webview_build) {
	cflags += [
	"-march=$arm_arch",
	"-mfpu=$arm_fpu",
	"-mfloat-abi=$arm_float_abi",
	]
	if (arm_tune != "") {
	cflags += [ "-mtune=$arm_tune" ]
	}
	if (arm_use_thumb) {
	cflags += [ "-mthumb" ]
	if (is_android && !is_clang) { # Clang doesn't support this option.
	cflags += [ "-mthumb-interwork" ]
	}
	}
	}
	}

	defines += [ "_FILE_OFFSET_BITS=64" ]

	# Omit unwind support in official builds to save space. We can use breakpad
	# for these builds.
	if (is_chrome_branded && is_official_build) {
	cflags += [
	"-fno-unwind-tables",
	"-fno-asynchronous-unwind-tables",
	]
	} else {
	cflags += [ "-funwind-tables" ]
	}
	}

	# Linux-specific compiler flags setup.
	# ------------------------------------
	if (is_linux) {
	cflags += [
	"-fPIC",
	"-pipe", # Use pipes for communicating between sub-processes. Faster.
	]
	if (!is_android) {
	cflags += [ "-pthread" ]
	}

	if (cpu_arch == "x64") {
	# Use gold for linking on 64-bit Linux only (on 32-bit it runs out of
	# address space, and it doesn't support cross-compiling).
	gold_path = rebase_path("//third_party/gold", root_build_dir)
	ldflags += [
	"-B$gold_path",

	# There seems to be a conflict of --icf and -pie in gold which can
	# generate crashy binaries. As a security measure, -pie takes
	# precendence for now.
	# TODO(brettw) common.gypi has this only for target toolset.
	#"-Wl,--icf=safe",
	"-Wl,--icf=none",

	# Experimentation found that using four linking threads
	# saved ~20% of link time.
	# https://groups.google.com/a/chromium.org/group/chromium-dev/browse_thread/thread/281527606915bb36
	# Only apply this to the target linker, since the host
	# linker might not be gold, but isn't used much anyway.
	# TODO(raymes): Disable threading because gold is frequently
	# crashing on the bots: crbug.com/161942.
	#"-Wl,--threads",
	#"-Wl,--thread-count=4",
	]
	}

	ldflags += [
	"-fPIC",
	"-pthread",
	"-Wl,-z,noexecstack",
	"-Wl,-z,now",
	"-Wl,-z,relro",
	]
	}

	# Clang-specific compiler flags setup.
	# ------------------------------------
	if (is_clang) {
	cflags += [
	"-fcolor-diagnostics",
	]
	cflags_cc += [
	"-std=gnu++11",
	]
	}

	# Android-specific flags setup.
	# -----------------------------
	if (is_android) {
	cflags += [
	"-ffunction-sections",
	"-funwind-tables",
	"-fno-short-enums",
	]
	if (!is_clang) {
	# Clang doesn't support this one.
	cflags += [ "-finline-limit=64" ]
	}
	if (is_android_webview_build) {
	# Android predefines this as 1; undefine it here so Chromium can redefine
	# it later to be 2 for chromium code and unset for third party code. This
	# works because cflags are added before defines.
	# TODO(brettw) the above comment seems incorrect. We specify defines
	# before cflags on our compiler command lines.
	cflags += [ "-U_FORTIFY_SOURCE" ]
	}

	if (is_asan) {
	# Android build relies on -Wl,--gc-sections removing unreachable code.
	# ASan instrumentation for globals inhibits this and results in a library
	# with unresolvable relocations.
	# TODO(eugenis): find a way to reenable this.
	cflags += [ "-mllvm -asan-globals=0" ]
	}

	defines += [ "ANDROID" ]
	if (!is_android_webview_build) {
	# The NDK has these things, but doesn't define the constants
	# to say that it does. Define them here instead.
	defines += [ "HAVE_SYS_UIO_H" ]
	}

	ldflags += [
	"-Wl,--no-undefined",
	# Don't export symbols from statically linked libraries.
	"-Wl,--exclude-libs=ALL",
	]
	if (cpu_arch == "arm") {
	ldflags += [
	# Enable identical code folding to reduce size.
	"-Wl,--icf=safe",
	]
	}

	if (is_clang) {
	if (cpu_arch == "arm") {
	cflags += [
	"-target arm-linux-androideabi",
	"-mllvm -arm-enable-ehabi",
	]
	ldflags += [ "-target arm-linux-androideabi" ]
	} else if (cpu_arch == "x86") {
	cflags += [ "-target x86-linux-androideabi" ]
	ldflags += [ "-target x86-linux-androideabi" ]
	}
	}
	}
	}

	# runtime_library -------------------------------------------------------------
	#
	# Sets the runtime library and associated options.
	#
	# How do you determine what should go in here vs. "compiler" above? Consider if
	# a target might choose to use a different runtime library (ignore for a moment
	# if this is possible or reasonable on your system). If such a target would want
	# to change or remove your option, put it in the runtime_library config. If a
	# target wants the option regardless, put it in the compiler config.

	config("runtime_library") {
	cflags = []
	defines = []
	ldflags = []
	lib_dirs = []
	libs = []

	if (is_component_build) {
	# Component mode: dynamic CRT.
	defines += [ "COMPONENT_BUILD" ]
	if (is_win) {
	# Since the library is shared, it requires exceptions or will give errors
	# about things not matching, so keep exceptions on.
	if (is_debug) {
	cflags += [ "/MDd" ]
	} else {
	cflags += [ "/MD" ]
	}
	}
	} else {
	# Static CRT.
	if (is_win) {
	# We don't use exceptions, and when we link statically we can just get
	# rid of them entirely.
	defines += [ "_HAS_EXCEPTIONS=0" ]
	if (is_debug) {
	cflags += [ "/MTd" ]
	} else {
	cflags += [ "/MT" ]
	}
	}
	}

	if (is_win) {
	defines += [
	"__STD_C",
	"__STDC_CONSTANT_MACROS",
	"__STDC_FORMAT_MACROS",
	"_CRT_RAND_S",
	"_CRT_SECURE_NO_DEPRECATE",
	"_SCL_SECURE_NO_DEPRECATE",
	"_UNICODE",
	"UNICODE",
	]
	}

	# Stlport setup. Android uses a different (smaller) version of the STL.
	if (is_android) {
	if (is_clang) {
	# Work around incompatibilities between bionic and clang headers.
	defines += [
	"__compiler_offsetof=__builtin_offsetof",
	"nan=__builtin_nan",
	]
	}

	defines += [
	"USE_STLPORT=1",
	"_STLP_USE_PTR_SPECIALIZATIONS=1",
	"__GNU_SOURCE=1", # Necessary for clone().
	]

	ldflags += [
	"-nostdlib",
	]


	# NOTE: The stlport header include paths below are specified in cflags
	# rather than include_dirs because they need to come after include_dirs.
	# Think of them like system headers, but don't use '-isystem' because the
	# arm-linux-androideabi-4.4.3 toolchain (circa Gingerbread) will exhibit
	# strange errors. The include ordering here is important; change with
	# caution.
	if (use_system_stlport) {
	cflags += [
	# For libstdc++/include, which is used by stlport.
	"-I$android_src/bionic",
	"-I$android_src/external/stlport/stlport",
	]
	libs += [
	"stlport",
	]
	} else {
	android_stlport_root = "$android_ndk_root/sources/cxx-stl/stlport"

	cflags += [ "-I$android_stlport_root/stlport" ]
	lib_dirs += [ "$android_stlport_root/libs/$android_app_abi" ]

	if (component_mode == "shared_library") {
	libs += [ "stlport_shared" ]
	} else {
	libs += [ "stlport_static" ]
	}
	}
	}
	}

	# chromium_code ---------------------------------------------------------------
	#
	# Toggles between higher and lower warnings for code that is (or isn't)
	# part of Chromium.

	config("chromium_code") {
	if (is_win) {
	cflags = [
	"/W4", # Warning level 4.
	"/WX", # Treat warnings as errors.
	]
	} else {
	cflags = [
	"-Wall",
	"-Werror",

	# GCC turns on -Wsign-compare for C++ under -Wall, but clang doesn't,
	# so we specify it explicitly.
	# TODO(fischman): remove this if http://llvm.org/PR10448 obsoletes it.
	# http://code.google.com/p/chromium/issues/detail?id=90453
	"-Wsign-compare",
	]

	# In Chromium code, we define __STDC_foo_MACROS in order to get the
	# C99 macros on Mac and Linux.
	defines = [
	"__STDC_CONSTANT_MACROS",
	"__STDC_FORMAT_MACROS",
	]

	# TODO(brettw) this should also be enabled on Linux but some files
	# currently fail.
	if (is_mac) {
	cflags += [ "-Wextra" ]
	}
	}
	}
	config("no_chromium_code") {
	cflags = []
	cflags_cc = []
	defines = []

	if (is_win) {
	cflags += [
	"/W3", # Warning level 3.
	"/wd4800", # Disable warning when forcing value to bool.
	]
	defines += [
	"_CRT_NONSTDC_NO_WARNINGS",
	"_CRT_NONSTDC_NO_DEPRECATE",
	]
	}

	if (is_linux) {
	# Don't warn about ignoring the return value from e.g. close(). This is
	# off by default in some gccs but on by default in others. BSD systems do
	# not support this option, since they are usually using gcc 4.2.1, which
	# does not have this flag yet.
	cflags += [ "-Wno-unused-result" ]
	}

	if (is_linux \|\| is_android) {
	cflags += [
	# Don't warn about printf format problems. This is off by default in gcc
	# but on in Ubuntu's gcc(!).
	"-Wno-format",
	]
	cflags_cc += [
	# Don't warn about hash_map in third-party code.
	"-Wno-deprecated",
	]
	}

	if (is_android_webview_build) {
	# There is a class of warning which:
	# 1) Android always enables and also treats as errors
	# 2) Chromium ignores in third party code
	# So we re-enable those warnings when building Android.
	cflags += [
	"-Wno-address",
	"-Wno-format-security",
	"-Wno-return-type",
	"-Wno-sequence-point",
	]
	cflags_cc += [ "-Wno-non-virtual-dtor" ]
	}
	}

	# rtti ------------------------------------------------------------------------
	#
	# Allows turning Run-Time Type Identification on or off.

	config("rtti") {
	if (is_win) {
	cflags_cc = [ "/GR" ]
	}
	}
	config("no_rtti") {
	if (is_win) {
	cflags_cc = [ "/GR-" ]
	} else {
	cflags_cc = [ "-fno-rtti" ]
	}
	}

	# Warnings ---------------------------------------------------------------------
	#
	# This is where we disable various warnings that we've decided aren't
	# worthwhile, and enable special warnings.

	config("default_warnings") {
	if (is_win) {
	# Please keep ordered and add names if you add more.
	cflags = [
	"/wd4018", # Comparing signed and unsigned values.
	"/wd4100", # Unreferenced formal function parameter.
	"/wd4121", # Alignment of a member was sensitive to packing.
	"/wd4125", # Decimal digit terminates octal escape sequence.
	"/wd4127", # Conditional expression is constant.
	"/wd4130", # Logical operation on address of string constant.
	"/wd4189", # A variable was declared and initialized but never used.
	"/wd4201", # Nonstandard extension used: nameless struct/union.
	"/wd4238", # Nonstandard extension used: class rvalue used as lvalue.
	"/wd4244", # Conversion: possible loss of data.
	"/wd4245", # Conversion: signed/unsigned mismatch,
	"/wd4251", # Class needs to have dll-interface.
	"/wd4310", # Cast truncates constant value.
	"/wd4351", # Elements of array will be default initialized.
	"/wd4355", # 'this' used in base member initializer list.
	"/wd4396", # Inline friend template thing.
	"/wd4428", # Universal character name encountered in source.
	"/wd4481", # Nonstandard extension: override specifier.
	"/wd4503", # Decorated name length exceeded, name was truncated.
	"/wd4505", # Unreferenced local function has been removed.
	"/wd4510", # Default constructor could not be generated.
	"/wd4512", # Assignment operator could not be generated.
	"/wd4530", # Exception handler used, but unwind semantics not enabled.
	"/wd4610", # Class can never be instantiated, constructor required.
	"/wd4611", # C++ object destruction and 'catch'.
	"/wd4701", # Potentially uninitialized local variable name used.
	"/wd4702", # Unreachable code.
	"/wd4706", # Assignment within conditional expression.
	"/wd4819", # Character not in the current code page.
	]
	} else {
	# Common GCC warning setup.
	cflags = [
	# Enables.
	"-Wendif-labels", # Weird old-style text after an #endif.

	# Disables.
	"-Wno-missing-field-initializers", # "struct foo f = {0};"
	"-Wno-unused-parameter", # Unused function parameters.
	]

	if (is_mac) {
	cflags += [
	"-Wnewline-eof",
	]
	}

	# TODO(brettw) Ones below here should be clang-only when we have a flag
	# for it.
	if (is_clang) {
	cflags += [
	"-Wheader-hygiene",

	# 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",

	# Don't die on dtoa code that uses a char as an array index.
	# This is required solely for base/third_party/dmg_fp/dtoa.cc.
	# TODO(brettw) move this to that project then!
	"-Wno-char-subscripts",

	# 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",

	# Clang considers the `register` keyword as deprecated, but e.g.
	# code generated by flex (used in angle) contains that keyword.
	# http://crbug.com/255186
	"-Wno-deprecated-register",

	# Clang spots more unused functions.
	"-Wno-unused-function",

	# Warns when a const char[] is converted to bool.
	"-Wstring-conversion",
	]
	}

	if (is_android) {
	# Disable any additional warnings enabled by the Android build system but
	# which chromium does not build cleanly with (when treating warning as
	# errors).
	cflags += [
	"-Wno-extra",
	"-Wno-ignored-qualifiers",
	"-Wno-type-limits",
	]
	cflags_cc = [
	# Disabling c++0x-compat should be handled in WebKit, but
	# this currently doesn't work because gcc_version is not set
	# correctly when building with the Android build system.
	# TODO(torne): Fix this in WebKit.
	"-Wno-error=c++0x-compat",
	# Other things unrelated to -Wextra:
	"-Wno-non-virtual-dtor",
	"-Wno-sign-promo",
	]
	}
	}
	}

	# This will generate warnings when using Clang if code generates exit-time
	# destructors, which will slow down closing the program.
	# TODO(thakis): Make this a blacklist instead, http://crbug.com/101600
	config("wexit_time_destructors") {
	if (is_clang) {
	cflags = [ "-Wexit-time-destructors" ]
	}
	}

	# Optimization -----------------------------------------------------------------
	#
	# Note that BUILDCONFIG.gn sets up a variable "default_optimization_config"
	# which it will assign to the config it implicitly applies to every target. If
	# you want to override the optimization level for your target, remove this
	# config (which will expand differently for debug or release builds), and then
	# add back the one you want to override it with:
	#
	# configs -= default_optimization_config
	# configs += [ "//build/config/compiler/optimize_max" ]

	# Default "optimization on" config. On Windows, this favors size over speed.
	#
	# IF YOU CHANGE THIS also consider whether optimize_max should be updated.
	config("optimize") {
	if (is_win) {
	cflags = [
	"/O2",
	"/Ob2", # Both explicit and auto inlining.
	"/Oy-", # Disable omitting frame pointers, must be after /O2.
	"/Os", # Favor size over speed.
	]
	} else {
	if (is_ios) {
	cflags = [ "-Os" ]
	} else {
	cflags = [ "-O2" ]
	}
	}
	}

	# Turn off optimizations.
	config("no_optimize") {
	if (is_win) {
	cflags = [
	"/Od", # Disable optimization.
	"/Ob0", # Disable all inlining (on by default).
	"/RTC1", # Runtime checks for stack frame and uninitialized variables.
	]
	} else {
	cflags = [ "-O0" ]
	}
	}

	# On Windows, turns up the optimization level. This implies whole program
	# optimization and link-time code generation which is very expensive and should
	# be used sparingly. For non-Windows, this is the same as "optimize".
	config("optimize_max") {
	if (is_win) {
	cflags = [
	"/O2",
	"/Ob2", # Both explicit and auto inlining.
	"/Oy-", # Disable omitting frame pointers, must be after /O2.
	"/Ot", # Favor speed over size.
	"/GL", # Whole program optimization.
	]
	} else {
	if (is_ios) {
	cflags = [ "-Os" ]
	} else {
	cflags = [ "-O2" ]
	}
	}
	}

	# Symbols ----------------------------------------------------------------------

	# TODO(brettw) Since this sets ldflags on Windows which is inherited across
	# static library boundaries, if you want to remove the default symbol config
	# and set a different one on a target, you also have to do it for all static
	# libraries that go into that target, which is messed up. Either we need a
	# more flexible system for defining linker flags, or we need to separate this
	# out into a "symbols_linker" config that is only applied to DLLs and EXEs.
	config("symbols") {
	if (is_win) {
	cflags = [ "/Zi" ] # Produce PDB file, no edit and continue.
	ldflags = [ "/DEBUG" ]
	} else {
	cflags = [ "-g2" ]
	}
	}

	config("minimal_symbols") {
	if (is_win) {
	# Linker symbols for backtraces only.
	ldflags = [ "/DEBUG" ]
	} else {
	cflags = [ "-g1" ]
	}
	}

	config("no_symbols") {
	if (!is_win) {
	cflags = [ "-g0" ]
	}
	}