path: root/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")
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).
      "/FS",  # Preserve previous PDB behavior.
    ]
  } 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",
        ]
        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" ]
  }
}