# Copyright 2017 The Chromium Authors
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
import("//build/config/sanitizers/sanitizers.gni")
import("//build_overrides/build.gni")
declare_args() {
# Use in-tree libc++ (buildtools/third_party/libc++ and
# buildtools/third_party/libc++abi) instead of the system C++ library for C++
# standard library support.
# Don't check in changes that set this to false for more platforms; doing so
# is not supported.
use_custom_libcxx = is_fuchsia || is_android || is_apple || is_linux ||
is_chromeos || (is_win && is_clang)
# Use libc++ instead of stdlibc++ when using the host_cpu toolchain, even if
# use_custom_libcxx is false. This is useful for cross-compiles where a custom
# toolchain for the target_cpu has been set as the default toolchain, but
# use_custom_libcxx should still be true when building for the host. The
# expected usage is to set use_custom_libcxx=false and
# use_custom_libcxx_for_host=true in the passed in buildargs.
use_custom_libcxx_for_host = false
# Builds libcxx Natvis into the symbols for type visualization.
# Set to false to workaround http://crbug.com/966676 and
# http://crbug.com/966687.
libcxx_natvis_include = true
# When set, enables libc++ debug mode with iterator debugging.
#
# Iterator debugging is generally useful for catching bugs. But it can
# introduce extra locking to check the state of an iterator against the state
# of the current object. For iterator- and thread-heavy code, this can
# significantly slow execution - two orders of magnitude slowdown has been
# seen (crbug.com/903553) and iterator debugging also slows builds by making
# generation of snapshot_blob.bin take ~40-60 s longer. Therefore this
# defaults to off.
enable_iterator_debugging = false
}
use_custom_libcxx =
use_custom_libcxx || (use_custom_libcxx_for_host && !is_a_target_toolchain)
use_custom_libcxx = use_custom_libcxx && !is_nacl
declare_args() {
# WARNING: Setting this to a non-default value is highly discouraged.
# If true, libc++ will be built as a shared library; otherwise libc++ will be
# linked statically. Setting this to something other than the default is
# unsupported and can be broken by libc++ rolls. Note that if this is set to
# true, you must also set libcxx_abi_unstable=false, which is bad for
# performance and memory use.
libcxx_is_shared = use_custom_libcxx && is_component_build
}
# TODO(https://crbug.com/1385662): This is temporarily guarded to make it easier
# to roll out this change. Once the various projects (ANGLE, v8, et cetera)
# rolling in Chrome's //build have updated, remove this entirely.
if (!defined(enable_safe_libcxx)) {
enable_safe_libcxx = true
}
# libc++abi needs to be exported from executables to be picked up by shared
# libraries on certain instrumented builds.
export_libcxxabi_from_executables =
use_custom_libcxx && !is_apple && !is_win && !is_component_build &&
(is_asan || is_ubsan_vptr)
# On Android, many shared libraries get loaded from the context of a JRE. In
# this case, there's no "main executable" to export libc++abi from. We could
# export libc++abi from each "toplevel" shared library instead, but that would
# require adding an explicit dependency for each one, and might introduce
# subtle, hard-to-fix problems down the line if the dependency is missing.
#
# export_libcxxabi_from_executables was added to avoid having an RPATH set in
# static sanitizer builds just for executables to find libc++. But on Android,
# the Bionic dynamic loader doesn't even look at RPATH; instead, LD_LIBRARY_PATH
# is set for tests. Because of this, we make libc++ a shared library on android
# since it should get loaded properly.
if (is_android && export_libcxxabi_from_executables) {
export_libcxxabi_from_executables = false
libcxx_is_shared = true
}
libcxx_prefix = "//buildtools/third_party/libc++/trunk"
libcxxabi_prefix = "//buildtools/third_party/libc++abi/trunk"
assert(!(is_ios && libcxx_is_shared),
"Can't build libc++ as a shared library on iOS.")