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# Copyright 2021 The Chromium Project. 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/chrome_build.gni")
import("//build/config/compiler/compiler.gni")
import("//build/toolchain/toolchain.gni")
if (is_android) {
import("//build/config/android/config.gni")
}
declare_args() {
# Whether to allow Rust code to be part of the Chromium *build process*.
# This can be used to create Rust test binaries, even if the flag below
# is false.
enable_rust = false
# Whether to allow Rust code to contribute to the main Chromium binaries.
enable_rust_in_chromium = false
# Use unverified, untrusted, Rust toolchains from the internet
# (which support more platforms and options than those we trust for real
# builds).
use_unverified_rust_toolchain = false
# If using an unverified Rust toolchain, use this prefix for where to find
# the binaries.
rust_bin_dir = ""
# Use LTO when using rustc to link binaries. Experimental. Currently incompatible
# with the options we use in our C++ toolchain to split LTO units.
# This has no effect on the production of normal Chrome binaries, which are
# linked by clang/lld rather than rustc.
use_lto_in_rustc_linking = false
# Use goma for Rust builds. Experimental. The only known problem is
# b/193072381, but then again, we don't expect a build speedup before much
# more work is done.
use_goma_rust = false
}
# Rust code may end up being linked into a final executable by:
# * rustc (which calls lld)
# * our pre-existing C++ linker invocations
# At the moment, this first pipeline is incompatible with the ldflags we use
# for thin LTO, due to some problem in escaping gn rules. There's a further
# problem with -lunwind on Android.
# However, Rust code is still useful if it's contributing to our existing
# C++ linker invocations, so this doesn't disable Rust entirely. It does
# disable Rust unit test executables, so we do need to fix this.
rustc_can_link = !use_thin_lto && !is_android
# Has a Rust toolchain available in the build by default.
toolchain_has_official_rust =
(!is_nacl &&
(is_android && (target_cpu == "arm" || target_cpu == "arm64" ||
target_cpu == "x64" || target_cpu == "x86"))) ||
(is_linux && target_cpu == "x64")
toolchain_has_rust = enable_rust && (toolchain_has_official_rust ||
use_unverified_rust_toolchain)
# We use the Rust linker for building test executables, so we only build them
# if we're able to use the Rust linker. We could use the C++ linker for this
# too, we've just not set up GN to do so at the moment.
build_rust_unit_tests = rustc_can_link
if (use_unverified_rust_toolchain) {
assert(rust_bin_dir != "")
rust_prefix = "$rust_bin_dir/"
} else if (toolchain_has_official_rust) {
if (host_os != "linux") {
# assert(false,
# "Attempt to use standard Rust toolchain on an unsupported platform")
}
rust_prefix =
rebase_path("//third_party/android_rust_toolchain/toolchain/1.54.0/bin/")
}
assert(!toolchain_has_rust || defined(rust_prefix))
# Figure out the Rust target triple (aka 'rust_abi_target')
#
# This is here rather than in the toolchain files because it's used
# also by //build/rust/std to find the Rust standard library.
#
# The list of architectures supported by Rust is here:
# Although most of these are not yet supported by our limited
# official Rust toolchain (see 'toolchain_has_official_rust' above)
# it's useful to be able to experiment with our other platforms,
# so we try to be comprehensive here.
#
# It's OK if rust_abi_target is blank. That means we're building for the host
# and the host stdlib will be used.
rust_abi_target = ""
if (is_android) {
import("//build/config/android/abi.gni")
rust_abi_target = android_abi_target
if (rust_abi_target == "arm-linux-androideabi") {
# Android clang target specifications mostly match Rust, but this
# is an exception
rust_abi_target = "armv7-linux-androideabi"
}
} else if (is_fuchsia) {
if (target_cpu == "arm64") {
rust_abi_target = "aarch64-fuchsia"
} else if (target_cpu == "x64") {
rust_abi_target = "x86_64-fuchsia"
} else {
assert(false, "Architecture not supported")
}
} else if (is_ios) {
if (target_cpu == "arm64") {
rust_abi_target = "aarch64-apple-ios"
} else if (target_cpu == "arm") {
# There's also an armv7s-apple-ios, which targets a more recent ARMv7
# generation CPU found in later iPhones. We'll go with the older one for
# maximal compatibility. As we come to support all the different platforms
# with Rust, we might want to be more precise here.
rust_abi_target = "armv7-apple-ios"
} else if (target_cpu == "x64") {
rust_abi_target = "x86_64-apple-ios"
} else if (target_cpu == "x86") {
rust_abi_target = "i386-apple-ios"
} else {
assert(false, "Architecture not supported")
}
}
# Arguments for Rust invocation.
# This is common between gcc/clang, Mac and Windows toolchains so specify once,
# here. This is not the complete command-line: toolchains should add -o
# and probably --emit arguments too.
rustc_common_args = "--crate-name {{crate_name}} {{source}} --crate-type {{crate_type}} {{rustflags}} {{rustdeps}} {{externs}}"